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intermittent voltage alarm

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New Member
Hello this is my first post!

I haven't touched electronics for about 10 years since i was 16, but I'm starting to get into it again. I have really basic knowledge of electronics. not so good with logic in circuits though.

I'm wanting to build a circuit which intermittently checks the voltage of a battery (every 10 mins to an hour) and if it is below or above a certain value to sound a buzzer. I'd buy a device if i could find something that does this but it looks like ill have to make one.

the circuit discussed in this thread looks like it would be close -

but I need to alter it to be done intermittently so it doesn't drain the battery. would there be any other circuits here i could look at to connect the two together?

thanks for any help guys.


Active Member
What kind of battery?

Several friends of mine have developed applications for microcontrollers where the operation of the circuit consumes so little current that battery life is barely affected. They would put the microcontroller into what I understood to be "sleep" mode.

If you have the time and motivation to learn the basics you might use a microcontroller - PIC or otherwise. For my own applications I took some time to work with a PIC. What I learned is that there is an investment that needs to be made - more time than money. The money part can be quite inexpensive as many here will tell you. I set the PIC aside for another time. I have looked at PICAXE as a simple way of doing some simple things - that might be a place to begin.

Any battery has standby losses. You may find that the current required by whatever you do is only a very small amount anyway. It's hard to comment on this without knowing more about the battery.


New Member
sealed lead acid. 4.2Ah 12v.
beacause i am doing careful measurement of its input/output, i was thinking of running the circuit on a seperate battery and using a relay to check the voltage on the test battery.
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