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High Output IR LED ratings on Electronic Goldmine?

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Bighead

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Hello, new to the forum. This looked like a good place to find the answer to my question.

I'm interested in building a custom Wii sensor bar powered by USB, and I have been looking around for the cheapest IR LEDs and I found a 3 pack on electronic goldmine.

Link: https://www.goldmine-elec-products.com/prodinfo.asp?number=G14670

Problem is, there is no voltage or current ratings on them, so I'm not sure if 4 of them in series is going to exceed the 5V limit on USB or if I'm going to need a resistor. Does anyone know the specs on these LEDs?
 
I've seen some projects around the web that use 4 of Radio Shack's IR LEDs in series (link below) to make a USB powered sensor bar without a resistor, although they probably should have used one. They are a tad expensive for LEDs, that's why I was wondering what the ratings are on the ones from Electronic Goldmine. I'd be happy with just 2 LEDs and a resistor since I'm not going to be that far back, but they failed to list the specs.

https://www.radioshack.com/product/index.jsp?productId=2062565

The ones from Radio Shack are rated at 1.28V 100mA, although everyone has stated in other places and the reviews that the voltage drop across them is actually 1.2V. So if this is true, a 2.2 Ohm resistor should be used in series with these. This in itself is kind of a pain because neither EGM or RS sells them, plus I don't want to buy what I don't have to.
 
The Radio Shack LEDs you linked to are IR LEDs meaning they do not emit any visible light. A good example would be the IR Remote for a TV. You don't see the light.

A typical red LED will generally have a forward voltage of about 1.6 volts with a forward current of about 10 to 20 mA. So let's say 1.6 V @ 15 mA for an example. We have a 5 volt supply.

Vsupply - Vled / Iled so we get 5 Volts - 1.6 volts = 3.4 volts / .015 amp = 226 ohms with the closest common size being 220 ohms so we would place a 220 ohm resistor in series with this LED for 5 volt operation.

Ron
 
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