This power supply is nothing more than a dual-circuit 12VAC outdoor lighting transformer housed in an acrylic case with three pairs of binding posts for each circuit.  Each circuit can supply 20 amps.  This power supply is particularly useful for building circuits out of 12V light bulbs.

You can power three bulbs separately from each circuit.  You can create series lamps on one circuit and parallel on the other.  You can use combinations of 25 watt (2 amps each) and 50 watt (4 amps each) 12V bulbs.

If you connect too many bulbs—or create a short circuit—and draw over 20 amps on a circuit, a circuit breaker may pop.  If your lights go out, press the white round circuit breaker buttons on the top of the black transformer box.  The square circuit breaker is the 120V line cord and should not pop first.