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
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.
Title: Low Voltage Alarm
electronic circuit
Source: www.aaroncake.net/circuits/
Published on: 2005-02-10
Reads: 851
Print version: 
Other electronic circuits and schematics from Security and other sensors and detectors
-
Sound Operated Switch
-
Color Sensor
-
Power supply failure alarm
-
Electronics Telephone Talking Circuit
-
4 channel Telemetry System
-
Electronic Lock
-
Mains Remote-Alert
-
Theft preventer alarm
-
Factory Siren
-
Infrared beam barrier/ proximity sensor