Using an LDR, this Philips circuit directly activates a relay when light strikes the sensor. The relay is 45 V with 20k coil resistance. The 220 nF capacitor must be polyester for 400 V.
Placed in the vicinity of a telegraphic transmitter (CW), this circuit produces an audible signal on...
This circuit for light data transmission (visible or IR) has a maximum speed of 1 Mbps and can be...
This circuit aims to recover electrolytic capacitors by applying currents higher than normal for a...