This circuit was found in the March 1984 issue of Radio Electronics magazine. The sensor is a transistor. The module is a common type at the time.
Suggested by an American documentation for 1969 neon lamps, this circuit provides SCR control with...
This circuit is designed to measure very weak currents, in the order of picoamperes. We found it...
The 709 integrated circuit is not common today. The circuit is from American technical...