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    homebrew LED light solution, solder what to what now?

    Having made a couple of halogen-based bike lights last year, I decided to try my hand at a couple of LED lights this year. I have some novice electronics and soldering skills, and love to go to the hardware store to see what random bits and pieces I can turn into something entirely unintended but useful. After hearing so much about dealextreme.com on this site, I went up there and ordered up some optics, cree LED's, and some drivers. My initial thought was that I may like to make a 3-LED light, but if the LED's are bright enough with my 7.2v 3500mAH NiMH batteries, I'll make a couple single-LED lights.

    My shipment arrived yesterday. The LED's are: these and drivers: these. Here's what I got:


    I'm not sure if I was expecting some instructions, or maybe some more obvious markings, but it's not clear to me where to connect the battery leads, and then where to connect the driver to the LED's. I'm assuming the battery leads get connected to the circles on the bottom of the driver, but there's an inner and outer, and neither are marked + or -. There are clear + and - leads coming off of the driver, which I assume goes to the LED, but the LED has two + and two - connection points, and I'm not sure if it matters which ones I use.

    If any of you have any experience with this and can point me in the right direction, I'd much appreciate it!
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  2. #2
    Zoom zoom zoom zoom bonk znomit's Avatar
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    Quote Originally Posted by heyjaffy View Post
    I'm assuming the battery leads get connected to the circles on the bottom of the driver, but there's an inner and outer, and neither are marked + or -. There are clear + and - leads coming off of the driver, which I assume goes to the LED, but the LED has two + and two - connection points, and I'm not sure if it matters which ones I use.
    It doesn't matter which + or - pad on the LED you use(some have three of each)... yes the black wire goes to -, red to +.
    For the power supply, its for a flashlight tube so + usually points to the center, - to the outside.

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    Quote Originally Posted by znomit View Post
    It doesn't matter which + or - pad on the LED you use(some have three of each)... yes the black wire goes to -, red to +.
    For the power supply, its for a flashlight tube so + usually points to the center, - to the outside.
    Excellent - thanks!

    Any idea if I can run more than one LED off of one driver, or do I need one driver for each LED? I'm not sure if I'm going to have a 3-LED light or 3, 1-LED lights.
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    Junior Member netbug's Avatar
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    Hi heyjaffy,
    I am in the middle of building a bicycle LED light myself. Unlike you however I am building with only 2 LED with 2 different type of lens/collimator, one spot another using wide angle. Depends of the type of what driver that you use you can connect more than one LED (usually in series).

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    Zoom zoom zoom zoom bonk znomit's Avatar
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    Quote Originally Posted by heyjaffy View Post
    Any idea if I can run more than one LED off of one driver, or do I need one driver for each LED? I'm not sure if I'm going to have a 3-LED light or 3, 1-LED lights.
    On the DX page it says 3.7v output which is just one LED.

    Looks like some nice parts, have fun and keep us posted on your progress!

    BTW...when you first power up the LED have some sunglasses handy!

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    Scott n4zou's Avatar
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    Quote Originally Posted by netbug View Post
    Hi heyjaffy,
    I am in the middle of building a bicycle LED light myself. Unlike you however I am building with only 2 LED with 2 different type of lens/collimator, one spot another using wide angle. Depends of the type of what driver that you use you can connect more than one LED (usually in series).
    Thats what I did as well. I used a standard wet location aluminum outlet box to house a 15X30 lens and holder and a 10 degree narrow lens and holder with SSC P4 U-BIN Z-power LED's. I'm driving them with a dynamo so no batteries are required or current regulating driver circuits. The circuit I use is just 4 1N5818 diodes as a bridge rectifier and 1,000mF capacitor to stop flashing at very low speed, IE: walking the bike up steep hills.


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    Quote Originally Posted by heyjaffy View Post

    I'm not sure if I was expecting some instructions, or maybe some more obvious markings, but it's not clear to me where to connect the battery leads, and then where to connect the driver to the LED's. I'm assuming the battery leads get connected to the circles on the bottom of the driver, but there's an inner and outer, and neither are marked + or -. There are clear + and - leads coming off of the driver, which I assume goes to the LED, but the LED has two + and two - connection points, and I'm not sure if it matters which ones I use.

    If any of you have any experience with this and can point me in the right direction, I'd much appreciate it!
    Positive is the center circle and the outside circle is negative. You'll need a switch between the negative circle and the negative post on the battery. Visualize a flashlight with standard batteries. The positive post of the first battery put
    put into the flashlight contacts the center circle. The Negative post of the last battery installed rests on a spring with a copper strip running up the interior side of the flashlight body, to the switch, and then to the outside circle of the driver board. The red wire on the driver board connects to the + marked solder pad and the black wire connects to the - marked solder pad.
    You need a separate driver for each of the LED's in your order. I would suggest a separate switch for each driver. This allows the option of running each LED in a separate mode. Personally, I would set it up with one LED in high with a large switch to turn it off and on like that used on a vehicle for the high beam, the second LED on a dimmer setting, and the third LED set to a high visibility blinking mode.
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    Junior Member netbug's Avatar
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    n4zou,
    The lights looks great. How waterproof is it ? Did you put extra sealant at the base of the LED lens ?

