Small Light Source Box...

Community Projects
1

Hello everyone,

I would like to build a small light source with a flat base that emit a powerful white light. I envision something like a little box, 1"x 0.5" in area (or so), with a small switch and I guess several interconnected LEDs to provide a strong local illumination to the area under the box and nowhere else. The box needs to be wireless (i,e. work on batteries).

Do you have any suggestion? I was thinking about using 2 coin batteries and several (maybe 4) powerful white LEDs connected in parallel with the proper resistors… Or do you any any better option or device that I can already buy?

thanks,

antennaboy

2

Are you looking for something like this?

http://www.instructables.com/id/DIY-Bot … lashlight/

3

You’ll get more, and brighter light with a CR14250 form factor cell than coin cells.

4

Hello,

I would like to use these led strips:

https://www.superbrightleds.com/search/ … x3%201465/

which require 12V. Considering that I want to use coin batteries, like the CR type, whose voltage is typically 3V, what small voltage converter should I get? Is there anything already available in the sparkfun catalog?

Thanks,

antennaboy

5

Those are 4W LED strips. A CR3032 is 0.5W-hour best case: meaning under very low drain conditions. How long do you want the battery to last?

6

Lyndon,

thanks for the reply. I would like it to last a while so it seem the coin batteries would be drained quickly. Maybe these strips are not the way to go. I like the strips because of their form factor, i.e. they are nice flat strips and I could make a thin, flat light source. What other types of leds would you suggest considering that I am limited to using small batteries and need powerful leds to illuminate an area 1x1 or 1x2 inches, something smaller than a box of matches?

7

Your problem isn’t the LED’s it’s the power source. Coin cells are designed for very low discharge currents. You can use them at higher currents but they won’t last very long.

Take a single 3V coin cell and you can directly connect a plain white LED to it and get usable light. It is not good design, but it will work. Try that and see if it works for what you want.

Alternately, smaller, flat batteries that are more suitable do exist. For example, [this one is 3.7V and rated for 250mA discharge current. It looks like it would fit into a matchbox.](http://www.mouser.com/ProductDetail/Renata/ICP521630PM/?qs=sGAEpiMZZMt9AXHBRDCflqZb28c3vv4W1nfso9bJox8%3D)

8

Thanks again Lyndon.

I bought this small led light source at Home Depot: http://www.energizer.com/flashlights-li … net-lights and opened it up. It contains 2 coin batteries (3V each) connected in series (6V total) and a single LED. There are some resistors and a black chip inside…I wonder if that chip is a voltage regulator or a voltage amplifier (to go from 6V to 12 V or to down-amplify from 6V to 3V).

Many websites sell LED light strips which work with 12 V. These strips are formed by short sections connected in parallel to each other. Each section contains 3 led connected in series. Each led needs about 3.3V, hence the 9.9V (~12V) to power the light strip (I guess)…

In my design, I would like to use those 2 coin batteries and two or 3 leds to build something similar to the energizer magnet light…

thanks,

antennaboy