This is what happens when you cross a 3Watt Luxeon with a battery-powered RC Truck.
The battery packs give about 14-15 volts (unregulated, of course, since the two electric motors cause the voltage to sag). I used a simple LM317T configured as a current regulator, and dialed up white star (vf of about 3.8-9 volts) to about 835mA. The little metal box gets pretty warm, but from the linear regulator which of course is wasting most of the energy as heat. Given the short run of the RC truck on bateries, and that I simply swap for another set of charges batteries, I was not worried about trying to get the most efficient setup. I did however, build a separate battery pack that I can mount on the back of the truck (using 4 series/parallel 17670 cells with a protection circuit) in case I wanted even longer running time. The battery pack was also used during all testing/building, so it was nice to have around anyway!
The white "stuff" around the switch and the star is simply silicone to seal and protect the connections from corrosion - yes, my monster truck does go off-road often!
The switch of course was needed so that I can keep the lux off during the day (simple ON/OFF double pole). At night it is a LOT of fun since you can't even see the car, just the light /ubbthreads/images/graemlins/grin.gif. My neighbor and his kids and I had a great time following the car in complete darkness /ubbthreads/images/graemlins/tongue.gif
I tried with the 17mm, 20mm, and 27mm reflectors, but the wider beam of the 17mm was about perfect to have enough light to the sides. I then epoxied the reflector to the star (which was AA epoxied to the metal box), and then epoxied a 22mm UCL lens to the reflector to seal the emiter and protect it. I though about using a cheap plastic lens, but it would have gotten all scratched up right away.
The time consuming part was figuring out how to mount the LED "module" to the truck, since I need to be able to remove the plastic cover all of the time. Also, the LED module had to be recessed so that then the truck hit something (not that it happens that often /ubbthreads/images/graemlins/crazy.gif) the LED module wouldn't break. The LED module/metal box can be moved slightly to ajust the angle (that is why it looks crokked).
The other thing that was tough was to cut the plastic - that was VERY hard to cut smootly, so right now I have a kind-of ugly cut in front /ubbthreads/images/graemlins/frown.gif. At least the LED module does work as designed /ubbthreads/images/graemlins/grin.gif
I need to work more with my new camera - photos are still not as good as they could be. Now I realize first-hand how hard it to take pictures of lights /ubbthreads/images/graemlins/wink.gif
Here are the project's pictures, some with and some without flash:
Here it is fully assembled - notice recessed LED for protection (although with ugly plastic cut):
This view shows the cable routing used:
Not in focus, but that is the small switch to turn the LED on/off:
Module tilted to adjust beam angle:
Hookup to the 14-15 volts - all soldered and tie-wrapted:
The battery packs give about 14-15 volts (unregulated, of course, since the two electric motors cause the voltage to sag). I used a simple LM317T configured as a current regulator, and dialed up white star (vf of about 3.8-9 volts) to about 835mA. The little metal box gets pretty warm, but from the linear regulator which of course is wasting most of the energy as heat. Given the short run of the RC truck on bateries, and that I simply swap for another set of charges batteries, I was not worried about trying to get the most efficient setup. I did however, build a separate battery pack that I can mount on the back of the truck (using 4 series/parallel 17670 cells with a protection circuit) in case I wanted even longer running time. The battery pack was also used during all testing/building, so it was nice to have around anyway!
The white "stuff" around the switch and the star is simply silicone to seal and protect the connections from corrosion - yes, my monster truck does go off-road often!
The switch of course was needed so that I can keep the lux off during the day (simple ON/OFF double pole). At night it is a LOT of fun since you can't even see the car, just the light /ubbthreads/images/graemlins/grin.gif. My neighbor and his kids and I had a great time following the car in complete darkness /ubbthreads/images/graemlins/tongue.gif
I tried with the 17mm, 20mm, and 27mm reflectors, but the wider beam of the 17mm was about perfect to have enough light to the sides. I then epoxied the reflector to the star (which was AA epoxied to the metal box), and then epoxied a 22mm UCL lens to the reflector to seal the emiter and protect it. I though about using a cheap plastic lens, but it would have gotten all scratched up right away.
The time consuming part was figuring out how to mount the LED "module" to the truck, since I need to be able to remove the plastic cover all of the time. Also, the LED module had to be recessed so that then the truck hit something (not that it happens that often /ubbthreads/images/graemlins/crazy.gif) the LED module wouldn't break. The LED module/metal box can be moved slightly to ajust the angle (that is why it looks crokked).
The other thing that was tough was to cut the plastic - that was VERY hard to cut smootly, so right now I have a kind-of ugly cut in front /ubbthreads/images/graemlins/frown.gif. At least the LED module does work as designed /ubbthreads/images/graemlins/grin.gif
I need to work more with my new camera - photos are still not as good as they could be. Now I realize first-hand how hard it to take pictures of lights /ubbthreads/images/graemlins/wink.gif
Here are the project's pictures, some with and some without flash:
Here it is fully assembled - notice recessed LED for protection (although with ugly plastic cut):
This view shows the cable routing used:
Not in focus, but that is the small switch to turn the LED on/off:
Module tilted to adjust beam angle:
Hookup to the 14-15 volts - all soldered and tie-wrapted:
