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.
ON Semiconductor AMIS−3910XGEVB Evaluation Board demonstrates the features and capabilities of the...
This circuit was obtained in a Popular Electronics of the 90s. It against a kitchen hood based on...
The original version of this circuit was found in an old English publication that comes to...