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.
This conventional series reducer circuit reduces the voltage of a 12 V battery to the selected value...
In the figure we have a converter that generates a negative voltage from a positive voltage...
This circuit covers the bands from 1.8 to 150 MHz, with plug-in coils whose characteristics are...