Found in an American publication of 1968, this circuit makes use of a pilot light of the time. It can be replaced with LED with appropriate series resistor. Transistors may be modern equivalents.
This circuit consists of a traditional version amplifier with complementary output transistors...
This circuit is from a manual of linear integrated circuits of the 80s. The operational is of the...
Also suitable for use as a noisy alarm, this Morse Code or telegraph practice oscillator was found...