Note that all these links are external and we cannot provide support on the circuits or offer any guarantees to their accuracy. Also note that some of the circuits are illegal to operate in most countries, please check your local regulatory bodies if concerned. Other circuits are dangerous to construct and should not be attempted by the inexperienced.

NEW - CLICK HERE TO LINK YOUR OWN CIRCUITS OR OTHER SITES

Total schematics: 2657
Last updated: 29-June-2009

Alarms and security related schematics

• Easy to build tripwire activated alarm
  
• Fridge door Alarm
  
• Emergency Light & Alarm
  
• Door Alarm circuit diagram
  
• Everything-that-moves alarm works by inducing eddy currents in living beings
  
• Electronic locker digital combination lock circuit diagram
  
• Gate alarm
  
• 5 Zone Alarm System
  
• Miniature Loop Alarm
  
• Modular Burglar Alarm
  
• Water Activated Alarm
  
• Enhanced 5 Digit Alarm Keypad
  
• Enhanced 4 Digit Alarm Keypad
  
• Automatic Intruder Alarm
  
• Single Zone CMOS Alarm
  
• Travel Touch Alarm
  
• Water Level Indicator with alarm
  
• Fire alarm circuit diagram based on LDR (light-dependent resistor)
  
• Sun - Up Alarm
  
• Doorbell for the Deaf
  
• Electronic door codelock (PIC16F84)
  
• Ultrasonic remote control & alarm system
  
• Wire loop alarm
  
• MC68HC908-based wireless monitoring system is adaptable for use in domestic and industrial settings
  
• Transistor based single zone intruder alarm
  
• CMOS single zone intruder alarm
  
• Automatic Intruder Alarm
  
• Door knob alarm (PDF)
  
• Water seepage alarm (PDF)
  
• Micro-power over temperature alarm (PDF)
  
• Frost alarm
  
• Ultrasonic radar alarm
  
• Refrigerator door alarm
  
• Emergency Light & Alarm
  
• iButton electronic lock (Dallas DS1990A)
  
• Electronic combination lock
  
• Proximity detector for humans / living creatures using eddy current detection
  
• Constructing your own Light Alarm
  
• 5 Zone Alarm Circuit
  
• A Basic RF Transmitter for PIR Sensors
  
• PIR motion detector
  
• Alarm system
  
• Simple alarm system
  
• Multi-zone burglar alarm
  
• Ultrasonic Radar Alarm Circuit Diagram
  
• Home security project
  
• 5 Zone alarm circuit
  
• Miniature loop alarm
  
• Novel Buzzer
  
• Gate alarm circuit
  
• Modular Burglar Alarm
  
• Motorcycle alarm
  
• Enhanced 5 Digit Alarm Keypad
  
• Enhanced 4 Digit Alarm Keypad
  
• RF Alarm
  
• Single Zone Alarm
  
• Water Activated Alarm
  
• Water level alarm
  
• Perimeter monitor
  
• Cold activated switch (frost alarm)
  
• Digital combination lock
  
• Alarm control keypad
  
• Wireless alarm system based around Nutchip microcontroller
  
• Smartcard controlled relay circuit based around Nutchip microcontroller
  
• RF Pad - combination-controlled, fully customizable radio frequency remote control
  
• 2-input alarm
  
• Refrigerator Door Alarm
  
• Rain alarm / rain detector
  
• Touch activated alarm system
  
• Waterpump Safety Guard for fish pond / fish tank
  
• Wailing alarm siren
  
• Combination Lock (PIC16F84)
  

Audio power amplifier schematics

• LM380 2.5 watt audio amplifier circuit
  
• Stereo audio amplifier based on TDA2822M
  
• Miniature audio amplifier
  
• DPA 220 amplifier schematic
  
• Low impedance microphone amplifier
  
• DPA 440 amplifier schematic
  
• Quadraphonic Amplifier based on pair of LM1877 devices
  
• DPA 880 amplifier schematic
  
• Class-A/AB Amplifier delivering 100W into a 4 ohm load
  
• 25 Watt MOSFET Audio Amplifier using IRF532 / IRF9532 hexfet transistors for output stage
  
• Easy to build DIY 50W amplifier based on ICL8063
  
• 20 Watt Audio Power Amplifier
  
• 22 Watt Stereo Amplifier using TDA1554
  
• Two Transistors Audio Amplifier
  
• 10 Watt Audio Amplifier
  
• 300W Subwoofer Power Amplifier
  
• Audio amplifier with squelsh-control
  
• Class-C power amplifier
  
• Ampliefied speaker, built for MP3 player but can be used with other headphone only devices (PDF)
  
• Simple class-D amplifier based on 555 pulse width modulator
  
• Headphone practice amplifier
  
• CMoy pocket headphone amplifier
  
• 4W amplifier
  
• Headphone amplifier based on 12AX7 tubes
  
• 8 watt audio amp
  
• 22W Audio Amplifier
  
• 50W Amplifier
  
• Super linear Headphone amplifier
  
• 150W audio amplifier that's cheap to build using TIP142 / TIP147 Darlington power transistors
  
• Tube amplifier
  
• 100W RMS Amplifier
  
• Voice Amplifier
  
• 25W MOSFET audio amplifier
  
• 50W audio amplifier using ICL8063
  
• Amplified ear for surveillance
  
• Push-Pull Class A Amp using type 5687 dual triodes
  
• Push-Pull Class A 2A3 Stereo Amp
  
• Single Ended Class A2 SV811-10 Stereo Amp
  
• Compact 50W Integrated Amplifier with Meier Headphone Section
  
• Audio amplifier output relay delay
  
• Spatial Distortion Reduction Headphone Amp
  
• 4 channel power amplifier with bi-amping and bridging options
  
• Amplifier based on LM4780 including a thermal shutdown feature
  
• HeadBanger Headphone Amp
  
• 2W Audio Amplifier using BD139 and BD140 transistors
  
• TDA2030 8 Watt amplifier
  
• Headphone monitor amp
  
• 50W audio power amplifier
  
• Low Power Audio Amp Experiments
  
• More Discrete BJT, Low Power AF Amp Experiments
  
• High quality exponential VCA
  
• Selection of Integrated Circuit Audio Amplifiers
  
• Potpourri of Transistor Audio Amplifier Circuits
  
• 16 Watt amplifier
  
• 8 Watt amplifier
  
• Speech Amplifier Box
  
• Mini-MosFet Audio Amplifier
  
• Build a good Audio Buffer Amplifier
  
• 20 Watt Class-A Power Amplifier
  
• El-Cheapo - A Really Simple Power Amplifier
  
• Single Chip 50 Watt / 8 Ohm Power Amplifier
  
• Hi-Fi Headphone Amplifier
  
• 100W Guitar Amplifier
  
• Death of Zen (DoZ) - A New Class-A Power Amp
  
• Soft-Start Circuit For Power Amps
  
• Thermo-Fan To Keep Your Amp Cool
  
• Audio Amp Output Power Limiter
  
• 300W Subwoofer Power Amplifier
  
• 20 Watt / Channel Stereo Power Amplifier
  
• Mini bench amplifier (LM386)
  
• Small bench amplifier ideal for testing audio stages in circuits
  
• Five Tube Stereo Amplifier
  
• 13.5 Watt Power Amplifier using a TL081 opamp and TIP125 / TIP120 power transistors
  

Audio preamp circuits

• Bat detector microphone pre-amplifiers
  
• Low impedance microphone amplifier
  
• Ultra-Simple Guitar Preamp
  
• High quality audio preamplifier (OPA2134)
  
• Basic low frequency preamplifier circuits
  
• Microphone pre-amp with high emphasis
  
• Microphone preamp for portable transceivers
  
• Masthead preamp
  
• Intercom preamp
  
• Simple microphone preamplifier
  
• Tube microphone preamp
  
• Simple Stereo Electret Microphone Preamplifier
  
• Phono Preamp
  
• Simple microphone preamplifier
  
• Hi-Fi Preamp with remote-control and other advanced features
  
• ECM Mic preamp
  
• Hi Fi preamp
  
• Balanced microphone preamp
  
• Electret mic amplifier
  
• Audio preamplifier
  
• Vacuum Tube Microphone Preamp
  
• FET Preamp Cable
  
• Altec 1564A Preamp Power Supply
  
• Neumann U67 microphone preamp power supply
  
• Audio preamp
  
• Altec 428B Microphone Preamplifier schematic
  
• API 321 mic preamp schematic
  
• RCA BA-1A two-stage preamp schematic
  
• RCA BA-21A preamplifier schematic
  
• RCA BA-31A preamplifier schematic
  

Automative, car and motorcycle schematics

• 12V battery level indicator for car batteries
  
• Car burglar alarm circuit
  
• Flashing light / emergency beacon for vehicle
  
• Headlight guard
  
• Interior light extender
  
• Seatbelt reminder circuit
  
• Two LED trouble light system
  
• Car power supply unit for digital projects, small car PCs etc
  
• Large capacitor charge "controllers" (Car Audio)
  
• Brakelight Flasher
  
• Adaptive Windscreen Wiper Control
  
• Car OBDII diagnostic interface cable schematic pinout
  
• Car OBD II J1850 PWM, J1850 VPW, ISO-9141 cables schematic pinout
  
• Grand Cherokee Off-Highway Lights
  
• Engine control unit schematics
  
• Portable CD Player Adapter For Car
  
• Car battery charger
  
• Wireless Auto Tachometer
  
• Car acceleration meter
  
• Hijack alarm
  
• KITT (from Knight Rider) Car scanner using incandescant lamps
  
• Headlight reminder
  
• Wiper Speed Control
  
• Simple car battery charger
  
• Flashing / pulsing third brake like for cars
  
• Headlight flasher
  
• Speed alert - wireless portable unit
  
• Parking aid senses distance to rear of vehicle
  
• Automatic headlight brightness switch
  
• Car battery charger circuit
  
• Electronic car ignition circuit
  
• Car battery voltage tester using LM3914
  
• Synchronized multi-spark module (SMSM) for Electronic Ignition Devices (EID)
  
• Economy radar detector
  
• Headlight timer
  
• Parking sonar
  
• Fuel injector pulse width monitor
  
• BMW R Series Motorcycle Regulator Schematic
  
• Authentic Looking Knight Rider Led Project
  
• Custom USB tyre pressure monitoring system
  
• 80188XL Engine Tachometer / Race Computer
  
• Opendiag OBD-II Schematics & PCB Layout Opendiag OBD-II Schematics & PCB Layout
  
• Ultrasonic parking sonar electronic circuit diagram using transistors and 4000 series CMOS
  
• Common Ground for Older VPW OBD Circuit
  
• Simple Car Preamplifier and Artificial Earth
  
• Breakdown safety beacon
  
• FCD (Fuel Cut Defencer)
  
• Interface between GM's 5 Volt 8192 baud ALDL data stream and a PC serial port
  
• 5301 wideband fuel mixture display
  
• Wide Band Fuel Mixture Display
  
• 3rd brake light
  
• Car backup / reversing alarm
  
• 12V to 9V car coverter
  
• Third brake light pulser circuit
  
• Motorcycle battery charger
  
• Motorcycle low battery voltage warning circuit
  
• Motorcycle brake light flasher
  
• Motorctcle turning signal system
  
• Car Nicad charger
  
• Combination lock for car liftgate
  
• Car Timer with Atmel ATiny45 to automatically turn of accessories to prevent flat battery
  
• Simple car battery voltage monitor
  
• Car Battery Charger, an SCR Design with a 10 Amp rating
  
• 3 Channel, 12 Volt Color Organ for a car
  
• Simple Vehicle Loop Detector (inductive loop for driveway etc)
  

Data acquisition (DAQ) and data logging schematics

• Data Acquisition & Logging System Using AT89c51 and Visual Basic
  
• Data Acquisition System using ATmega8
  
• Simple RS422 Converter for Minilogger
  
• Simple device for connecting serial instrument with RS485 or RS232 to the internet
  
• USB datalogger - simple-to-use, long-term measurement solution
  
• Acceleration Sensor Network
  
• 8 Photo-Detector Circuit Board
  
• Self made data-logger V2.5 (second edition)
  
• XL-DIG 3-axis Accelerometer board - 3-axis digital I2C/SPI accelerometer board
  
• Analog input section based on AD9220
  
• Universal flight controllers / datalogger (PDF)
  
• Rain detector
  
• Home Brew Compass Sensor
  
• Connect a NTC with a wheatstone bridge to a normal AD-Input
  
• Making an LM35 temperature recorder (based on PIC12F675) - logs to EEPROM
  
• Making an LM35 temperature recorder (based on PIC12F675) - serial output
  
• Accelerometer with microcontroller and display
  
• Using a 555 Timer as an A/D converter
  
• Honey Bee counter (PDF)
  
• Capacitance type liquid level measurement (PDF)
  
• A PIC Based Temperature Data Logger
  
• Transducer Amplifiers
  
• Thermostat node schematic
  
• Ultrasonic Range Finder & Imager
  
• Precision Digital Altimeter
  
• Remote digital thermometer sends data over AC power line
  
• Voltage follower with 1G ohm input resistance
  
• Strain gauge sensor interface
  
• Temperature datalogger
  
• Serial Port A/D-converter
  
• Centronics port D/A converters and low-pass filter
  
• LCD Thermometer
  
• Wireless Liquid Level Sensing for Restaurant Applications
  
• 4 Bit Digitizer / flash ADC using discrete components
  
• Accelerometer Schematic
  
• Pressure Sensor-Based Altimeter Circuit
  
• Ultrasonic range finder circuit
  
• 1-Wire Barometer Project
  
• Water-level sensor
  
• Addressable ADC
  
• ADXL202 break-out board
  
• Wireless weater station
  
• ADC logger 6ch Measurent and serial port logger with wireless longrange link
  
• Atmel Mega32 8ch Analog signal measure logger
  

Filter schematics

• Filters for the RadioJove Receiver
  
• Galaxy Noise Filter
  
• Low pass filter for subwoofer
  
• Low-pass active filter
  
• Filter Circuit for the Earthworm Seismic Data Acquisition System
  
• 45 to 90Hz hum filter
  
• Active 2nd Order Filters
  
• RC Notch Filter (Twin T)
  
• 'A' Weighting Filter For Audio Measurements
  
• Multiple Feedback Bandpass Filter
  
• Active bandpass filter with TDA2320A
  
• CW filters
  
• Self-tune filter
  
• SSB AF filter
  
• CW Filters
  
• Self-tuning CW filter
  
• SSB AF filter
  
• 136KHz bridged-T notch filter to reduce strength of the German utility station DCF39 on 138.83 kHz
  
• Matching Low Pass Filter for 136kHz transmitter
  
• 3KHz low-pass filter plus audio amp (PDF)
  
• Active bandpass filters
  
• Bandpass filters
  
• Narrow band audio bandpass filter
  
• Bandpass and IF Filter Circuits
  
• Discrete Component Audio-Frequency RC Filters
  
• 440 Hertz Peaked Low Pass Audio Filter Experiments
  
• Chebyshev / Butterworth filters
  
• Biquad Active Bandpass Filter Schematic
  
• "A" Weighting Filter For Audio Measurements
  
• Multiple Feedback Bandpass Filter
  
• Digital signal processor (DSP) for radio communications
  
• 29.85 MHZ bandpass filter schematic
  
• 29.85 MHZ notch filter schematic
  
• Variable notch filter with both high and low pass filters
  
• LC filter design
  

Games and fun stuff (electronic schematics)

• Visor cradle serial interface
  
• Decision maker
  
• 3-up decision maker
  
• LED dice with fast roll
  
• LED dice using PIC16F88
  
• Two player quiz master game
  
• VCR ping pong game
  
• Video ping pong game
  
• Dual LED dice (available in kit form)
  
• Single LED dice kit circuit diagram
  
• MBC5/CPLD for the GameBoy
  
• Dreamcast PC serial adapter
  
• How to use a SCART TV as a Monitor for MAME arcade game emulator
  
• LED dice project based on 555 timer and CD4017 decade counter
  
• SRX1 (Stephane's Robotic eXperiment 1)
  
