This circuit was found in an article in Radio Electronics magazine. The issue is from July 1992 and the circuit uses components that are common today.
With a strong positive feedback (via a 10 M resistor) we can get the trigger setting for the...
Light falling on the transistor changes both the mark and the space of the generated signal thanks to the...
This circuit monitors the humidity of a pot or plant bed, providing indication on two LEDs. The...