REMOTE CONTROL

Made By:-Shivam kumar(2014161),Akshit Singh(14010)and Mohammad Nayeem(2014147)

INTRODUCTION:-

Remote controls are Consumer IR devices used to issue commands from a distance to televisions.The first remote was developed by connecting to tv by remote. It worked by shining a beam of light onto a photoelectric cell, but the cell did not distinguish between light from the remote and light from other sources. The Flashmatic also had to be pointed very precisely at the receiver in order to work.

TECHNOLOGY:-

The circuit board is a thin piece of fiber glass that has thin copper "wires" etched onto its surface. Electronic parts are assembled on printed circuit boards because they are easy to mass produce and assemble. It is also easy to have a machine drop the parts (the chips, transistors, etc.) onto the sheet of fiberglass and then solder them on to connect them to the copper wires.

Board of Remote

When you look at the board, you can see a set of contact points for the buttons. The buttons themselves are made of a thin rubbery sheet. For each button there is a black conductive disk. When the disk touches the contacts on the printed circuit board, it connects them and the chip can sense that connection.

LED

At the end of the circuit board there is an infrared LED, or Light Emitting Diode. The signal between a remote control handset and the device it controls consists of pulses of infrared light, which is invisible to the human eye, but can be seen through a digital camera, video camera or a phone camera. The transmitter in the remote control handset sends out a stream of pulses of infrared light when the user presses a button on the handset. A transmitter is often a light emitting diode (LED) which is built into the pointing end of the remote control handset. The infrared light pulses form a pattern unique to that button. The receiver in the device recognizes the pattern and causes the device to respond accordingly.Most remote controls for electronic appliances use a near infrared diode to emit a beam of light that reaches the device. A 940 nm wavelength LED is typical.The emission spectrum of a typical sound system remote control is in the near infrared.

For multi-channel remote controls more sophisticated procedures are necessary: one consists of modulating the carrier with signals of different frequency. After the receiver demodulates the received signal, it applies the appropriate frequency filters to separate the respective signals. One can often hear the signals being modulated on the infrared carrier by operating a remote control in very close proximity to an AM radio not tuned to a station. Today, IR remote controls always use a pulse width modulated code, encoded and decoded by digital computer: a command from a remote control consists of a short train of pulses of carrier-present and carrier-not-present of varying widths

Serial ports use a 10-bit protocol to transfer each character. The idle state of the serial TX pin is high. For bit 1, the start bit, the signal goes low. It is followed by the 8-bits of ASCII character data and a high stop bit (total of 10 bits). The rate at which bits change is called the baud rate. The low cost devices used in the demos will operate at 2400 baud (or bits per second (BPS) ). For the demo, both the transmitter and receiver are attached to mbed, but in a typical application they would be on different subsystem with its own processor, and physically separated by several meters.

MANUFACTURERS OF REMOTE:-

Different manufacturers of infrared remote controls use different protocols to transmit the infrared commands. The RC-5 protocol that has its origins within Philips, uses, for instance, a total of 14 bits for each button press. The bit pattern is modulated onto a carrier frequency that, again, can be different for different manufacturers and standards, in the case of RC-5, the carrier is 36 kHz. Other consumer infrared protocols include the various versions of SIRCS used by Sony, the RC-6 from Philips, the Ruwido R-Step, and the NEC TC101 protocol.

On pressing the button the circuit gets completed

POWER SUPPLY (BATTERY)

PREESING BUTTON (Each button have a thin rubber which has black conductive disk below it)

Pulses of infrared light ray come out through

LED.

(different for different button)

Receiver

(TV,AC or any electronic device)