Seeedstudio Super White LED lighting bar 3W — first test

I finally got my trusty digital power supply back. It must be more than 10 years old by now, but it still works like on the first day ;-) Don’t remember how much I payed for it, but looking at what’s available today it must have been quite a lot.

Here’s a picture of the 3W LED bar I bought at Seeedstudio a while ago. I ‘stole’ the image form their shop. I hope they won’t sue me (would be counterproductive, wouldn’t it ?).


The bar is rated 240mA at 12V. Here are some videos to illustrate the MASSIVE brightness of it. I’m using my power supply in current limiting/auto shutdown mode, so I don’t need a resistor. Don’t use a standard wall wart / power supply without current limiting mode !

Increasing the voltage by 0.1V starting at about 8.7V:

Some numbers:


This is filmed through 10 sheets of laser printer paper:

These babies will go on my bike when I have some time to do it. I’ll need to cook up a DC/DC converter to get 12.x volts with current limiting capability. LM3410 seems a good choice. That way I could run it using 4 AAA cells. Riding my bike in the dark will look like a “ray of light” ;-) Maybe I’ll find a person with a camera that can do long time exposure. Too bad my current digital camera can’t do that. The Nikon Coolpix 990/5 I had before could do that no problem. In theory I “could” use my old SLR, but do they still sell film cartridges for these ? Nah, too much trouble with that.

Update 1: 18.08.2009:

Switching to LT1618. Includes voltage and current regulation/adjustment. There’s also a LTSpice model for it.

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17 Responses to Seeedstudio Super White LED lighting bar 3W — first test

  1. ericwertz says:

    Thank you for the videos. I just received one of these from Seeed, soldered on the wires and attached the bar to the heatsink with some thermal compound. I hooked mine up to a 0-20V PSU with a current gauge, no resistor, starting at 0V. I turned up the voltage slowly to 9V and expected to at least see something, but didn’t. I kept going up to 12V…. nothing. I got a 68ohm resistor, put it in series, started again and went up to 13V. Even tried a whimpy 9V transistor radio battery. Nothing. Ammeter in-line never shows any current, nor does the PSU.

    This shouldn’t be difficult to get going, as you demonstrated well. Am I missing something? Any ideas of what else I can try?

    Did you ever get this on your bike? Hit any stunned deer yet?


  2. robert says:


    Well, it might sound silly, but did you reverse the voltage ?

    I haven’t had the chance to put it on my bike yet. Up till yesterday I didn’t have the voltage converter circuit going (see here). I don’t want to carry a 12V lead acid battery on my bike. It should run with at most 4 AAA cells. The circuit works fine. I only need to get a 0.22Ω precision resistor to activate current regulation. Then I can have some boards made and bring light to the dark places.

  3. Mike Prevette says:

    I got one a while back, and following your lead hooked it up to my 18v PSU. Mine worked exactly as described here. Possibly @robert you got a bum unit?

  4. Mike Prevette says:

    I also should have said it flipped on around 9v. also *.LEED.*

  5. ericwertz says:

    @Mike Prevette

    It was actually me that couldn’t get mine working. I sent it back to them a number of weeks ago and asked them to take a look at it. I don’t believe that I did anything unreasonable with it, even though i didn’t have a regulated current supply on it. I did the very same test with a 1W or 3W red LED that I got from them and it went fine as expected.

    I haven’t heard anything back from them, so I need to find out if they got it. I have a second one on order. I’ll probably current-limit drive it first to prove that it’s working, then go back and redo my first test.

  6. ericwertz says:


    Forgot to mention that they said that they haven’t seen any bad units of these yet.

  7. robert says:

    Well, there’s always a first time. I hope this won’t be delayed unreasonably by Chinese new year celebrations. It seems that once they’ve started, they just keep on celebrating.

  8. ericwertz says:


    I just got my second light bar in the mail the other day and just finished playing with it for a minute or two.

    Just to see some signs of life I put 12V with a 1K resistor on it and it did light-up (which I never got to see with the first one). Knowing now that it works I re-ran my initial test with no current-limiting resistor or current-regulated supply and started going up in 0.5V from 7.0V.

    It did just what I’d expect it to do, starting lighting-up through 10V just fine. Just ran enough current through it to turn it on faintly.

    I sent my first one back Dec 22 and as of a week ago, they still hadn’t gotten it yet. And we thought that them sending us stuff could be slow… the other direction seems worse.

  9. robert says:

    It’s a curse. And it can only get worse in the future. Once jet fuel starts getting really expensive… I don’t want to know how long it would take if standard mail were transported by ship.

    And there’s always our ever watching friends at the customs office.

  10. Jack says:

    Does anyone know of where to find the data sheet for this? or mainly I wanted to know the reverse voltage of the LED.
    Thanks in advance

  11. ericwertz says:


    I don’t know of a datasheet. As Robert demonstrated, its proper use is left as an exercise to the reader.

    You should know that DealExtreme also carries this item ( and is a little cheaper, and there’s no shipping charge. They don’t ship quickly but everything that I’ve ever received from them has been packed well (not that I’ve had any packing problems from Seeed either).

    There’s no datasheet for it at DealExtreme — Seeed provides more information about it than DX does (like the 240mA reference). I’m curious about why you’d care what the reverse (maximum) voltage is — that is, unless you’re also trying to use it as a light sensor… :-).

    Personally, I’d be wary of reverse-biasing them at all. Some whites aren’t designed to tolerate any significant reverse voltage — for instance, the Luxeon Rebels come to mind. However, most standard LEDs are usually good for 3-5V reverse max per device. Unclear if these are setup as 12×4 or 16×3 parallel-series chains (or something else entirely).

  12. ericwertz says:


    Wow — nice find (and fast ! :-))

  13. Pingback: Another LED backlight idea -

  14. James says:

    Why go to the trouble of soldering, heat sink and the rest, take a look neatly packed:

    Scroll down to see the use.


  15. robert says:

    Looks neat. But I like to solder ;-)

  16. led lighting says:

    They look good. Very fancy type of led lighting. I like them as well cause they’re cheap to run.

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