• Pine Racecar Victory Judge
  
• Interfacing Sony control stick to Empeg
  
• Electronic Nicad glow plug driver
  
• Multi-User Jeopardy Game (Fastest Finger First)
  
• LED Dice implemented with a PIC microprocessor
  
• Quiz show indicator
  
• Dreamcast interface
  
• JAM(Just A Minute) Quiz Game Circuit
  
• Electronic Astrologer (decision maker)
  
• Electronic dice
  
• Reflex Action Game
  
• Flashing heart
  
• Bingo!!! (on your tv)
  
• Slot car TV cronograph
  
• Furby reverse-engineered circuit
  
• Judge Dredd pinball locking ring modification
  
• Burger Time Arcade Game circuit diagram (PDF)
  
• Dig Dug Arcade Game (800k ZIP)
  
• Frogger Arcade Game circuit diagram (PDF)
  
• Galaga Arcade Game circuit diagram (PDF)
  
• Gyrus Arcade Game circuit diagram (PDF)
  
• Junior Pacman Arcade Game circuit diagram (PDF)
  
• Ladybug Arcade Game circuit diagram (PDF)
  
• Mappy Arcade Game circuit diagram (PDF)
  
• Moon Cresta Arcade circuit diagram (PDF)
  
• Mr.Do Arcade Game circuit diagram (PDF)
  
• Pengo Arcade Game circuit diagram (PDF)
  
• PacLand Arcade Game circuit diagram (PDF)
  
• Q*Bert Arcade Game circuit diagram (PDF)
  
• Qix Arcade Game circuit diagram (PDF)
  
• Scramble Arcade Game circuit diagram (PDF)
  
• Time Pilot'84 Arcade Game circuit diagram (PDF)
  
• Xevious Arcade Game circuit diagram (PDF)
  
• LED dice project including nice veroboard layout (PDF)
  
• Magic Wand Conjuring Trick
  
• Quiz game circuit
  
• E.S.P. Conjuring Trick
  
• Repairing & Upgrading Gottlieb System 80 Pinballs from 1980 to 1989
  
• Space invaders game using PIC microcontroller
  
• Low-cost bingo game for a TV based on an Atmel microcontoller
  
• Virtual Game System - A game console with a mechanically scanned display
  
• PIC10F200-based electronic dice
  
• PIC16F84-based video game system
  
• SX28-based color video game system
  
• DIY shutterglasses controller
  
• Hangman game
  
• LED dice with slow down tumbling action
  
• LED Zeppelin game of skill and patience
  
• Lotto number selector helps you win a fortune
  
• Simon Says memory game using a PIC16F84A or PIC16F628 microcontroller
  
• Spin the device educational project based on PIC12F629 microcontroller
  
• Tic Tac Toe game based on Microchip PIC16F628 microcontroller
  
• Game Show Timers
  
• Archery timer
  
• Coin tosser
  
• Battery Meter for Pinball Machines
  
• Lego Mindstoms IR Link PIC transceiver
  
• Lego Mindstorms Double Rotation Sensor
  

Infrared based schematics

• IR detector
  
• Infrared beam door alarm
  
• IR wheel encoder board
  
• Simple Infa-Red Remote Control
  
• IR Remote Control Extender Circuit
  
• TV remote control Blocker
  
• Wireless IR headphone transmitter
  
• Wireless IR headphone receiver
  
• IR illuminator for night-vision tv cameras and scopes
  
• 50MHz Transmitter for the IR detector
  
• 50MHz Receiver for the IR Detector
  
• Infrared Proximity Detector based on Vishay TSOP4830
  
• Infrared Receiver Module Schematics
  
• Infrared transmitter for locomotives
  
• Infrared gate for door
  
• Infrared circuits for remote control
  
• Serial port controller infrared transmitter (PIC16F628)
  
• Digibox interface
  
• IR remote control
  
• Universal Serial Infrared Receiver
  
• Inexpensive infrared reflectometer
  
• 40KHz light receiver (PDF)
  
• 40KHz TV-VCR repeater (PDF)
  
• Micro based PIR to IR remote converter
  
• IR-related ASCII Schematics V1.00
  
• Infrared remote transponder
  
• Build an Infrared night scope
  
• Decoding IR Remote Controls
  
• IR detector
  
• PC IR Remote Control Hardware
  
• Infrared beam barrier / proximity detector
  
• Simple on-off IR photoswitch without use of comparators
  
• Infrared gate (door entry alarm)
  
• Infrared switch using any infrared remote control
  
• Improved infrared receiver for PC with status LED
  
• Infrared link for 10-BASE-T / 100-BASE-T PC network card
  
• iRDA transceiver to extend IR port range up to 15 meters
  
• Infrared level detector for liquid level detection and proximity detection
  
• IR remote control tester
  
• Infrared Transmitter and Receiver schematic diagrams
  
• Direction sensing infrared motion detector using PIR (PDF)
  
• Infrared Motion Detector using a PIR sensor (PDF)
  
• Pyroelectric Infrared (PIR) Sensor
  
• Simple IR transmitter circuit
  
• Simple infra-red detector
  
• Infra Red Switch
  
• IR remote control extender
  
• IR Remote Control Extender Circuit (Mark 2)
  
• IR Remote Control Extender Circuit (Mark 3)
  
• Infra Red wired Repeater circuit to control appliances from a remote location
  
• IR Link
  
• IR remote control tester
  
• Infrared lamp
  
• 40khz IR Tester
  
• 555 timer 40khz IR Oscillator
  
• IR detector / emitter
  
• Fire-Stick infrared remote control
  
• Simple infrared remote control
  
• Infrared / Ultrasonic beacon
  
• DVD thermometer - display temperature on TV by remotely controlling DVD player by infrared
  
• Implementing Infrared Object Detection
  
• Remote control uses an IR receiver chip to receive the IR signal from the remote
  
• Computerized Infrared Remote
  

Laser related power supplies and data transmission

• Laser link communicator project from Electronics Australia magazine
  
• Home Built Laser Projector
  
• Simple LASER Transmitter/Receiver using HeNe laser tube
  
• LASER Transmitter/Receiver using Pulse Width Modulator (PWM) for 12V / 24V applications
  
• Circuit for temperature stabilisation of laser diodes
  
• Low Cost Scanning Laser Rangefinder (PDF)
  
• Sniper tag laser beam detector
  
• Heathkit modulated HeNe laser power supply kit (HK-HI1)
  
• Diode laser electronic circuits for atom optics
  
• Circuit to measure speed of light with nanosecond pulsed 650 nm laser diode
  
• Laser high-voltage power supply
  
• Laser power supply
  
• Laser transmitter/receiver
  
• Laser light output intensity meter
  
• 20MHz VCSEL 3mW laser test circuit (PDF)
  
• 20MHz laser light detector (PDF)
  
• Micro-power 40KHz burst laser diode driver (PDF)
  
• 40KHz laser burst detector (PDF)
  
• Modulated laser diode tester (PDF)
  
• LASER/LED light output intensity meter (PDF)
  
• Laser range finder and reflectivity meter for the MARS-96 international space project (PDF)
  
• Ar/Kr Ion Laser Power Supply
  
• RS-232 Laser Transceiver
  
• RS-232 laser transceiver
  
• Digital radar speedometer - laser reflexion using discrete logic
  
• OPT301 Laser receiver
  
• HeNe laser power supply
  
• OPT201 Laser receiver
  
• OPT301 Laser receiver
  
• Laser transmitter schematics
  
• Rangefinder with Fast Multiple Range Capability
  
• Laser diode transmitter RF section
  
• Laser Diode Power Supplies
  
• Complete Helium Neon (HeNe) Laser Power Supply Schematics
  
• Home built 100kW nitrogen laser
  
• RS-232 Laser Transceiver
  
• Experimental laser data link
  
• Low noise PIN diode laser receiver circuit
  
• Circuits for biasing and modulating laser diodes
  
• Guide to Building a Homemade XY Scanner
  
• Laser Target Finder Sensor
  
• Micro-Laser range finder
  
• Simple laser communicator
  
• Real-time Laser Range Finding Vision System
  
• Laser beam alarm system
  
• Simple high current pulsed laser driver using an avalanche transistor
  

LED related schematics

• High power LED driver using LTC3780
  
• Single and Two Cell White LED Drivers Without Inductors
  
• Bicycle rear flashing LED light
  
• Little bike light using LEDs
  
• Big 7-segment LED display board with SPI interface
  
• Bicycle LED POV (persistence of vision display) LED display
  
• LED Chaser using 4011 / 4017 CMOS chips
  
• Fading LEDs
  
• Dancing LEDs
  
• LED Running Message Display using CD4017 with transistor drivers rather than a CPU
  
• Seven Component Regulated LED Lamp
  
• LED Mood Light
  
• 13 Color LED Rainbow
  
• 60 LED Clock
  
• LM3909 replacement using discrete components
  
• 10, 8 And 6 Step LED Circuits (CD4017)
  
• Using Common Cathode Or Anode LEDs As Bipolar LEDs
  
• Colour Shifting For Bi-Colour LED's
  
• Current Regulators For Light Emitting Diodes
  
• Incandescent LED Circuit
  
• Various LM555 LED Blinker Circuits
  
• Color fade
  
• LED Voltage Indicator Board
  
• LED color fade
  
• 1.5 Volt LED Flashers
  
• AC Line Powered LEDs
  
• Astable Multivibrator
  
• 9 Second Digital Readout Timer
  
• 9 Second LED Relay Timer
  
• 16 Stage Bi-Directional LED Sequencer, other sequencer and flaser circuits
  
• 10 Stage LED Sequencer
  
• 28 LED Clock Timer
  
• Fading Red Eyes
  
• Two Transistor LED Flasher
  
• 16 Stage Bi-Directional LED Sequencer
  
• Expandable 16 Stage LED Sequencer
  
• LED Photo Sensor Circuit
  
• Single cell LED flasher with two-year battery life (LM3909 replacement)
  
• Pocket Ignignokt LED display
  
• LED chaser
  
• 7 Segment LED Counter
  
• Scrolling LED sign based on Atmel ATtiny2313 AVR microcontrolle
  
• Driving led display matrix from a PIC micro
  
• White LED Drive Circuit
  
• Simplest LED Flasher Circuit using a 2N2222 transistor Simplest LED Flasher Circuit led
  
• 1.5V LED flasher B (PDF)
  
• Low current LED flasher (PDF)
  
• 1.5V LED flasher A (PDF)
  
• Flashing LED advertising badge (PDF)
  
• Flashing LED advertising badge (PDF)
  
• Pulsed LED test circuit (PDF)
  
• Low battery voltage flasher (PDF)
  
• Adjustable flashing LED
  
• Running Message Display
  
• Discrete LED Color Organ
  
• Knight rider scanning LED lights
  
• 3V LED chaser using 4017
  
• 6V ultra-bright LED chaser using 74HC4017
  
• Led display digital Voltmeter
  
• "Peggy" - A Light Emitting Pegboard Display
  
• Heart of LEDs
  
• Christmas Star
  
• Christmas tree
  
• LEDMATRIX, a 80x32 pixel DIY LED matrix display
  
• POV Persistence Of Vision 2 x 32 LED display
  
• LED Counter
  
• PIC16F84 LED chaser
  
• PIC16F84 LED signboard
  
• PIC16F84 LED signboard 2
  
• "Mini-Beacon" miniature programmable LED Flasher that is based around a PIC12F629 microcontroller
  
• PointLess LED Array - A 8 by 8 array displays something using POV
  
• A "persistence of vision display" (POV display) using LEDs
  
• White LED circuits
  
• Selecting of LED projects including a flashing Christmas tree
  
• Fun with LEDs - a variety of LED flahser projects
  
• Assorted LED circuits
  
• LED dimmer circuit
  
• AVR Color Clock using RGB LEDs
  
• Making an Amplified Color Sensor from an LED and an Op Amp
  
• 13 Color LED Rainbow
  
• Seven Component Regulated LED Lamp
  
• High Efficiency 12V White LED Driver
  
• LED Mood Light
  
• LED Audio VU Meter
  
• 5x7 Display
  
• Various LED flashers
  
• Kitt car scanning LED sequencer
  
• Robot beacon light display for mounting on top of a robot
  
• Sky writer - displays 'in air' messages and features inertia switch
  
• Animated LED signboard (PIC16C84)
  
• Picxie 2 - 8x8 Animated LED Signboard
  
• Digital Up / Down Counter with 7-segment display
  

Lighting and ligh controller schematics

• Electronic candle
  
• Night light saver using AT89C2051
  
• TRIAC Light Dimmer
  
• LEDs or Lamps Sequencer is versatile modular design with no limits on number of lights
  
• Battery-powered Night Lamp
  
• Courtesy Light
  
• Brightness Control for small Lamps
  
• 12VDC Fluorescent Lamp Driver
  
• Adjustable Strobe Light
  
• Black Light powered by a 6 volt battery
  
• Bicycle back Safety Light
  
• Flashy Christmas Lights
  
• Automatic Room Lights
  
• Bike Light Flasher
  
• Flashing neon christmas lights
  
• 220 Volts Flashing Lamps
  
• Strobo Disco Light Using Standard Tube Lamp (TL)
  
• Xenon Flash Indicator (XFI)
  
• DMX lighting and special effects
  
• 1200 Watt Lamp Dimmer Circuit using Q4015LT combination Diac
  
• Diode Type Constant Lighting Circuits
  
• Easy Xenon DC-DC Converter using LM386
  
• Varying Brightness AC Lamp
  
• 12 Volt Lamp Dimmer
  
• 120VAC Lamp Chaser Using Solid State Relays
  
• Flashing Neons (NE-51 / NE-2)
  
• Sequencing Neons (NE-51 / NE-2)
  
• Touch Activated Lamp
  
• Emergency light flasher schematic
  
• TRIAC light dimmer
  
• 12VDC Fluorescent Lamp Driver
  
• Strobe light
  
• Adjustable Strobe Light
  
• RHINO8 EL Sequencer
  
• 5W Fluorescent light intensity modulator (PDF)
  
• 1W Fluorescent lamp night light (PDF)
  
• Automatic Staircase Light 1
  
• Automatic Staircase Light 2
  
• Mini emergency light
  
• 6 Channel Auto Reverse Sequential Disco Running Lights
  
• Low-voltage light dimmer
  
• Light chaser
  
• Digi Pack DMX 512 lighting controller
  
• DMX PC keyboard interface
  
• 4-channel dimmer rack
  
• Fluorescent Tube "Strip light" Driver
  
• PIC16F873 light controller
  
• Digitally Addressable DALI Dimming Ballast (PDF)
  
• Disco light controller (ZIP file)
  
• Neon desklamp
  
• Electronic night light
  
• Neon lamp dimmer
  
• Automated crib light
  
• LED Mood Light
  
• LX-800 Lighting system
  
• Xenon Strobe Light
  
• 12V florescent light inverter
  
• 3 Xenone flashing circuits found in flash for disposable cameras
  
• 12V stroboscope
  
• Courtesy/Dome Light Delay
  
• Lightning bulb - Create an electrical storm in a light bulb
  
• Lamp flasher/dimmer
  
• Christmas lights tester
  

Medical and health related schematics

• Snore alarm electronic device
  
• EKG/EEG circuit
  
• Wireless Electrocardiogram Monitor
  
• Galvanic Skin Response (GSR) Circuit
  
• Tiny EEG interface schematic
  
• OpenEEG open hardware EEG project
  
• Heart Rate Monitor (HRM) Receiver Circuit
  
• Simple lie detector
  
• ECG Measurement and Analysis
  
• Cardiac monitor
  
• Digital pedometer circuit
  
• Jogging timer
  
• Tan timer to prevent sunburn
  
• Muscular Bio-Stimulator using 555 timer
  
• Muscular Bio-Stimulator
  
• Sleeping aid based on electromagnetic-field radiation
  
• Salt taster - detects the amount of salt contained in liquid foods
  
• Electronic Stethoscope
  
• Heartbeat transducer using infrared LED / detector
  
• ECG amplifier with right leg drive
  
• Optical Heart Rate Monitor
  
• Model 2030 XRAY monitor instruction manual including schematics (PDF)
  
