Free electronic circuit design and schematic diagram
Using the circuit shown in the schematic diagram below, we can control the low-level audio signals with ±3V variable DC voltage. This attenuator circuit uses a field effect transistor (FET) to shunt the signal to ground. The R2 is used to control the output level (the attenuation level), but you can use other source of voltage signal to control the […]
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This is a schematic diagram of video amplifier circuit with bi-phase output. Bi-phase output provides both positive-going and negative-going signal, and can be used as balanced signaling. The main component of this circuit is LM1201. In this circuit, the inverted video is obtained at pin 10 because of the 75Ω termination to the power supply voltage. The voltage divider on […]
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This amplifier circuit is very popular audio power amplifier circuit type. We call it a complementary since the final transistors is an NPN-PNP pair, each with the same characteristics. This circuit produce an AB class amplifier, since each transistor works in slightly more than half cycle of the signal. There is overlap area when both transistor conduct a current, […]
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Interfacing high power load can be done in many ways, such as using voltage divider resistors, transformer, or optocoupler. In the circuit shown below , an optocoupler method is presented. This optocoupler serve the logic level translation with flexible input, accepting wide range of voltage level, which is suitable for many high power load/devices. To couple a high-voltage load to […]
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Logic indicator circuit / logic probe is used to identify logic level at any point of logic circuitry. The indicator can be visual (using LED, LCD, of 7 Segments) or auditory (using beeper or speaker). This circuit has a audible indicator, with the help of a loudspeaker to produce indication tone. Using the opamp,U1, as schmitt trigger, the Audio oscillator […]
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Ni-Cad (NiCd, NiCad) battery, sometimes doesn’t work as expected, gives no power and cannot be recharged. In this situation, the battery need to be reconditioned. It’ is possible that the battery is internally shorted, and we can get the battery into life again by recondition the Ni-Cad battery using a zapper circuit. This circuit restore the Ni-Cad battery from shorting […]
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A Wien-Bridge oscillator circuit can be built from HA2541 and some basic components. This circuit can generate good-quality sine wave of 40 MHz with an upper limit of 50 MHz. The R3 through R7 and D2 and D1 provide the diode limiting for this circuit. Here is the schematic diagram of this circuit: For frequency stability, this circuit need a […]
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