This circuit was found in Motorola's Linear Interface ICs of 1993. The integrated circuit used is not common and the load current depends on the Triac.
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...