CHANNEL RF

BASED REMOTE

CONTROL

M.ABHISHEK

T.JAGADISH

S.PRAVEEN

INTRODUCTIONWHY IR…? WHY NOT RF…?

• Radio frequency controlled devices. RF based remote controls do not

have to be pointed and also have a better range, going through doors and

walls. Even better, radio technology is as reliable and almost as

inexpensive as infrared.

• Yes, the radio-based remote control is past due, and the infra-red based

remote control is on its way out, even to the point that within a few

years we will look back with amazement at such antique IR powered

remote controls and marvel at the fact that we had to point and shoot to

control our home entertainment systems.

• These RF remote controls will easily transmit through walls and cabinet

doors, and enable “two-way” communications.

• Channel radio frequency based remote control is the circuit in which this

circuit utilizes the RF module (TX/RX) for making a wireless remote,

which could be used to drive an output from a distant place. RF module,

as the name suggests, uses radio frequency to send signals.

COMPONENTS

• Micro Controller(AT89S52)

• RF MODULE TRANSMITTER (HT12E)

• RF MODULE RECEIVER (HT12D)

• SWITCHES

• LED

Why Microcontroller?

• Microcontroller contains microprocessor, memory (RAM

& ROM), I/O interfacing circuit and peripheral devices

such as A/D converters, serial I/O, timers etc.

• It has many bit handling instructions.

• Less access times for built-in memory and I/O devices.

• Microcontroller based systems requires less hardware

reducing PCB size and increasing reliability.

PIN DIAGRAM OF

MICROCONTROLLER

POWER SUPPLY UNIT• Initially power supplies are designed to convert high voltage AC mains

electricity to a suitable low voltage supply for electronics circuits and other

devices. A power supply can by broken down into a series of blocks, each of

which performs a particular function. A d.c power supply which maintains the

output voltage constant irrespective of a.c mains fluctuations or load variations

is known as “Regulated D.C Power Supply”.

• Transformers convert AC electricity from one voltage to another with little loss

of power. Step-up transformers increase in output voltage, step-down

transformers decrease in output voltage. Most power supplies use a step-down

transformer to reduce the dangerously high mains voltage to a safer low voltage.

There is no electrical connection between the two coils; instead they are linked

by an alternating magnetic field created in the soft-iron core of the transformer.

Transformers waste very little power so the power out is (almost) equal to the

power in. A step-down transformer has a large number of turns on its primary

(input) coil which is connected to the high voltage mains supply, and a small

number of turns on its secondary (output) coil to give a low output voltage.

POWER SUPPLY UNIT

• A circuit which is used to convert a.c to dc is known as RECTIFIER. A bridge rectifier makes use of four diodes in a bridge arrangement to achieve full-wave rectification. This is a widely used configuration, both with individual diodes wired and with single component bridges where the diode bridge is wired internally.

• A Filter is a device which removes the a.c component of rectifier output but allows the d.c component to reach the load.

• Voltage regulator ICs is available with fixed (typically 5, 12 and 15V) or variable output voltages. Negative voltage regulators are available, mainly for use in dual supplies. Most regulators include some automatic protection from excessive current ('overload protection') and overheating ('thermal protection'). Many of the fixed voltage regulator ICs has 3 leads and look like power transistors, such as the 7805 +5V 1A regulator shown on the right. The positive lead of unregulated DC power supply (anything from 9VDC to 24VDC) is connected to the input pin, connect the negative lead to the Common pin and then the power is turned, gets a 5 volt supply from the output pin.

WORKING

• The RF module, as the name suggests, operates at Radio Frequency. The

corresponding frequency range varies between 30 kHz & 300 GHz. This RF

module comprises of an RF Transmitter and an RF Receiver.

• The transmitter/receiver (Tx/Rx) pair operates at a frequency of 434 MHz.

The RF module has been used in conjunction with a set of four channel

encoder/decoder ICs.

• The encoder(HT12E) converts the parallel inputs (from the remote switches) into

serial set of signals. These signals are serially transferred through RF to the

reception point. The decoder is used after the RF receiver to decode the serial

format and retrieve the original signals as outputs. These outputs can be observed

on corresponding LEDs.

SCHEMATIC

ADVANTAGES

• Not line of sight means it can penetrate through most solids and

pass through walls.

• Longer range.

• RF allows two-way communication.

• Not as sensitive to weather/environmental conditions.

DISADVANTAGES

• Interference: communication devices using similar frequencies -

wireless phones.

• Lack of security: easier to "eavesdrop" on transmissions since

signals are spread out in space rather than confined to a wire

• Higher cost than infrared

APPLICATIONS

• Commonly used in remote control of TVs, VCRs and CD players

• Home automation.

• Commands can be sent directly to the robot.

CONCLUSION

The adoption of RF remote controls is going to

change how we interact with the world around us

as well as how we take care of our environment.

Bye-bye IR. Hello, RF.

BIBLIOGRAPHY• 8051 Microcontroller: An Applications Based Introduction

by David Calcutt, Frederick Cowan, and Hassan Parchizadeh

• 8051 Microcontrollers, Hardware, Software, and Applicationsby D. M. Calcutt

• C and the 8051by Tom Schultz

• www.atmel.com

• www.circuitxpert.com/blog/2009/04/4-channel-rf-remote-control

• http://www.coolcircuit.com/project/rf_remote/

• www.electronicsmaker.com/em/admin/pdf/free/4%20channel%20RF%20remote.pdf

• www.wikipedia.com

THANK YOU

QUERIES ???