Here is a little back story for this quick and very useful project.  I am in the process of designing and building a small indoor green house, which will have LED based grow lights in it.  I bought a couple of LED grow light boards from homegrownlights.com, so I needed to install 256 LEDs per board and having a total of 10 boards to populate with some 2,560 LEDs, I wanted a way of testing the LEDs before I went through the process of soldering them in.  I had a couple requirements as I went into building my tester.  First it had to be easy to use.  Second it had to be simply and compact once built.  Third it had to be cheap, but would last a while for other LED projects.  So here is my design, it's quick, clean, and easy to use.  I was able to test 2,000 LEDs in about an hour and 15 minutes.

Step 1: Parts + Tools

- Small project box (3"x2"x1")
- A piece of 2-sided copper clad PC board (2"x2")
- CR2032 Button Battery holder
- CR2032 Button Battery
- Small peice of wire (not in picture)

Optional potentimeter to be able to turn voltage down for LEDs that require lower voltages.  I built it to test 3-4VDC LEDs, so running just a 3VDC button battery worked for me, but I am going to add the adjustability later.

(I bought everything at Radio Shack.  I'm lucky enough to live in a college town with a large engineering school, so the Radio Shack actually still carries components.)

the problem of button batteries is the luck of Ampers. What if your led will need more than 0,300mA? That's why is better to use 2xAA batteries....
nice idea...<br> you could also use a much smaller project box or use a smaller battery and place a similar device in an old usb flash drive housing which would also give you an end cap....<br><br>just a thought.
Good way to test a lot of LEDs.<br>THANKS!<br><br>Now, about your grow light... What colors are you using?<br><br>Will there be an instructable?
I am using 75% red and 25% blue. I am thinking about it. I am using the boards from homegrownlights.com, so it's pretty easy.
I would have thought there would be some yellow involved as well.<br><br>I asked the nice workmen at the highway traffic light maintenance place about some replaced signal lights.<br><br>I have plenty of extremely bright red, green and amber LEDS as well as some awesome diffusers and lenses.<br><br>While I was in the neighborhood, I also dropped in next door at the highway stripe painting division.<br><br>I also picked up a half gallon of the glass beads they use to make the reflectivity of the stripes.<br><br>Good sources of neat stuff found no place else.....<br>
Research has shown that plants benefit most from a combination of red and blue light. As green light is reflected by the plant making it look green. And to get yellow you use green and red, so only half the light is useful to the plant. <br> <br>Cool source of LEDs though.
I prefer to use normal batteries that button cells. The reason is the Amps. The AA or AAA batteries has more Amps.
I thought about using AA or AAA but I wanted it to be clean and not to bulky when done. Also button cell should be able to last at least 8 hours with a LED hooked up, and considering I only have a LED hooked up for a couple seconds at a time then that 8 hours is extremely conservitive.&nbsp; The battery should last the lifetime of the tester easy.&nbsp; I've already tested 3000 LEDs with it, which took about 2 hours and I am still reading the exact same voltage I got when I built it.&nbsp; Also being that it is just testing LEDs which only draw 40mA peak and 20mA continuos, it puts out more than enough current.&nbsp; With the 10,000mcd red LEDs I am testing, you can't look into them as they are so bright with just a button cell.&nbsp;<br> <br> But yes if you have AA or AAA holders and batteries sitting around you can use them.&nbsp; I didn't have any and I was at Radio Shack and the button cell holder was cheaper and would allow me to make it nice and clean.
correct, good job!<br> thnx for the reply
Good idea. I've just been using coin cells to test LEDs for years. This looks like its a bit faster to use.
nice idea!<br>i would like to add that with small currents like coincell batteries, you never need resistors, shown in the LED trowies.<br>

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