Low Voltage Alarm


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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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Comments

Add A Comment

Kashinath
Low Voltage cut off circuit at 3V for 1A load current
Friday, November 15, 2013 12:12:19 AM
hi everyone.. I need to provide battery back up facility to my one project. so for that purpose i used Li-ion battery(Max 4.2V/ 1A) to provide the supply to load. so i need to cut off the load at 3V. can i use above circut for that purpose?? please anyone help me. Thanks in advances
saurabh
Low Voltage Alarm
Tuesday, May 01, 2012 10:42:02 AM
where do we give the i/p and take the o/p and i hve a 9V battery and 12V zener would it work
anonymous
Low Voltage Alarm
Wednesday, January 04, 2012 1:44:37 PM
What if I have a 12 volt battery and want it to alarm me when it drops to say 9 to 10 volts. How does this work?
bhanu pp
Low Voltage Alarm
Monday, April 18, 2011 1:19:29 PM
nice ckt
Doug
Low Voltage Alarm
Tuesday, March 01, 2011 8:51:26 PM
Substituted a HA17339 for the LM339, used a 6.2V zener, a 2.2V (green) LED and a 6K POT. Left out the piezo buzzer. The circuit works like a charm.
ARSALAN AFRIDI
electronics
Thursday, December 23, 2010 2:40:39 AM
AOA I WANT CONSTRUCT THE WATER FLOW ALARM CIRCUIT SO PLZ KINDLY HELP ME ABOUT THIS PROJECT ME WAITING OF YOUR REP AND PLZ SEND THE DEMO CIRCUIT FOR TH E IDEA ,,, THANK YOU DEAR
Prash
Low Voltage Alarm
Friday, April 16, 2010 3:25:43 PM
Nice project..it works perfect..Thank u!
Taylor
Low Voltage Alarm
Friday, March 12, 2010 8:27:35 AM
The schamatic I downloaded had the Zener backwards and the LED stayed on. Turned around and worked great. Made another on for my neighbors stored RV battery. Thanks
Terry
Low Voltage Alarm
Sunday, January 31, 2010 8:37:43 PM
hi, i cannot get a 6v zener diode in New Zealand, will a 5.6v or a 6.2v work instead?
Ritesh Agarwalla
Low Voltage Alarm
Thursday, December 10, 2009 9:21:30 AM
I am planning to trigger the 12V Cutout at 11V so please suggest me the alternative for 5k pot.
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