The presented circuit uses an opto-SCR. We found the circuit in the GE semiconductor manual. Equivalent triacs, depending on the load current and voltage, can be used.
This traditional doubler configuration with the 555 IC can be found in other articles on the...
This traditional circuit with a neon lamp is a flip-flop that draws which of the two lamps will...
This sophisticated circuit is from old Motorola documentation, using common integrated devices...