Mains Remote Control: Encoder

This application can actually be considered to be a slight adaptation of the standard use of the Holtek HT12E encoder (www.holtek.com). We have used this IC several times already, so it does not need any further explanation. The small circuit described here is intended to be used as an extension to the ‘Mains Remote Transmitter’, but it also clearly illustrates how the IC can be used in a non-standard manner.The HT12E is normally used with its internal oscillator by connecting a resistance between the OSC1 and OSC2 pins. Here we instead use the carrier frequency of the transmitter.

Resistors:
R1 = 1kOhm 
Capacitors:
C1,C2 = 100nF
Semiconductors:
IC1 = HT12E Holtek (Farnell)
IC2 = 4066
IC3 = 4040
Miscellaneous:
K1 = 4-way SIL-header
S1 = 8- way DIP-switch
S2 = 4- way DIP-switch
S3 = pushbutton, 1 make contact