Youritronics member Florin brings you a wonderful design that enables you to add an Auto-OFF feature for 15 mins in your old and cheap digital multimeter(DMM). With this you can save your battery consumption even if you forgot to turn-OFF your DMM.
To add the Turn-OFF feature, you will be requiring a very few components like – microcontroller (tiny25 in the present case), a voltage regulator, a npn transistor and the associated capacitors and resistors. The circuit is powered from the multimeter 9V battery and cuts off the ground path to the meter to turn off its power.
The source code and Eagle based circuit schematics are accessible on github here. Also you can find the complete design steps at Florin’s post here.Â
