The Triac trigger integrated circuit is not very common nowadays. The circuit was found in the Radio Electronics Experimenter magazine from 1989. The triac should be in accordance with the heater.
Found in 1965 Delco Radio documentation, this circuit uses transistors from that era. Modern...
This circuit was obtained in a 1979 publication but can still be easily assembled today by...
This receiver was found in a documentation by Gernsback from 1960. The circuit uses high impedance...