We found this circuit in a 1996 publication. The circuit uses components that are still common. The timing depends on C1, which can be changed, and the triac can be of any type.
This circuit consists of a speed regulator for direct current motors. The integrated circuit used...
When the sensor of this circuit is cut for a moment, the second 555 produces a tone for a time...
This circuit for generating precise reference signals was found in the April 1973 issue of Radio...