This circuit can operate with different voltages, depending on the zener used. We found it in a 90s American documentation.
This 1-transistor circuit appeared in a February 1962 Radio Electronics. The coils for the...
This recyclable automatic timer was found in Radio Electronics magazine from July 1960. The...
This transistor tester was found in a publication by Gernsback from 1960. The circuit can be used...