This circuit was found in a Popular Electronics from the 90's. Its purpose is to detect the ionization of the air. The meter can be replaced by the current scale of an ordinary multimeter.
This circuit for igniting gas flames was found in a 1967 Electronic Design. The SCR firing device is a...
This circuit, which can generate voltages up to 25 V, was found in the December 1992 issue of...
This circuit was obtained from a 1966 General Electric documentation. It can serve as a basis for...