638Views10Replies

Author Options:

Multiple LED Flashlight Help Answered

Hello all, I just ordered 10 blue and 10 green non-diffused LED's from besthongkong.com. They work great and are super bright. What I want to do is put them all together in a PVC pipe or something like that to make one super-bright flashlight. My question is, how do I attach all of these LED's together in a circular form in a series circuit? I dont know the best way to do this. If anyone has an answer or a link that will help, it will be greatly appreciated. Thanks alot! Brennn10

10 Replies

user
Brennn10 (author)2007-02-28

DC forward voltage : VF (IF =20mA)
3.2V-3.4V Typ, 3.8VMax

DC reverse current : IR (VR =5V)
100uA

Intensity luminous : Iv (IF =20mA)
BA09 : 6000-8000mcd

Wavelength : Wp (IF =20mA)
465-470nm

Here are the specs for the LED I used. I hope this can help.

THanks a ton in advance Las Vegas. I appreciate it.

Select as Best AnswerUndo Best Answer

user
LasVegas (author)Brennn102007-03-11

The attached schematic should allow you to drive up to 10 of those LEDs with 3 batteries (AAA, AA, C or D). It's a current regulating circuit as opposed to the popular (on this site) of voltage regulation. The nice thing about this circuit is that you can drive one to ten LEDs and adjust for optimal current. If you set the potentiometer higher, you will get less current, lower brightness and longer battery life. Adjust it lower, for more current (more LEDs), higher brightness and shorter battery life.

Select as Best AnswerUndo Best Answer

user
Brennn10 (author)LasVegas2007-03-12

Thanks Las Vegas! You are the man. I really appreciate it.

Select as Best AnswerUndo Best Answer

user
Brennn10 (author)Brennn102007-03-11

If anyone would help me out that would be so helpful. Thanks alot!

Select as Best AnswerUndo Best Answer

user
westfw (author)2007-03-11

Connecting LEDs in parallel (without individual current limiting resistors) can be a bad idea if the Vf voltage drops are not pretty closely matched. From a pure EE point of view, I'd say you should hardly ever do it, but hundreds of commercial flashlight designs and vendors would contradict me. I guess that in practice, the Vf's of any particular batch of white LEDs are pretty closely matched. However, if you're going to be combining LEDs of different colors, that is LESS likely to be true. Connecting a red and blue LED in parallel will result on all the current going through the red led, for example. You can test this ahead of time using just two LEDs and a resistor, to see if it's a problem.

Select as Best AnswerUndo Best Answer

user
Brennn10 (author)2007-02-28

If I am using 3 Blue LED's, could some nice person possibly draw me up a schematic. I cannot picture what you guys are saying. I will probably have a source voltage of 3 Volts and the LED's can take up to 3.4 Volts. Thanks.

Select as Best AnswerUndo Best Answer

user
LasVegas (author)Brennn102007-02-28

Again, you still need to supply the current requirements of the LEDs. That would determine the appropriate current limiting resistor for the LEDs.

Select as Best AnswerUndo Best Answer

user
LasVegas (author)2007-02-25

What are the specs on the LEDs? If they'll run on 3 volts, put them in parrallel and connect across 2 D Cell batteries. 4.5v = 3 batteries, 6v = 4 batteries. Depending on the current rating of the LEDs, you may want to add a resistor.

Select as Best AnswerUndo Best Answer

user
fungus amungus (author)LasVegas2007-02-25

LasVegas is right, parallel's the only way to go. Arrange the LEDs in two concentric circles. Make sure that the anodes are all facing out in the outside ring and in in the inside ring. Wiring it up from there should be a snap.

Select as Best AnswerUndo Best Answer

user
trialex (author)2007-02-25

Did you try doing a search?

PVC Flashlight

Not that I think it's the best design, but it works.

Select as Best AnswerUndo Best Answer