RF remote control circuit designed with 434 MHz ASK (Amplitude shift keying) transmitter and receiver, Here IC HT12E act as encoder and IC HT12D act as decoder, this circuit is constructed with easy available components. This remote gives approximately 150 meter coverage by extending the ariel wire it can be increased up to 200 meters.
This project has two stages that is 1. Transmitter circuit, 2. Receiver circuit first we go with transmitter circuit design.
Transmitter circuit diagram
This circuit has three stages they are
- Input switch
- Encoder IC HT12E
- RF transmitter (434 MHz ASK module)
The input switches are connected with encoder ICs data pin, these switches decides the on / off condition by turn on any switch we connect data input pin of encoder ic to the ground, the oscillator pins connected with 1 MΩ resistor because the encoder ic has internal oscillator, Address lines A0 to A7 of encoder is terminated to the ground which is used for address data encoding with unique identity but we don’t need these pins in this project. Output Dout pin 17 is connected with data pin of RF transmitter then the encoded data from IC HT12E is converted as RF signal by ASK transmitter chip and transmitted through air, an ordinary wire is enough to transmit RF signal in short distance by choosing ariel or antenna we can transmit RF signal to long distance.
Receiver circuit diagram
This receiver circuit also has three stages they are
- RF receiver (434 MHz ASK receiver module)
- Decoder IC HT12D
- Output data line
The RF receiver receives RF signal that is transmitted by ASK Transmitter module, and gives output through pin 2, this signal is fed to input pin 14 of decoder IC HT12D, here the Address pin A0 to A7 are terminated to the ground as done in encoder IC, hence we ensure the same address in transmitter and receiver circuit, the decoder IC provides the data output from D3 to D0 pins, this outputs are same as per the switch conditions in transmitter circuit.
ASK transmitter module
ASK Receiver module
You can get datasheet of IC HT12E here.
You can get datasheet of IC HT12D here.