i got 2 of these from another pack rat he said they date from the 80's i tested them with a light bulb and they work ok i can not find a datasheet for them would one of these, a rectifier, and capacitor work for a stepper power supply http://www.ebay.com/itm/Lot-of-6-Douglas-Randall-Proportional-Controller-Model-R15A-120V-15A-/150800378506 richard