This circuit uses a novel approach
to produce a fully isolated and regulated 5 volts @30ma from the 120vac power line. It
uses two tiny SCRs that alternately discharge two capacitors through a miniature high
frequency transformer. The voltage spikes produced through the transformer are
rectified, filtered and regulated. A very common 8 ohm audio impedance matching
transformer can be used for the transformer.
Published in EDN, Feb. 17, 1992