Question about LEDs and resistors.

[tribaloverkill]

I am wiring up some case lights for my computer. I was actaullt thinking about making several more to sell them too. Its kinda fun soldering these things together. Now,... the tubes that I am making now are an improvement over the las the last tubes I made. The last tubes being 16" long and having 15 LEDs each. Thats 5 paralelled series of 3. Now with the blue LEDs i had no problem when it came to brightness. But the UV LEDs,... they are kinda weak. I ran the blue ones at 3.6v@50mA with a 22hom resistor. They worked flawlessly and blindly. They didnt heat up at all so didnt the resistor. The UV LEDs,... I ran those at 3.6v@30mA with a 39ohm resistor. Those worked,... fine, as in they didnt generate any heat. But they were kind of weak when it came to intensity. I tried to run them at 40mA with a 33ohm resistor, that would acutally be a bit less then 40mA, but they started to generate some heat. Now my question is,... how much heat is bad? I know LEDs can run with no heat but how about some? It's really the resistor that heating up a bit. The LEDs generate some heat themselves to but noe as much as the resistor. How much is to much? By the way, the UV shined very nicely at 40mA. Also,... say I was to,... well, before I ask this let me show you what I am doing.

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The bottom tube is going to be the tube I am using for the case light. The LEDs will be pressed through the holes from inside to out. Now,... my question is,... if I was to fill the inside of the tube with some of that expanding foam,... how would that effect everything inside? You think the LEDs would generate alof more heat as oppose to just sealing up the tube air tight? I dont think there would be a difference. but what do I know. Let me know. Also, wheres a good place to get resistors? I need 22ohm for my blues and either 33 or 39ohm depending your opinion above.

 

[Nigel Goodwin]

Thats 5 paralelled series of 3. Now with the blue LEDs i had no problem when it came to brightness. But the UV LEDs,... they are kinda weak.

You seem to have the wrong idea about UV?, UV stands for Ultra Violet, which is an invisible light, too high a frequency for the human eye to see.

 

[tribaloverkill]

That I understand but it also gives off a hint of violet. Also, I am using the UV to light up my UV reactive cables. I would like to possibly squueze a bit more light out of them to light up the UV reactive cables a bit more.

 

[Nigel Goodwin]

That I understand but it also gives off a hint of violet. Also, I am using the UV to light up my UV reactive cables. I would like to possibly squueze a bit more light out of them to light up the UV reactive cables a bit more.

Use more UV LED's then, visible light output is going to be low, the reactive cables won't be very efficient, and I suspect the output of UV LED's is probably lower than normal LED's as well.

 

[tribaloverkill]

Well,... I answered my own question today. I ran the UV at 3.6v@40mA, which is the 33ohm resistor and they got hot. So thats out of the question. It's weird but if I use the 39ohm they are very much cool. Just a couple of ohms, huh. Anyways,... where is a good place to buy resistors bulk?

 

[williB]

i would be interested in seeing what they look like when they are on..
as for resistors Jameco. i have delt with them.Not sure about minium order though..