This circuit is better than the previous one in that the control is isolated by a transformer. The transformer has 110 or 220 V primary and 6.3 to 12 V secondary with 200 to 500 mA current.
An oscillator that can be frequency controlled by a resistive sensor is shown in the figure. The...
The idea of this circuit from a 1960 publication is simple: we can switch the transistor being...
This circuit was found in a Radio Electronics from February 1966. With it it is possible to trace...