LED Voltage indicator  

Voltmeter Circuits
Added on
Nov 15, 2012
When the input voltage is 0 the LED glows. The LED stops glowing when the voltage rises to the level determined by R2. Reverse + and - pins to reverse operating mode. To set voltage at which LED goes off, (1) Set 0V at input. (2) Set input voltage at desired level. (3) Adjust R2 to point right after LED goes out.
LED Voltage indicator - schematic

Parts List D1 LED R1 1.2k Resistor R2 10k Var. Resistor U1 UA741 OP AMP

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