This circuit was found in General Electric's 1965 documentation. It appears elsewhere on the site. The SCR and the diodes must be in accordance with the motor current.
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...