Found in 1980s Electronic Engineering, this circuit uses common phototransistors as sensors. The circuit is CMOS using an integrated 4011.
We can either supply this circuit with 12 V if we use a relay for this voltage as well as 6 V if...
Two NAND gates are used in the configuration shown here to perform as a monostable triggered by...
Frequency and active cycle of this circuit are fixed by the two crystals that may have different...