The transformer in this power supply can have a secondary winding from 1 to 15 A of current. Voltage is given by the zener diode. Transistor 2N3055 must be mounted on a good heat radiator.
This 3-transistor circuit is from a Radio Electronics magazine from May 1963. The transistors used...
This is the traditional configuration for a limit comparator or window comparator, using two...
This circuit was found in a 1966 General Electric publication. The circuit applies to other triacs...