Sunday, May 24, 2015

Make a Hi-End RF Remote Control Circuit


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. Build the “amazement” right on your workbench.
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.


Circuit Description



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.







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.
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.

Saturday, May 23, 2015

Wireless Transmitter and Receiver using ASK RF Module

Wireless Transmitter and Receiver using ASK RF Module

A wireless radio frequency (RF) transmitter and receiver can be easily made using HT12D Decoder, HT12E Encoder and ASK RF Module. Wireless transmission can be done by using 433Mhz or 315MHz ASK RF Transmitter and Receiver modules. In these modules digital data is represented by different amplitudes of the carrier wave, hence this modulation is known as Amplitude Shift Keying (ASK). Radio Frequency (RF) transmission is more strong and reliable than Infrared (IR) transmission due to following reasons :
  • Radio Frequency signals can travel longer distances than Infrared.
  • Only line of sight communication is possible through Infrared while radio frequency signals can be transmitted even when there is obstacles.
  • Infrared signals will get interfeared by other IR sources but signals on one frequency band in RF will not interfeared by other frequency RF signals.

Transmitter Circuit Diagram

ASK RF Transmitter
ASK RF Transmitter
HT12E Encoder IC will convert the 4 bit parallel data given to pins D0 – D3 to serial data and will be available at DOUT. This output serial data is given to ASK RF Transmitter. Address inputs A0 – A7 can be used to provide data security and can be connected to GND (Logic ZERO) or left open (Logic ONE). Status of these Address pins should match with status of address pins in the receiver for the transmission of the data. Data will be transmitted only when the Transmit Enable pin (TE) is LOW. 1.1MΩ resistor will provide the necessary external resistance for the operation of the internal oscillator of HT12E.

Receiver Circuit Diagram

ASK RF Receiver
ASK RF Receiver
ASK RF Receiver receives the data transmitted using ASK RF Transmitter. HT12D decoder will convert the received serial data to 4 bit parallel data D0 – D3. The status of these address pins A0-A7 should match with status of address pin in the HT12E at the transmitter for the transmission of data. The LED connected to the above circuit glows when valid data transmission occurs from transmitter to receiver. 51KΩ resistor will provide the necessary resistance required for the internal oscillator of the HT12D.