The article explains how to make an RF remote control circuit using ready-made RF modules and without incorporating microcontroler ICs.

With the easy availability of RF modules today making an RF remote control has become a childs play.

It's all about procuring the RF modules ready made from the market by spending a few bucks and configuring them together for the intended results.

Here I'll show you how to make an approximately 100 meter range RF remote control circuit using RF modules, without the help of any microcontroller stage.

To begin this you will have to procure the following readymade RF modules and the respective encoder and decoder chips, for the present project we use the HOLTEKs modules:

RF 433Mhz Transmitter/Receiver Modules


The following picture shows the Rx (left) and the Tx (right) Modules.





The following figure shows the pinout details of the above modules.






Encoder IC = HT12E



Decoder IC = HT12D






The above encoder and decoder ICs do the jobs exactly as per their assigned names that is encode and decode the bit information for enabling easy interfacing with analogue circuits.

After you have procured the above components it's time to put them together.

Assembling the Modules


Configure the transmitter circuit by assembling the Tx (Transmitter) Module with the Encoder IC as given in the following circuit:





Next, assemble the Rx (Receiver) module with the decoder IC, as per the following diagram:



In the above Rx (receiver) circuit we can see that four of its outputs are terminated through LEDs at the points A.B,C,D and another output which is terminated via the VT pinout of the IC.

The four outputs A,B,C,D become high and latched in response to the pressing of the  four push buttons shown in the Tx transmitter) circuit.

Pin13 switch of Tx influences the Pin13 output of the Rx and so on....

Suppose when output "A" of the  Rx module is activated by the relevant switch of the Tx, it gets latched and this latch breaks only on activating any of the other outputs.

Thus the latch breaks only when a different subsequent output is rendered high through the Tx relevant push buttons.

The output from pin VT "blinks" momentarily every time one of the outputs A,B,C,D get activated. Meaning VT output can be used in case a flip flop is required to be operated.

The above can be very easily interfaced with a relay driver stage for operating any equipment such as a remote bell, lights, fans, inverters, automatic gates, locks, RC models etc.

How to Connect the Address Pins


The pinouts A0-----A7 of the Rx, Tx modules are very interesting. Here we can see them all grounded which creates an impression that these are of no use and are simply terminated to ground.

However these pinouts enable a very useful feature.

These address pinouts can be used for rendering a particular Rx, Tx pair uniquely.

It's simple, let's say for pairing the above modules we ensured that the address pins are identically configured.

Alternatively we could make the above pair unique let's say by opening A0 for both the modules. This will make the pair respond only with each other and never with any different module.

Similarly if you have more number of such pairs and want to make unique pairs out of them, just assign the pairs in the explained manner. You can do this by either connecting the address pins to ground or by keeping them open.

It means by rendering different configurations to the relevant address pinouts between A0 and A7 we can create a huge number of unique combinations.

The range of the above explained RF module is around 100 to 150 meters.

The above circuit was successfully tested by Mr. Sriram on a breadboard, the following images of the built prototype were sent by him for reference.

Circuit Prototype Images






Making a 433 MHz, 315 MHz RF Remote Control with Relay Flip Flop


Building a hi-end remote control device using very few components today looks pretty plausible. The proposed remote control light switch circuit idea provides you with the opportunity of building and owning this amazing device through simple instructions.

Moreover the unit provides a 4-bit data to be exchanged between the transmitter and the receiver modules.

This Hi-tech remote control light switch enables you to control four individual lights or any electrical appliance for that matter from any corner of your house remotely using a single tiny remote control hand set.

Imagine switching a light, a fan, washing machine, computer or similar gadgets from any corner of your room without taking a step!

Doesn't that sound great?

Controlling a particular gadget remotely through a single flick of your finger definitely feels very amusing and amazing too.

It also gives you the comfort of doing an act without moving or getting up from a particular position.
The present circuit idea of a remote control light switch enables you controlling not only just a single light but four different electrical gadgets individually using a single remote control hand set.

Let’s try to understand its circuit functioning in details of the 433MHz Rx and Tx modules.

Transmitter (Tx) Simulation and Working










I have already discussed the wireless control modules through one of my previous articles, let’s summarize the entire description yet again and also learn how simply the stages may be configured into the proposed unit.

The first figure shows a standard transmitter module using the RF generator chip TWS-434 and the associated encoder chip the HOLTEK’s HT-12E.

The IC TWS-434 basically does the function of manufacturing and transmitting the carrier waves into the atmosphere.

However every carrier signal needs modulation for its proper execution, i.e. it needs to be embedded with a data that becomes the information for the receiving end.

This function is done through its complementing part – the HT-12E 4-bit encoder chip. It has got four inputs, which can be triggered discretely by giving them a ground pulse individually.

Each of these inputs produces coding which are distinctly different to each other and become their unique signature definitions.

The encoded pulse from the relevant input is transferred to the IC TWS-434 which carries forward the data and modulates it with the generated carrier waves and finally transmits it into the atmosphere.
The above operations take care of the transmitter unit.

Receiver (Rx) Simulation and Working




433 MHz Receiver (Rx) Simulation and Working

The receiver module does the above operations just in the opposite manner.

Here, the IC RWS-434 forms the receiving part of the module; its antenna anticipates the available encoded pulses from the atmosphere and captures them immediately as they are sensed.

The captured signals are relayed forward to the next stage – the signal decoder stage.

Just like the transmitter module, here too a complementing device the HOLTEK’s HT-12D is employed to revert the received encoded signals.

This decoding chip also consists of a 4-bit decoding circuitry and their outputs.

The received data is appropriately analyzed and decoded.

The decoded information gets terminated out through the relevant pin-out of the IC.

This output is in the form of a logic high pulse whose duration depends on the duration of the ground pulse applied to the encoder chip of the transmitter module.

How to use a Flip-Flop Relay Circuit at the Receiver module Output


The above output is fed to a Flip-Flop circuit using the IC 4017, whose output is finally used to switch the output load via a relay driver circuitry.

One such flip/flop idea is shown you may construct four of them to access each of the generated 4-bit data discretely and control four gadgets individually.





Whether you use it as a remote control light switch or to control many more appliances……the option is all yours.

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