IR Remote Controls for Satellite TV, VCR, DTV, TV, DVD player
Audio and video components today almost always have a remote control. These handheld devices allow the user to sit back in a comfortable chair or sofa and control the power on/off, play, stop, volume up/down and similiar functions of components such as a TV, DVD, receiver or set-top-box.
Most remote controls today operate using infra-red (IR) light signals where the remote control is the transmitter and the audio/video component is the receiver. Depending on which button is pushed on the remote, a coded light signal is sent out across the room and the A/V component interprets the coded signal and acts on it. The IR light signal is invisible to the naked eye because it is of a frequency below human eye sensitivity and detection. Our eyes do not see these frequencies in the electro-magnetic spectrum.
It is interesting to note that today's digital cameras and mobile phones are indeed able to detect these IR light signals and in fact you can use your digital camera or the mobile phone camera to test your remote control to determine if it is working or not.
How to test your IR remote control
Most often, if your remote is not working it is because your remote's batteries are weak or drained completely. Installing a new set of batteries will more often than not get the remote working again. However if someone has abused the remote or changed the setup and you are not sure if the remote is broken or what is going on, you can use a digital camera to test it.
1. Make sure you have new batteries in the remote control.
2. Power on the digital camera as you normally would to take pictures.
3. Make sure you have a dark background.
4. Hold the remote in one hand in front of the camera, pointing it at the camera as if you were going to send a signal towards the camera lens. You should be able to see the remote on the digital camera's LCD display.
5. Look at the camera's LCD display and press a button on the remote.
6. If the remote is working, you should see a small solid circle of light, purple/blue in color on the camera's LCD display. Each time you press a button on the remote, you should see the light on the camera's LCD viewer.
7. If you do not see a circle of light, then your remote could be broken or your camera is filtering out IR light.
Testing a IR remote control using a digital camera
A new Universal remote control costs about $8 if you need to replace one for a standard TV, VCR or DVD player. They usually have all the codes you need, all you have to do is setup the proper device you own in the remote, such as your TV or DVD player. Sometimes you need an exact replacement remote and in this case you may find one on E-Bay or from the original manufacturer, but it may cost much more.
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IR Remote Controls:
A remote control is made up of two plastic outer pieces, top and bottom which house the inner parts, and the keys you press for each function. The inner parts do the work and consist of the batteries, an infra-red LED or light emitting diode, a chip or integrated circuit and several resistors, capacitors, transistors and a resonator all mounted on a printed circuit board which connects all the parts in the proper way.
The chip is packaged in what is known as an multi pin Dual Inline Package, or a DIP. The chip can detect when a key is pressed. It then translates the key into a sequence or code, with a different sequence for each key. The chip sends that signal out to the transistor to amplify the signal and make it stronger. The signal then goes to the LED for transmission out to a device only in the case of a infra-red LED, the light signal is invisible to your eyes.
Of course the whole process depends on the device that receives the signals. The device that receives the signals from the remote has to be capable of decoding the sequence of light signals and acting appropriately upon them. Just sending out signals from any remote will not work unless the receiving device is compatible. Different manufacturers use different codes in their remotes and even within the same manufacturer they use different codes for various devices. This is why you have to setup a universal remote to work with a certain device.
How does the IR code work?
IR remote controls use light waves in the Infra Red part of the electromagnetic spectrum. The physical communication is formed by the emmiter (a photo diode) that emits the signal and a receiver (another photo diode) that receives the signal.
The light waves are modulated by the emitter. This is done in order to eliminate other sources of IR light that may interfere with the remote control.
The data or codes are made up of binary pulses like a computer uses. Different techniques are used such as Pulse coded
where the length of the pulse is varied to represent data. In other words (in binary code) a one is a longer pulse than a zero. Space coded and Shift coded are other ways to interpret data. This all happens very fast, in milliseconds, and digital processing is required to execute the codes.
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