This circuit, to control air conditioning systems, was found in July 1984 Radio Electronics magazine. The circuit is for old types of the time that did not have microcontroller control.
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...