This circuit is from a 1975 RCA tube manual. It appears elsewhere on the site. R5 depends on the voltage of the amplifier with which it is used and can be changed.
This circuit, from a 1990 documentation, can serve as a basis for a game of target-game. The...
While BC547 is not a suitable transistor, it can work on this circuit. The ideal would be the...
This power supply that we found in an old American documentation uses an integrated circuit that...