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This is a LED Analog Meter, This can be used as a Resistance Meter and Low Impedance Voltmeter for Battery Levels. To measure battery voltage, the R5-R12-R17 etc. part of the Reference Resistor Divider Network can be modified to suit. Shown here is for 4 LEDs, Use Three LM324 for 12 or More LEDs and [...] This is easy to rig millivolt source for field calibration or troubleshooting of 4-20 mA current loops. Here a Darlington pair is used for current amplification which reduces the Ib error as gain is very high. A rotary switch selects, 4-12-20 mA Preset points. A Bourns multi-turn wirewound Pot can also be used with a digital [...] Here is a current source you can build for resistance measurement. When the current is held constant, you know as per Ohm’s Law the Voltage across Resistor is proportional to Resistance value. The supply is +12 and -12, The total voltage across R6 + R7 is 24V. Then 24V / 120K = 0.2mA. The voltage across [...] Measurement of resistor values in circuit configurations are required to be made often, as these might have changed in value due to various tolerance ranges, and hence could be the cause of faults. Likewise the resistance of components used in a circuit, may need to be known. In such cases the measurement of resistance is [...] |
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