Suggested by a 1968 Motorola power semiconductor manual, this circuit uses a special transformer and transistors from the era. The frequency is 60 Hz.
This circuit is from a Radio Electronics issue of May 1972. It consists of a commercial heating...
Found in the American 73 magazine for radio amateurs, this circuit can test common quartz...
This circuit is from the 1995 National Semiuconductor Linear Application Handbook. The technique...