GBARC

The Georgian Bay
Amateur Radio Club

APRS

Est. October 18th, 1973
P.O. Box 113, Owen Sound, Ontario Canada N4K5P1

Automatic Power Off circuit

A while back we got the APRS bug here and it wasn't too long before trackers were being ordered and built and set up with that old rig we couldn't use for much else. It didn't take long and I forgot to turn the rig off and the next day when I tried to start the vehicle, the battery was dead. As a matter of fact I did this several times, and before long the battery was a dud and had to be replaced. So this situation could not go on, first step, I replaced the rig with a Kenwood TM-241a which has a nice memory feature and an lcd display. Then I came up with this circuit, an collection of ideas from the web and a bit of trial and error. It looks at the battery voltage when the vehicle is off and then when the engine is running. Things are explained on the circuit diagram below.

Use of this information is the sole responsibility of the internet visitor and is accepted by the user 'as is', with no warranty whatsoever. The www.gbarc.ca website or club is not responsible for any harmful or erroneous information or action resulting from the use of this information.

Fuses should be added to the control circuit as well as the rig supply, you are responsible to select the correct size and rating

This circuit is simply an experiment offered to radio amateurs to modify, improve and utilize in their pursuit of the hobby. If you would like to include it on your website, please make a reference to this site..73