• Brain-Wave Machine
  
• Cranial Electrotherapy Stimulation (CES) circuit diagram
  
• Lie detector
  
• Simple lie detector
  
• Portable blood pressure monitor
  
• PC based biofeedback monitor
  
• Heart rate sensor
  
• The ESP SIM (Sound Impairment Monitor)
  
• Stress meter educational project using PIC12F629 microcontroller
  

Microcontroller based schematics

• PIC based packet radio encoder (PDF)
  
• Simple CW Keyer based on Atmel ATtiny 2313
  
• AT89C2051/4051scanning 7-segment display and keypad
  
• AT89C2051/4051 Driving dot LED
  
• AT89C2051/4051stepper motor interface
  
• AT89C2051/4051connecting dumb terminal
  
• Motorola 68K SBC (single board computer)
  
• 8051 SBC (single board computer)
  
• 8051SBC V1.1
  
• Atmel 89 Series Device Programmer
  
• 89S52 Project Board
  
• Using the AT89C4051 as a RTC (real-time clock)
  
• Simple RS232C Level Converter using Transistors
  
• AVR Thermometer
  
• Motorola 68HC11 evaluation board
  
• C-52 EVB Robot Controller
  
• Mains clock controller using AT89C2051
  
• AT89C2051/4051 Easy-Downloader
  
• AT89C51/52/55 Easy-Downloader
  
• PIC16F84 programmer
  
• PIC16F84 miniature real-time controller
  
• Isolated RS232 for PIC16F84
  
• PIC16F84 debugging terminal
  
• MiniLOGGER V1.0
  
• Analog datalogger based on T89C51RD2
  
• MTK-85 8085 Microprocessor Training Kit
  
• Atmel 89C Series Flash Microcontroller Programmer
  
• In-Circuit PIC Loader (ISP programmer) over parallel port
  
• PIC18F2550 Project Board
  
• Atmel 89C2051 prototype board
  
• AT89C2051 real-time controller
  
• PIC12C508 Night-light saver
  
• AT89C2051 Night light saver
  
• Atmel 8051 Flash Based-Microcontroller Programmer
  
• SPI Flash Microcontroller Programmer
  
• AT89Sxx Cheap and Simple Learning Board
  
• AT89C2051 Digital thermometer and clock
  
• Tiny 2313 Project Development Board
  
• 4-Channel Timer using Atmel 89C4051 and MAX7219 display driver
  
• RS-232 to TTL Translator
  
• PIC16F84 CW decoder (PDF)
  
• Atmel ATmega128 development board
  
• Atmel AT90USB development board
  
• Atmel ATtiny26 development board
  
• TekBots universal device programmer with USB interface
  
• Serial LCD controller using a PIC16F628
  
• Several Atmel AVR programmer circuits
  
• PIC Light Chaser using PIC16C84
  
• ADC conversion using ADC0804LCN and 8051
  
• Multi PIC Programmer 5 Ver.2
  
• Ultrasonic Distance Measurement With the MSP430 (PDF)
  
• Basic Stamp based altimeter
  
• Interfacing EEPROM to a Basic Stamp
  
• Homebrew Basic Stamp project
  
• Interfacing the MAX186 8 Channel ADC to the BSII
  
• Interfacing the MAX187 ADC to the BSII to measure voltages
  
• RF remote control based on Basic Stamp
  
• 80C31 stepper motor controller
  
• (E)EProm, PIC and GAL Programmer
  
• Build a PIC controlled DDS VFO, 0 to 6 MHz
  
• Parallel AVR programmer
  
• AVR-Core V1.1 - DIP-like development board for ATmega128 processors (PDF)
  
• AVRlinx V1.1 - Development board for ATmega16, ATmega32 processors with data radio transceiver (PDF)
  
• AVRmini8 V1.0 - Development board for ATmega8, ATmega44, ATmega88, ATmega168 processors (PDF)
  
• AVRmini V2.0 - Development board for all AVR processors in 40-pin packages (PDF)
  
• AVRmini V3.1 - Development board supporting all AVR processors in 40-pin and 64-pin packages (PDF)
  
• AVRmini V4.0 - Development board with Ethernet/USB for 40-pin AVR processors (PDF)
  
• CF/IDE Adapter V1.0 - CompactFlash and IDE interface for your microcontroller
  
• USBmini V1.0 - Generic USB Full-speed interface board (PDF)
  
• PIC16F84 line following robot
  
• PIC16C505 IR / wireless remote control
  
• Automatic door opener with PIC12C508
  
• 3-wire serial LCD interface for the PIC
  
• RS485-like multi-drop bus with half duplex serial protocol
  
• LCD thermometer using PIC16F871
  
• Electronic irrigation controller based on PIC
  
• 50 MHz frequency counter, voltage meter & SWR/PWR indicator
  
• Serial LCD Controller using Microchip PIC16F628
  
• Programmer PIC16F84,12C50x and EEPROM 24Cxx
  
• PIC 18 programmer (PIC18F458, PIC18F452, PIC18C252, PIC16C745, PIC18F6620, PIC18F6720)
  
• Serial-based PIC16F84 Programmer For Windows 95/98/NT/2000/ME/XP
  
• LCD clock based on AVR Attiny2313
  
• PIXpand - TI calculator to Playstation memory card interface
  
• PIC16F877 to IDE interface
  
• 90S2313 AVR Robot Board
  
• ATmega8 based TNC with GPS and WX support
  
• Atmel AVR 90s2313 based POCSAG encoder (ZIP file)
  
• Atmel 90s2313 based TNC
  
• ATmega48 based Nixie Clock
  
• POCSAG encoder/decoder (Zip file)
  
• Rotating Sprocket Wheel Generator (PIC16F84)
  
• Talking PIC - based on SP0256
  
• Serial to parallel converter using the AT89C2051
  
• AT89C2051 serial COMs to LED driver
  
• 89C2051 microcontroller programmer
  
• PIC16F877 Programmer And Development System
  
• DS1820 Arbiter V2.00 Schematic
  
• Driving high-power loads with a microprocessor
  
• IDE interface to a Microchip PIC16F877 microcontroller
  
• PIC sonar (ultrasonic) range finding project with seven segment display using PIC micro
  
• A Real Time Clock IC (DS1307) project using the PIC micro
  
• PIC Serial LCD project - An RS232 serial LCD interface using a standard HD44780 LCD
  
• 101 AT Keyboard to ASCII Decoder using 68HC705J1A MCU
  
• Serial port I/O interface using AVR microcontroller
  
• A Scenix (and PIC) Programmer
  
• MMC to PIC16F876 circuit diagram
  
• Circuits for interfacing microcontrollers to a wide number of real-word interfaces
  
• Atmel Microcontroller based Ultrasonic Ranger
  
• Hardware Random Number Generator with an SX microcontroller
  
• 8088 maximum mode SBC
  
• EZ80 single board computer schematic (Z80)
  
• 8051 Development System Circuit Board
  
• Long-period watchdog timer
  
• Touch senstor based on Atmel AT90S2313
  
• PIC Web Server Schematic
  
• PIC ICD
  
• Tachometer Measures Very Low Frequencies (PIC16F872)
  
• Smart card programmer
  
• Jupiter card programemr
  
• PIC Project #1 - RS232 to I2C Interface
  
• Galvanic decoupling of I2C bus
  
• Ultrasonic Distance Measurer based on Freescale MC9RS08KA2 (PDF)
  
• Programmer PIC16F84,12C50x and EEPROM 24Cxx (PDF)
  
• Graphic LCD interface
  
• Interfacing a 4X4 keypad to a BS2 using a 74922 encoder chip
  
• FSK modem with PIC16C84
  
• Talking YODA project (PIC16C84)
  
• Microcontroller interface for 5KW microwave oven
  
• PIC16F84 Based Morse Code Reader
  
• T89V51CC01 Development board
  
• AVR-Based Serial Port IR Receiver
  
• SPI2CF, a fast and efficient WLAN interface for the AVR
  
• Victoria TAFE programmer (based on AT89C2051)
  
• JDM programmer
  
• PIC micro programmer
  
• Speech recognition using HM2007
  
• PIC microcontroller servo motor interface
  
• PIC micro multiple servo motor interface
  
• PIC16F84 countdown timer
  
• PIC16F873 ultrasonic range meter
  
• PIC16F873 Digital clock
  
• PIC16F873 remote display
  
• PIC16F84 stepper motor controller
  
• PICADC - a free, PIC based "intelligent" A/D converter
  
• PIC-Programmer 2
  
• PIC-Programmer 2 for PIC16C84 etc
  
• KD7LMO Micro Beacon (PIC18F252)
  
• GPS LCD Display Project
  
• PIC16F84 LED chaser
  
• PIC micro LED projects
  
• PS/2 keyboard keystroke logger based on Atmel 89C2051
  
• Electronic distance meter based on Motorola 68HC908QY4
  
• Fan timer based on Motorola 68HC908QT2
  
• Atmel AVR and 8051 series ISP programmer
  
• AT89C2051 line-follower robot
  
• Night light saver (PIC12C508)
  
• USB and GLCD expansion board for 8051 SBC
  
• Microcontroller sensor and actuator interfaces
  
• Complete Design for Giant 8-foot LCD Counter (Zip file)
  
• PIC12C509 logic gate replacement for nitrogen filler (ZIP file)
  
• PIC demo board
  
• PIC12C509 Gym Timer (ZIP file)
  
• PIC LCD and Keypad driver
  
• PIC12C508 Phase Controller for 2kW heater (ZIP file)
  
• PIC16F84 TRIAC / IGBT brightness phase controller
  
• PIC16F84 pulse monitor with date/time output (ZIP)
  
• Cheap Ultrasonic Range Finder based on PIC16F877A with a 8MHz crystal
  
• LCD to PIC16C54 schematic
  
• Acceleration monitor using ADXL202 and AVR
  
• 40+ MHz 5-digit frequency counter with an AVR 2313
  
• Interfacing DRAM to AT90S8515
  
• Temperature monitor/controller: AVR 2313 / DS1621
  
• PIC micro to ISA bus interface
  
• Linuxstamp general purpose processor module based on Atmel AT91RM9200
  
• PC to microcontroller communications using power from the PC serial port
  
• Microchip PIC ICD (in-circuit debugger)
  
• Variety of circuits for RS232 to TTL Signal Conversion
  
• Variety of circuits for TTL to RS232 Signal Conversion
  
• Tony Nixons Pocket Programmer (PIC)
  
• PicoWeb V5.1 (AT90S8515) tiny web server
  
• Atmel 89C2051 In-Circuit Programmer Schematic
  
• 8051 Development System Circuit Board
  
• 8051 Development System Circuit Board
  
• 8051 Development System Circuit Board
  
• Microprocessor using Xilinx FPGA
  
• Temperature controlled based on AT89CX051
  
• I2C LCD interface
  
• AFSK 1200 Modem based on PIC16C620
  
• PicCon - Hidden Radio Transmitter Controller
  
• PIC16F84 tone generator with source code
  
• PIC16F84 tone generator
  
• PIC16F84 tone generator (6-Bit)
  
• Designing a 4-Channel A/D (ADC) converter with the PIC12C671
  
• Ser-Key 10-Key Serial Keypad Encoder
  
• 2-wire LCD interface using PIC16CF84
  
• PIC16F84 Serial I/O-expander with PicBasic
  
• Wireless communications using a Basic Stamp and low-cost wireless data modules
  
• Digital compass using PIC16F84
  
• CASIO datalogger system based around Microchip PIC microcontroller
  
• Scriptable thermometer / thermometric controller based around a COP8-CCR9-PLC44 microcontroller
  
• Cypress PSoC based digital wallet to record secret codes and passwords securely
  
• Low cost Atmel in-system programmer
  
• Ultra low-cost programmer for AT90S family
  
• Connecting AT90S2313 with LCD display 2x16 char and 4x4 keypad
  
• Electronic safety lock based on ATtiny26
  
• 128x64 LCD Driver for AT90S2313 (ZIP file)
  
• Connecting LED to PIC Micro I/O pins (PDF)
  
• Microprocessor RS-232 Reset
  
• AT90S8515 experimenter board
  
• Multi-chip programmer for PIC microcontrollers
  
• 2-Digit Counter using the PIC12F629 chip
  
• Multi-chip programmer for Microchip PIC microcontrollers
  
• Multipurpose buffered PIC microcontroller development system
  
• TTL to RS232 adapter using 2N3906 / 2N3904 transistors
  
• ScanMate audio activated recorded
  
• PIC vacuum fluorescent display (VFD) interface
  
• PIC16F876 Datalogger
  
• Wisp628 ISP Microchip PIC Programmer
  
• WLoader - PIC16F877 application loader / bootloader
  
• Poor man's analog to digital converter (ADC) using a 2N222 transistor and a few passives (PDF)
  
• Nixie clock (PIC16F876)
  
• Atmel Mega88 Dual Temperatur meter
  
• Atmel Mega88 Temperatur meter, Type K sensor, Heat set and regulator
  
• PIC16 DemoKit3 with programmer and displays
  
• Picxie 2 - 8x8 Animated LED Signboard (PIC16F84) Picxie 2 - 8x8 Animated LED Signboard
  
• Darkroom timer using PIC16F84A
  
• 10 tricks for interfacing to the PIC16C508
  
• Interfacing the PIC16C508
  
• LED 5x7 display using a PIC microcontroller
  
• Analog to digital (ADC) conversion notes
  
• Multi-chip programmer
  

Misc audio (also see Music, Amplifiers, Preamp)

• Audio Indicator - monitor a loudspeaker, alarm, or audio source for presence of an audio waveform
  
• Stereo Audio Isolator
  
• Voltage Controlled Panner
  
• Audio VU Meter based on pair of LM324 quad opamps
  
• Voice-Over Circuit
  
• Underwater microphone used in a home aquarium to monitor fish sounds
  
• Room Noise Detector
  
• Novel buzzer using a relay and transformer
  
• Cuckoo sound Generator
  
• Police Siren
  
• Digital Volume Control using DS1669
  
• Electronic Canary
  
• Peak-reading meters
  
• ISD4002-120 audio recording circuit
  
• CMOS IC 1 kHz Audio Oscillator
  
• Two Tone Audio Oscillator
  
• Beat Tracking Strobe
  
• Voice Message Recorder / Player (uses an obsolete voice recorder chip)
  
• Low Power Op-Amp - Audio Amp (Intercom)
  
• 555 Tone Generator (8 Ohm Speaker)
  
• 3 Transistor Audio Amp (50 milliwatt)
  
• Low Frequency Sinewave Generator
  
• Bass booster using a TL702 opamp
  
• Automatic Charger for Battery Operated Hi-Fi Preamps
  
• Regulatable audio amplifier using a 741opamp
  
• Bass EQ pre-amp correction for high impedance ceramic crystal pickup
  
• 12 watt audio amplifier with tone using TDA1020
  
• 5 watt audio amplifier using TDA1010
  
• Low frequency / audio frequency dB output meter
  
• 1 Watt audio amp using a TDA7052
  
• Six-channel Mixer and Amplifier
  
• Audio Signal Source
  
• Voltage controlled amplifier
  
• Audio graphic equaliser
  
• FET audio mixer
  
• Microphone mixer
  
• Tone control circuit diagram
  
• Digital volume control
  
• Sound level meter
  
• JFET Bass Preamp
  
• Very loud beeper (PDF)
  
• Digital noise generator (PDF)
  
