SparkFun Forums

[forgewithinfire]

Hey guys, I'm no electrical engineer... hell I only know how to solder and read a schematic. I was wondering if anyone could get/give me a simple schematic for a driver of the Green Luxon LED sold at Parkfun (AA battery source)? Or just some simple instructions? Again I have no idea how to design a circuit, just build one using Radio Shack-like components.

I'm making a unique product for cyclists, hopefully to take a completely different approach to nightime safety/riding. I would post the completed project.

Thanks for any help you can give me!

[lyndon]

Take a look at www.dealextreme.com You can often find high power LED driver boards selling for less than it would cost you to build them, with free shipping from Hong Kong!

[riden]

If you are producing a product, you will want to have a reliable supply of your components. So make sure that either order sufficient inventory or ensure that your driver boards will be available in the future.

If you want to roll your own solution, you will need some type of constant current source circuit. If you Google, you'll find a number of circuits, including one using a LM317. These work, but can waste a lot of power (radiated as heat). A little more complicated design costing a little more and uses PWM (pulse width modulation). This approach is very efficient (i.e., longer battery life). With the PWM approach, the LED is pulsed on and off very quickly to maintain a constant current.

For you initial design phase, you can start with a commercial regulator board or put together a LM317 regulator for testing. Google "lm317 led" to get some example circuits. Here is one example of using a LM317 for a LED driver. Later you can use a PWM design if your design could benefit from it. I have used several variations powered by a PIC microcontroller from Microchip at a cost of around $3.

Remember, don't exceed the specifications of the LED unless you want to burn it out or short its life.

[forgewithinfire]

Thanks ... but on LuxDrive.com I'm having trouble finding the right driver for my Luxeon K2 Star - Green, 100 Lumens @ 700mA. I will only be powering one and I need a relatively compact driver with wires. PWM would be nice, but I will stick with constant current for now. I don't think I have the skill to make my own driver.

I know it's a high amperage for a battery powered device but I NEED the 100 lumen output (60 doesn't cut it) from a single point light source. I was going to go with Lithium Ion batteries so I can decrease the weight and size. Does that make sense to do?

Thanks for your help guys, I haven't done anything electrical in 7 years and I appreciate the know-how.

B

[noptical]

Take a look at www.dealextreme.com You can often find high power LED driver boards selling for less than it would cost you to build them, with free shipping from Hong Kong!

or even better, for multiple seller instead of only one, try ebay

[riden]

These work well and the price is for 3 units. I purchased the 120vac version, though.

http://c-leds.com/shop/product_info.php ... cts_id=141

[forgewithinfire]

I ordered my LED driver from http://www.luxeonstar.com/ they were very helpful in selecting the right one. Not very inexpensive but the BuckPuck has the option for control that can also be used for a strobe/continuous mode! Perfect for bicycle applications!

I'm using this heatsink: http://www.primelec.com/Cooling-Product ... 76559.html

I'm using Arctic Silver Thermal Adhesive. It is a small heatsink, so I'm going to plate the heatsink (I do jewelry work) to make it corrosion resistant so it can stick outside of the project enclosure.

Thanks for all the help!

Ben

[riden]

Good luck with your project, Ben. Although the BuckPuck isn't the cheapest solution, it is a good one.