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:
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. 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.
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.