We’ve all done it. You point the tv remote at the tv and press the button, but nothing happens. Immediately you think, “When was the last time I changed these batteries?” If the answer is long ago, you might change them, but if the lights on the remote light up or it was very recently, you start to wonder if something else could be wrong.
To most people, the remote control is a magical thing that they don’t understand whatsoever. You know you press buttons and stuff happens. You might know that it shoots out infrared light, but that’s about the extent of it.
I used to work for a company that did all sorts of fun things with remote control in large, expensive houses, so I thought I’d share a little more about it.
If you watch the video above (sorry that the audio is quiet), you’ll see me hack a remote to extend the reach of the IR over a longer distance. Basically, the remote just produces an electrical signal that turns the LED on and off rapidly and the device “sees” that flashing pattern and does what its programming says to do as a result.
Since, it’s just an electrical signal, it’s simple enough to extend the wire a little bit, as long as you make sure that positive stays positive and negative stays negative (LEDs only work one way).
Why would you want to do this? You could turn on and off a projector using this method without trying to hold the remote exactly right. You hack the remote, extend the wire and put the LED closer to the projector’s IR sensor.
That’s fine for one device, but what about if you have six TVs at church that all need to be turned on and off every week. Wouldn’t it be great if there was a device that could take the IR from a remote, amplify it and split it to send it to multiple locations at once? There is. Tons of manufacturers make them, but you can get them, run the wires to each location, plug them in and you have a single IR “target” to hit that will distribute the signal to multiple locations at once.
IR isn’t a perfect technology, though. In addition to the line-of-sight problem that these solutions overcome, devices can react poorly, totally ignore the signal, or even randomly do things as a result of environmental factors.
The sun is the largest source of IR light we have, so if it shines directly on a television (for example), that IR can block out the weak IR signal from a remote. Compact fluorescent lights can do the same thing.
I’ve even seen satellite boxes that won’t work with an IR distribution system like the one above because the good signal from the remote was too strong after it was amplified.
This post just touches on how you can manipulate IR to control things in your AV system, so ask other questions below in the comments.
Next time, we’ll talk about RF control and how to use it.
Paul