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.
Found in 1968 Mullard documentation, this circuit uses period components. The transistors are...
In the figure we have a modified multiplier circuit that can operate with the sextuplicator with...
This circuit converts signals from the 350 to 500 kHz band to the 4.36 to 4.5 MHz band, enabling...