• Tone display system
  
• Condenser microphone hookup
  
• Phase shifter
  
• Paradoxical Sound Syntheizer
  
• Simple electronic buzzer
  
• Big Ben sound effects generator
  
• Clack Clack Electronic Bell
  
• Musical Electronic Bell
  
• Digital volume control
  
• Electronic attenuator
  
• Speech recorded using ISD2560
  
• Automatic loudness control
  
• Three channel audio spectrum analyzer
  
• Base / treble control circuit using LM1036N
  
• Cuckoo sound generator
  
• Room noise detector
  
• Various tube crossover circuits
  
• 4 channel audio selector
  
• Minimum Theremin Kit Schematic
  
• Audio line isolator
  
• Dynamic microphone to electret microphone input
  
• Line level signal to microphone input adapter
  
• Simple two line output combiner
  
• Electret microphone powering circuits
  
• Use amplifier phono input as line level input
  
• Speaker signals to line level inputs
  
• Spring reverb unit
  
• Sine wave generator
  
• Simple amplifier using National LM386
  
• RC Audio Oscillator
  
• Subwoofer Filter, Gainer, Auto Power System
  
• Actvie speaker based on a dual op-amp (LM833) and TDA2030 power amp
  
• 3-Band audio graphic equalizer
  
• 6-Input mixer
  
• Doorphone intercom
  
• Stereo audio line driver for running audio over long distance cables
  
• Audio notch filer
  
• Peak reading audio level meter using CA3140 opamp
  
• Tone control circuit schematic
  
• Speaker Microphone Circuit
  
• Electronic canary sound effects
  
• Electronic siren
  
• Analog Synth Keyboard Schematic
  
• Weird Sound Generator
  
• Microphone phantom power supply
  
• Audio DAC3 (SPDIF->Analog Audio)
  
• Dual Voltage Controlled Oscillator w/Modulator
  
• MS Stereo Decoder
  
• RIAA Equalized Stereo Phono Preamp
  
• RDS Encoder
  
• Improved PL tone decoder
  
• Audio Speech Processor
  
• Magnetic cartridge amplifier
  
• LM358 preamp
  
• Sound detector
  
• Tone detector circuit diagram
  
• Tone generator circuit diagram
  
• Warbler siren circuit diagram
  
• Sound Pressure Level Meter
  
• An Audio Limiter for NBFM use
  
• An Audio-Noise-Based Voting Circuit
  
• Audio Detector Circuit
  
• Voltage Controlled Panner
  
• Guitar Reverb Effect Version 2
  
• Stereo Audio Isolator
  
• Panner Waveform Generator
  
• Voltage Controlled Panner
  
• Low Noise Microphone Preamplifier
  
• Bridging Adapter For Power Amplifiers
  
• Simple Surround Sound Decoder
  
• Simplest Ever Amplifier Bridging
  
• Stereo Width Controllers
  
• Power Amplifier Clipping Indicator
  
• Phono Preamps For All
  
• Digital Delay Unit For Surround Sound
  
• Parametric And Sub-Woofer Equaliser
  
• High Quality Sound Mixer
  
• Loudspeaker Protection and Muting
  
• Direct Injection Box for Recording & PA Systems
  
• Minimalist Discrete Hi-Fi Preamp
  
• Signal Detecting Auto Power-On Unit
  
• Load Sensing Automatic Switch
  
• Amplifier thermal protection
  
• Active Sub-Woofer and Controller
  
• Balanced Line Driver & Receiver
  
• VU And PPM Audio Metering
  
• Variable Amplifier Impedance
  
• Linkwitz Cosine Burst Generator
  
• Low Noise Balanced Microphone Preamp
  
• Fast Audio Peak Limiter
  
• Subwoofer Equaliser
  
• Arc welder sound simulator
  
• Telephone ring sound simulator using SMT (surface mount technology)
  
• Stereo LED VU meter using discrete components (BC547 transistors)
  
• Sound activated relay, V1
  
• Sound activated relay, V2
  
• Audio mixer
  
• Envelope generator ADSR
  

Miscellaneous schematics

• Mobile APRS / GPS tracking system
  
• Simple moisture indicator
  
• Two-tone doorbell using 555 timer
  
• Air flow detector
  
• Digital Remote Thermometer
  
• Capacitive Sensor
  
• Mains Remote-Alert - Remotely operates beeper and/or a LED via mains supply line
  
• Touch activated switch using CD4011 CMOS NAND gate
  
• Voice activated switch (VOX) circuit diagram
  
• UltraSonic Radar
  
• Ultrasonic Pest Repeller
  
• Nocturnal Animals Whisker
  
• Beat Balance Metal Detector
  
• Texas Instruments collection of differential op-amp circuits (PDF)
  
• Texas Instruments collection of buffer op-amp circuits for ADC
  
• Laboratory Control System for Cold Atom Experiments
  
• Chaos generator
  
• A Two-Way Morse Practice Set
  
• Voltage Comparator Information And Circuits
  
• Visible and Infrared Light Detectors
  
• Light Activated Detector Circuit (LM393/LM555)
  
• 10 GHz CW Radar based on a X-band Gunnplexer
  
• GoldPic 3 Pulse Induction Metal Detector (has electronic kit available)
  
• DIY 3-axis CNC milling device
  
• Transresistance photodiode amplifier that behaves as a current-to-voltage converter
  
• Full-duplex doorphone with 3 wires connection
  
• G Strain energy absorber
  
• Home-Built Magnetic Levitator
  
• Project for experimenting with magnetic levitation
  
• FET based metal detector using MPF102 / J310 BF998 FETs
  
• Ultrasound detector
  
• Discrete Set/Reset Flip Flop
  
• Monostable Flip Flops (one shot)
  
• Discrete Bistable Flip Flop
  
• Sony RS-422 ADAT sync cable pinout
  
• Garmin Foretrex 101,201, Forerunner 101,201 to Serial DB9 cable schematic pinout
  
• Simple DTMF Repeater Controller using PIC16F84
  
• Capacitance to Voltage conversion
  
• Biasing Op-Amps into Class A
  
• Bleeper box for time reference
  
• Analog computer
  
• BayComm packet modem
  
• Morse monitor
  
• Morse paddle keyer
  
• UV light box
  
• Random noise generator
  
• Analog pulse counter
  
• Analog opto-isolator
  
• Pulse width modulators (PWM)
  
• Pulse width to voltage converter
  
• APRS system for GPS tracking
  
• Air flow detector using an incandescent lamp to detect airflow
  
• Fantastic Atom Expander
  
• Black Light
  
• Computerize Your Room/Home
  
• Suddent ionospheric disturbance (SID) receiver
  
• Magnetic levitation device
  
• Tesla power receiver
  
• Basic Homebuilt Discrete DTL gate circuits (Diode Transistor Logic)
  
• Lazer Tag Equipment Modifications
  
• Garmin GPS data interconnect
  
• Inexpensive APRS Weather Station
  
• Two-component metal detector using a 4093
  
• Induced voltage sensor delta-peak trigger for coilgun
  
• Open loop pulse trigger module for coilgun
  
• Optical speed trap to measure the the velocity of the projectile
  
• Optical trigger module for coilgun
  
• Power MOSFET module for coilgun
  
• Three stage induced voltage triggered coilgun
  
• Thyristor fired coilgun circuit diagram
  
• Magnetic levitation project from Electronics Now, February 1996
  
• LNS Technologies Levitator Kit circuit diagram
  
• Magnetic levitation project from Popular Electronics, May 1966
  
• Magnetic levitation project from Popular Electronics, May 1989
  
• Barry's magnetic levitation project
  
• Barry's Coilgun Mark I circuit diagrams
  
• Barry's Coilgun Mark II circuit diagrans
  
• Barry's Coilgun Mark III circuit diagrans
  
• Barry's Coilgun Mark IV circuit diagrans
  
• Circuit diagram for Coilgun Pistol Pskov 1100
  
• Miscellaneous 741 opamp schematics
  
• Ion detector
  
• 1uS light pulse descriminator plus F to V converter (PDF)
  
• Broadband 2MHz optical fiber receiver (PDF)
  
• Modulated light receiver circuit (PDF)
  
• 1uS light pulse receiver plus post amp (MISC)
  
• Broadband 5MHz optical fiber receiver (PDF)
  
• High-speed 75MHz light receiver (PDF)
  
• Basement doorbell beeper (PDF)
  
• Time to dust indicator - battery powered dust indicator (PDF)
  
• Low-power optical interrupter (PDF)
  
• Simple nitrogen spark generator (PDF)
  
• Ultrasonic sonar unit using MAX232 to drive ultrasonic transducer
  
• Hacking the Hot Wheels Radar Gun - includes circuit of analog front end
  
• Ultrasonic transducer oscillator circuit
  
• Build logic gates using discrete parts
  
• Jacob's Ladder
  
• Circuit for gold wafer card
  
• Nokia 3310 Lcd Thermometer using DS18B20
  
• Lost keys finder using HCF4069
  
• Lightning Detector
  
• Geomagnetic field detector
  
• Seismic detector interfaces to datalogger
  
• Miniature magnetic gun (rail gun)
  
• High voltage stun gun
  
• Mini efficient magnetic coil launcher from disposable camera flash
  
• Bat detector (new)
  
• Bat detector (old)
  
• Variety of quick designs
  
• Gold wafer (smartcard) programmer
  
• GPS receiver support kit
  
• Programmers for FunCard
  
• Fogger smoke machine controller
  
• 6 Pole ElectroMagnet Motor (aka Simple Brushless motor)
  
• Solid State Tesla Coil and Wireless Power
  
• Tesla coil
  
• Vareity of circuits for interfacing to/from TTL logic
  
• Electronic inclinometer ("clino"), a surveying device
  
• Dinsmore 1490 digital compass
  
• Geiger counter
  
• Electric field disturbance monitor
  
• Inexpensive seismometer project
  
• Digital dial for quadrature rotary encoder
  
• Aurora Alarm: Automated Detection System for the Northern Lights
  
• Lie detector
  
• How to Make a Roomba Serial Interface
  
• Photo sensor application note showing photodiode and phototransistor circuits
  
• Doorbell for the Deaf
  
• Electromagnetic field detector
  
• Insect Repellant (22KHz audio oscillator)
  
• High Quality Intercom
  
• Magnetic Gun.
  
• Metal detector using Cherry Semiconductor CS209A
  
• Static Electricity / Negative Ion Detector
  
• Ultrasonic dog whistle
  
• 2D3 Nixie clock schematic using Atmel microcontroller
  
• Popular Electronics Ultrasound Detector
  
• Navigator 555A radio direction finder (RDF) circuit diagram
  
• Touch switches
  
• Build your own UFO Bino-Scope unit - upgrade binoculars to become a photosensitive bino-scope
  
• Color sensor circuit
  
• PASCO scientific model SF-9211 stroboscope schematic (PDF)
  
• CMOS Logic Experiments
  
• Miscellaneous Circuits for Idea Purposes
  
• u-Blox GPS receiver board
  
• Assorted digital circuits
  
• Basic opamp circuits
  
• Miscellaneous simple circuits
  
• Simple electronic keyer
  
• FM Morse Code Keyer
  
• Easy Morse Code Keyer Circuit
  
• CW Tone Keyer
  
• Digital Call Sign Annunciator
  
• Monitor output from Motorola Oncore GPS engine in HP Z3801A in GPS Disciplined Oscillator
  
• Ultrasonic switch
  
• Plant Watering Watcher (moisture meter)
  
• Sound finding cricket with phase detector
  
• Sound finding cricket
  
• A small collection of quick to build electronic circuit designs
  
• DIY Plasma Globe using an automotive ignition coil
  
• DIY Tesla coil - DC Powered with Plasma Output
  
• Very basic circuits
  
• Bat detector
  
• High Speed ISO9141 Interface using Motorola MC33290D ISO driver IC
  
• FCTS Project
  
• Count Accumulator for Radiation Levels (CARL)
  
• Modifications for CDV700 Geiger Counter
  
• Big Ear Stereo Parabolic Microphone
  
• Ultra Low Power LCD Indicator
  
• 12 Volt Toilet Tank Refiller
  
• Morse Code Beacon Keyer
  
• Building a Hardware Random Bit Generator
  
• Simple metal detector circuit using BC547
  
• Metal detector Mk1 - find hidden treasure at the beach
  
• Metal detector Mk2 - More sophisticated 5 transistor metal detector (BC547, BC557, BC338)
  
• Spy circuits
  
• Weather station with pressure reading, relative humidity, indoor & remote temperature reading
  
• Induction receiver for tracing wiring behind walls, hearing lightning and other electric discharges
  
• Driving N-channel FETs from TTL
  
• Electronic canary doorbell
  
• Electronic dazer
  
• Jacob's Ladder
  
• Negative Ion Detector
  
• Negative Ion Generator
  
• Tesla coil
  
• Solid state tesla coil
  
• High voltage zappers
  
• Morse Code Practice Keyer 1
  
• Morse Code Practice Keyer 2
  
• 741 Light Sensor
  
• Fluid level detector
  
• Touch switch using transistors
  
• Delayed shutter control for Kodak DC-20
  
• Morse code display
  
• Kenwood TH-D7 NMEA GPS bug fix
  
• Waveform conversion
  
• Intercom schematic
  
• Single chip metal detecor with a range of a few inches based on CS209A
  
• omentary High Voltage Arc Circuit - can be used to Ignite a barbeque or a Gas in a Potato Gun
  
• Simple BFO metal detector using 2N3906 and 2N3904 transistors
  
• Cat or Dog Detector - can be used to control entry on a Cat or Dog Door
  
• CMOS based electric fence design
  
• Hydrogen Generator, PWM Circuit
  
• Scaling ADXL50 accelerometer output
  

Models, remote control toys, robotics

• autopilot: Do it yourself UAV
  
• Roomba robotic vaccum cleaner serial interface
  
• Balancing robot (PDF)
  
• AVR Line Following Robot
  
• Analog controller for TekBot robot
  
• Charger board for TekBot robot
  
• Motor controller board for TekBot robot
  
• Tactile whisker for TekBot robot
  
• Sonar and PIR Sensor Board for TekBot / general robotics
  
• Walking robot (PDF)
  
• Build A Roomba Bluetooth Adapter
  
• RC Receiver for airplane (35MHz)
  
• Traffic light controller with 20-output sequencing
  
• 556 Timer Stall-Motor Switch Machine Drivers
  
• 5 Times Around Circuit
  
• Automatic - Railway Grade Crossing Circuit (2008 design)
  
• Audible Train Approach Warning Circuit
  
• Across The Track Infrared Detectors
  
• Block Occupancy Detector For DCC
  
• Rail Crossing Diamond Protection Circuit
  
• Automatic Railway Grade Crossing Flashers
  
• Incline Railway Control Circuit
  
• Model Railroad Odometer Car
  
• Turnout Anti-Derail Protection Circuits
  
• Various Transistor Throttles Cicuit Schematics
  
• Three Terminal Regulator Type Throttle (LM350K)
  
• 5 Second Ramp Generator for Locomotive Sound Card Demonstration
  
• Adding External Meters to DC Throttles
  
• Grade Crossing Bell Ringer (LM555)
  
• Train Mounted Camera Battery Charger
  
• Timed Uncoupling Ramp Driver (LM555)
  
• DCC To DC - Accessory Power Supplies
  
• DCC Circuit Breakers
  
• Grouped DCC Block Occupancy Detectors
  
• Model Railroad - Infrared Proximity Switch
  
• First Across The Line Race Scorer Circuits
  
• School Bus Signals Circuit
  
• LED Out Circuit For Tortoise Switch Machines
  
• Timed DC Throttle
  
• DCC - Zero Stretching Simulator (LM555)
  
• Basic DC controller for model trains (PDF)
  
• Bi-Ped robot project
  
• Bi-Ped Project 2
  
• Miniature bipedal robot that starts to walk when you clap your hands
  
• RC Servo Controller with preset
  
• Snuf simple autonomous mobile robot
  
• A Receive Signal Decoder
  
• 27Mhz toy car receiver
  
• 27Mhz toy car transmitter
  
• LED traffic lights
  
• Various radio control schematics
  
• PIC-Bot II using Microchip PIC16LF84
  
• Proportional radio remote control
  
• Walking robot
  
• Signal braking module
  
• Locomotive signal braking module
  
• Simple Traffic Light Controller
  
• Electronic millipede robot
  
• Downed model locator
  
• Precision Receiver Battery Low Voltage Alarm
  
• Launch controller for multiple rockets
  
• Discharger for Receiver Battery Packs
  
• RC Receiver Battery Low Voltage Alarm
  
• Downed model locator Mark 2
  
• A selection of robotics projects
  
• Walker walking robot
  
• Robot with PIC16F84 brain & InfraRed eyes
  
• Making a FRED photopopper
  
• 0-10V control for RC servos
  
• PC Controlled RC Car
  
• Robotic microcontroller board
  
• Multi Rocket Launcher
  
• Model rocket launch controller
  
• Pad launch controller for model rockets
  
• Simple flashing light circuit
  
• Simple flashing light circuit
  
• A dual alternating flashing light circuit
  
• Simple flashing light circuit
  
• A dual tandem flashing light circuit powered by a 9 volt battery
  
• Simulate the Gyralite (dual flashing headlights).
  
