How do you use your 360nm 5mm UV LED from the group buy?

moraino · Oct 7, 2005

It starts here http://candlepowerforums.com/vb/showthread.php?t=92509

Please post your host choice, power source and means of driving it. And how you are going to use it for.

I am thinking of replacing the 1AA Dorcy 3LED. I will use it to shine on the paper bills to see what's hidden. I don't have cat or dog at home so I can't find their secret marks...I don't think I can find scorpions in my neighbourhood either. Hmmm, I have to think what else I can use it for....

I know this is going to be a fun light, I should say interesting light because of its dangerous nature, so please show me your actual use of it. Thanks.

Henry

IsaacHayes · Oct 7, 2005

I'm going to use a 19led 3xAAA light I got from Dae. On second thought I should of gotten a different style from him that doesn't have a lens, as the lens glows from the UV. I might cut out the center of the lens. Best to use lights that have holes drilled for the LEDs and not a lens over it for that reason. I'm hoping either the stock resistor in the light will work ok with 4.5v alkalines, or no resistor DD for ~3.9v NiMH. I'll probably get to it on Sunday. I'll update this post here with progress.

My goal is lots of UV (multiple LEDs) and at the correct drive level (20-30ma).

Ken_McE · Oct 7, 2005

Right now I'm looking for a head that will fit all 12 LEDs

rdshores · Oct 7, 2005

I have one of these 12 LED AA that will take 12 LEDS. I haven't tried to take it apart yet though.

IsaacHayes · Oct 7, 2005

rdshores: I suggest something that will power them at greater than 7ma... 1AA bosted lights are weak, and the VF of these UV leds are high, so better to go with a 3xaaa light instead.
These would be cool hosts for 12 leds...
http://www.qualitychinagoods.com/12-led-gt-p-225.html
http://www.qualitychinagoods.com/12-led-long-p-329.html

rdshores · Oct 8, 2005

I think to get the most out of these 360nm UV leds, we need to use a current regulator set to about 15-20ma. If you look at Chimo's graph of I/V, it looks like the leds would be overdriven with 3 AAA alkalines and underdriven with 3 NIMH.

chimo · Oct 8, 2005

I have also noticed quite a variance for the Vf of these LEDs:

You will likely want to group by Vf or run them in series as much as possible.

Paul

icebeng · Oct 13, 2005

I gather that it's best to run these leds at 20mA?
Has any tried to or knows what's likely to hapen if we were to drive them at 30mA?

chimo · Oct 13, 2005

icebeng said:
I gather that it's best to run these leds at 20mA?
Has any tried to or knows what's likely to hapen if we were to drive them at 30mA?

For the V/I plot above I ran them right up to 70mA. The LED did not fail, however, I would not run them in a long-burning application at that current. 30mA should be a fairly safe "normal" usage current.

Paul

PaulW · Oct 14, 2005

moraino said:
Please post your host choice, power source and means of driving it. And how you are going to use it for.
Henry

I'm going to install them in a 12 LED resistorized light in a 3C host I bought 2 1/2 years ago. I don't have particular plans for its use. I guess I'll mainly experiment. But I certainly won't use it in the bathroom until I clean it . . . don't know when that'll be.

Paul

icebeng · Oct 14, 2005

Ok, I'm going to ask Peak to run them at Hi-Power for me in a 3 led Matterhorn and 7 led Kilmanjaro.

Will let you guys know how it turns out.

Also, I'm thinking of replacing the leds in a Streamlight Twintask 1 Cell Lithium with these leds.

Could I have some input from anyone regarding this?

Thanks!

wmpwi · Oct 14, 2005

I put them in a X5 and everything seems good, but the beam of the individual LEDs were like a donut with a light spot in the center of lighter ring. Since I did the beam on a highly florescent surface, it was clear the beam was not going to be very even. Very strange. :thinking: I wound up pulling them all from the X5 and now I'm waiting to see how everyone else manages before I try something different.

Ken_McE · Oct 16, 2005

What Is Proper Voltage For The GB 360nm UV LEDs?

