Results 1 to 15 of 15
  1. #1
    more carbon=more awesome
    Reputation: The Understater's Avatar
    Join Date
    May 2007
    Posts
    1,308

    Question on wire gauge for L332MC

    So I have to drill some holes in my housings to wire up up Quazzle's 332 board, and I have been up to the local electronics shop to get some wire. The guy there reckoned the smaller gauge wouldn't support 1 amp, and told me I needed the next size up. The two sizes including housing measure 1.7mm and 2.3mm. Doesn't sound like a lot, but in these tiny light heads it makes a difference.

    Any thoughts?

    b.
    Attached Thumbnails Attached Thumbnails Question on wire gauge for L332MC-sv400231.jpg  

    Posting on the basis that ignorance shared is ignorance doubled.

  2. #2
    Drinkin' the 29er KoolAid
    Reputation: kwarwick's Avatar
    Join Date
    Jun 2004
    Posts
    992
    Look for some printing on the insulation... it will say AWG xx, with xx being a gauge number like 22,24,26, etc. Google "AWG current capacity" and you'll get some tables with the maximum current for each gauge. Basically anything with a number of AWG 28 or lower can easily handle 1 amp. I usually use 26 or 24 (smaller number = larger diameter) for my DIY lighting projects.

  3. #3
    mtbr member
    Reputation:
    Join Date
    Apr 2007
    Posts
    311
    28AWG has a voltage drop of about 0.25V per metre @ 1A.

    FYI a good rule of thumb: one metre of 1mm^2 conductor has a voltage drop of 20mV @ 1A.

    1mm^2 is around 17AWG.

    HTH

  4. #4
    Drinkin' the 29er KoolAid
    Reputation: kwarwick's Avatar
    Join Date
    Jun 2004
    Posts
    992
    Quote Originally Posted by Mark2c
    28AWG has a voltage drop of about 0.25V per metre @ 1A.

    FYI a good rule of thumb: one metre of 1mm^2 conductor has a voltage drop of 20mV @ 1A.

    1mm^2 is around 17AWG.

    HTH
    That's a very good point! The longer the cable the thicker the gauge of wire one should use to minimize losses in the cable. The 26 or 24 gauge wire I only use for interconnects inside the light. For the longer cables going between the light head and battery pack I've been using 22AWG.

  5. #5
    more carbon=more awesome
    Reputation: The Understater's Avatar
    Join Date
    May 2007
    Posts
    1,308
    Thanks guys.
    Unfortunately the only wire I could get here has no markings at all on the sheath, so I'm still pretty much in the dark.

    b.
    Posting on the basis that ignorance shared is ignorance doubled.

  6. #6
    mtbr member
    Reputation:
    Join Date
    Apr 2007
    Posts
    311
    Where are you located ? I'll send some thin stuff via fastpost (I'm in Tawa, Wellington).

  7. #7
    more carbon=more awesome
    Reputation: The Understater's Avatar
    Join Date
    May 2007
    Posts
    1,308
    Quote Originally Posted by Mark2c
    Where are you located ? I'll send some thin stuff via fastpost (I'm in Tawa, Wellington).

    PM sent. Thanks.
    Posting on the basis that ignorance shared is ignorance doubled.

  8. #8
    more carbon=more awesome
    Reputation: The Understater's Avatar
    Join Date
    May 2007
    Posts
    1,308

    New Question... about positive/negative.

    So I was trying to work out if it was the inside or outside part of my plug (Magicshine extension lead) is positive, but no matter which way I stick the multi-meter across it I get the same voltage. If I put the leads back to front on an AA I get the needle banging on the stop. Any idea what's happening? Id really rather not fry my L332 boards wiring them up back to front.

    b.
    Posting on the basis that ignorance shared is ignorance doubled.

  9. #9
    mtbr member
    Reputation:
    Join Date
    Apr 2007
    Posts
    311
    Quote Originally Posted by bshallard
    So I was trying to work out if it was the inside or outside part of my plug (Magicshine extension lead) is positive, but no matter which way I stick the multi-meter across it I get the same voltage. If I put the leads back to front on an AA I get the needle banging on the stop. Any idea what's happening? Id really rather not fry my L332 boards wiring them up back to front.

    b.
    I found the Magicshine plugs unreliable and have changed to EC5 conectors.

    Magicshine are centre-positive.

  10. #10
    Drinkin' the 29er KoolAid
    Reputation: kwarwick's Avatar
    Join Date
    Jun 2004
    Posts
    992
    Quote Originally Posted by bshallard
    So I was trying to work out if it was the inside or outside part of my plug (Magicshine extension lead) is positive, but no matter which way I stick the multi-meter across it I get the same voltage. If I put the leads back to front on an AA I get the needle banging on the stop. Any idea what's happening? Id really rather not fry my L332 boards wiring them up back to front.

    b.
    Center pin is positive. I use the Magicshine extension leads on my Troutie and Gili lights without issue (so far ).

    It sounds like you've got an old school analog multimeter from your description. Are you sure you've got it set on the correct DC voltage scale? Almost sounds like you've got it set on ohms...
    Last edited by kwarwick; 07-06-2010 at 04:16 AM.

  11. #11
    mtbr member
    Reputation:
    Join Date
    Jul 2005
    Posts
    1,681
    Voltage will read the same...it's just that if it's backward...then it will read negative...same number though...it'll just have a " - " in front of it.

  12. #12
    mtbr member
    Reputation: yetibetty's Avatar
    Join Date
    Dec 2007
    Posts
    1,780
    Quote Originally Posted by chelboed
    Voltage will read the same...it's just that if it's backward...then it will read negative...same number though...it'll just have a " - " in front of it.
    Thats the problem with the anolog meters the needle will simply want to go backwards if its the wrong way round.

  13. #13
    mtbr member
    Reputation:
    Join Date
    Jul 2005
    Posts
    1,681
    Oh yeah...I forgot about those things...LOL.

  14. #14
    more carbon=more awesome
    Reputation: The Understater's Avatar
    Join Date
    May 2007
    Posts
    1,308
    Yeah, the meter is an analogue unit. I hardly ever use it, as I have more sophisticated test equipment for watch batteries, but I occasionally break it out to test an AA from some horrible battery wall clock; it works correctly and the needle hits the correct voltage on the scale. That is why I couldn't figure out why the needle was giving positive voltage whichever way I laid the points across the plug. One way should have sent it backwards into the stop, but this didn't seem to be the case.

    Anyway, never-mind. I now know the plug is center positive and the polarity mystery will have to go unanswered.

    On a slightly related topic, I just got back from my regular Wednesday night group ride. The fast boys weren't there tonight, so I drew the lead slot. Man, my current light is starting to give me grief! I think the battery pack is on the way out or something. The guy behind me, with the same brand light as mine (iblaast) was casting a big shadow in front of me. I hope Quazzle comes through with the goods soon. Then I will be the cause of some serious light-envy in the group.

    b.
    Posting on the basis that ignorance shared is ignorance doubled.

  15. #15
    mtbr member
    Reputation:
    Join Date
    Jan 2007
    Posts
    754
    Quote Originally Posted by bshallard
    Yeah, the meter is an analogue unit. I hardly ever use it, as I have more sophisticated test equipment for watch batteries, but I occasionally break it out to test an AA from some horrible battery wall clock; it works correctly and the needle hits the correct voltage on the scale. That is why I couldn't figure out why the needle was giving positive voltage whichever way I laid the points across the plug. One way should have sent it backwards into the stop, but this didn't seem to be the case.
    You probably have the meter set to AC Volts instead of DC Volts.

Posting Permissions

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