• Moderately complex train detector using an infrared LED and an infrared detector
  
• Simple train detector using ambient light and a photocell
  
• Deriving power from Lego NXT® motor port A
  
• External power supply for Lego NXT®
  
• Wire guidance sensor
  
• GP2D12 distance sensor
  
• Lego compatible, compact rotation sensor
  
• R/C digital camera controller
  
• R/C helicopter camera
  
• Building an RF Remote Control System
  
• Slot car TV cronograph displays the lap times of your model cars on a regular TV
  
• Connecting Multiple SRF08 Sonar Modules to a BS2 (Basic Stamp 2)
  
• Circuit diagram for connecting the SRF08/10/235 sonar modules to the BS2p Basic Stamp
  
• RF Modem Robotics Project
  
• Motor walker circuit
  
• The Coat Hanger Walker - Simple BEAM robot
  
• Level crossing for model railways
  
• Building a robot arn using Nitino muscle wire
  
• Signal module for model railways adds a high degree of realism
  
• Simple throttle control ideal for railway shuting yards or a second main track line
  
• Simplest R/C circuit
  
• Glowplug driver for radio control models
  
• Two tone train horn
  
• R/C Emergency locator alarm
  
• Angelfire rocket GPS payload
  
• Glow Plug driver for model engines
  
• Miniature line follower robot
  

Motor and general control schematics

• Bridge head
  
• PWM motor controller
  
• Home Automation Over Internet
  
• CMOS control voltage for firing Crydom Soft-Start Motor Module
  
• FAN Thermostat controlled by IR remote controller
  
• Digital logic controller
  
• Light switch using LDR
  
• Heating System Thermostat
  
• Touch switch based on CD4011 flip-flop
  
• DC Motor Control Circuit
  
• Fan control based on a TL082 opamp and IRF510 power MOSFET
  
• Radio Remote Control using DTMF
  
• Simple 120 VAC motor speed controller based on a TRIAC
  
• Electronic Control for DC Motors Using Discrete Bridge Circuits (PDF)
  
• Smart switch, short press for on, longer press to turn off
  
• One component stepper motor driver
  
• Dual Stepping motor drivers using UDN2540
  
• PWM DC motor control with SG3525
  
• Stepper Motor Driver using TEA3718/3717
  
• Microstepping with PBM3960 and TEA3718
  
• DC Motor Driver with L6203
  
• Stepper Motor Driver using L298 and L297
  
• Several stepper motorol control circuits
  
• Wireless RF PWM dual motor controller
  
• 556 Timer Stall-Motor Switch Machine Drivers
  
• Bipolar stepper motor driver based on 74194 chip
  
• H Bridge Motor Control Circuits
  
• Unipolar stepper motor driver based on 74194 chip
  
• HIGH or LOW Power Switch For Lights or Small Motors
  
• Push Button Motor Control Circuits
  
• Motor speed controllers
  
• MotorDriver V1.0 - Dual DC Motor Driver Board (LMD18200T based, 55V 3A, 6A peak) - PDF
  
• Relay circuit using 74LS573 to driver 5V DC relays
  
• Safe Universal Mains Switching Box
  
• Electronic Thermostat Relay Circuit
  
• Interfacing 5 volt CMOS to 12 volt loads
  
• Light Activated Relay
  
• CMOS Toggle Flip Flop With Relay(CD4013)
  
• 555 Timer Monostable Circuit Using Pushbutton
  
• Current loop interface
  
• Switching solenoid driver
  
• Modular relay system
  
• Light/dark detector
  
• Pulse Width Modulation DC Motor Control
  
• Stepper motor controller
  
• Touch switch
  
• Stepper motor driver using PIC12F675 that offers serial port command interface
  
• Stepper motor driver using PIC12F675
  
• Simple temperature regulated FAN speed controller
  
• Three electronic circuit diagrams for thermal controllers including linear and PWM control
  
• Rolling code 4-channel UHF remote control
  
• Shadow activated (or hand wave) motion detector
  
• Pushbutton one-shot and latch (PDF)
  
• Charge coupled bi-directional power MOSFET relay (PDF)
  
• Finger touch activated switch (PDF)
  
• Machine vibration triggers hour meter (PDF)
  
• Solid state relay (PDF)
  
• Line-powered Xenon flash transmitter (PDF)
  
• 9V Xenon photoflash controller (PDF)
  
• No-Hum Fan Controller
  
• AC switching with TRIAC from TTL
  
• Control 120VAC relay with TTL
  
• Driving a relay with a CPU
  
• Clap activated remote control
  
• Light Operated Switch
  
• Solid-state power controller
  
• High And Low Voltage Cut Off With Time Delay
  
• Optically isolated stepper motor controller
  
• Stepper motor controller
  
• 35KHz Magnetic-Radiation Remote-Control
  
• Voice activated switch using MC2830
  
• Combination-controlled, fully customizable RF remote control
  
• Thermoelectic controller (scriptable thermometer)
  
• Stepper motor positioner
  
• 555 Based Simple Servo Controller
  
• H Bridge controller for DC motors
  
• 5A H-bridge motor driver based on TIP122 / TIP127 power transistors
  
• Thermostat
  
• Frequency switch
  
• PIC16F84 RF remote controller
  
• DC Motor Controller using 74 series chips
  
• Water system controller (PDF)
  
• DS1821 programmable thermostat
  
• Hot Water Tank Level Indicator
  
• Temperature monitor using 741 opamp
  
• Voltage comparator switch
  
• Dark activated switch
  
• DC Push Button Motor Control Circuit
  
• Light detector
  
• DC Motor Reversing Circuit
  
• Sound operated switch
  
• LDR light/dark activated relay switch
  
• Touch Switches
  
• 6090 digital decoder schematics
  
• Remote Motor Controller
  
• Assorted relay control circuits
  
• Thermal cooling fan controller
  
• NPN transistor circuit for relay control (relay driver)
  
• 4-bit receiver for DC motor control
  
• Serial servo controller
  
• A Simple Repeater Fan Controller (PDF)
  
• Electronic circuit diagram of cell phone SMS remote control device
  
• DIY Power Pulse Controller
  
• DC Motor-Driver H-Bridge Circuit
  
• Relay controller based on Microchip PIC16F84 (PDF)
  
• Constant Temperature Circuit
  
• PWM Motor Speed Controller / DC Light Dimmer
  
• Constant Temperature Circuit
  
• PWM DC Motor Speed Control
  
• Solenoid starter
  
• MOSFET based speed controller uses 9 IRFZ40 power MOSFETS
  
• CO2 controller for planted tanks
  
• Light / dark activated relay
  
• Relay circuit for relay control via an RS232 port
  
• Micro-step driver - connect a bipolar steppe motor to a PC through the parallel port
  
• PA fan temperature controlled speed motor speed controller
  
• Homemade Water Drain Pump controller
  
• 4 Digit Keypad Switch
  
• Simple keypad operated switch
  
• Delayed Power Circuit using an SCR
  
• H-Bridge Circuit
  
• MOSFET H-BRIDGE schematic and theory
  

Music related schematics (also see Audio)

• Simple metronome using LM1458
  
• Portable Mixer with high-quality modular design (9V battery powered)
  
• Guitar Reverb Effect Version 2
  
• Guitar Reverb Pedal
  
• Metronome Circuit
  
• Octave screamer
  
• The 203 Theremin - A Battery-Operated Version of the Wien-Bridge Theremin
  
• Amiga MIDI interface
  
• Apple Mac to MIDI synthesizer interface cable
  
• Apple Macintosh MIDI interface schematic (basic version)
  
• Apple Macintosh MIDI interface schematic (deluxe version)
  
• Standard MIDI to MIDI interface cable diagram
  
• Simple MIDI switcher
  
• MIDI interface / cable tester
  
• MIDI keyboard circuit diagram
  
• MIDI merger schematic
  
• 25-pin PC serial port to MIDI synthesizer interface cable
  
• 9-pin PC serial port to MIDI synthesizer interface cable
  
• Serial MIDI interface
  
• Microcontroller MIDI interface
  
• Spring reverb unit
  
• Music player built on microcontroller AT91SAM7S256 with ARM core
  
• B. Blender: Blends an effects chain with the input signal. Works well with bass guitar
  
• Mr Smooth is a clean boost to mild overdrive effect
  
• Simple colour organ
  
• Guitar fuzz effect
  
• 8 note tune player
  
• Colour (Sound) Organ
  
• Transistor organ
  
• Wave Multiplier for music synthesizers
  
• Infinite melody for music synthesizers
  
• Miniature metronome
  
• Homebuilt MP3 Player
  
• Bazz Fuss is a simple fuzzbox circuit, cheap and easy to build
  
• Synthstick: A ribbon controlled oscillator (sound generator)
  
• Zonk Machine and Treble Booster
  
• Simple line mixer
  
• Simple MIDI tester
  
• :ossless portable digital audio player using the Microchip PIC32
  
• MIDI Controller Footpedal
  
• DIY Serial MIDI Interface (80C51/80C31 Version)
  
• Electronic metronome
  
• Sound Effects Generator
  
• Sound Effects Generator 2
  
• Sound Lab Mini-Synth analog music synthesizer
  
• Digital Guitar Tuner
  
• Spring reverb
  
• Drum percussion sensor schematics
  
• 2 Note Ribbon Controller
  
• Using the Hot Springs Reverb reverberation unit
  
• midi2cv8 to Drum Tone Board Connections
  
• Practical MS Decoder Circuit
  
• Drum Tone Oscillators
  
• Theremax Theramic Circuit Schematic
  
• Vocal zapper
  
• Theremin controller
  
• MP3 Player circuit schematic
  
• MIDI drum machine project
  
• MIDI Drum Machine Analog Input Schematic
  
• MIDI Pedalboard Encoder
  
• Tone Filters for Electronic Organs (PDF)
  
• Compact DJ station
  
• Guitar Reverb Pedal
  
• Guitar Tremolo Unit
  
• Spring Reverb Unit For Guitar
  
• Ultra Simple Bass Guitar Compressor
  
• Guitar Vibrato Unit
  
• Musical Instrument (Expandable) Graphic Equaliser
  
• Daisy MP3 player project
  
• Simple open source MP3 player with SD/MMC memory card support
  
• Midibox 64
  
• Theremin
  
• 3 Channel Color Organ
  

PC related schematics

• I2C printer port adaptor
  
• Yaesu FT-897 - PC interface (PDF)
  
• RS232C Level Converter
  
• PC electrically isolated RS422 interface using SN75176B or MAX485
  
• PC electrically isolated RS485 interface using MAX487 or SN75176B
  
• Short circuit protected power supply from PC 12V supply
  
• Isolated Full Duplex RS232C Interface
  
• RS232 DB-9 switch to flip between two serial ports
  
• USB camera circuit
  
• DB-9 Connector to DB-25 (both RS-232)
  
• Mac Serial Port (RS-422 DIN-8) to RS-232 DB-25
  
• Yaesu VX-7 / VX-7R to PC interface
  
• USB LCD/VFD Controller Hardware
  
• Commodore 64 24-bit parallel port interface with 8255
  
• Ericsson phone to PC serial port interface
  
• PC serial port receiver
  
• Parallel port relay interface
  
• Mac to HP48 cable pinout
  
• RS232 serial to USB converter cable circuit schematic
  
• Serial port temperature datalogger
  
• Game boy camera PC serial interface
  
• 300/1200 baud BAYCOM MODEM (revision and improved)
  
• HAMCOM (SSTV, RTTY, FAX...) modem using PC-speaker for TX
  
• PTT and/or soundcard interface
  
• PTT and soundcard interface for the TM255/455
  
• HAMCOM (SSTV, RTTY, FAX...) modem using serial audio for TX
  
• HAMCOM & SoundCard MODEM using serial- or soundcard audio
  
• TM-441 9600bps packet modification
  
• Using a PC power supply as a benchtop power supply
  
• Parallel (Printer) Port Interface
  
• RFID evaluation kit for PC serial port (PDF)
  
• RS-232 line monitor and loopback cables
  
• The KD2BD Pacsat Modem
  
• SWTP PR-40 Printer Interface Schematics
  
• A Serial Infrared Remote Controller
  
• Simple music synthesizer for an ATARI
  
• Interfacing 16x2 character :LCD to parallel port
  
• RS-232 Protocol Analyser
  
• Radio clock for PC's
  
• General purpose ISA interface card for PC
  
• PC ISA Card Random Number Generator
  
• MIDI cable for Sound Blaster cards
  
• PC ISA board containing a Z80 microprocessor (coprocessor card)
  
• Extremely simple ADC for the PC (parallel port interface)
  
• Analog Signal Acquisition for PC Printer Port
  
• More accurate PC/AT clock
  
• Getting power from RS-232 interface
  
• PC based Frequency Meter
  
• 7 segment rolling display using PC
  
• SmartCard PC Emulator
  
• Relay interface add-on board for PC
  
• 8-way relay interface board for PC parallel printer port
  
• Stepper motor controller for PC parallel port
  
• 3-axis stepper motor controller for PC parallel port
  
• PC based thermometer based on Dallas DS1621
  
• Simple PC thermometer for serial port but using R/C network for measurement
  
• Dallas DS1620 based USB Digital Thermometer
  
• PC thermometer using PC game (joystick) port
  
• iRDA interface for motherboard using Vishay TFDS4500
  
• LCD2LPT with LIRC (LCD to LPT printer port) interface
  
• FM radio with PC parallel port interface
  
• Build your own iRDA SIR Transceiver (Dongle) using MCP2120
  
• PC thermometer
  
• Dive computer interface
  
• Parallel port servo controller
  
• DCF77 receiver to PC RS232 serial port interface
  
• GPS receiver (Gamin, Eagle etc) to PC interface cables
  
• Ethernet interface for Commodore 64 computer
  
• i2c-tiny-usb, a simple i2c interface for the usb port
  
• LCD2USB, cheap open source text LCD interface
  
• TiltStick, a motion sensing device (USB interface to accelerometer)
  
• Building an Infrared Transmitter for Your PC
  
• Connect two CD-ROM drives to one soundcard
  
• Headphone driving circuit for soundcards
  
• Get power out of PC parallel port
  
• Null Printer Adapter
  
• PC speaker volume control circuit
  
• How to get power from PC to your circuits
  
• RS-232 surge protection
  
• Simple RS-232 serial port buffer circuit
  
• Get power out of PC RS-232 port
  
• Sound Blaster Microphone Preamplifier
  
• Sega 3D glasses interface circuit diagrams
  
• Convert Atari-style joystick to PC joystick port
  
• Fake Joystick circuit
  
• Using the joystick port as general purpose input
  
• Connect other circuits to PC joystick port
  
• Schematic of a standard PC joystick
  
• Simple PC SmartCard reader
  
• Fax to modem interface
  
• Serial servo controller for interfacing hobby servos via RS232 to a PC
  
• Sanyo 20EZ monitor circuit diagram
  
• PC interface for point controller
  
• PC-based ISA data acquisition and control board
  
• Linux Infra-red Remote Control (LIRC)
  
• Homebuilt RS232 LCD Interface
  
• Homemade Serial to Nokia MBus Interface on a PCB, without using Zener diodes
  
• Computer microphone
  
• Machine Independent Parallel Interface
  
• PG31 GPS RS232 GPS development board
  
• PG31 GPS RS232 USB development board
  
• RS232 RS485 USB Converter Board
  
• Thermal fan control circuit designed for overclocked PCs
  
• CCD linear image sensor to PC parallel interface
  
• Laptop Computer Serial Port Power Booster
  
• Various sound card interfacing circuit diagrams
  
• Assorted computer interface circuits
  
• Apple II/II+/IIe IDE Drive Interface
  
• Basic Stamp I & PC Relay Controller
  
• PC based digital thermometer based around a Dallas Semiconductor DS1621
  
• RS-232 to TTL cable
  
• Hi-Fi PC Speaker System
  
• How to construct Garmin GPS receiver interface cables
  
• Jasmin floppy disk controller schematics
  
• 160 Baud ALDL Hardware Interface
  
• iLINK Interface
  
• 9-pin null modem cable
  
• Simple Hankel USB oscilloscope for a PC
  
• RS232 - Lowe HF-225 interface
  
• Serial to parallel converter - connect a large number of digital outputs to a PC parallel port
  
