We found this circuit in the magazine Eletcronics Now of July 1994. The power supply is according to the relay and the transistor can be any general purpose one.
Suggested by Philips in a 1970 publication, this circuit uses components from that time. No...
This circuit is designed to measure very weak currents, in the order of picoamperes. We found it...
This circuit was found in an American documentation from the 80's. The transistor is a...