All 2692 schematics are available on a single page here.

Misc audio circuit diagrams / circuit schematics (also see Music, Amplifiers and Preamp circuits)

• 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
  
• Cuckoo sound Generator
  
• Electronic Canary
  
• CMOS IC 1 kHz Audio Oscillator
  
• Two Tone Audio Oscillator
  
• Voice Message Recorder / Player (uses an obsolete voice recorder chip)
  
• 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
  
• JFET Bass Preamp
  
• Simple electronic buzzer
  
• Big Ben sound effects generator
  
• Clack Clack Electronic Bell
  
• Musical Electronic Bell
  
• RC Audio Oscillator
  
• Subwoofer Filter, Gainer, Auto Power System
  
• Actvie speaker based on a dual op-amp (LM833) and TDA2030 power amp
  
• Audio Speech Processor
  
• Sound pressure level meter circuit diagram
  
• An Audio Limiter for NBFM use
  
• An Audio-Noise-Based Voting Circuit
  
• Sound activated relay, V1
  
• Sound activated relay, V2
  
• Envelope generator ADSR
  
• Beat Tracking Strobe
  
• Electronic canary sound effects
  
• Peak reading audio level meter using CA3140 opamp
  
• Tone control circuit schematic
  
• 3-Band audio graphic equalizer
  
• 6-Input mixer circuit diagram
  
• Doorphone intercom
  
• Stereo audio line driver for running audio over long distance cables
  
• Voltage Controlled Panner
  
• Improved PL tone decoder
  
• Magnetic cartridge amplifier
  
• LM358 preamp circuit diagram
  
• Sound detector circuit diagram
  
• Tone detector circuit diagram
  
• Tone generator circuit diagram
  
• Warbler siren circuit diagram
  
• 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
  
• Paradoxical Sound Syntheizer
  
• Condenser microphone hookup
  
• Phase shifter
  
• Very loud beeper (PDF)
  
• Digital noise generator (PDF)
  
• Spring reverb unit
  
• Peak-reading meters
  
• Voltage controlled amplifier
  
• Audio graphic equaliser
  
• Dual Voltage Controlled Oscillator w/Modulator
  
• MS Stereo Decoder
  
• RIAA Equalized Stereo Phono Preamp
  
• Audio mixer (ASCII circuit diagram)
  
• Tone display system
  
• Audio Signal Source
  
• Electronic siren
  
• Speaker Microphone Circuit
  
• Six-channel Mixer and Amplifier
  
• Microphone phantom power supply
  
• Various tube crossover circuits
  
• Automatic Charger for Battery Operated Hi-Fi Preamps
  
• Digital volume control
  
• Electronic attenuator
  
• Speech recorded using ISD2560
  
• Cuckoo sound generator
  
• Minimum Theremin Kit Schematic
  
• Voltage Controlled Panner
  
• Guitar Reverb Effect Version 2
  
• Stereo Audio Isolator
  
• Panner Waveform Generator
  
• Audio Detector Circuit
  
• RDS Encoder
  
• Room Noise Detector
  
• Novel buzzer using a relay and transformer
  
• Voice Scrambler
  
• Voice / Audio Record / Playback Circuit
  
• Sound operated switch
  
• 3 Channel Spectrum Analyzer
  
• FET Audio Mixer
  
• Microphone Mixer
  
• Mono To Stereo Synthesizer / Simulator
  
• Digital Volume Control using DS1669 Digital Pot IC
  
• Sound Level Meter
  
• Tone Control using TDA1524A Tone Control IC
  
• Assortment of Siren Circuits
  
• Precision Audio Millivoltmeter
  
• Parabolic microphone project circuit (can be used with shotgun directional microphone also)
  
• Using a speaker as a microphone - impedance matching circuit
  
• Speaker cabinet simulator - professional-quality frequency response in a DIY-friendly circuit
  
• Digital Volume Control based around CD4067 CMOS chips
  
• Three-Level Audio Power Indicator
  
• Three channel audio spectrum analyzer
  
• SCMS killer circuit for DAT decks using Sony CXD2601 signal processor chip
  
• Power Amplifier Clipping Indicator Circuit Diagram
  
• Loudspeaker Protection and Muting
  
• Bridging Adapter For Audio Power Amplifiers
  
• DC Fault Protection Circuit for Audio Amplifiers
  
• Sound alarm based on LM741 opamp and LM386 amplifier
  
• Super mixer with microphone input / amplifier including a PCB layout
  
• Cicuit diagram for super long range microphone for use with a shotgun microphone or parabolic dish
  
• High Quality Audio Mixer
  
• Audio Spectrum Analyzer and Equalizer Designs
  
• "Anti-RIAA" Equalizer for Line to Mag Phono Converter (PDF)
  
• NE555 drives a speakes: Pulse Width Modulation Amplifier
  
• Parametric And Sub-Woofer Equaliser
  
• Simple surround sound decoder circuit schematic
  
• Better Volume (and Balance) control circuit diagrams
  
• Build a Tape Linearizer and a Distortion Analyzer
  
• Additional RFI protection for line input circuit diagram (PDF)
  
• High Output Line Driver for Single Ended Power Supply (PDF)
  
• High CMRR Balanced Interface for Crystal 18 or 20 Bit A/D Converters (PDF)
  
• VU And PPM Audio Metering
  
• Defeating SCMS on DAY recorders using a Sony CXD2601 chip
  
• Slew rate control circuit diagrams
  
• Home theater system
  
• Voltage controlled audio panner
  
• Microcontroller (AT89C2051) based tachometer (PDF)
  
• Simple Audio Tone Control Circuit
  
• Binaural Synthesizer/Mono to Stereo Converter for Small Speaker/Phones
  
• Powerline Carrier System Transmitter for Audio (Music/Speech)
  
• Compact 3W BTL Audio Power Amplifier TDA7056
  
• Wind Sound Generator
  
• White / LF noise generator
  
• Stereo audio simulator