Suggested by Intersil in documentation from the 90's, this circuit is valid for modern operating equivalents, including types that operate with low voltages.
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...