White Wire Light System

Discussion in 'Lighting and Electrical' started by LEDHead, Jan 14, 2011.

  1. LEDHead

    LEDHead New Member

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    Ever since I built my motorized bike 2 years ago I have experimented with LED based light systems powered soley by the white wire and without batteries. I tried half wave rectification of the positive as well as the negative half cycles from the generator but ultimately settled on a full wave bridge. One thing I discovered was the usable output voltage ranges from about 25VDC down to about 8VDC depending upon the electrical load. The generator can source 3-4 watts which is adequate for a decent LED light system. The key is to efficiently convert the relatively high output voltage down to the 3 volt range for a high brightness white LED. As others on this forum have noted, the best way is to use a stepdown or buck DC-DC converter. This is what I did for driving the head light. I also included a tail light and side lights to make my bike more visible. I connected 4 red LEDs for the taillight, 2 red and 2 white LEDs for the side lights all in series and power them directly from the output of the generator. The attached photos show the results. The beam pattern on the garage door is from about 20 feeet down my driveway.
     

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  2. Tacomancini

    Tacomancini Member

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    Those look really good. What kind of led's are they, and what do the enclosures look like? It all looks seriously bright!
     
  3. Erich_870

    Erich_870 New Member

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    That is very impressive! Can you share more about your full wave bridge design as well as the LED's you chose?

    Erich
     
  4. LEDHead

    LEDHead New Member

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    I bought the head light and tail light on eBay. Chinese package that included both. I gutted the tail light and use only the enclosure to house 4 high brighness red LEDs. They came from a trailer hitch brake light I found at Harbor Freight. The side red LEDs are from Radio Shack and the white side LEDs are from a 6 LED flashlight I took apart. The head light is advertised as 5 Watt but that is pretty optimistic. I drive it with 500 mA @ ~3.4 volts. I mounted the headlight with a couple of pipe straps bent into a "U" shape.
     

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  5. Rockenstein

    Rockenstein New Member

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    I take it your driving your LEDs using the LED driver circuit you posted here?

    I need bright lights like that (^)
     
  6. LEDHead

    LEDHead New Member

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    Rockenstein - yes, that is the schematic of my lighting setup. It has evovlved from a pretty basic buck voltage regulator to something a lot more complicated than I had intended. I just kept finding ways to improve the performance but each iteration seemed to require adding more circuitry.

    I am working on another design that should replicate all the features of this one but will be a lot simpler at least in terms of parts count. I hope that it will be something that anyone with good mechanical skills and some basic soldering skill will be able to build. I think that most of the motorized bicycle builders out there have those abilities. I will post the results (good or bad) when I finish building and testing it. Some warmer and drier weather in Seattle would help.
     
  7. Rockenstein

    Rockenstein New Member

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    Yea it always seems when you start a project like that that you end up adding on things that you weren't thinking much about when you first started...lol

    I don't find your schematic too hard to follow though and I may only use part of it to do what I'm thinking I'd like to do. Basically I want to either eliminate the 6v SLA my setup uses with a completely white wire driven on or off setup or I'd like to build a circuit that will maintain the 6v SLA without me having to worry about plugging in a 120v charger should I be out in the boonies roughing it for a few days.
     
  8. 2lazy2pedal

    2lazy2pedal New Member

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    Hello LED Head Can u tell us where did you get ur buck converter? Really like ur set up
     
  9. 66cc

    66cc Member

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    LED that lighting system looks awesome!

    I had a question, I hooked up a CREE led 3v, and it it bright at idle, but flickers and goes out and mid to WOT?
     
  10. TheSignGuy

    TheSignGuy Member

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    Voltage cannot spike what about watts though
     

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