I have a 4-30 current controlled setup. At 6VDC, I am able to maintain 5mA constant. I switch polarity by means of simple switch. The switch is made after the constant current. I would like to switch polarity automatically. What is the simplest circuit to do that? I would like to see a switch made about every 5 minutes or have the ability to increase or decrease the timer, but 5 to 10 minutes would be ok. As I am not an electronics expert I need the simplest solution. I managed the constant current with a few resistors, a diode, and some other 3 connector thing of which I do not the name. Any help would be greatly appreciated. Thanks!