Building UV flashlight... Help needed

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Bushman

Flashlight Enthusiast
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Jan 8, 2002
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I need help in building a UV flashlight. The host will be M*glite 3D cell model. First of all, does anybody have experience on the cramming a bunch of 5 mm LEDs in an M*glite head? I need to know how many will most likely fit.
I need to know, if running off of 4.5 volts, how much resistance will be needed.

Do I need to run them in series or parallel?

Any suggestions will be appreciated I have a bunch of UV LEDs laying around here.

The only caveats to this are that it must be a 3-DM*g. Set up. (Unless you have another very cheap alternative that you have in mind.) And No electronics other than a dropping resistor!
 
I ordered a $50 Inretech 20 NUV adapter. People such as Craig have commented that the 395 nm LED's used appear to be the best currently available on the market.

This adapter is tweaked to pull 400 mA off of 3 alkaline D's.
 
You should be able to get around 25 5mm LED's in your mag. They will definitely be crammed in /ubbthreads/images/graemlins/wink.gif.
To find how much resistance you need you need to know what the forward voltage is and how many milliamps the manufacture specifies.
Hope This Helps
 
Forward voltage of the LED is 3.6 volts milliamp rating is 20 milliamps per LED we will probably only use about 15 LED's.
 
Thank you. Do you mind to give me some idea of how you calculated this?
 
I think Mike from Inretech posted some formula for resistor choices in the fun with UV thread.(something like that)
 
I measured the Inretech 20 LED UV adapter I received this week. It pulls 450 ma and has a single 1 ohm surface mount resistor on the board.
Hope this is of some help.
 
the formula is....
(supplied volts - voltage drop of LED) / specified amps of LED = number of ohms

make sure everything is in fundamental units i.e. amps not milliamps etc...

then after finding the number of ohms divide by the number of LED's.

So in you case, (4.5v-3.6v)/(.02amps)=45ohms
45ohms/15LED's=3ohms

hope this helps
Jason
 
I have an Inretech UV Adapter, but if I remember right it only drew about 250mA from its three D cells, not 450mA.
I knew the adapter was being changed a bit from the earlier model, so this was probably the change.

The 450mA version ought to be signicantly brighter (outputs more UV) than the one I have, for this very reason.
 
I have an uncommitted array for 37 5mm LEDs that I can spare. You'll have to do a bit of wire work and cut it round (it's a 2" square), but I think you'll find it servicable. If you want it, just PM you address to me.
 
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