Published in an old Popular Electronics, this circuit makes use of components that are still current. The circuit must be powered with 9 V and eventually adapted to function as a shield.
The CMOS 4046 integrated circuit is not very common today, consisting of a very efficient PLL for...
In the circuit shown in the figure to the side, the relay is activated when the light stops...
With this name, the English publication where we found this circuit indicated a sensitive touch...