We found this battery eliminator in a Radio Electronics magazine from August 1974. The transistor must be equipped with a heatsink and other voltages can be achieved by replacing the zener.
We found this circuit in an old documentation. The instrument can be an ordinary multimeter in the...
This simple electroscope with bipolar transistors is not the most sensitive, but can detect static...
This circuit was found in an old Popular Electronics. It causes an LED to pulse and, at the same...