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The project described in this article requires basic electronics skills and is provided for information purposes. Do not attempt to replicate it or use it for any purpose unless you've got the proper knowledge and skills.
It’s easy to recover infrared LEDs and photo transistors from junk electronics you can obtain for free. Old remote controls, VCRs, and broken DVD players are excellent sources.
I keep two boxes of remote controls, one box with the original remotes from each of my current electronics (normally I use a multi-function remote on a day-to-day basis) and a junk box with old remotes after I’ve tossed out broken electronics. Why do I keep the old remotes? Just in case they are useful in the future. For example, one of my junk box remotes was for an old Panasonic VCR and would also control a TV set. I recently found a Panasonic TV set for $5 in a thrift store and realized it was the right size for my guest bedroom. It turns out that the junk remote operates all of the functions I need for that television, saving the cost of getting a universal remote for that TV.
But there are plenty of remotes in the junk box that I’m extremely unlikely to ever use again.