This circuit uses an optocoupler with a phototriac or optotriac to drive an external triac. The circuit is from a Radio Electronics magazine from December 1989.
We found this circuit in an American documentation from the 60s. The circuit can be made with...
This three-chanel remote control transmitter uses a unijunction transistor as low frequency...
This digital potentiometer is from a 1993 publication, but it can be easily assembled today. R1 to...