Found in a 1965 CQ magazine, this circuit uses period components. The unijunction transistor can be a 2N2646 and the relay has voltage according to the supply.
Found in a 90s Electronic Design, this circuit produces a pure 3 750 Hz sinusoidal signal. The...
This circuit, from an American publication of 1974, provides a 0.005% regulation with a variation of...
This circuit was found in a 1970 US publication. Transistors are still common and the circuit can be...