Found in a 90s Popular Electronics, this circuit makes use of power MOSFETs. Equivalent MOSFETs can be used. The circuit acts as a shield.
This interesting circuit for testing NPN and PNP transistors for general use and medium power was...
We found this circuit in a 1986 documentation. It uses only LEDs, batteries, resistors and the...
Published in Radio Electronics in January 1963, this circuit uses 5 transistors of the time. The...