4 Channel Transmitter and Receiver Introduction : Hello Friends today I will show you how my transmitter and receiver works on laser and photodiode .So in our project we have used HT12E as a encoder in transmitter and HT12D as a decoder in receiver. Working : In Encoder there a 1M resistor is connected b/w pin 15 and 16 of HT12E then it oscillates and makes high frequency signals to pin 17 that's the data out pin the we connect 1K resistor to base of npn transistor and connect laser with NPN transistor and 4 push buttons are connected from pin 10 to 13 respectively and common pin to GND now transmitter is ready. For the long rang and better connectivity we use laser for transmitting signals to our distant receiver when we point laser to photodiode then HT12D decodes and receivers signals and our 4 channel transmitter and receiver works. Here Pinout of HT12E : ...