Have you ever wanted to have an infrared interface on your PC? You could buy a readymade one with USB interface or you can make your own. If you are the DIY (Do It Yourself) kind of person keep on reading... Since all modern (and not so modern) motherboards have an IrDa connector, the job is halfdone! I will try to explain how you can add IrDA capability to your PC. Your PC will then easily connect to any (mostly portable) devices that have an IR interface. Personally I use it to interface with my cellular phone. It's good for synchronizing contacts and calendar information with a press of a button, instantly. Just make sure the two IR "eyes" are pointing to each other up to a distance of 5-6 meters (and an angle of less than 30 degrees)

Before getting all excited about this, make sure your computer's motherboard supports IrDA. Everything you need to know is stated in the "user manual" that came with the motherboard. You need it to identify the location of the IR connector on the board and most importantly to see the pin assignment. (Which signal is assigned to each pin)

  1. VCC ( + 5V) = Power, positive
  2. N.C. = No Connection
  3. IRRXD = IR Receive Data
  4. GND = Ground, negative
  5. IRTXD = IR Transmit Data

My motherboard happens to have 5 pins on the IR connector (labeled JIR1), but 1 of them is "No Connection"...so much the better...I recommend the use a multimeter to verify power pins! You might want to know that IrDA is classified into to categories, SIR and FIR. In other words Slow IR, and Fast IR reaching a maximum of 115 kbps and 4 Mbps approximately. From what I know, PCs at the time of writing, only support SIR. But this is more than enough if you are connecting to a PDA or cellphone. Trust me.

Notes: The 9.10 Ohm resistor regulates the maximum power of the transmitting "eye". Most people use this value. Note that this resistor has to be 1/2W and not the usual 1/4W. If possible try to get a resistor with exactly this value (precision resistor). Or just measure a "normal" 9 ohm resistor with a good multimeter and make sure its roughly this value. One last word of warning: All this assumes u One last word of warning: All this assumes have a minimum knowledge of electronics. As always...if you screw things up its not my fault