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    Healthy and active twobikes's Avatar
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    Also, remember that LED's are diodes. A digital volt-ohmeter with a diode checker can tell you which is positive and which is negative. The advantage is that a diode checker uses low current so you cannot damage the diodes with it.
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    I may just be missing it, but you do have some sort of heat sink and thermal epoxy you're going to use right?

    Those won't run very long without some sort of heat sink...

    Also remember that if you reverse the polarity on an LED it won't light. If you get everything together and it doesn't work check that first.

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    Scott n4zou's Avatar
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    Quote Originally Posted by netbug View Post
    n4zou,
    The lights looks great. How waterproof is it ? Did you put extra sealant at the base of the LED lens ?
    I cut clear plastic to fit between the front cover and gasket that came with the front cover. This seals everything including the optics. That plastic cover is easily replaced. I know you have purchased small items in those tamper resistant molded clear plastic blister packs. You also know how tough and optically clear they are. Thats what I used to seal up the housing. It's also easy to cut a new cover when it's necessary to do so.
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    Scott n4zou's Avatar
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    Quote Originally Posted by ovrrdrive View Post
    I may just be missing it, but you do have some sort of heat sink and thermal epoxy you're going to use right?

    Those won't run very long without some sort of heat sink...

    Also remember that if you reverse the polarity on an LED it won't light. If you get everything together and it doesn't work check that first.
    A heat sink is mandatory! Old computer CPU heat sinks work very well. You don't need a fan as long as the heat sink is exposed to the air. I am using the aluminum enclosure as the heat sink for my LED's. They are mounted to sheet copper with copper straps attached to brass screws and nuts to conduct heat from the LED's to the enclosure housing. My dynamo provides 500mA or about half the rated current of the LED's I am using so the LED's run cooler as well. Here is a photo of the bottom side of my setup.



    You can see the copper straps attached to the brass screws and nuts along with the capacitor. The 4 diodes are on the other side of the perf board but you can see where wires are soldered to the leads.
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    Quote Originally Posted by ovrrdrive View Post
    I may just be missing it, but you do have some sort of heat sink and thermal epoxy you're going to use right?

    Those won't run very long without some sort of heat sink...

    Also remember that if you reverse the polarity on an LED it won't light. If you get everything together and it doesn't work check that first.
    Heatsink, check, thermal epoxy, check - the picture was just some of the bits that I picked up. I have another order on the way from dealxtreme (more cree LEDs) and another from ledsupply.com (more cree lense options and buckpuck), and I have to make a trip or two to the hardware store for casing materials.
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    Quote Originally Posted by n4zou View Post

    Great idea Scott, thanks for sharing, I'm sure I'll steal, ahem, borrow some ideas from you.
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    Scott n4zou's Avatar
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    Quote Originally Posted by heyjaffy View Post
    Great idea Scott, thanks for sharing, I'm sure I'll steal, ahem, borrow some ideas from you.
    Go for it! You'll be surprised at how bright it is just with dynamo power. I've tried this light with batteries at full rated current of 1 amp. It's shockingly bright.

    Here is where I purchased my parts.
    10 degree lens and holder.
    http://www.luxeonstar.com/item.php?i...HS-HNB1-LL01-H
    15X30 degree lens and holder.
    http://www.luxeonstar.com/item.php?i...HS-HEB1-LL01-H
    LED's
    http://www.dealextreme.com/details.dx/sku.1445

    If powering with a standard bicycle dynamo use these parts.
    1N5818 diodes 4 each required as full wave bridge rectifier. Go ahead and buy 30 at .13 cents each; you'll use them all eventually!
    http://www.mouser.com/Search/Product...252bMGzA%3d%3d
    1000uF capacitor 1 each. Optional: to reduce low speed flashing.
    http://www.mouser.com/Search/Product...jh7eJ0Sg%3d%3d
    Moderate speed boost capacitors, 2 each required. Optional; boost moderate speed light output.
    http://www.mouser.com/Search/Product...dwQkc49g%3d%3d
    Link to detailed dynamo driven LED light circuits. A must read site if your using a dynamo!
    http://pilom.com/BicycleElectronics/DynamoCircuits.htm

    Optional circuit (simplified) shows how to use devices such as GPS units and cell phones that are powered and/or recharged via a computer USB port.

    Last edited by n4zou; 04-28-08 at 09:19 PM.
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  16. #16
    Junior Member netbug's Avatar
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    Thanks for sharing.
    Currently I am using battery (4xAA energizer 2500 mAh) to power mine, my next plan is to power it by a dynamo, and create a switch so that I can power it by dynamo or battery.
    I am using this driver:
    http://www.dealextreme.com/details.dx/sku.1885
    and some cree LED:
    http://www.dealextreme.com/details.dx/sku.2394
    Driving both LED's at 1 Amp results in a VERY bright light . Battery runtime is now about 1 hour with both light on, or around 2 hours with single light. I mostly use only 1 light unless it is really dark.

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