VOX (Voice-Operated Switch)

This schematic diagram below show a circuit of VOX Box (voice-operated switch). This circuit consist of a Schmitt trigger, a relay driver, and microphone preamplifier. The microphone preamplifier(U1) receive input signal which will be amplified. THRESHOLD control (R8) is fed by the amplified signal. The trigger’s output goes high when the preselected threshold voltage level is exceeded. Here is the […]

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Opto-Coupled Discrete Pulse Stretcher

This is a pulse stretcher circuit using optocoupler. This circuit uses a 4N26 opto-coupler combined with a standard one-shot circuitry. This circuit is triggered by pulse about 3μs (minimum width)  at 15mA. The output’s amplitude of this circuit is not depend on the input’s amplitude. The output pulse amplitude is a function of (or proportional to) supply voltage on the […]

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Radio Buttons Using Push On Switch Latching Circuit

This is a switching circuit that provide latching mechanism to make a set of radio buttons using push buttons. This circuit consist of interlocking circuit that manipulate the signal to latch and release the previous latched section. The circuit latches the output when one of button is pushed and previous selected output will be unlatched. The  latch of each input […]

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