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.
We found this circuit in the March 1980 Radio Electronics magazine. The circuit used is the HA2400...
This simple circuit can be used in a robot that follows the light directly feeding a small motor....
This circuit was found in a telecommunications publication of 1978. Its purpose is to obtain...