We found this circuit with duty cycle adjustment in the May 1988 Radio Electronics magazine. The source must be symmetrical, and the frequency given by R3 and C1.
This circuit is suggested by General Electric in 1966 documentation. The Triac must match the...
This circuit was suggested by Popular Elecronics from the 90's. The circuit has high input...
This circuit is nothing more than a turn signal for two alternating LEDs that can decorate a robot...