This power supply puts out 24V DC if plugged directly into the wall socket or 0 - 24V DC if plugged into a variac that feeds it 0 - 120V AC. I made this power supply from scratch using plans on the Low Voltage Power Supply section of Samuel M. Goldwasser's high voltage generator page. Initally I'd intended it just for powering a 30kV high voltage power supply but I've since found plenty of use for the low voltage range, 0 to 24V. The output is through banana plug connectors.

The 24V power supply is on the left. The red thing on the right is a variac. Plug it into the wall and it gives you AC output in the range 0 - 120V. I plug the 24V power supply into the variac.	Inside view. Even the case is homemade.
Here it is all connected together powering my 30kV power supply which is on the left. The red tube thing at the back is a Fluke 80k-40 40kV high voltage probe which is feeding the analog meter on the right.	Label from the transformer.