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DIY LED Blue/Red Light

Has anyone considered building their own LED light source from scratch? LEDs are relatively cheap and the circuitry is simple. I would guess that a Blue/Red light source with upto 100 LEDs of each color should only cost about $60 to build. The main issue's I've encountered is locating 415nm LEDS. The closest I could locate were 400-410nm. It seems possible to at least locate the 660s. The other issue is calculating the correct light intensity and the optimal viewing distance. If anyone is interested in kicking this around let me know.

-Adam

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Has anyone considered building their own LED light source from scratch? LEDs are relatively cheap and the circuitry is simple. I would guess that a Blue/Red light source with upto 100 LEDs of each color should only cost about $60 to build. The main issue's I've encountered is locating 415nm LEDS. The closest I could locate were 400-410nm. It seems possible to at least locate the 660s. The other issue is calculating the correct light intensity and the optimal viewing distance. If anyone is interested in kicking this around let me know.

-Adam

I though about doing this. Another consideration is how tight the distribution of wavelengths is. Its not only the peak wavelength, but how concentrated the output is around that peak. The thing is, I believe you will get some effect with light that is even close to 415nm, its just that number is the optimum. The chemical that the lights excite is apparently excited to a lesser degree even by green light, and the photochemical reaction that produces O- still takes place.

So I'm thinking its realistic to do this even with readily available LED's. The created device just won't be as efficient as an optimized one. As for the intensity, we should have the baseline intensity of a single LED from the manufacturer, and we can always adjust the treatment distance or number of LED's to get to where we need to be.

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So I managed to buy 100 Blue(400-410nm) and 100 Red(660nm) LEDs off ebay

Red Blue

Size: 5mm 5mm

Forward Voltage: 1.8 - 2.2 Volts 3.2 - 3.6 Volts

Forward Current (max.): 30 mA 30mA

Viewing Angle: 20 Degree 20 Degree

Typical Wave Length: 660 nm 400-410 nm

Luminous Intensity: 2500 mcd 3000 mcd

Total Cost: $23.19

Once the parts show up I'm heading to radio shack to pick up boards, soldering iron, wire, resistors and power supply.

Keep everyone posted

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Guest ~Wolfy~

It should work. Might be worth putting some kind of diffuser over the LEDs though. The angle is a bit narrow. Sounds like you've got plenty of power, and the wavelengths are about right for it to work.

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Guest ~Wolfy~

Ok, I did some calculations on this, if I haven't screwed up my maths (rare!) you'd need about 20 blue LEDs for this to give a 15 minute treatment per day to cover a roughly 100 cm^2 area (a 4 inch square).

I also found a document with a graph of the action potential:

http://www.caci.co.nz/imagelibrary/100060.pdf

400-405nm looks about spot on. (FWIW The erythemal (i.e. sunburn) spectrum for light is here: http://en.wikipedia.org/wiki/Image:Erythem...on_spectrum.svg at first glance it looks like you'll be ok- the roll off is pretty steep by 400nm, it's logarithmic.)

As you said, there's another weird peak out at ~540nm in the green, but you'd need 10x the power. The good thing though is you're further from the UV.

Presumably you knew all this anyway.

So how's it going? Have you built it?

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Guest ~Wolfy~

I've done some more calculations. I'm vaguely concerned with the 400nm LEDs, I found the light spectrum here:

IPB Image

This shows the intensity of the light at slightly different colours. The 380nm line and below represents Ultraviolet, and you can see that nearly all of the light is above the ultraviolet, which is good. And if you compare it with the action spectrum, there's plenty of overlap, so it should kill P.Acnes just fine.

The only downside is that there's some ultraviolet produced with this LED, where it's below 380nm wavelength; and really the difference between ultraviolet and visible light is a bit vague, many sources claim that everything below 400nm is ultraviolet (half the light is ultraviolet by that definition.) Still, I think that 50% wildly overestimates the effect of the light, we're not planning to use these lamps for hours per day.

So, I tried to estimate how bad the effects of the ultraviolet would be, it looks like using these LEDs is about the same as standing in the sun for about a minute. (In terms of sunburn anyway.) It may be better than that, the calculation is just back of the envelope.

So it's not ideal- a better LED would be a bit lower frequency; further away from the UV, but I've been unable to find a powerful enough LED for a reasonable price.

(The Hong Kong LEDs are a great deal, only about $0.16 each, which is a briliant price, by way of contrast I found one LED by Maplins which was a longer wavelength but you would need several hundred LEDs to get enough power, and they are ~$5 each.)

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hmmmm, i guess it should work. Wiring led's up is a piece of cake too.

A 15cm X 15cm board would probably take bout 60/100 led's and im guessing thats plenty of power + you can always move it closer to the skin for deeper penetration of the light. But LED's tend to produce a little light at a high intensity, so i dont think that would even be nessecary.

pls keep us posted :)

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It wouldnt have any side effect... right? :shifty: I'm scared of leds

i wouldent think so, led's are just light emmiting diodes, all the do is emmit light at a specific frequency. Like wolfy sai the only side effect i can think of is uv exposure since 410nm wavelenght is close to teh uv spectrum, but he said that the ammount of uv that would be given off is extremly minimal.

I dont think that the original poster of this thread is going to reply cause his last post here was in october :o

So anyone else up to try this???

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I'd love to, but I know very little about electronics ( took my first class this semester), hopefully I will understand this when I finish studying my career :angel:

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I'd love to, but I know very little about electronics ( took my first class this semester), hopefully I will understand this when I finish studying my career :angel:

well, i found these on ebay:

http://cgi.ebay.com/2-x-30-LEDs-GU10-ultra...1QQcmdZViewItem

there 220v ac led bulbs rated at 2w each and have a frequency of 400nm.

I dunno if they'll work or not, i'm waiting for wolfy to get back to me and give me his opinion on them.

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