• PC parallel port eight DC power switch cam driver two unipolar stepper motors, lights etc
  
• Interfacing PC sound card to SSB rig
  
• Pic-Plot GPIB to RS-232 converter
  
• Pic-Plot2 GPIB to USB converter
  
• USB to parallel port converter using Cypress CY7C68013A-56PVXC
  

PDA / music player interfaces and schematics

• TomTom One V3 connector pinout
  
• Palm PDA based datalogger
  
• Palm Keyboard interface board
  
• SHARP palm-top/hand-held to RS232 serial converter
  
• Portable iPod charger
  
• Fitting a JTAG interface to an iPAQ 3600
  
• Apple iPod and iPhone dock pinout
  
• Casio calculator interface schematic
  
• Palm Pilot, Palm III, V, VII, VIIx, Handera interface port pinout
  
• DIY iPhone 3G Charger circuit
  
• SHARP palm-top/hand-held to RS232 serial converter
  
• iPod / USB MP3 charger using MC34063 switchmode regulator
  
• Casio datalogger
  
• Design and build your own iPod docking station
  
• Casio datalogger
  
• USB charger for iPod using 7805 linear regulator
  
• Interfacing ADXL202 accelerometer to PalmPilot
  
• Serial interface adapter for iPod Linux
  
• Aladin interface
  
• PalmPilot turbo boost guage interface
  
• MIDI interface for PalmPilot
  
• Mass storage and printer interface for the FX-700P calculator
  
• Wireless local network for PalmPilot (large PDF)
  
• DIY iPhone Charger circuit
  

Photography related electronic circuits

• Dual cable (serial + USB) for Nikon Coolpix cameras
  
• kShutter: Simple remote shutter for Nikon Coolpix camera
  
• kShutter2: Advanced remote shutter for Nikon Coolpix cameras
  
• Slave flash trigger
  
• How to Build Your Own Light Meter (PDF)
  
• High speed flash photography for amateur photographers
  
• Computer controlled EOS camera shutter trigger
  
• Lightning Activated Camera Shutter Trigger
  
• Universal sound and optical slave flash trigger
  
• Homebrew Wired Remote for Canon EOS 350D Camera
  
• Slave Flash Trigger Circuit
  
• Digital cameras (AGFA, Olympus) to PC (COM) cable pinout
  
• Making your own RS-60E3 Remote Control for Canon EOS cameras
  
• Flash slave trigger
  
• Electronic shutter release with ultrasonic remote control
  
• Control your camera (Canon DSLR) with your Palm PDA
  
• Computerized Shutter Control of Canon DSLRs
  
• Infrared remote control with intervalometer function for Nikon cameras
  
• IR Remote Control for Nikon cameras, standard version
  
• Serial cable for Casio QV-200 digital camera
  
• Remote shutter (or 'cable release') for SLR and DSLR cameras
  
• Darkroom camera shutter timer
  
• Flash Slave Trigger for Digital Camera
  
• Programmable Optical Slave Flash Trigger for Digital Cameras using PIC12F675
  
• AI-1 ("All-in-one") Remote - photographic accessory that you can build
  
• Densitometer & Intervalometer projects
  
• Camera remote control system using Basic Stamp
  
• Lightning Activated Camera Shutter Trigger
  
• DIY Intervalometer for a Canon SLR camera
  
• Stop Action 3D-Photography using an audio flash trigger
  
• Kodak DC-20 camera interface (PIC12C509)
  
• Kodak DC-20 camera interface (PIC16F84)
  
• Universal Exposure Timer and Event Counter
  
• CamTrig - A home-made light-operated camera trigger
  
• A simple home-made light-operated camera trigger
  
• A home-made light-operated camera trigger using the stamp microprocessor
  

Power supplies and control schematics

• 13.8V 30-40A Power Supply (PDF)
  
• DC Voltage and Current Source
  
• Power supply provides +5VDC regulated, +10VDC unregulated and 7.5VAC
  
• Controller for hybrid (photovoltaic- wind turbine and diesel engine) power plant
  
• 3rd harmonic distortion meter for measuring the quality of AC supply
  
• Alkaline battery charger
  
• Low Voltage Alarm for batteries and other volatile DC power sources
  
• 1A Variable Regulated Power Supply
  
• Regulated Power Supply Circuits
  
• Basic Solid State Relays
  
• LM311 Thermostat circuit diagrams
  
• Transformer Secondary Voltage Reduction
  
• Back And Forth - Bidirectional Bipolar Stepper Motor Driver
  
• High Side Current Monitors (LM358, Zetex - ZXCT-1009)
  
• Low Battery Voltage Cutout Circuits
  
• Preselect Twin Coil Switch Machine Circuit
  
• N.O. Magnetic Reed Switch ON /OFF Circuit (SCR equivalent)
  
• Team digital - SCR16 - Twin Coil Switch Machine Adapter
  
• Efficient unipolar stepper motor driver (only uses power when it makes a step)
  
• Fast NiMH / NiCd Battery charger
  
• Alternative power source for Magellan GPS receivers
  
• LED battery voltage monitor. A fuel gage for your gel cell battery.
  
• 0-14 volt, 0-2 amp current limited variable power supply regulator
  
• Dynamo Current and Voltage Regulator
  
• Generating Negative 5 Volts from 9 Volt Battery
  
• LED Battery Condition Indicator
  
• LM317 Variable Voltage Regulator
  
• LM317 Regulator With Pass Transistor
  
• High Current Regulated Power Supply
  
• Simple Variable Voltage Source
  
• Various switching power supplies
  
• Variable 3 - 24 Volt / 3 Amp Power Supply
  
• 2 watt switching power supply
  
• Variable Voltage and Current Power Supply
  
• Low Power DC to DC Converter
  
• Constant Current Battery Charger
  
• Nicad battery charger
  
• Simple power supply
  
• Voltage converter
  
• Bench power supply
  
• Easy power supply
  
• Valve power supply
  
• 6V to 12V Converter
  
• 6V to 12V Converter
  
• Tesla coil / HV generator
  
• High Current Power Supply
  
• Dual Polarity Power Supply
  
• High Voltage High Current Power Supply
  
• Transformerless Power Supply
  
• Fixed Voltage Power Supply
  
• Voltage Inverter
  
• Voltage Inverter
  
• Dual power supply
  
• Negative voltage generator
  
• Economic battery sufficiency tester using a BC547 transistor
  
• Power reminder beeper (PDF)
  
• Unplugged power cord alarm
  
• Machine power loss beepter (PDF)
  
• Low-dropout 12V regulator (LM324)
  
• HV supply: 12VDC in, 12KV out
  
• Generating -5VDC from +5VDC
  
• Filtering PC bus POWER
  
• Charge Monitor for 12V lead acid battery
  
• Nagative voltage generation using 555 timer
  
• NiCd Cell Charger
  
• Flyback transformer driver
  
• Basic UPS Power Supply
  
• Fuse monitor / alarm
  
• 500W low cost 12V to 220V inverter
  
• TTL power supply with crowbar protection
  
• Pulse Charger for reviving tired Lead Acid batteries
  
• Voltage monitor with LED indicator
  
• High current regulated power supply
  
• CEMF (counterelectromotive force) charger
  
• Ignition Coil High Voltage Generators
  
• One 9V battery gives +18, +25, +33V
  
• +9V *and* -9V from one battery
  
• Adjustable power supply using LM317
  
• Simple +5V power supply circuit
  
• Advanced High Voltage PSU circuit
  
• 12 Vdc - 120 Vac Inverter Schematic
  
• +12V/-12V Power supply unit
  
• +/-12V to +/-5V Power unit
  
• +5V Switching regulator (1)
  
• Switching regulator (2)
  
• Electric power controller
  
• +30V power supply with +5V
  
• +30V DC-DC converter
  
• DC/AC inverter (2)
  
• DC/AC inverter (1)
  
• PIC16F873 DC motor speed controller
  
• Single to 3-phase power conversion
  
• Lead-Acid Battery Monitor
  
• 12V 30A power supply
  
• Dual regulated power supply
  
• Fuse blown indicator
  
• Gyrator circuit
  
• Variable power supply
  
• LM317 Regulator Circuit
  
• Nicad battery charger
  
• Regulated 12V supply
  
• Unregulated power supply
  
• Snowmobile GPS power adapter
  
• Simple switching power supply
  
• AC Power Meter
  
• Assorted power source and control circuits
  
• Build A Simple Rechargeable CMOS Battery
  
• Build A High Performance Voltage Regulator From Discrete Components
  
• 12 Volt Gel Cell Charger
  
• Build A 10 Amp 13.8 Volt Power Supply
  
• Adjustable Voltage Regulator using a 7805 or other fixed linear voltage regulator instead on LM317
  
• Using Pass Transistors Beef Up Voltage Regulator current output
  
• 12 volt battery monitor
  
• 12 volt power supply
  
• 5 volt power supply
  
• Battery voltage monitor
  
• LM3914 battery monitor
  
• Multiple voltage power supply
  
• Voltage doubler
  
• Voltage inverter
  
• Simple switching regulator (experimental)
  
• PWM DC Motor Speed Control
  
• Battery Low Voltage Beeper
  
• PWM Motor Speed Controller / DC Light Dimmer
  
• PWM Motor/Light Controller
  
• Low Power LED Voltmeter
  
• Temperature Controlled Nicad Charger
  
• PWM Motor/Light Controller
  
• PWM Motor/Light Controller variants
  
• Low Power LED Voltmeter
  
• Temperature Controlled NICD Charger
  
• Simple Capacitance Multiplier Power Supply For Class-A Amplifiers
  
• Simple DC Adapter Power Supply
  
• Variable Dual Lab Power Supply
  
• Two amp variable power supply
  
• Automatic AA nicad battery charger
  
• Battery charge for 12V SLA batteries
  
• Turn an ordinary wall wart / plug-pack into a regulated device
  
• Battery Charger Ideas
  
• DC to AC inverter using a 555 timer
  
• Dual (postive and negative) 12V power supply
  
• Current booster for 78nn series voltage regulators
  
• 12V Lead-Acid Battery Monitor using LM3914
  
• Charger for gel lead acid batteries
  
• Compressor-mate power protection for refrigerators, freezers and air conditioners
  
• High voltage DC generator
  
• High-Voltage Pulse Generator
  
• Automatic 9V NiCad battery charger
  
• Active Power Zener
  
• Solid state relay circuit
  
• NiCad Discharger for Tx & Rx Packs
  
• Lead acid battery charger with float
  
• Simple constant current source
  
• Battery Characterizer
  
• Lead/acid battery charger
  
• 200 Watt Modified PC Power Supply 13.5 Volt 14 Amp
  
• Cockcroft-Walton voltage multipliers (PDF)
  
• Amplified zener regulator
  
• Battery Charger, Current and Voltage Regulated for Sealed Lead Acid batteries
  
• Inverter, A 12 volt unit, Very Basic type
  
• Inverter, 12 volt unit, MOSFET design
  
• Lithium Battery Rejuvinator
  

Radio-frequency schematics (also see Transmitters)

• 4 channel 433MHz remote control transmitter / receiver based on SM5162 and SM5172 chips
  
• Digitally tuned radio board to create an embedded FM radio controlled by a Mega128
  
• Electronic Eavesdropping Devices Detector
  
• Radio Wave Alarm
  
• Linear FM 50Watt with BLY90
  
• UHF Preamplifier covers 450MHz - 800MHz based on MPSH10 / BF180 / BCY90
  
• 60W Linear amplifier using IRF840 power MOSFET
  
• QRP - Circuits for measuring RF Voltage, RF Current, RF Power, SWR
  
• WLW 500KW Transmitter Schematic
  
• AM-Receiver for Aircraft communication (118.250MHz)
  
• Improved AM-Receiver for Aircraft communication
  
• 50MHz RF Power Amplifier using BFG97
  
• 60-120MHz FM receiver with AFC
  
• Super improved AM-Receiver for Aircraft
  
• PLL synthesized FM radio that can decode DTMF
  
• GPS jammer
  
• MC13136 based narrow band receiver
  
• 1.5 W RF Power Amplifier type class-C
  
• RF Power Amplifier Module using Toshiba S-AV10H
  
• AM receiver for aircraft communications
  
• 78-80 MHz Superfast Scanner using a DDS (direct digital sythesizer)
  
• 50 MHz Receiver based on MC3372
  
• SA602, SA612 RF Mixer
  
• Superior TV-tuner receiver 45-860MHz in 2500Hz step
  
• Super Scanner 45-860MHz with 0.01Hz stepsize
  
• TR1001 868.35 MHz Hybrid transceiver schematic
  
• 45-860MHz Radio receiver based on UV916-tuner
  
• 30 W Digital Wattmeter for RF (0-500MHz)
  
• Send Morse on your VHF Rig
  
• An end-fed antenna, L-match coupler and resistive bridge for HF
  
• Regenerative receiver for the AM broadcast band using two transistors
  
• Car radio tunes the amateur bands
  
• Novel crystal set requires no antenna, earth
  
• 80 meter direct conversion receiver
  
• A compact L-match ATU for portable use
  
• Converter to yune six metres on your two metre receiver
  
• High quality AM through your FM stereo
  
• Compact 20 - A 14 MHz Direct Conversion Receiver
  
• Converter to Hear Amateurs on your FM Radio
  
• RF Actuated Keying Monitor
  
• LF to HF Converter
  
• Super 80 ultra-simple SSB receiver for 3.5 MHz a basic superhet
  
• 80 Meter CW ARDF receiver
  
• Four channel RF remote control
  
• Basic 10GHz / 24GHz gunplexer / gunn diode control circuit (PDF)
  
• Receiver building blocks
  
• VHF receiver converterer
  
• Simple wireless radio data link
  
• RX3302 receiver module schematic
  
• Superregenerative 27MHz receiver
  
• 49MHz walkie-talkie
  
• 6 Meter SSB transceiver
  
• Deluxe Direct Conversion Reciever
  
• PSK Transceiver - Unique transceiver design does not use a SSB transmitter
  
• SSB Receiver / Exciter and Linear amp
  
• AM Short Wave Broadcast Receiver circuit diagram
  
• Convert 2m VHF FM PMR transceiver Motorola Radius M110 into an amateur radio
  
• Wideband SWR meter
  
• SCA Subcarrier Demodulator for FM broadcast stations
  
• Simple Op-Amp Radio
  
• 50MHz converter project based on a NE602/SA602/NE612
  
• HF/6M Antenna Tuner Preselector and Antenna Switcher
  
• Direct Crystal radio receiver examples
  
• MW Enhanced Crystal Receiver using 741 IC
  
• 455 Khz MF to AF converter used for DRM reception in a Yaesu FRG-100 receiver
  
• Sensitive LW/MW/SW Shortwave general coverage receiver
  
• 10 meter (28MHz) band RF amplifier
  
• MW/SW Radio receiver
  
• 450-2000KHz AM receiver (ZN414)
  
• Bipolar transistor RF mixer
  
• HF/VHF mini portable antenna tuner
  
• Wideband VHF/UHF/SHF 22dB RF preamp with MAR-6 or MAR-8 (MSA-0885)
  
• HF 10 watt amplifier for 18MHz using a 2SC1969/2SC1944 transistor
  
• RF Power meter / dummy load
  
• SWR bridge covering HF to VHF
  
• VHF 6 Meterband RF amplifier
  
• HF/VHF portable antenna tuner
  
• RF front-end for triple conversion GPS receiver (PDF)
  
