Found in a 90s Elektor, this circuit makes use of general-purpose transistors, except T4 that can be replaced by an equivalent.
This amplifier was found in a Japanese publication in 1972. Transistors are uncommon today, and...
The current of this source is 200 mA at the most, and the output depends on the zener that may...
Found in Mallory documentation from 1968 this circuit uses an integrated circuit from that time. The...