This is a linear DC supply I built on an old Aerotron 1093 sub-chassis. It was part of some old Aerotron repeaters I salvaged many years ago. The Aerotron 1093 has a nice 50A capable transformer, and a basic VR board underneath. I installed a circuit breaker on the AC mains, some computer grade can-type filter caps, used a LM-317 VR ic, and a buffer stage. I built a basic latching type over voltage interrupter, triggered by a 1w 15v zener. 3ea 2N3055 pass transistors were fitted onto an ample heat sink for output control. A little cheapie digital voltmeter was installed to keep an eye on things. I installed a bridge to allow for a backup battery to be connected for full uninterruptable capability. Cost was about $0, as it was all "junk box stuff", my favorite! Here's a few pics of the project...
A nice clean, flat line on the DC when viewed on the scope. Even when loaded to 30+ amps, the ripple was almost non-existent.
Dave WB4IUY
