Building an RF remote control

The easiest solution would be to take a cheap wireless toy car take out its receiver module along with its remote and use them in your robot. The other way round is this to make your own RF remote .

We will be using ASK (Amplitude Shift Keying) based Tx/Rx (transmitter/receiver) pair operating at 433 MHz. The transmitter module accepts serial data at a maximum of XX baud rate. It can be directly interfaced with a microcontroller or can be used in remote control applications with the help of encoder/decoder ICs.

RF Receiver Transmitter Module

The encoder IC takes in parallel data which is to be transmitted, packages it into serial format and then transmits it with the help of the RF transmitter module. At the receiver end the decoder IC receives the signal via the RF receiver module, decodes the serial data and reproduces the original data in the parallel format.

 

RF communication flowchart

 

Now in order to control say a dc motor, we require 2 bits of information (switching it on/off) while we need 4 bits of information to control 2 motors. HT12E and HT12D are 4 channel encoder/decoder ICs directly compatible with the specified RF module. The schematic is as shown below.

 

RF transmitter

RF receiver

 

In order to drive motors, we would need to connect a suitable motor driver at the output of the decoder IC. The motor driver circuit can consist of a relay, transistorized H-Bridge or motor driver ICs like the L293D, L298 etc. 

The example above shows the receiver section using the HT-12D decoder IC for a 4-bit RF remote control system.  Similarly the transmitter and receiver module can also use the Holtek 8-bit HT-640/HT-648L remote control encoder/decoder combination for an 8-bit RF remote control system.

 

Driving a motor through NPN

Driving a motor using PNP

 

Here we have used a flyback protection diode to prevent the damage of the diode. The data output of the decoder ICs should be connected to base of transistor (as shown in the figure).

Tip: Also note that we can also use a Darlington pair ULN2803, as it will provide higher voltage and eliminate the need of flyback diode (as it has an internal diode for protection.

 

Download the datasheets of encoder/decoder -

 

 

  

Comments

Member since:
23 August 2009
Last activity:
7 years 16 weeks

can i get the IC's HT12E and HT12D from a distributor in nigeria?

Member since:
23 August 2009
Last activity:
7 years 16 weeks

good day

 is the tx and the rx module in the RF remote control system a single IC or a RF circuit diagram?if it is a single IC,what is the IC?

Member since:
22 August 2009
Last activity:
8 years 16 weeks

Hello,

 

Can anyone design a program in C to send a bit HIGH (1) to the input of a relay circuit to turn on the relay?

 

Thank you

 

Ed

 

Member since:
13 August 2009
Last activity:
8 years 17 weeks

In this type  of RF remote control above, can we operate the receiver and the transmitter with 1.5 volts batteries size AA, or AAA, or mini lithium battery 3 volts?

 

Thank you.

Member since:
13 August 2009
Last activity:
8 years 17 weeks

Please some suggestions

Member since:
13 August 2009
Last activity:
8 years 17 weeks

Hi there,

 

I would like to build a RF REMOTE CONTROL with an ask receiver module that can operate from 4.9 to 5.1 volts, and an ask transmitter module that can oprerate from 3 to 12 volts. the system should control two motors bi-directional. Therefore, can I operate the rceiver and the transmitter with 4 batteries 1.5v size AA or 1.5v size AAA, or mini battery lithium 3v?

 

Thank you.

Member since:
15 March 2009
Last activity:
8 years 18 weeks

yes u can... 

Member since:
26 July 2009
Last activity:
8 years 20 weeks

please some suggestion.

Member since:
24 June 2009
Last activity:
8 years 17 weeks

hello...

can i use push switches in encoders pin AD8, AD9, AD10, AD11 to provide data...???

Member since:
26 July 2009
Last activity:
8 years 20 weeks

Hi,

All the above posts provide examples of either switches or parallel port to control the bot. i want to achieve the same using the pc serial port.

i need your suggestion/help on designing a circuit that will do the follwoing.

1. take the serial input from pc and transmit it to the bot.

2. At bot end the receiver will pass the output to some circuit that will provide parallel output and based on the bit which is high turn the corresponding relay on.

 

Thanks in advance.