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.
The simplest filter for this purpose is the one shown in the figure consisting of two coils and...
We found this automotive alarm circuit in a 90's Popular Electronics circuit. The circuit emits a...
This basic op amp filter configuration was found in July 1975 Radio Electronics magazine. The...