According to this thread, the group buy UV LEDs can be driven at

Min - Typ. - Max - unit
3.6 - 3.8 - 4.5 - V

http://candlepowerforums.com/vbshowthread.php?t=92796&highlight=360nm

However, if I visit the Fox Group, who I understand made these, at:

http://www.thefoxgroupinc.com/website_F_E/HomePage.html

Their PDF for both the 3 and 5 mm's states:

Min - Typ. - Max - unit
3.2 - 3.6 - 4.0 - V

I had planned to direct drive my UV LEDs with three AA batteries, giving me 4.5 volts, max. According to the group buy info this is driving them hard, but acceptable. According to the company PDF this is overdriving them. What's up with this? Who's right?

PhotonWrangler · Oct 16, 2005

Re: What Is Proper Voltage For The GB 360nm UV LEDs?

I'm puzzled. The dominant wavelength that shows on their "Fox Blue" LED is 460nm, not 360, and I can't find anything on their site that states otherwise. 460 is nowhere near UV...?

chimo · Oct 16, 2005

The Fox website does not have the specs for the UV LEDs. The FoxBlue LED is a different beast than the FoxUV. The information posted here was emailed to me from a rep at the Fox Group. Use the info in post #1 for driving the LED.

Paul

Ken_McE · Oct 16, 2005

chimo said:
The Fox website does not have the specs for the UV LEDs. The FoxBlue LED is a different beast than the FoxUV. The information posted here was emailed to me from a rep at the Fox Group. Use the info in post #1 for driving the LED.

Paul

Phew. Three double A's, here I come. Thanks Chimo!

PaulW · Oct 16, 2005

Ken_McE said:
Phew. Three double A's, here I come.

The 4.5 Volts is the maximum Vf at 20 mA you would find when testing a group of these LEDs. Others in the group might test out as low as 3.6 Volts.

The parameter you have to be careful with is the current. The max spec is 30 mA. Anything more will shorten the LED life.

Placing 4.5 Volts across the LED would yield 20 mA if the Vf = 4.5. But if the Vf is lower, the current will be larger. If the Vf is 3.6 (or even 3.8), the current could be very large, depending on the internal resistance of the cells you're using.

I think it's wise to add some series resistance and check what the resulting current is.

Paul

attowatt · Oct 16, 2005

PaulW said:
The 4.5 Volts is the maximum Vf at 20 mA you would find when testing a group of these LEDs. Others in the group might test out as low as 3.6 Volts.

The parameter you have to be careful with is the current. The max spec is 30 mA. Anything more will shorten the LED life.

Placing 4.5 Volts across the LED would yield 20 mA if the Vf = 4.5. But if the Vf is lower, the current will be larger. If the Vf is 3.6 (or even 3.8), the current could be very large, depending on the internal resistance of the cells you're using.

I think it's wise to add some series resistance and check what the resulting current is.

Paul

OK....

So is it safe to say that if i set my variable power supply to... 3.7 volts, and then power up each of my 20 leds independently,1 at a time... get a current reading on each 1. Then grab the 6 that i need for my project, based on those that are closest in current to each other, I should be fine driving them at a slightly higher voltage than 3.6 volts.

gadget_lover · Oct 16, 2005

attowatt said:
OK....

So is it safe to say that if i set my variable power supply to... 3.7 volts, and then power up each of my 20 leds independently,1 at a time... get a current reading on each 1. Then grab the 6 that i need for my project, based on those that are closest in current to each other, I should be fine driving them at a slightly higher voltage than 3.6 volts.

I would say that's exactly what you want to do. After you have your six, you might even go back and find at what voltage they hit 20ma (or 30, if that's what you want) and use the appropriate resistors.

Daniel

gadget_lover · Oct 16, 2005

icebeng said:
Ok, I'm going to ask Peak to run them at Hi-Power for me in a 3 led Matterhorn and 7 led Kilmanjaro.

Will let you guys know how it turns out.

Also, I'm thinking of replacing the leds in a Streamlight Twintask 1 Cell Lithium with these leds.

Could I have some input from anyone regarding this?

Thanks!

Remember that if you send these to anyone else for assembly you really should make sure they understand about UV damaging their eyes if they look into the beam. The last thing you want is for your favorite modder/assembler to drop out of the business.

Daniel

How do you use your 360nm 5mm UV LED from the group buy?

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