The $1 Infrared Solution For Your Pc

IR Transmitter

infrared comes on a lot of cool devices, but not everyone has a transmitter/reciever to take advantage of it. well now you can and for about a buck. just make sure your pc has room for an IR port. if it does, you’ll need to pick up the following to get going:
+An infrared LED, an infrared photo-diode
+Two BC548 transistors
+A 10 nF capacitor
+A 4K7 resistor, a 47 K resistor, a 15K resistor, a 22 ohm resistor and a 1 K resistor (all of them 1/8 W)

That’s it aside from your trusty soldering gun and a lil’ solder. Wire it up, connect it, and start waving your cellphone, palmone, or whatever it is with IR around to have windows recognize it!

thanks [captain]

46 thoughts on “The $1 Infrared Solution For Your Pc

  1. Very cool. Now, what does one have to do to connect this to a non-windows based motherboard (e.g. an Apple motherboard)? What about getting it recognized in Linux?

    I also wonder how hard it is to now give more power (range) for controlling other devices?

  2. can anyone confirm that the 2N2222A NPN transistor is a valid substitute for the bc548? my research suggests so, but i was hoping for techie confirmation. additionally, does anyone know if this device can be used to control apps with an ir-remote?

  3. I researched Mac USB IrDA info a few weeks ago and here’s what I found:

    Complete Mac USB IrDA hardware and software solution (though it’s a bit pricey) – see

    Bafo Technologies makes 2 USB IrDA adapters that are Mac compatable (BF-7030/BF-7040) – see

    Sigmatel make 3 USB IrDA chipsets that are Mac compatable (4210/4220/4116), but I couldn’t find anyone selling USB IrDA adapters with these chipsets – see

    I don’t think current Mac hardware has IrDA connections on the motherboard. The last Mac desktop that shipped with IrDA was the original 233 MHz iMac in 1998 AFAIK. Apple removed IrDA from the iMac in 1999 with the introduction of the 266 MHz iMac.

  4. Not to be nitpicky, but where does the “$1” come from? I just priced this stuff (albeit, Radio Shack) and the project came to about $12.00. Is there somewhere else I should be picking up my things, or did I overlook something?

  5. rkmase: really depends on who you are and where you would get your stuff.

    Radioshack is over priced, and chances are they are making you buy multiple pieces all shrink rapped etc.

    At my local elec store its 50c cdn for 10 resistors (2.50), maybe 80c for each ir led (1.60), transistors 50c or less, cap 50c for 5.

    So if you go to a proper electronics store its prob about 6-9$, and your getting extra parts.

    imo most of these parts are common and I probably have most of them.

    You are right though 1$ is way under.

  6. rkmase: or much cheaper than radio shack but of course you have to pay shipping which is usually $5 or so.

    This is nice but I scored a BAFO usb IrDA device for $5 after rebate sometime ago at PC Club but this is a nice thing to know about when doing custom PCs because I’ve yet to find anyone that sells these buggers already made for the headers that are included on the motherboard.

  7. Just a quick question if someone could email me a part number for something. Trying to price this out from RadioShack and cannot find an infrared photo-diode. Photo-transistors but I know they’re different. If cannot get from RadioShack, any suggestions, with part number, fo this? Thanks in advance!!

  8. Talk about timing- I finished my first ciruit a month ago and am still looking for aome simple projects to do, PLUS I was just having problems getting my cell phone (cable)’s drivers to work properly this morning.

    I haven’t cracked open the PC to find the interface yet, but I’m assuming it’s like the one for power/LEDs/etc. Does Mouser/Digikey sell the connectors for these (what would they be called?)

  9. This is a great hack, but I think it bears saying that this is not a full IRDA implementation. It might be more appropriate to call this an IRDA dongle, because that’s what it is and also the word “dongle” is hilarious. Anyway, your motherboard must implement IRDA and have an IRDA connector with no IR LEDs, which is what this hack provides.

  10. #18 you’re thinking of a simple linear circuit. If the 22ohms and the LED were just hooked between vcc and gnd then the current through it would be huge (( vcc – .7 ) / 22 ). However, in this case, the current is limited by the transistor so there is no need to worry.

  11. About the current limiting resistor: typical forward voltage drop for an IR LED is more like 1.3V, not .7V, and IR LED’s often have a higher forward current (100 mA isn’t uncommon) rating than typical visible LED’s. Another consideration is, the LED is being pulsed in this application, and a litle googling shows that IRDA specs specify a “maximum 25% duty-cycle return-to-zero pulse to limit power dissipation in the IR emitter”, so you can get away with slightly higher currents. 22 Ohms should be fine.

  12. A note to people who want to control a tv, AFAIK this is IrDA only, not the same as what standard TV remotes use. The IrDA protocol is much faster than that of a standard TV Remote.

    Those looking to control a TV from a computer or vise versa should look at I have been using Girder for many years and it will do anything you can think of. I have been using it to enable the multimedia keys on my keyboard.

  13. Pls help…..
    I m using Intel motherboard SE440BX-2
    I think I have assembled circuit properly but when connect to motherboard window fails to recognise Irda.
    somebody tell me any way to check circuit or the procedure to recognizing this Irda as new hardware on motherboard or if there any bios settings are needed. thanks

  14. if this recognizes any infrared ports around it and then tells you about access, then is it possible to make a one way port to a psp..the reason it would be one way is because there is no software out that uses the psps infrared port.

  15. Yeah I built this today and it’s not recognising for me either.
    I’ve measured it through, all the parts are ok & I’m getting the correct voltage on all the connectors, bios settings are correct too.

    I did cut the following corners;
    – used 1/2W resistors (shouldn’t matter?)
    – didn’t have any 15k reistors so used a 10k & a 4k7 (shouldn’t matter either?)

    I’m also using a phototransistor instead of a photodiode. Could that be the problem? The LED in the pic looks like one aswell though.
    Any help?

  16. about the only way this would cost a dollar is if you already had some of the parts laying around or if some place will actually sell you 1 resistor — the capacitor alone will cost you at least 50 cents. by the time I did the min order on, i’m looking at about $17 — that’s not even including a way to hook it to the mobo [my guess would be a ribbon cable with the plastic connector]. wow… $17 just to have a piece of crap hanging out of my comp, sitting on my desk.

    IMO, just go pick up a usb irda for about $16. This is NOT a $1 project.

  17. A comment for the last guy that added a comment (bubba ho-tep). Why do you have to go and add negative comments? 1$ project is just a figure of speech. Do you really have so much time on your hands that you go looking for things to complain about?

  18. i would like to know what other alternative transistors i could use..
    and the spots that you are suppose to connect it to.. i found them on a realy old sound card of mine..would it work the same?

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