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 obtained in the 1977 RCA CMOS manual. The circuit has the frequencies determined by the...
We found this circuit in a 2004 documentation. The circuit consists of a standard lamp for testing...
Found in a Popular Electronics of the 90s this configuration can be seen elsewhere on our site....