This very low current circuit was found in the April 1995 Electronics Now magazine. The frequency should be chosen for maximum efficiency according to the small transformer used.
This 1969 Mullar circuit appears elsewhere on this site. The circuit uses germanium diodes and the...
For reference only, this is the second IF amplifier stage of a common transistor radio from the...
This electronic variac has the traditional configuration with triac already explored on the site,...