This 1965 circuit uses a Philips 4068 tube to measure extremely small charges. The circuit has as indicator a micro ammeter and the transistors are of the time.
This old radio with a germanium transistor was obtained from an English documentation from the...
Found in an old American publication, this article is suitable for incandescent lamps. SCRs can be of...
We found this circuit in 1967 General Electric documentation. SCRs can be replaced by current...