We found this circuit in a 1987 documentation. It is a multi-tester with neon lamp and LEDs operating with both low continuous voltage and high alternating voltage.
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...