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Stereo Tv Decoder Circuit – Circuit Schematic
Stereo Tv Decoder Circuit
A block diagram of the stereo-TV decoder is shown in A. It shows the overall relationships between the separate sections of the circuit; through show the deta...
Siren Circuit – Circuit Schematic
Siren Circuit
An LM380 audio IC is configured as a feedback audio oscillator. A transistor astable modulates this oscillator at a low frequency, ...
Sound Effects Generator Circuit – Circuit Schematic
Sound Effects Generator Circuit
The circuit consists of four parts: a binary counter, a D/A converter, a VCO, and an audio output amplifier. The speed at which the counter counts depends on t...
Electronic Gong Circuit – Circuit Schematic
Electronic Gong Circuit
The electronic gong is comprised of an oscillator (built around half of a 74COON quad 2-input NAND gate), an active twin-T filter (built around a TL081), and w...
10 Note Sound Synthesizer Circuit – Circuit Schematic
10 Note Sound Synthesizer Circuit
As shown, three ICs are used to produce the sounds. ICl is a 555 timer that generates clock pulses. It is configured as an astable multivibrator. The frequency...
110Db Beeper Circuit – Circuit Schematic
110Db Beeper Circuit
This circuit will generate an ear-splitting 110 dB from 9 V. The setup uses a single 74C14 (CD40106B) CMOS hex inverting Schmitt-trigger IC, wliich must be use...
Canary Sound Simulator Circuit – Circuit Schematic
Canary Sound Simulator Circuit
This circuit generates the sound of two canaries singing in a cage. Two LM324 quad amps make up seven oscillators. One oscillator is an on/off control, the oth...
Audio Controlled Mains Switch Circuit – Circuit Schematic
Audio Controlled Mains Switch Circuit
This circuit will switch off the line supply to audio or video equipment if there has been no input signal for about 2 seconds. SI provides manual operation an...
Speech Scrambler Circuit – Circuit Schematic
Speech Scrambler Circuit
Using digital techniques, this circuit accomplishes the frequency-inversion algorithm via digitization of the audio, inversion of the sign of every alternate s...
Audio Controlled Switch Circuit – Circuit Schematic
Audio Controlled Switch Circuit
The audio-controlled switch combines a pair of 741 op amps, two 2N2222 general-purpose transistors, a hexFET, and a few support components to a circuit that ca...
Voice Activated Switch And Amplifier Circuit – Circuit Schematic
Voice Activated Switch And Amplifier Circuit
In certain applications, such as transmitter or other communications and control applications, this circuit should be useful. Both audio output and dc control ...
Audio Light Circuit – Circuit Schematic
Audio Light Circuit
This circuit will produce an output when the sound exceeds a preset level. The LM3915 is a log-output bar graph driver. Use the transistor driver shown for hig...
Voice Identifier Circuit – Circuit Schematic
Voice Identifier Circuit
Using an ISD1016 audio record/playback chip (Information Storage Devices, Inc.), this circuit records and plays back messages on command. Although intended for...
Automatic Fader Circuit – Circuit Schematic
Automatic Fader Circuit
In this circuit, audio fed to the control channel is amplified and rectified by Dl and D2. This dc level activates LED D3 via Q2. The light from D3 causes R9, ...
Sonic Kaleidoscope Circuit – Circuit Schematic
Sonic Kaleidoscope Circuit
The microphone input, MIC1, is fed through C3 and R4 to inverting amplifier U2-a; the gain of U2-a is controlled by potentiometer R5. The output of U2-a is fed...
Vocal Stripper Circuit – Circuit Schematic
Vocal Stripper Circuit
Right- and left-channel signals pass through 1 C4-a and -b buffer amps into active crossover IG5; low frequencies are sent to the IC6-c mixer, and middle and h...
Tv Sound System Circuit – Circuit Schematic
Tv Sound System Circuit
An LM2808 performs IF amplification of the 4.5-MHz sound subcarrier, limiting, detection, and audio amplification. ...
Loudspeaker Protector Circuit – Circuit Schematic
Loudspeaker Protector Circuit
Transistors Ql, Q2, and Q3 monitor the two outputs of the stereo amplifier. If the offsets exceed 2 V, Q7 is turned off, which turns off Q8 and the normally on...
Ear Protector Circuit – Circuit Schematic
Ear Protector Circuit
The ear protector is actually a peak audio-detector/shutdown circuit that disables the amplifier through its chip-disable input when the output volume of an am...
Speaker Protection Circuit Circuit – Circuit Schematic
Speaker Protection Circuit Circuit
A speaker system can be protected against amplifier failure when dc voltages (on speaker line a-b) arc sensed by the circuit. Either positive or negative dc vo...