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12V monitoring circuit needed.

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2Gunz

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Hi Im new to the site and have a specific circuit in mind. Forgive me it its been covered already.

Im looking for a simple circuit that is able to monitor low voltage DC and trigger a warning light if the voltage is to low.

It will be used basically as a "dummy" light to indicate if a cars alternator is working or not.

So.... It looks at the cars voltage and if its below 12.5 volts it turns on a red LED. Once it goes above 12.5 volts the red Led goes off or changes the LED to green.

Anyway I realize cars already have this. But Im looking to do this to a classic car that came stock with an amp gauge. I dont want to replace the amp gauge with a voltage gauge and ruin the look of it. However it would be nice to know that the alternator is working properly.

Im also interested in some sort of voltage meter that looks like it belongs in an old car. This is for another project.


Once again thanks for your help, and great forum.
 

on1aag

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Hi 2Gunz,

This will do the trick, at 6 volts the red led will light and at 12,5 volts
the green led will take over from the red led.
Here's the datasheet:

https://www.alldatasheet.com/datasheet-pdf/pdf/67448/INTERSIL/ICL7665.html

60_1180804951.gif


on1aag.
 

    2Gunz

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2Gunz

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Your awesome thank you!!

Few Questions as the diagram is a bit hard to read.

So parts its......

2 X 130K

1 x 15k

1 x 36k

1 x 1k

1 x 10 ? Capacitor

And Chip # ICL7665


Few questions....


If I want to change the 12.5v to say 13v or to 12v what would I change?

Is there a chain store that would have this stuff in stock?

If not wheres a good place to order online.


Once again thanks alot.
 

IanP

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You can do the same but with 555-timer configured as voltage comparator .. see picture below ..
The LM555 (or any 555 IC) is just easier to get than the ICL7665, and every store near you should have them in stock ..

Regards,
IanP
 

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