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 circuit was found in English documentation from the 90's. Transistors are general purpose types....
This instrumentation circuit is from the June 1986 issue of Radio Electronics magazine. Equivalent...
This is an interesting idea that we found in the May 1971 issue of Radio Electronics magazine. It can...