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.
LTC7841 PolyPhase® Synchronized Boost Controllers Mouser Announces Analog Devices LTC7841...
This circuit was found in a 1987 edition of the United States' Hands On Electronics magazine. The...
This circuit can be made usng the TIP32 transistor but must use carbon microphone (not very common these...