This circuit appears in several versions in publications of the time and can be modified by changing the capacitors. This one is from Radio Electonics magazine from October 1992.
This circuit is from a documentation from the 60s. The circuit can be built with transistors like...
Found in a 1966 General Electric documentation, this dimmer should only be used with incandescent...
To control relays safely with double insulation, we suggest the circuit in the figure. The optical...