21-12-2010, 05:20 PM
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Infra Red Remote Control
In modern electronics, electronics remote control system is well known system. Infrared remote control kits available in the market are quite expensive and it some one wishes to assemble one, their IC’s may not be easily available. More over for simple ON-OFF function such as controlling a lamp or fan we do not need very complex circuit.
The IR remote control circuit using photodiode and phototransistor sensor suffer from major drawback of being affected by ambient light and a very low range. The IR remote control circuit described here can be used for any simple ON-OFF function. This system has memories application than other remote control system. The advantage is that this circuit is absolutely free form ambient light interference and provides control range of any to focusing lens. The components use in this system is in so convenient manner that whole assemble is easier to built. This reduce complex city of the system.
The advantage of this circuit lies in the fact that it can easily be converted into a multichannel remote control system. The system comprise two unit transmitters, Receiver both transmitter and receiver can be assembled on a general purpose PCB. Transmitter section consist of power supply, on oscillator and in output stage including IR LEDs in the transmitter section IC 555 is wired as an a stable multivibrator with a Centre frequency of about 36 KHz. The transmitter is powered from a GP 22 size gv. Battery. The receiver uses IR sensor module which is commonly used in colour T.V. for sensing IR Signal from transmitter section. The IR signal from the transmitter sensed by sensor and it’s output at pin and goes low which is in turn switch on transistor T1 (BC 557) consequently capacitors start charging through resister R5, when voltage across capacitor C8 reaches about 3.5V IC 2 (Decade counter 4027) receive a clock pulse at pin 14 and it’s output at pin 2 goes high. This result in forward biasing of transistor to (be 148) which energies a really connected at it’s collector. The output of IC 2 (pin 2) is also used for lighting LED, indicating presence of signal for this circuitry 12V-0-12V 25 mA transformer is used for supplying the power & IC 7805 is used for 5 V regulation purpose at it’s output. This regulated 5 v output is given to receiver section (4027).