This circuit shows that we can implement a voltage-controlled oscillator with almost any CMOS that can be connected as an inverter. The circuit is from Radio Electronics from January 1987.
Any general-purpose germanium or silicon PNP transistor can be used on this receiver. The handset...
When this circuit is activated the LED flashes for a moment indicating that the function has been...
In the circuit of the figure, when pressing S1 the sound varies according to the value of R2 and...