Found in old documentation, this circuit can use modern equivalent components. The signal has good strength thanks to the use of a power transistor. The Q1 transistor is a unijunction of the time.
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...