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 obtained from an old American documentation, and practically any general-purpose transistor...
This circuit is intended for monitoring an environment. It fires a relay with a sound, but only if...
This circuit is from an old documentation, but perfectly current. In place of the battery, 2 or 4...