Circuits similar to this can be found in this section. This is from 1967 General Electric documentation. The main SCR must be fitted with a heat sink.
We found this circuit in Popular Electronics from 1992. Time is given by C1. The circuit provides an...
A Popular Electronics from the 90's suggests this circuit that is based on a low voltage...
The frequency of a 555 oscillator depends on the capacitance of capacitor C. We can take advantage of...