This circuit was published in an article in Radio Electronics magazine in October 1988. It uses components that are still common today, except for the sensor, which is a special type from that time.
This circuit was obtained in a 1989 English magazine. Despite using a fixed 5 V regulator, it can...
With the feedback of the output circuit, the monostable acts as a frequency divider, that is, it...
In this circuit of an old American documentation, the input impedance is the same as the output...