DIY: build your own c200 'IR eye' for cheap

[linuxworks]

here it is, the long-awaited DIY article on how to build your own 'IR eye' module using commonly available parts.

essentially, 2 things are needed; the jack+cable and the IR receiver module.

the IR module I used was from radio shack:

http://www.radioshack.com/product/index....Id=2049727

$3.99 locally. I would not pay more than this since the parts (better ones, in fact) are available via the mailorder places. here are some links to known good IR modules:

http://search.digikey.com/scripts/DkSear...51-1227-ND
part # TSOP38238 digikey # 751-1227-ND ($0.98 each)

http://search.digikey.com/scripts/DkSear...-1385-5-ND
part # TSOP34338 digikey # 751-1385-5-ND ($1.31 each)

what you need to search for is 38khz and that it accepts 5v (in range) for power. they all should, though.

you can also check mouser. do a search on 'vishay tsop 38khz' and parts should show up:

http://www.mouser.com part# 782-TSOP34838 ($1.14 each)
http://www.mouser.com part# 782-TSOP4838 ($0.95 each)

you can also check newark.com and farnell.com

that covers the IR receiver module.

the 1/8" stereo TRS (tip ring sleeve) jack comes from any old abandoned walkman stereo earbuds. or just buy a 1/8" male jack and wire it up yourself.

some photos:







the last one shows how to connect the various pins on the IR module to the various 'bands' on the TRS male plug. you cannot assume that manufacturers followed any standard ;( usually, tip is left, ring is right and sleeve is ground. use a continuity or ohm-meter to 'ring out' which wire in your cable goes to which band on the plug.

double check that. IR modules are known to break (quickly) if you connect power and ground incorrect.

reminder: center pin is ground! center pin is ground. center pin is ground.

(repetition is the key to learning)


safety note: since TRS plugs temporarily short connections when you insert or remove, I STRONGLY SUGGEST you power down the PCH before you insert or remove the plug. this goes for any kind of device that uses shorting metal TRS or TS (mono) jacks for carrying power. (when, oh when, will manufactuers STOP sending power over shorting-style pins! argh!!!)

that's about all I can think of, for this mod. it might be a good idea to get some heat-shrink tubing to cover the bare soldered leads. install this unit with not too long of a cable. if you run a cable more than, say, 4 feet, you may want a 'filter cap' across the +5v and ground lines. something like a 1uF or 10uF cap (watch polarity! electrolytics have a band marking MINUS or ground. note it.) would work ok. I would only use the cap if the cable was really long, though. see if you can get by without it.

hope this is useful to those who don't want to wait or spend money on the IR eye.

total cost can be as low as $1+shipping from the mailorder places, assuming you have some junk earbuds you can sacrifice for this job. total build time should be less than half an hour.

cheers!