Found in a 90s Popular Electronics, this circuit checks if a remote-control transmitter is emitting signals. The sensor is a general-purpose type found in many electronic devices.
This circuit for audio signals was found in the March 1990 Radio Electronics magazine. The circuit...
In the figure we have the way to implement a sinusoidal oscillator with the 4093 IC. The component...
Equivalent transistors, like the BC548 and BC558 pair can be used in this circuit that we find in an...