© <in der past>
Build an IRDA transceiver
Somebody asked me to post a write-up about building an IR module. When I built this, it was cheaper to buy the parts and build the module than to buy a module, your mileage may vary.

First things first, you'll need an IRDA module, I used a HP(Agilent) HSDL-3610. The biggest problem I had with these is that they are SMT mount components, and require a fairly steady hand at soldering to get the little buggers on a PCB.
These are supposedly drop in replacements for HSDL1001s, so one of those should work fine, but I believe a few extra components may be required.

The spec sheet for the HSDL-3610 can be found at HP's web site.
The HSDL-3610 is only capable of SIR, which is only 9.6 - 115.2 kb/s. HP also offers more powerful IRDA modules capable of 4 Megabit/s transfer rate.
I ordered mine from Newark, they do a reasonable small purchase online ordering.

The components required for the rest of the circuit are a 15 ohm resistor, a 0.47 microFarad cermaic capacitor, and a 6.8 microFarad electrolytic capacitor. Note that HP recommends that the cermaic cap be at most 7mm from the module, and I used a 10 microF electrolytic instead of the 6.8 microFarad tantalum they recommend (Radio Shack didn't have any). As usual, YMMV.

This is the circuit

Sample circuit board (enlarged)

Soldering the components on is fairly straigtforward, except for the actual module, because it's meant for SMT. I tinned the points where the module was going to sit and the leads on the module itself, held it in place and gently applied a fine soldering iron to the copper traces, and waited till the heat liquified both blobs of solder. Not exactly pretty, but it worked.

Hooking it up to the IRDA header on my motherboard was simple, I glued two cd-rom cable plugs side by side to make a five-pin connector, and wired the appropriate wires to the leads off the PCB. I tested mine on both my BH6 and BP6 motherboard, and it should work on any standard motherboard with a 5 pin IRDA connector. (It might even work on the larger connectors, but you'll have to find the correct pins yourself).

5 PIN IDC MALE at the motherboard.

Pin Name Description
1 +5v Power
2 n/c Not connected
3 IRRX IR Module data received
4 GND System GND
5 IRTX IR Module data transmit

I do suggest you mount the module in some sort of a shielded box with a small window, as I found that light interferes with operation, and I suspect that EMF would also have an effect (especially if you don't use shielded cable to your IRDA header.

Set your bios appropriately, which should be something like enabling IRDA on COM2 (which disables the actual COM2 port), and setting the transmit levels. I think I had to use HI for one and LO for the other, but this may vary with motherboards. Experiment and see what happens.

As expected, I take no responsibility if you fry your motherboard.