Remote control for light switches 2

Just like the associated hand-held transmitter (see previous article), the receiver is simple to construct. As can be seen from the circuit diagram, parallel tuned circuit Li-C, receives the transmitter signal, which is first buffered by means of a dual gate MOSFET - Ti - in order to pre- vent excessive loading of the tuned circuit. Further amplification is per- formed by T2, before rectifier circuit Di-C6 can provide a pulsating voltage to T3, which drives PLL detector IC, with a sawtooth-like signal. The lock output-pin 8-of IC, controls Re, via relay driver circuit T4 Ts As to a few details concerning the receiver circuit, the PLL chip signals the lock condition by pulling pin 8 low; C14 is charged and functions as a buffer device in case the PLL input voltage disappears because of the fact that the transmitter coil is no longer held steady for optimum reception (directive effect of the fer- rite rod). At the receiver input, Ri should be mounted direct at the rel- evant...