I found this circuit in a documentation for radio amateurs from 1975. The FET could be the BF245. The circuit works in the range of 40, 80 and 160 meters of radio amateurs.
This circuit can linearly control the temperature of showers, taps or heaters up to 2 500 W. The...
May 2017 - Microchip LAN8710A and LAN8710Ai integrated circuits, low-power, high-performance...
This is a circuit suggested by Linear Technology in a 1980s documentation. The integrated circuit is from...