General Electric suggests this circuit in an 80's documentation. The circuit makes use of PUTs that are not common components today. Note the timing components that may change.
This step-down converter with 10 to 60 V input produces a 5 V output with a maximum current of 5...
Found in an old American documentation, this step has as input and output transformers coupling. Two...
This circuit was found in a 1963 magazine, but can still be easily assembled with some current...