Results 1 to 4 of 4
  1. #1
    Canuckistan
    Reputation:
    Join Date
    Mar 2008
    Posts
    131

    First light Questions

    Hi there,

    I'm looking to build my first light, and I think I've settled on an simple? single XML build.
    I'm planning on doing just a simple sled type/square tubing build, you know, keeping it simple.

    I have some scavenged 18650's and a gemini titan. So I'd like to do a double 18650 series pack (8.4V) so I have battery compatibility with all my lights/future lights. Also planning on using the trailtech plugs.

    What has me confused though, with this light build, is drivers. From my reading I think I need a buck circuit, but to be honest, I have no idea what constitutes a 'good' driver. I don't need anything fancy, just on/off is perfect to start.

    As for what amperage I'm driving the LED at, not really sure, looking for a bit of advice on that too.

    To throw a monkey wrench into I'm also canadian, so I think I'll be importing almost everything, so minimizing suppliers would be preferred.



    Thanks in advance guys

  2. #2
    mtbr member
    Reputation:
    Join Date
    May 2005
    Posts
    2,234
    You do need a buck driver with the configuration you have planned. For cheap drivers look around at Dealextreme or Kaidomain for P7 or MCE drivers. Here is an example..

    http://www.dealextreme.com/p/regulat...ax-input-20330

    With good heat dissipation you can run the XML to >3A. The sled design won't handle that for long without additional heat sinking or high speeds (lots of air movement). Drop the amperage to 2 or 2.5 and you'll still have lots of light and less heat to deal with. It will still get d@#n hot if going slow or stopped. That's one reason for having more levels than on/off.

  3. #3
    Canuckistan
    Reputation:
    Join Date
    Mar 2008
    Posts
    131
    Thanks for the info,

    If I was to put some simple heatsinks pulled off of a CPU on the sled type, would that probably be sufficient provided I turn it off when I am not moving?

    Also, I have looked at the Lflex driver, from what I have read, am I correct in thinking that if I only have one XML my pack can only have 4.2V but if I run a pair of XMLs I can run my originally planned 8.4V pack? I think I read somewhere the Lflex is direct drive? how does that work if the LED is supposed to only get 3.35V at 3A?

    Thanks a bunch

    CC.

  4. #4
    mtbr member
    Reputation:
    Join Date
    May 2005
    Posts
    2,234
    Quote Originally Posted by CrazyCanuck
    If I was to put some simple heatsinks pulled off of a CPU on the sled type, would that probably be sufficient provided I turn it off when I am not moving?

    Also, I have looked at the Lflex driver, from what I have read, am I correct in thinking that if I only have one XML my pack can only have 4.2V but if I run a pair of XMLs I can run my originally planned 8.4V pack? I think I read somewhere the Lflex is direct drive? how does that work if the LED is supposed to only get 3.35V at 3A?
    Additional heatsinks will help greatly. You are right that you could not leave it on when stopped for more than a few minutes. I personally would go with one of the Taskled flex drivers over anything from DX or KD. It will work to use your 7.4V battery with an lflex and 2 XMLs in series. The lflex is a linear regulator. That means it drops the voltage by turning into heat. That's why you need to have the battery voltage and LED Vf matched as close as possible for decent efficiency. The lflex only goes into direct drive when the battery voltage drops below the LED Vf.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •