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Audio operated relay – Circuit Schematic
Audio operated relay
Ql and Q2 are general purpose transistors. The 10 K input pot is adjusted to a point just short of where Ql turns on as indicated by K pulling in. K is any 5 V ...
Siren-space war-phasor gun – Circuit Schematic
Siren-space war-phasor gun
The one shot and decay functions could be added to make an ideal phasor...
Stereo reverb enhancement system – Circuit Schematic
Stereo reverb enhancement system
The system can be used to synthesize a stereo effect from a monaural source such as AM radio or FM-mono broadcast...
Sound effect generator – Circuit Schematic
Sound effect generator
This waveshape generator is basically a slow running oscillator with variable attack and decay. A variable amplitude (high impedance) output is available via th...
Musical chime generator – Circuit Schematic
Musical chime generator
The circuit is that of a multiple feedback bandpass filter. A short click (pulse), makes it ring with a frequency which is its natural resonance frequency. Osci...
Four channel synthesizer – Circuit Schematic
Four channel synthesizer
This circuit will synthesize two rear channels for quadraphonic sound when fed with a stereo signal. The rear output for the left channel, is a combination of t...
Stereo reverb system – Circuit Schematic
Stereo reverb system
The LM378 dual power amplifier is used as the spring driver. The recovery amplifier is a low noise dual preamplifier...
Musical envelope generator and modulator – Circuit Schematic
Musical envelope generator and modulator
When a gate voltage is applied, Ql is turned on and capacitor C is charged via the attack pot in series with the 1 K resistor varying this pot, attact time cons...
Music synthesizer – Circuit Schematic
Music synthesizer
Three modes of operation are available in the music synthesizer mode...
Audio continuity tester – Circuit Schematic
Audio continuity tester
This low-current audio continuity tester indicates the unknown resistance value by the frequency of audio tone...
Sound activated strobe trip – Circuit Schematic
Sound activated strobe trip
Take strobe-flash pictures the instant a pin pricks a balloon, a hammer breaks a lamp bulb or a bullet leaves a gun. Use a transistor amplifier of 1-watt rating...
Pink noise generator – Circuit Schematic
Pink noise generator
A reverse-biased pn junction of a 2N2712 transistor is used as a noise generator. The second 2N2712 is an audio amplifier. The 005 µf capacitor across the am...
Audio noise generator – Circuit Schematic
Audio noise generator
This simple circuit generates both white and pin noise. Transistor Q1 is used as a zener diode. The normal base-emitter junction is reverse-biased and goes into...
Stylus organ – Circuit Schematic
Stylus organ
IC2 is an audio frequency oscillator. Its frequency is primarily controlled by the resistance between pins 2 and 7. RV4-11 eontrol the oscillator frequency and ...
Tape recorder – Circuit Schematic
Tape recorder
Complete record/playback cassette tape machine amplifier...
Micrometronome – Circuit Schematic
Micrometronome
This compact metronome will run for years on a single nine-volt transistor battery. Has both tone and pulse rate controls, and uses touch plates to start and st...
Sound level monitor – Circuit Schematic
Sound level monitor
Loudness detector consists of a 555 IC wired as a Schmitt trigger. The output changes state—from high to low—whenever the input crosses a certain ...
Peak level indicator – Circuit Schematic
Peak level indicator
The LED is normally lit, but it will be briefly extinguished if the input exceeds a preset (by RVl) level...
Guitar fuzz – Circuit Schematic
Guitar fuzz
The 741 has a maximum gain of 20,000, but the circuit is so designed that the IC"s gain is 2,700,000 which then distorts the output. This distortion gives the f...
Fuzz box 5 – Circuit Schematic
Fuzz box 5
Transistors Q1 and Q2 amplify the incoming signal, and the gain is such that the input will overload when used with an electric guitar. RVl adjusts the amount o...