to know how small a resistor I can use (for maximum IR lighht emission strength).
That is likely to depend on how you drive it. An arduino should not be asked to deliver more than 40mA and most IR LEDs can take more than this.
Typically you can use a 33R resistor if you drive it with a transistor.
Thanks for the heads up! I'm driving it with the Arduino.
Hmmm. I don't understand why the IR Transmitter is composed of an IR LED with 2 pins connected to some other and seemingly meaningless component with 3 output pins.
There are two little "metal squares", one above each of the two right-most pins. Perhaps that is something. I'm still trying to find this at alldatasheet.com. No luck yet, but the search continues
Thanks alot! I'm going to write these things down for further reference
I'm building a radio-to-infrared interface, so I can control my devices from a greater distance If it works well I will maybe to a Web-to-infrared interface as well
There is a reason for that IR-emitter board to look a bit strange - it's meant for a pushbutton with pullup resistor - it's simply being re-purposed as a carrier for the IR LED.
thecoon:
I don't understand why the IR Transmitter is composed of an IR LED with 2 pins connected to some other and seemingly meaningless component with 3 output pins.
I can't see this component from your photograph. In fact I can't see any components at all.
I would connect it up with a 220R seriese resistor to 5V and ground and measure the voltage across the LED. Look at the LED through the electronic viewfinder of a camera to see which way round it lights. Then drive it with a transistor and work out the resistor to give you 80mA current through it.