Found in a 1960s RCA documentation, this circuit applies to most common triacs. The trigger device is a neon lamp and the sensor is an LDR. R is typically 100k and C is 220 nF.
This circuit provides a 60 Hz or 50 Hz precision clock or time base, depending on the network. It serves...
With the values of the indicated components, this oscillator produces a sinusoidal signal of 1...
I found this circuit in a Popular Electronics from November 1999. The magazine is no longer...