This circuit produces sounds of 6 different notes depending on the keys activated. The circuit is from a Radio Electronics from May 1965. The transistor must be equipped with a heat radiator.
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...