• 2M - 20M transverter
  
• Improved CMOS RF PLL sythesizer
  
• Harmonic oscillator
  
• Direction finder system
  
• One transistor regenerative receiver
  
• Synthesized HF receiver
  
• TBA120 narrowband FM receiver
  
• TDA7000 receiver
  
• ZN414 receivers
  
• 10W HF linear amplifier
  
• 500W HF linear amplifier
  
• 3W HF QRP linear amplifier
  
• Phasing SSB exciter
  
• 500mW HF linear amplifier
  
• Generic VHF power amplifier
  
• 10.7MHz FM detector
  
• RTTY terminal unit
  
• Q-multiplier
  
• CMOS RF PLL sythesizer
  
• Op-amp based radio receiver
  
• Op-Amp Radio
  
• Class E Power Amplifier Design (136KHz operating frequency)
  
• TX Module Combiners (copied from commercial circuits)
  
• Receive Loop Preamplifier for LF reception
  
• Class B series modulator
  
• Advanced VHF power meter (PDF)
  
• The MRX-40 Mini Receiver (PDF)
  
• 300 baud RF modem circuit schematic
  
• External antenna for the GPS-38, Magellan 2000, or Eagle Explorer GPS receivers
  
• 175KHz inductive pulse receiver (PDF)
  
• 200-400 MHz voltage controlled oscillator (PDF)
  
• AM/FM/SW active antenna
  
• RF Sniffer under 0.5MHz to above 500MHz
  
• Demodulator Schematic/Design using Gilbert Cell Mixer
  
• 73MHz remote controller hallogen light
  
• Electronic Eavesdropping Devices Detector (bug detector)
  
• 20dB VHF Amplifier
  
• 30 watt FM linear amplifier
  
• Linear FM 50 watt amplifier with BLY90
  
• CB (27MHz citizens band) receiver
  
• CB (27MHz citizens band) 2.5W transmitter
  
• AM to FM conveter
  
• 60W RF linear amplifier using IRF840
  
• AM BCB radio receiver
  
• Regenerative shortwave receiver
  
• 7MHz SSB Transceiver
  
• Frequency Synthesizer
  
• Digital Automatic Gain Control (AGC)
  
• Four Channel Wireless Transmitter and Receiver using RF modules (PDF)
  
• PLL synthesizing oscillator (1)
  
• PLL synthesizing oscillator (2)
  
• PLL synthesizing oscillator (3)
  
• 2N2222 40 Meter CW/DSB Transceiver
  
• inexpensive high speed microwave data link using an Alpha Gunnplexer for 10 Mbps data rate
  
• 18 dB LT1253 DDS Amplifier
  
• 23 dB Bipolar DDS Amplifier
  
• 15M CW Transceiver Design
  
• 20 Meter CW Transceiver
  
• 30 Meter, Discrete Component CW Transceiver Built Manhattan-style
  
• K8IQY's Original 2N2/40 CW Transceiver Rig
  
• 40 to 6 Meter "No Tune" Transverter
  
• SW30+ 30 Meter CW Transceiver
  
• Wave Bubble self-tuning portable RF jammer
  
• Yaesu FT-736R doppler compensation
  
• 30M PSK31 Transceiver
  
• SOP receiver (PDF)
  
• SOP direct conversion receiver
  
• Electroluminescent Receiver Kit includes circuit diagram
  
• Receiver based on NE602
  
• 30M Direct Conversion Receiver Project
  
• Active Antenna Experiments
  
• Cascode 7 Experimental Receiver
  
• 75 Meter QRP SSB Transceiver
  
• Junk Box NDB Low Pass Filter
  
• Popcorn Direct Conversion Main Frame
  
• 40 Meter Popcorn Superhet Receiver
  
• RF preamp circuit diagrams
  
• Some experiments with active or voltage probe antennas (VPA)
  
• MF and HF Receive Antenna Splitter
  
• Medium Frequency TRF Receiver
  
• 40 Meter Band Direct Conversion experimental receiver
  
• Stacked Torroid VFO Experiments 2008
  
• Wee Willy 75 Meter DSB Transceiver Project
  
• 10 MHz WWV Receiver
  
• Cascode Hybrid-Based WWV Receiver for 5 MHz
  
• 40m band direct conversion receiver
  
• 80m band direct conversion receiver
  
• Regenerative Short Wave Radio
  
• Homebrew 20m CW Transceiver
  
• Homebrew 30m CW Transceiver
  
• Homebrew 40m CW Transceiver
  
• Homebrew 6m SSB/CW Transceiver
  
• Homebrew 6m DSB Transceiver
  
• 136 kHz direct conversion receiver
  
• Audible S-Meter
  
• 40 Segment LED S-Meter
  
• Bi-Directional 2.4 GHz One Watt Amplifier
  
• Bi-Directional 900Mhz One Watt Amplifier
  
• 20 Watt GaAaFET Power on 2.3 GHz
  
• 1 Watt 2.3 GHz RF Amplifier Using a MRF2001
  
• One Watt 2.45 GHz Linear Amplifier using RF Micro Devices RF2126
  
• 2.3 GHz Power Amplifiers
  
• 2304 and 3456 MHz Power Amplifiers
  
• Dopler RDF (radio direction finder) circuit
  
• 222 MHz Transverter
  
• VFO from 2001 ARRL Handbook, page 17.74
  
• VFO from 2001 ARRL Handbook, page 14.20
  
• Assorted RF circuits
  
• 14MHz SSB 10mW Transceiver
  
• Yaesu band decoder schematic
  
• VLF radio receiver schematic
  
• VLF Upconverter for Shortwave Receiver
  
• Basic Vox Circuit
  
• Variable Bandwidth CW Filter
  
• An Inexpensive Tone Encoder
  
• 5 watt, 80 meter QRP CW Transceiver
  
• How to Build a 300MHz AM, RF Remote Control System
  
• Build a good GaAs FET preamp for 2 meters, 222MHz or 440MHz
  
• COR Carrier Delay timer / Hang Timer
  
• Build a COS Detector to detect the presence of a carrier on a receiver
  
• KL 400 RF linear amplifier
  
• ICOM CI-V interface with RS232 RTS to PTT
  
• Galvanic isolated CAT & audio interface for amateur radio
  
• Improved FM Stereo Modulator
  
• Morse Code Beacon Keyer
  
• QRP Antenna Tuner
  
• Smooth Tone Clickless CW Sidetone Generator
  
• Variety of receiver converter projects
  
• One transistor FM receiver
  
• 42 Mc Band to 88 Mc Band (retrofit converter) Project
  
• RF noise bridge for HF
  
• 160m mini portable End Fed Half Wave Tuner - MkII
  
• 27MHz transmitter
  
• Crystal radio circuits including diode performance comparison
  
• Active Antenna AA-7 HF/VHF/UHF, 3-3000MHz
  
• Active antenna 1 to 20dB, 1-30 MHz range
  
• Active Antenna for AM-FM-SW
  
• FM radio active antenna
  
• Aviation band receiver
  
• Broadcast-Band RF Amplifier
  
• Bug detector with beep using 7413 or 74LS13
  
• Bug detector / countersurveillance monitor
  
• Basic RF oscillator
  
• Subcarrier adapter to listen to hidden subcarrier signals on FM radio
  
• 56K RF Modem
  
• 5 tubes SSB QRP Transceiver for 20m Ham band
  
• 2m (144MHz) Dual Gate FET Low Noise Amplifier
  
• Two Diode Odd-Order Multiplier
  
• RF Isolator Uses Differential Amplifiers
  
• Phase Locking and Tuning
  
• Phase-Locking ULNs for Optimum Performance
  
• Bootstrapping a Phase Locked Loop for Better Performance
  
• One watt class-C RF amplifier (PDF)
  
• Switching Diode Frequency Doublers (PDF)
  
• Low Power RF ID Transponder (PDF)
  
• Multiplier Generates Odd Harmonics (PDF)
  
• Low Frequency Circulator/Isolator Uses No Ferrite or Magnet (PDF)
  
• Kenwood TR-7950 manual & schematics (PDF)
  

Solar-power schematics

• Solar tracker
  
• Converter that enables long cable wiring for pyranometer
  
• Solar energy meter
  
• Measure solar radiation on an Ubuntu Server
  
• Photovoltaic Solar Battery Regulator and Load Controller
  
• Solar charge controller
  
• Solar robots
  
• Digital Clock with Timer and Solar Panel Regulator
  
• Solar Tracker
  
• 1381 solar engine
  
• Solar car array controller schematic
  
• Solar car battery monitor schematic
  
• Solar car brake controller schematic
  
• Solar car main controller schematic
  
• Solar car display controller schematic
  
• Solar car electrical design and circuit index
  
• Portable solar battery charger
  
• Sensor Electronic Tracker with H-Bridge Drive
  
• Sensor Electronic Tracker with Simple Solar Charge Controller
  
• Solar tracking control system
  
• LED7 solar tracker
  
• Build a DIY solar iPod charger
  
• Zener-based solar engine
  
• Buck Mode Switching Regulator for Solar Applications
  
• Solar Panel Charge Controller / Low Voltage Disconnect Circuit
  
• Solar Panel Current Meter
  
• Remote Solar LED light
  
• SCC2 10 Amp Solar Charge Controller
  
• 12 Volt 20 Amp Solar Charge Controller
  
• Solar Charged LED Flashlight
  
• Self Powered Solar Box Furnace
  
• SPC2 6 Amp Solar Power Center
  
• Solar Powered Reading Lamp
  
• AA battery solar charger
  
• Solar Panel Charge Controller / Low Voltage Disconnect Circuit
  
• Solar Panel Current Meter
  
• Solar cell Nicad charger using Maxim MAX639
  

Telephone and intercom related schematics

• The 89C51 PABX
  
• Wireless Telephone Bug
  
• FM Telephone Bug
  
• Phone Broadcaster / telehone bugging device circuit diagram
  
• 900MHz cordless phone bug
  
• Digisound ring modulator
  
• Incoming call indicator (ZIP file)
  
• Telephone Ring Generator Using 60Hz Power Transformer
  
• Telephone Ring Generator Using Switching Power Supply
  
• Telephone In-Use LED Indicator
  
• Telephone In-Use Relay Circuit
  
• Telephone Audio Interface
  
• Simple alarm with telephone dialler interface
  
• Telephone line simulator
  
• Home made PBX / PABX
  
• Ringing Phone Light Flasher
  
• Phone Busy Indicator
  
• FM Telephone Bug
  
• Cut Phone Line Detector
  
• Simple Phone Tap
  
• Telephone Hold Button
  
• Telephone Recorder
  
• 1-line telephone status indicator powered from a 3V battery (PDF)
  
• Line in use indicator that handles two independent phone lines (PDF)
  
• 4-line telephone status indicator that is polarity independent (PDF)
  
• Cellular Phone calling Detector
  
• Caller ID decoder (requied Postscript file viewer and/or Ordcad schematic capture)
  
• Telephone in use light
  
• Detecting a telephone ring signal
  
• Phone In-Use Light
  
• Phone to audio interface for SSI202 input
  
• Phone Off-Hook Indicator using CD4049 hex inverter
  
• 'phone rang' indicator light
  
• Phone line to audio interface
  
• Phone in-use (manually activated)
  
• Telephone Line Monitor
  
• Use old telephones as an intercom
  
• Phone-In-Use indicator
  
• Hold function for Telephone
  
• Digital/Standard Phone Line Tester
  
• Cellular Phone calling detector (detects RF field)
  
• Phone line in use indicator
  
• Telephone music on hold interface
  
• Soft musical telephone ringer
  
• Telephone amplifier
  
• Telephone line monitor
  
• Cut telephone line detector
  
• FM telephone line bug transmitter (88MHz to 94MHz)
  
• Simple telephone line tap for intercepting telephone calls
  
• The Link A2B+1 (the Link Telephone Intercom - DTMF version)
  
• The Link 4+0 - Internal Intercom (Doesn't offer external line access)
  
• The Original 2 Phone Intercom Link Design
  
• 8-line intercom system using 89C51 microcontroller
  
• Universal telephone hold
  
• Talking phone dial monitor (PDF)
  
• Simple Skype VoIP analog adapter
  
• Telephone privacy adapter
  
• Telephone ringing circuits
  
• Simple circuit to connect telephone equipment to audio mixer
  
• Assorted telephone circuits (ring generator, in-use indicator, audio interface)
  
• Telephone Line Filter / Protector
  
• Greek telecard reader
  
• Isolated Telephone Interface (phone tap) for tape recorder, PC sound card etc
  
• Phone ring circuit schematic using a piezo buzzer for sound output
  
• Infinity bug for remote telephone surveillance
  
• Cut phone line detector
  
• DSL / ADSL phone line filter
  
• Telephone auto-dialler (useful for an alarm dialler)
  
• Taxi phone automatic dialler
  

Test equipment circuit diagrams

• Sensor to display, built with thermistor, 12-bit ADC, 89S52 and LED display
  
• Thermistor Thermometer: LCD version
  
• Ultra-simple Voltage Probe
  
• Wire tracer
  
• Exclusive 2.5 GHz Frequency Counter with Blue 2x16 LCD display
  
• RF field strength meter
  
• 2.5 GHz Frequency counter
  
• Wireless Frequency counter
  
• Frequency counter measures to 2.5 GHz and offers LCD display
  
• PIC based frequency counter
  
• Poor man's frequency counter
  
• 250MHz RF Generator with 1kHz display resolution
  
• Simple test equipment to build
  
• RF Power Meter for the QRP measures up to 25 watts
  
• Dip Oscillator for HF
  
• DCC Ammeter using ZXCT1009 current monitor
  
• Improved DCC Ammeter (2009) using Zetex ZXCT1009 current monitor
  
• High Impedance Voltmeter
  
• Servo Motor Test Circuit (LM555)
  
• 220V live wire-in-wall scanner
  
• Oscillopscope triggering circuit for recording long transients at fast sweep speeds (PDF)
  
• Digital SWR / Power Meter
  
• Linear scale analog watt meter / RF power meter
  
• Low Power Antenna Analyzer and ATU Tuning Aid
  
• Fixed Frequency "Tuner Dipper"
  
• pH probe electronic circuit diagram
  
• ESR Meter
  
• Line Output / Flyback transformer tester
  
• Build an inexpensive Hall effect Gaussmeter
  
• Design for a slightly more expensive Gaussmeter
  
• Capacitance meter - precision meter for small capacitors
  
• AC Line Current Detector
  
• Conrad Electronics MM3610D multimeter cable pinout
  
• 3 in one tester (audio, tone generator, diode/circuit tester)
  
• In-circuit electrolytic capacitor checker
  
• Logic probe with pulser
  
• Grid dip meter
  
• PCB VSWR bridge
  
• Electric field & leakage detector
  
• Simple Ph Meter
  
• Simple polarity detector
  
• RCM710 electronic scale, technical manual including schematic
  
• Simple Ground Loss bridge for Ground Loss Measurement at LF
  
• DDS from 1-60 MHz with built-in amplifier and variable output level using Analog Devices AD9851
  
• Schematics and C code for a PIC frequency counter operating up to about 50 MHz (7 segment)
  
• Schematics and C code for a 0-5V PIC LCD volt meter
  
• Schematics and C code for a PIC frequency counter operating up to about 50 MHz (LCD)
  
• TTL pulse counter/logic probe
  
• Frequency and capacitance meter
  
• Elecraft XG2 receiver test oscillator (PDF)
  
• Contactless Mains Voltage Indicator
  
• Mini tester: Handles continuity testing, resistor testing, capacitor testing and diode testing
  
• Precision audio millivoltmeter
  
• PIC16F84 based diode tester
  
• Triple Stroboscope
  
• Automatic heat limiter for soldering iron
  
• Ultra-simple voltage probe
  
• Live line detector
  
• Continuity tester using transistors
  
• Latching continuity tester using 4093
  
• Linear Resistance Meter
  
• Crystal tester
  
• Capacitance meter
  
• Digital voltmeter (DVM)
  
• Transistor tester using 555 timer and 4027
  
• Function generator based upon 8038 waveform generator IC
  
• Picoammeter circuit schematic with 4 ranges using CA3420
  
• Beeper to find short circuits (continuity tester)
  
• MOSFET tester for N-type MOSFET transistors
  
• Inductive meter adapter to measure inductance using a frequency counter
  
• Crystal tester that covers a range of 32kHz to 24MHz
  
• Oscilloscope testing module (Huntron circuit) that shows Lissajous patterns
  
• Logic probe with 7-segment display based on 74LS00 and 74LS47
  
• TDR cable reflection tester (Time Domain Reflectometer)
  
