# noob needs help designing circuit



## nabisko (Feb 4, 2009)

i own a few of those $5 led flashlights, 8 leds and three aaa batts...

i'm impressed with the light thrown by those 8 little leds, and i'd like to make a custom circuit to drive 18 to 24 leds at a similar intensity.

i haven't made up my mind as to 9v or cr123 batteries. i guess it would partly depend on how many batteries each option would take and how long of a life i could expect from the 9v.

also, what circuitry do i need? my preliminary research leads me to believe that this will require more than an inline resistor... i saw something called a 'joule thief'. do i need something like that?

i did some electronics in high school and used to make effects pedals for guitar, but i've never used a led for anything other than to indicate that a circuit was turned 'on'.


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## Gunner12 (Feb 4, 2009)

A single high power LED should easily out lumen and out throw the 5mm LEDs. A single current gen high power LED will easily beat 24 5mm LED.

It's probably easier to buy a new light.

8 cheap 5mm LED overdriven, around 30-40 lumen at most. A single Cree XR-E Q5 driven within spec can be up to 230 lumen. At around the same power as the 8 5mm LED the Cree(make) XR-E(model) Q5(flux bin) should be around 80-120 lumen.

Also you don't need 9v or CR123 for a bright light. A 9v battey has pretty low capacity and CR123s can be expensive unless you buy online. A single AAA light can hit over 50 lumen, a single AA can hit over 100(only few lights do this though).

It does take around 4x the output for a light to seem 2x brighter, so don't expect too much of a visial difference.

If you were to buy a new light, what price, output, beampattern, battery, modes(low, medium, strobe etc.) would you like?

If you would like to build a new light, I'd suggest playing with the high power LEDs.

:welcome:


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