similar circuits
- Circuit Board Checker
- Simple Logic Probe
- Live Line Detector-Indicator Circuit Schematic
- DC or AC Voltage Indicator Circuit
- Low Voltage Alarm
- Self-powered Fast Battery-Tester
- Logic Probe
- Picoammeter circuit with 4 ranges
- Precision Audio Millivoltmeter
- Digital Voltmeter
- Analog Milliamp Meter Used as Voltmeter
Low Voltage Alarm
Description
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.
Circuit diagram
Parts:
- R1, R3 1K 1/4W Resistor
- R2 5K Pot
- U1 LM339 Voltage comparator IC
- D1 1N5233B Zener Diode
- D2 LED
- BZ1 Piezo Buzzer
- MISC Board, wire, socket for IC
Notes:
- The circuit will operate from 9V to 12V.
- Adjust R2 until the alarm goes off at the correct voltage.
circuit from http://www.aaroncake.net/