What device does everyone use for draining condensate from your air compressor tanks ? 

I already have a water separator in line and drip legs with valves below each outlet but was looking for ideas on the tank itself. Currently it has a rather unhandy petcock on the tank that is difficult to open and close. I have seen a solenoid operated push button device that dumps collected moisture but have no leads on where to find what I'm looking for. Is this too elaborate an idea or would a simple extension and ball valve on the bottom be a better idea. Drain plug size is 1/4" pipe thread.