This circuit of the 70's uses transistors of the time. The circuit can amplify signals from 10 Hz to 100 kHz and modern equivalent components can be used. The circuit is from Ferranti.
Also suitable for use as a noisy alarm, this Morse Code or telegraph practice oscillator was found...
The figure shows a white noise generator circuit that uses a transistor junction to generate the...
Flybacks are no longer misused. However, if the reader wants to recover an old analog television...