Low Voltage Alarm Circuit Schematic With explanation

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.'

Parts

Part Total Qty. Description Substitutions R1, R3 2 1K 1/4W Resistor R2 1 5K Pot U1 1 LM339 Op Amp IC D1 1 1N5233B Zener Diode D2 1 LED BZ1 1 Piezo Buzzer MISC 1 Board, 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.s
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