ljm

Hello,

I would like to make a power supply that is:

1. Constant Current
2. Auto shut off when reaches a certain amperage, voltage, or resistance
3. The ability for this power supply to alernate the polarity back and forth, such as A/C does, not 60 Hz but like every 30-60 seconds to switch the polarity. (If possible and easy to make it A/C that would work also)


I'm looking to use about 30 volts and around 50mA current. The auto off could be around 450 ohms of resistance on the variable resistor (water bath is the variable resistor). I not opposed to using a wall wart for a power source, and add the remaining circuits to make it all happen or could make a power supply from a board mount transformer. Thanks for any help anyone can be. I hope I posted enough information to go on.