This sensitive circuit was found in the June 1995 Electronics Now magazine. R1 can be from 10k to 1M depending on the desired sensitivity. Power is supplied by the relay.
This circuit is from a 1967 General Electric SCR manual. The capacitors are polyester and the...
This oscillator for frequencies up to a few tens of kilohertz was found in a 1970s documentation. The...
This varicap-less modulator circuit was found in an Electronic Design from the 90's. The circuit...