Readers are advised to proceed with the construction of the presented circuits only after understanding the concepts from the core. Not adhering to this can lead to failures and frustrations.

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Thursday, December 22, 2011

RF Remote Control Encoder and Decoder Chip Pinouts Explained

Making your own universal remote control systems today is very easy. Such procure the relevant chips, assemble them and here goes, your hi-tech remote control device is working for you.
Here we explain a couple RF 433kHz remote control chips especially designed for the purpose. The IC TWS-434 along with its encoder chip HOLTEK’s HT-12E form a high class transmitter circuit, whereas the chip RWS-434 through its complementing decoder IC HT-12D operates as the receiver module. Both of the above modules are able to exchange 4-bits of discrete data for control four external loads separately.
With the easy availability of accurate remote control chips, making your own universal remote control modules is today just a matter of few hours. We discuss a couple of compact RF remote control transmitter and receiver modules here using the chips: HT-12E, HT-12D, TWS-434, RWS-434
Making a hi-end professional remote control system at home is a child’s play now. With the advent of micro remote control encoder and decoders chips, making a RF remote control is today a matter of a few hours or rather minutes. Applications of remote controls made from these chips are countless; you may use it for controlling practically any electrical gadget that you can think of, the best application being for car security systems.
A couple of RF remote control chips, the TWS-434 and the RWS-434 both complement each other, the first one being the transmitter and the later one the receiver.
The chip TWS-434 is basically a tiny 4-bit transmitter module, which is able to transmit 4 types of coded signals discretely, whereas the RWS-434 exactly compliments these signals by receiving them and generating 4 discrete decoded signals at its outputs.
However both the above primarily functions just as wireless sender and receiver and therefore require external encoders and decoders to be integrated for the said operations.

Understanding the Transmitter Module

A couple of HOLTEK’s encoder and decoder chips HT-12E and HT-12D work in conjunction with TWS-434 and RWS-434 respectively to produce the desired ideal universal remote control operating parameters.
Referring to the diagram alongside, we find a straightforward RF transmitter configuration using the chip TWS-434 and HT-12E.

The IC TWS-434 has in all 6 pin outs, 1 and 2 are the positive inputs, 3 and 4 are to be grounded, 6 receives the 4-bit encoded signals, pin 5 being the antenna for radiating the received signals.
The 4-bit encoding is done by the IC HT-12E. The wiring of this IC is also very simple; all its 1 to 9 pin-outs are shorted together to ground.
Pin 16 and 15 are coupled to each other through a 750 K resistor.
Pin-outs 10, 11, 12, 13, all receive 4 discrete data simply through the connections of the respective pins to ground via a push button switch.
Pin 14 confirms switching of the transmitter signals when connected to ground via another push button.
Pin 17 is the output and conveys the processed 4-bit ata to the IC TWS-434 for the final relay. Pin 18 is for the positive supply input

Understanding the Receiver Module

The diagram alongside shows a similar configuration to the above, but with exactly the opposite transits.
Here, the chip RWS-434,s antenna receive the data transmitted by the above transmitter module and sends it to the IC HT-12D for the necessary decoding of the 4-bit data which ultimately is decoded and produced at the respective outputs for driving the connected loads.
Understanding the pin-outs of the IC RSW-434 is pretty simple, pin 1, 6 and 7 are all shorted to ground.
Pin 4, 5 go to the positive supply.
Pin 2 outputs the received data to the decoder IC and pin 8 serves as the antenna.
The decoder chip HT-12D has its entire pin from 1 to 9 fixed to the ground potential.
Pin 15 is connected to 16 through a 33 K resistor as per its specs.
Pin 14 receives the information received by RSW-434 and after decoding the processed data is obtained from the pins 10, 11, 12, 13 respectively, which is further fed to the output driving circuit for activating the connected gadgets.
Both the modules of the above universal remote control work satisfactorily through a regulated 5 volt power supply unit.


  1. Hi swagtam

    i need your help remember you load circuit for over voltage and under voltage protection on Bright hub.
    can you tell me the part number for I wants to use The Ultimate High/Low Voltage Protector Circuit but i don't know what kind of part number to use for Transformer and for Relay. Part numbers from digikey.

    also i wants to use this ckt for a


  2. Hi Kristin,

    Welcome to my blog...

    The transformer is 0 - 12V, 500mA and the relay is 12 V, 400 Ohms, SPDT type.

    Thanks and Regards.

  3. hi
    how can i connect load in the receiver circuit?

    1. By using a resistor, transistor and relay network at any one output of the decoder chip

  4. hi,
    i made this ckt.
    but the ckt is not running ???

    1. Hi,

      The above circuits were taken from the manufacturers datasheet, you may check the following link to get more information about these chips:


  5. Hi ,so what does pressing the switches for pins 10,11,12,13 in the transmitter actually do and lets say to activate a transistor as a relay would you have to add anything? thx

    1. You'll have connect the flip flop to the relevant output of the second diagram as explained in the article.

    2. but why cant you connect the base of the transistor directly to the output pins of the decoder ? and can the 4 pins be used as 4 switches for 4 different circuits? such that when you activate pin 10 on the encoder it provides and output in the pin 10 of the decoder and when you activate pin 11 on the decoder it provides output in pin 11 of the decoder and so on. thx a lot for your help

    3. Yes you can connect via a limiting resistor, but the transistor and the subsequent relay will be ON as long as the Tx button remains depressed and will switch off when Tx buton is will not flip/flop.

      The 4 decoder outputs correspond to the 4 encoder switches.

  6. I am having problem with the circuit.I need to transmit 8-bit, so i used TPS12codec but no result can you tell me how to check the encoder/ decode. The TPS12CODEC can be configured as both encoder and decoder. pleae mail me a solution at...

    1. I am sorry I have no idea about it since I have never used it practically.

  7. hello..i used the same ckt shown above..but am not gtng any result..i hav checkd all the connections..when i checkd the voltage at all the points,and i found that voltage at the address pins is not zero..instead m gtng a potential of 2.5 smthng..can u plz suggest me sugst wt might b the possible error.

    1. I have put everything as per the manufacturers datasheet, I have never used these personally.....

  8. ok..i got that..but now the prblm gtng a voltage of 2.04V at the data out pin of rws 434..even if i remove the transmission circuit..i.e. without any reception..reciever is showing a voltage at its data out pins..what cn b the possible reason..

    1. You can refer to the following site and the to the given links that's been included there, it might help.

  9. hi i have seen rf tx'r contains 4 pins .. here u hav made tx'r 6 pin connection to encoder how is it possible. could you explain clearly......

    1. the outputs are four only, the extra pins are unused or are shorted.

  10. Will it be secure what if another person would build the same circuit will that person be able to control the output What can i do to make more personalize like the remote for the car alarm. Can i used a dual tone multiple frequency encoder decoder with the transmitter

    1. The possibility can be eliminated by configuring the address pins uniquely for the particular Rx/Tx sets.
      Suppose you disconnect all the address pins A1 to A10 of the Rx module and select A1 and A2 only for the ground connections, and you do the same with the Tx module....this will make the two unit compatible and paired with each other uniquely and will not respond to other modules in the vicinity which could have a different address pin configuration.

      In this way you can select different sets of address pins and group them with each other or with ground (identically for both the modules) for creating unique pairs.


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