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Low Voltage Alarm

This low voltage circuit can be used to monitor batteries and other volatile sources of current for problems. The circuit sounds an alarm and lights an LED, but can be interfaced to any number of other circuits for many different uses.

Schematic


Schematic for Low Voltage Alarm

Parts:


Part
Total Qty.
Description
Substitutions
R1, R321K 1/4W Resistor
R215K Pot
U11LM339 Op Amp IC
D111N5233B Zener Diode
D21LED
BZ11Piezo Buzzer
MISC1Board, wire, socket for IC

Notes:

1. The circuit will operate from 9V to 12V.

2. Adjust R2 until the alarm goes off at the correct voltage.

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