Free Simple Circuit Diagram
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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Bell103A modem standard specify that the originator (the caller) uses 1070Hz and 1270Hz frequency shift keying for transmission, and listen for 2025/2225Hz FSK transmitted by the answering modem. This bandpass circuit filter out any frequency beyond 2025-2250 Hz to improve originator’s decoding of the received FSK signal. Here is the schematic diagram of the circuit:
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This is a transistor crowbar circuit for overvoltage protection. This circuit is used to protect any devices, when the overvoltage occurs. This circuit consist of diode, transistor, and resistor, and a fuse. The device that needs to be protected should be connected in parallel with the transistor. The 1N87 diode cut off the transistor across supply line until overvoltage occur. […]
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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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