• Resistor decade box
  
• TXTVb - 70cm ATV Test Generator (PDF)
  
• Electronic Circuit for Crystal Parameter Measurement
  
• Simple light sensor adapter for oscilloscope
  
• Time Domain Reflectometer (TDR)
  
• Field Strength Meter (FSM) covers 2Mhz - 1Ghz with peak reception at 3-200Mhz
  
• 5Hz to 500KHz frequency meter
  
• UHF signal generator
  
• VHF signal generator
  
• -20 dB Couplers for use with a with a spectrum analyzer or other sensitive detector
  
• -20 dBm, 14.060 MHz Precision Signal Source
  
• Precision VXO for Crystal Characterization & Matching
  
• Return Loss Bridge
  
• Multi wire cable tester that handles up to eight conductors
  
• Connection tester for checking solder joints and other connections
  
• EMF field probe (electromagnetic field probe) covering up to 100kHz
  
• Function generator based on 8038PCD function generator IC
  
• Logic probe based on CMOS 4001 chip
  
• Zener diode tester based on a 555 timer
  
• Mini DDS (direct digital synthesizer) using an Analog Devices AD9832 (12MHz maximum frequency)
  
• AD9850 DDS daughterboard
  
• Signal Tracer and Injector
  
• TDS/PPM Meter for measuring of the amount of salts in a solution
  
• Precision Frequency Marker
  
• Simple Inductance Meter
  
• VCR Tuner Based RF Spectrum Analyzer Schematic
  
• LCD frequency counter (PIC16F84)
  
• Simple electronic S meter
  
• Service monitor / deviation meter circuit
  
• Simple diagnostic tool for use on repeaters in the field
  
• 10Hz - 100KHz D.D.S. Function Generator
  
• TTL Pulse Reading Logic Probe
  
• Stereo Test Tone Generator
  
• Pulse Reading Logic Probe
  
• Pink Noise Generator for Audio Testing
  
• Audio Millivoltmeter
  
• Audio Test Oscillator
  
• Full Featured Transistor Tester
  
• Opamp Design and Test Board
  
• Microphone Circuit Test Oscillator
  
• Distortion Analyser
  
• Self Oscillating Amplifier for Distortion Testing
  
• LC meter with LCD display for readout
  
• Capacitance meter that connects to multimeter
  
• Transistor tester and signal injector
  
• Continuity tester
  
• Square wave oscillator (555) for test applications
  
• 555 Timer IC Tester
  
• 555 go / no-go tester
  
• Battery Tester for 1.5 and 9V
  
• Continuity tester 2
  
• Continuity tester
  
• Logic probe
  
• Digital Wattmeter, measures from nanowatts to kilowatts using AD8307, PIC16F876, LCD Display
  
• SWR Bridge 1 to 1000 Mhz (1GHz)
  
• Low-Cost Phase Noise Measurement
  
• Field strength meter for the 137 kHz band
  
• Ground Fault Indicator
  
• In-circuit electrolytic capacitor tester
  
• PIC logic probe with pulser
  

Timing and oscillator circuits

• Budget timer
  
• D.I.Y. Clock Oscillator based on 555 timer
  
• Egg timer
  
• Digital Clock with Alarm Using DS1307
  
• Digital timer with 7-segment display and pushbuttons
  
• Countdown timer with relay
  
• DDS using AD9835
  
• VCO - Voltage Controlled Oscillator covers around 70-210 MHz
  
• 3 - 12 MHz Signal Generator
  
• Signal Frequency Beat Frequency Oscillator
  
• Wide-swing Variable Crystal Oscillator
  
• CA4060B Timer Circuits
  
• Special Function Timer Circuits (LM555)
  
• 1 Second Time Base From Crystal Osc.
  
• Power-On Time Delay Relay Circuit
  
• Low Voltage , High Current Time Delay Circuit
  
• Power-Off Time Delay Relay Circuit
  
• Triangle and Squarewave Generator
  
• Generating a Delayed Pulse With a dual 555 Timer
  
• AF variable frequency generator using 555 IC
  
• Crystal switcher using diodes
  
• IC oscillator 1...30MHz using 74LS04 chip
  
• Simple AF-oscillator / signal generator using pair on 2N2222 transistors
  
• Digital clock based on 74 series logic
  
• Two nixie display clock
  
• VFD (vacuum flourescent display) clock
  
• Single-digit Nixie clock
  
• Oscilloscope CRT Clock
  
• Weston Voltmeter Clock
  
• Time Delay Relay using 555 timer
  
• Time Delay Relay using 4011 CMOS NAND gate
  
• Mixer VXO circuit diagram
  
• Binary clock using LED matrix to display a binary clock with 6 digits of 4 binary bits each
  
• Digital clock that receives and displays the time from the Rugby MSF radio transmission (PIC16F877)
  
• Line powered 60Hz clock generator (PDF)
  
• Micro-power pulse generator (PDF)
  
• Divide by 1.5 counter (PFD)
  
• High-output square wave generator (PDF)
  
• D Flip-flot one-shot circuits (PDF)
  
• Clock divider
  
• Clock doubler
  
• CMOS oscillator using 74C14 inverting Schmitt trigger
  
• Crystal 32.768KHz CMOS Oscillator
  
• Crystal oscillator using a CMOS or HCMOS inverter
  
• Cheap 40KHz clock using one gate of a 74C14
  
• Astable 40KHz clock
  
• 'Rounding Off' a square wave
  
• Switch debounce using 555
  
• Square wave to sine wave converter
  
• Bedside lamp timer
  
• Sun tanning timer
  
• Digital Stopwatch 0-99sec
  
• Digital Stopwatch 0-60sec
  
• 28 LED clock timer
  
• Photo timer circuit using NE555
  
• Triangle / Square wave generator
  
• Day / Night / 24 Hour Select Sensor
  
• One transistor timer using a 2N7002 MOSFET or similar
  
• Variable timer
  
• Simple Function Generator using TL084 or other opamp
  
• Micropower pulse generator (PDF)
  
• Square wave oscillator using a CMOS Schmitt inverter
  
• Triangle wave oscillator using a TL082 opamp
  
• Sawtooth wave oscillator using a TL082 opamp
  
• Sine/Cosine wave oscillator using a pair of TL082 opamps
  
• 555 timer module driving a relay
  
• 555 based oscillator
  
• Astable multivibrator (IC)
  
• Stable multivibrator (Transistor)
  
• Simple GPS Stabilised 10 MHz Oscillator
  
• Push Button Switch Debouncer
  
• Square wave oscillator using CMOS 4011 NAND chip
  
• 5 to 30 Minute Timer
  
• NE555 Basic Monostable
  
• 24" Wall Clock
  
• Astable Multivibrator
  
• Experimental Base Bias Tuned VFO
  
• Astable Multivibrator Projects / Circuit diagrams
  
• Tuning VFOs With A PN-Junction
  
• Sleep Timer
  
• Super VXO
  
• High Precision GPS/TV controlled Reference Oscillator
  
• TV based Receiver for a Standard Frequency Generator
  
• AD9852 DDS schematic
  
• Decimal DDS Signal Generator
  
• Build A 100Khz Crystal Calibrator
  
• Alarm clock based on Atmel AT89C2051 and Dallas DS1307 RTC chip
  
• Crystal heater / temperature stablization circuit (TXCO)
  
• PTT Delay Circuit
  
• DDS oscillator based on an Analog Devices AD9859 and an Atmel ATmega16 microco (Microsoft Word)
  
• A GPS receiver based frequency standard
  
• 555 timer circuits
  
• Monostable multivibrator
  
• Clock generator
  
• 555 Timer Tutorial + Circuits
  
• GPS-based universal clock generator
  
• Homemade scope clock using a DG7 tube and a Microchip PIC16F876
  
• VCO covers 300MHz to 500MHz based on Maxim MAX2608 VCO
  
• Simple Divide-By-N using 161 series chip (PDF)
  
• Frequency Tripler using the CA3028 (PDF)
  
• Tiny Crystal Oscillator using LP2980 (PDF)
  
• Constant Reactance Voltage Controlled Oscillator (PDF)
  
• Unusual frequency dividers (PDF)
  
• HCMOS Gates Make Frequency multipliers (PDF)
  
• Low Distortion Crystal Oscillator (PDF)
  

Transmitter schematics (also see RF)

• One transistor FM transmitter / FM bugging device
  
• Two transistor FM transmitter / FM bug
  
• FM Beacon Broadcast Transmitter (88-108 MHz)
  
• Wireless FM Transmitter
  
• 4 Watt FM Transmitter
  
• 3-3.5 Watt FM Transmitter
  
• 4 Transistor Tracking Transmitter
  
• AM Transmitter
  
• FM Transmitter using two transistors
  
• AM/FM Simultaneous Transmitter Using Digital IC
  
• Medium range transmitter using pair of 2N3904 transistors
  
• 15 watt FM transmitter
  
• AM Transmitter
  
• FM transmitter based on Colpitts oscillator design
  
• Powerful AM transmitter
  
• Single transistor FM transmitter
  
• Long range FM transmitter using 2N3866 for output stage
  
• Coilless FM transmitter using CD4069 CMOS hex interverter chip
  
• Small FM transmitter using SMD components
  
• Miniature FM Transmitter
  
• Low Power FM Transmitter
  
• FM Voice Transmitter
  
• Sensitive FM Transmitter
  
• Small FM Transmitter
  
• FM transmitter for bird listening
  
• FM audio bug using BC817 and BRF92
  
• 50 MHz crystal controlled audio bugging device
  
• 500mW FM PLL transmitter 88-108MHz
  
• Digitally controlled FM transmitter with 2 line LCD display
  
• Ipod Stereo FM transmitter with 1W output power
  
• PLL based bug transmitter
  
• Cordless telephone bug
  
• Crystal controlled transmitter (46.515MHz, 1 transistor FM)
  
• Crystal controlled transmitter (46.515MHz, 3 transistor FM)
  
• 5W Chinese PLL FM Transmitter With LCD Printed Circuit Board (PCB)
  
• Two Valve 40m CW Transmitter
  
• 80m ceramic resonator VXO CW transmitter
  
• 80 Metre DSB Transmitter
  
• One Valve CW transmitter
  
• Europa30, a 10MHz QRP TX
  
• 433MHz transmitter using SAW resonator
  
• FM Microphone micro-transmitter that is small and sensitive
  
• Tube Transmitter with 5763 power amplifier
  
• A 3m (100 MHz) small bug (ZIP file)
  
• BC547 80M SSB QRP Transceiver
  
• Micro Power AM Broadcast Transmitter
  
• FM Beacon Transmitter (88-108 MHz)
  
• 1 Watt AM transmitter for the 10 meter band (28MHz)
  
• 12-meterband QRP AM oscillator transmitter using a 2N2219 transistor
  
• 500mW AM transmitter for the 20 meter band (14MHz)
  
• 1 valve CW transmitter
  
• 250mW HF CW transmitter
  
• 2 valve CW transmitter
  
• Transmitter using LM317
  
• 5 Watt HF CW transmitter
  
• Simple FM microphone
  
• FM bug
  
• High power FM bug
  
• 27MHz AM/CW transmitter
  
• Easy 2-meter transmitter
  
• QRP HF transmitter
  
• Spark gap transmitter
  
• QRP SSB transmitter
  
• Crystal controlled FM transmitter
  
• 150mW FM transmitter
  
• FM transmitter
  
• 500kHz Transmitter design
  
• Pocket APRS (GPS Position) transmitter
  
• Low Power PLL FM Transmitter based on LMX1601 and Atmel ATtiny2313 or AT90S2313 microcontroller
  
• 175KHz inductive pulse transmitter (PDF)
  
• 7MHz QRP transmitter
  
• Small Radio Transmitter
  
• MW Transmitter can be used as an inter-room radio telephone
  
• Pocket Transmitter that can cover 20 to 25 meters with a telescopic antenna
  
• 4 watt FM transmitter
  
• FM transmitter bug
  
• Small radio transmitter
  
• AM transmitter
  
• 2 Transistor FM Voice Transmitter
  
• 15 watt FM transmitter
  
• 4 watt FM transmitter
  
• Tiny FM transmitter using SMD (surface mount devices)
  
• Medium range transmitter circuit
  
• AM FM Simultaneous Transmitter Using Digital IC (CD4001)
  
• Wireless transmitter for PIR using Holtek HT12E
  
• KMDTA Wireless Motion Detector Transmitter Kit
  
• 88-108Mhz FM Radio Transmitter with 3 transistor stages
  
• simple 430MHz band FM transmitter uses only 2 FETtransistors
  
• AM transmitter using no power supply
  
• QRP transmitter circuit diagrams
  
• 40 Meter, 5 Watt QRP Transmitter
  
• Miniature FM transmitter
  
• Sensitive FM transmitter
  
• Simple RF transmitter
  
• 1.5 volt tracking transmitter
  
• Tracking transmitter
  
• Micro Power FM Broadcasting Circuits
  
• Low Power FM Transmitter
  
• RF/SS Handie Hopper Transmitter Schematic
  
• 30-Meter QRP Transmitter for Morse Code
  
• Miniature FM Transmitter #1
  
• Miniature FM Transmitter #2
  
• Miniature FM Transmitter #3
  
• 4-transistor transmitter
  
• FM telephone transmitter
  
• Miniature tracking transmitter
  
• Light sensing RF transmitter
  
• 1.5V tracking transmitter
  
• Micro-Spy with FETs
  
• Micro-Spy with USW
  
• Micro-Spy with TTL
  
• Wireless microphone
  
• 144.000 Mhz CW Transmitter
  

Video related schematics

• Video Clock Superimposer
  
• Video clock superimposer using PIC16C711
  
• TV Signal Amplifier covers frequencies from 40MHz to 900 MHz
  
• Motorized Video Camera Mount
  
• TV Transmitter - VHF band TV transmitter using negative sound modulation and PAL video modulation
  
• Video Signal Amplifier
  
• Simple AV (audio / video) wireless transmitter
  
• Apple IIe RGB to CGA
  
• 8 x 8 Audio-video switch
  
• VHF/UHF TV modulator
  
• TV video transmitter using LM1889
  
• LH0032 video amplifier
  
• LM359N video amplifier
  
• Video Activated Relay
  
• 23cm FM ATV Platinum Receiver (PDF)
  
• Closed-Caption Decoder
  
• PIC-Tock video clock
  
• Commodore RF modulator
  
• Video signal edge enhancement
  
• Video amplifier
  
• Decoder for encoded transmissions in Videocrypt and D2MAC
  
• S-Video to RCA adapter
  
• VGA to SCART adapter
  
• Television signal amplifier
  
• Video signal amplifier circuit
  
• VGA to RGB + composite sync -converter
  
• Video/Audio Wireless Transmitter
  
• 4 Stage 555 Timer for Video Cam Control
  
• Digital volt meter with video output
  
• Video switcher - run up to four cameras into one video monitor (PDF)
  
• Run video and camera power up to 2000 feet over ordinary four conductor telephone wire (PDF)
  
• TV/Radio antenna cable galvanic isolator
  
• S-video to composite video adapter
  
• VGA converter for video projectors and fixed frequency monitors
  
• VGA to TV converter
  
• VGA to PAL and NTSC converter
  
• PIC micro frame grabber (TDA8708)
  
• Commodore 64 Video Modulator 251025 Schematics
  
• Commodore 64 Video Modulator 251696 Schematics
  
• TV RGB signal output from a SVGA graphics card
  
• Circuits to transmit and demoludate RF / video signals over fibre optic cable
  
• Macrovision removal
  
• Video DVM - Display voltage on a TV - based on Atmel AT90S1200 and generates vid signal in software
  
• An automated, self-recording surveillance camera using an SD memory card for recording digital video
  
• Generate video signals in software using PIC
  
• Generate composite color video signals in software using an SX microcontroller
  
• AVR (AT90S2313) composite PAL colour bar generator
  
• Motorized Video Camera Mount
  
• Homebuilt video digitizer Mark I
  
• Homebuilt video digitizer Mark II
  
• VGA to TV conversion circuit
  
• Camera switching circuit to run multiple cameras with one monitor