Quote Originally Posted by sirvo View Post
Hello..

This situation of 250mA draining can occur for 40seconds and no more than that. Is it normal for the 7805 to get hot? Should I use a heat sink?

ps.. i can let my finger on it when it's full loaded.

thanks...

Sylvio
Yes...and yes. You are dissapating ~8 volts at .250A which is two watts. I believe the regulator will eventually fail without an adequate heat sink. You can also put a 6 volt .25A bulb in series with the battery supply line to drop the voltage. The advantage to this is you will know when the relays are activated.
Ron