The circuit shown is from National Semiconductor's Linear Applications Handbook. It makes use of the LM78S40 which is not an easy component to obtain today.
We adapt this circuit of Radio Electronics - March 1990. The magazine no more exists, but the...
This circuit is a digitally controlled variable capacitor. We found it in American documentation from...
In the circuit shown in the figure, when the input voltage rises to 27 V, the TL431 triggers the...