Free electronic circuit design and schematic diagram
A scope calibrator is a circuit that is used for calibrating the variable time base oscillator of general purpose scopes. This scope calibrator gives 100kHz reference, so if the scope is set to 10 cycles on 10 graticule divisions, then each division represents 10 microseconds or 100kHz. And each division will represent 1 Mhz or 1 microsecond if the scope […]
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This watt-meter circuit has measurement range up to 1-KW. This circuit can give the complete (X)(Y) function although uses only one transistor. Actually, this circuit is used for 117 Vac±50 Vac operation. For lower or lower voltage, this circuit can be modified easily. This circuit only measure power on negative cycles. The advantages of this circuit is this circuit does […]
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Using this continuity tester circuit, a failure of PCB tracks be examined without looking directly at the tracks routing, which is can be very frustrating. The indication of this circuit is done by an audible alarm (a buzzer). This circuit can be used to indicate continuity below any resistance value up to 35 ohms by adjusting the circuit. To make […]
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This is a schematic diagram of auto fuse monitor circuit. This circuit is very useful for automobile application, checking a live fuse without wasting any electrical power if the fuse is working fine. This circuit can check the fuse without removing the fuse from the working circuit. When the fuse is being tested, this fuse tester is connected across it. […]
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This is a 4-range AC millivolt meter circuit. This circuit is used to measure a AC voltage in millivolt range. This circuit has frequency response of a few Hz to about 50 kHz. The non-linearity of the rectifier circuit is eliminated by placing the rectifier inside the op amp feedback path. This circuit read the input signal’s full-wave rectified average. […]
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A meter amplifier can be designed using LM10 integrated circuit (IC). The accuracy of full-scale sensitivity is good for over 15°C to 155°C at 10mV and 100nA. Here is the schematic diagram of the circuit: R5 is used to correct the offset voltage error, while R4 is used to balance the bias current. The zero calibration uses the reference voltage […]
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Using LM134 and LM10 integrated circuits, we can build a thermometer which has -55 to 150°C sensing range. The ideal meter for this circuit is a 0-200uA digital ampere meter, which can show both positive and negative polarity. This will make the circuit suitable for indicating temperatures below 0°C. LM134 is basically a current source with very accurate and consistent […]
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