Found in a 1964 General Electric documentation, this circuit uses PUTs that are not currently common components. By changing the capacitors, the frequency can be changed.
This circuit was found in an Elektor from the 90s. The integrated circuits are not very common...
With this circuit, a well known configuration, small speakers and even low-impedance headphones...
Found in RCA documentation two years 70, this circuit triggers an incandescent lamp at dusk. The...