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Two-state-siren – Circuit Schematic
Two-state-siren
This is a two-state or on/off-type siren where the LM13080 oscillates at an audio frequency and drives an 8-0 speaker. ...
Siren – Circuit Schematic
Siren
This circuit uses one of the LM389 transistors.to gate the power amplifier on and off by applying the muting technique. The other transistors form a cross-coup...
Super-sound-generator – Circuit Schematic
Super-sound-generator
Six preset controls and seven selector switches enable a vast range of different sounds to be produced and altered at will. Such sounds as steam trains chuffin...
Two-tone-siren – Circuit Schematic
Two-tone-siren
This siren provides a constant audio output, but alternates between two separate tones. The LM13080 is set to oscillate at one basic frequency; ...
Electronic-bagpipe – Circuit Schematic
Electronic-bagpipe
This circuit mimics the dual-tone drone sound that"s produced by the unusual wind instrument. Urnjunction transistors Ql and Q2 are connected in similar audio-...
Audio-generator – Circuit Schematic
Audio-generator
This circuit produces a sinusoidal output of about 8 V pk-pk, which can be varied down to zero, at about 500 Hz. ...
Four-channel-mixer – Circuit Schematic
Four-channel-mixer
No description available. ...
Simple-mixer – Circuit Schematic
Simple-mixer
This mixer is built around a TL072 dual BiFET op amp with a JFET input stage, and can be powered from a single-ended 9-to 18-V power supply. The microphone inp...
Signal-combiner – Circuit Schematic
Signal-combiner
This circuit uses buffer stages to prevent channel crosstalk back through the mixer resistor network. The potentiometers used for each stage allow for conven...
Electronic-music – Circuit Schematic
Electronic-music
ICl, a 555 timer, is set up as an astable multivibrator to produce the signal that triggers IC2, a 7490 decade counter. That IC, in turn, produces a BCD output...
Central-image-canceller – Circuit Schematic
Central-image-canceller
The circuit allows you to eliminate the vocal portion of an audio signal, while leaving the instru mental portion. The circuit mixes two channels that must be...
Tracer-receiver – Circuit Schematic
Tracer-receiver
The tracer receiver is a stereo audio amplifier/detector circuit operating near 1 kHz. Inductors Ll and 12-hand-wound coils, consisting of 200 turns of #26 wir...
Sound-level-meter – Circuit Schematic
Sound-level-meter
Sounds are picked up by MIC1 and fed to the input of the first op amp. The signal is then fed to the input of second op amp Ulb, where it is boosted again by a...
Stereo-power-meter – Circuit Schematic
Stereo-power-meter
The Stereo Power Meter is made up of two identical circuits and a power supply. Each circuit contains Jwo LM3914 display chips which contain 10 voltage compara...
Noise-limiter – Circuit Schematic
Noise-limiter
This circuit is fed from the earphone jack of your receiver and goes to limiter control R6 and is then amplified by Ql: a common-emitter stage that has a volta...
Hands-off-intercom – Circuit Schematic
Hands-off-intercom
Amplifier A increases the microphone"s output to a usable level. The output signal is fed to op amp B, which inverts the signal180°. A balance-control poten...
Intercom – Circuit Schematic
Intercom
This intercom uses a single audio IC as a twoway amplifier, and the speakers as microphones. ...
Bidirectional-intercom-system – Circuit Schematic
Bidirectional-intercom-system
This system uses p.A759 audio IC devices and a common connection between the preamps as an interconnect. Either mike can drive either speaker. ...
Stereo-indicator – Circuit Schematic
Stereo-indicator
On most FM tuners, the stereo indicator lights upon detection of the 19-kHz pilot tone. However, this doesn"t mean that the program is actually stereophonic, s...
Biquad-audio-filter – Circuit Schematic
Biquad-audio-filter
This universal filter offers low-pass, high-pass, bandpass, band elimination, and all-pass functions. The Biquad consists of two successive integration stage...