Low battery indicator

Posted on Apr 29, 2012

Under good battery conditions the LED is off. As the battery voltage falls, the LED begins to flash until, in the low battery condition, the LED lights continuously. Designed for a 9-volt battery, with the values shown the LED flashes from 7.5 to 6.5 volts.

Low battery indicator
Click here to download the full size of the above Circuit.

The transistor is the BFY90 and the IC is the SN72741P.

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