We found this circuit in a Popular Electronics from the 90s. Transistors can be modern equivalents. Observe the high supply voltage.
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...