Using ultra-bright LEDs

Jonathan

Hi All,

I'm working on·a project for a friend of mine. She wants a traffic light that is triggered by noise levels in her classroom. I have the sound detection circuit working, and am playng with tweaking that.

My question is in regards to ultra-bright LED's and driving them. I purchased a traffic light that uses regular light bulbs, and I want to convert it over to LEDs to save power and make it more reliable. My plan is to replace the bulbs with clusters of LEDS.

So, my questions are:

How many LEDs of whawattage will I need to make the lights visible easily in a brightly lit classroom?

I was thinking of using a MOSFET to drive them. Any reccomendations?

Any reccomendations where to purchase the LEDs? Im seeing maybe 7-12 per cluster.

I will be using a Stamp, so the MOFSETS must be driven with 5V.

Thanks!

Jonathan



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Tim-M

A great resource for LED's, both·individual and modular is www.superbrightleds.com, take a look at what they have to offer.

Tim

Blackbird455

Superbright has alot of good leds, but depending on the size of the "lights " you might want to consider other Led types, such as luxeon LEDS http://luxeonstar.com/...
the luxeons make a ton more light for the dollar, and generally offer a 140 degree viewing angle, versus 15 to 30 degrees from a superbright.
The only thing that I would not recommend is driving the luxeons from 5 volts.........the amps and the heat will eat you up.....if you run the luxeons in a series of three, you can generally wind up @ 11.55v or 300mA, 700 mA, or even with the K2 bulbs 1500mA..........or if run off of a lm7805 regulator (5 volts)........ that would be one regulator per bulb, plus alot of heat dissipation per regulator. If the old light housing was run with a halogen bulb, I would assume that there is some type of reflector in place....that would mean that you could use just one luxeon K2 in the place of it, and it would be plenty bright. Are the lenses colored on the light housing? If they are then you could use a white K2 @ 1500mA , and just stick with a bank of 3 7805 regulators, and one 5.6 ohm 2 watt resistor. What is your supply voltage going to be? Well, whatever you use there is a solution, and I will be glad to help you with it.

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StampNut2

You can also acquire torch replacements, the head is a cluster of bright LEDS, I know they come in the colors you need,These are 6,12,24v.but you can still use them with a second p/s supply. I use them for headlights on my bot and they are quite bright.

www.superbrightleds.com/BA9S6_specs.htm

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Post Edited (StampNut2) : 8/29/2007 6:33:47 PM GMT

Blackbird455

OH and you do not have to use only MOSFETs to drive them, you can use just about any transistor. I recommend the TIP31A, easy, cheap and available. You can use the tip 31's as power amps and have the stamp switching them..........I switch 12 v @ 4.5a without any problem, with a bs1.

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ETERNAL NOOB, you could learn alot from a dummy

StarMan

Don't forget to look on ebay.· I've had great success finding good quality, bright LEDs there.· As mentioned previously, also look for the clusters used for flashlight replacements.

Also, not too long ago, I bought some Luxeon clusters mounted on aluminum of all three traffic signal colors at All Electronics and from Marlin P. Jones.· All Electronics still has these and they work very well at 12V.· You still might find the other colors elsewhere.

One of my favorite MOSFETs for driving relatively large arrays of LEDs from logic level is the FDP7030BL.

Chris I.

Jonathan

Thanks for all the info, folks! I knew I could find some help here.

Thanks again, saves me a lot of time experimenting!

Jonathan

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