soldering my own led strips need help

sassyness77

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Nov 21, 2011
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Hello everyone, I'm hoping you can help me since I am not very experienced with soldering at this level. Also if this is in the wrong spot, please move it and I apologize!

I'm trying to solder about 40 piranha leds together in a strip. 4 of them in parallel and then the groups of 4 in series. But I'm not sure what's the easiest way to connect all the negatives and positives cleanly. Is there some sort of strip I can use to simply tap into and run the length of the entire strip? Because I'm using perfboard and need it to be very small basically the same width of the leds themselves. It will be running on 12v so I'm not sure if I can use that thread solder? I will add pictures in a minute to help you guys and gals see what I mean.

I just found "strip board" now could I use the strips on this kind of board to run all the negatives together and just break the connections in the copper strips?
 
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sassyness77

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I hope this will help, I put these few together for a trial and test how bright they were but what is a much easier way to connect everything and keep it the slimmest possible?

IMG_20120210_232524.jpg
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IMG_20120210_232448.jpg
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IMG_20120210_232413.jpg
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pretmetled

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I was going to do some ascii art, but the helpful vb software keeps killing it. So fsck that.

Short version: if you want to prototype it, you may want to consider dead bug style. IMO perfboard is le suck, and in this application it's no exception. Normally it is signal integrity that's crap about perfboard, but in this case it's thermal conductivity that's crap about perfboard. ;) You can cut reasonly wide strips of copperclad, glue it to some backing material of your choice. For electronics I glue it on other copperclad to have a good groundplane, but for a simple led strip you could use whatever you have handy.

Since I don't have pics and am not going to try ascii art again let me try to describe it.

You run the copper strips vertically. Then in the horizontal direction you run the LEDs across the strips. In your example you want to run 4 leds in parallel. That would mean that between each copper strip you would be running ... oh alright I'll try it once more ...

Code:
  CC       CC       CC
  CC       CC       CC
  CC--|>|--CC--|>|--CC
  CC       CC       CC
  CC       CC       CC
  CC--|>|--CC--|>|--CC
  CC       CC       CC
  CC       CC       CC
  CC--|>|--CC--|>|--CC
  CC       CC       CC
  CC       CC       CC
  CC--|>|--CC--|>|--CC
  CC       CC       CC
  CC       CC       CC


Where CC is a copper strip. Copy paste this horizontally obviously, since you wanted more leds in series. Personally I wouldn't put it in this parallel/series arrangement as you described, but what the hell right? At least it makes this example a bit easier.

I guess my point is that perfboard is almost never worth it. Not even for throughhole components, and not even with something as simple as leds. Did I mention copperclad is waaay cheaper than perfboard?

Additionally: One thing it would depend on ... how easy to bend are the pins on those piranhas? If just as easy as on a regular 5 mm led or DIP package then no problem, the above method should work just fine.
 
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sassyness77

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I see! Thank you for the reply, this will be very helpful. But I was curious as to why I shouldn't run them in a series like I was planning? I need the maximum brightness as possible, which what I thought would be 4 of them connected parallel to 12v? If this is completely wrong, please let me know! :) I take constructive criticism very well!
 

pretmetled

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Well, you said ...

"4 of them in parallel and then the groups of 4 in series. "

So could you describe that a little more detailed before I am just making too many assumptions?
 

sassyness77

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Well I have 12v but only want 3v to each led so I was thinking 4 in parallel then all of the groups of 4 wired in a series so every led gets an even 3v.
 

pretmetled

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Exactly. And thus confusion abounds. :p

4 in series gives you a total forward voltage of about 12 volts.

4 in parallel is still a forward voltage of about 3 volts.

Well possible that you know all that, but in that case you chose an unfortunate sequence of words to convey your intentions. :p

Lets keep it simpler.

First make strings of 4 in series. Then you parallel those strings, and make sure you current limit each string.

You will note that that is different from what you described, which was to first do 4 in parallel, and then stuff those sets of "4paralleled leds" in series.

Yes the leds will get about 3 volts in both cases, but amount of current through each individual led will be different. In the case that I'd use you have better control over current through each led.

So yes, your method (or at least what I think you mean) will work fine too. You just will get larger differences of brightness between the leds.
 
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sassyness77

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Okay, I haven't hear of most things on here before so I am still learning, please bare with me. But this copper clad is just a solid board with copper covering it, so for me to make a circuit I would transfer the design onto the copper, etch it, and then drill it out to mount the LED's? Or is the Copper just very thin strips you can cut?
 

pretmetled

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No etching required. I'll try to dig up a few pictures of what I mean regarding the copper clad.

http://www.cliftonlaboratories.com/Prototyping.htm#Manhattan_Construction_for_RF

http://www.aoc.nrao.edu/~pharden/hobby/HG-MANHAT2.pdf

http://www.k7qo.net/manart.pdf

I just realized that this is getting to be beyond the scope of "how do I connect a bunch of leds", but since you asked ... :p

So it is just regular FR4 board with copper on one or both sides. You can get this super cheap if you shop around a little. Certainly cheaper than perfboard. I always get large pieces at the dump store for a few euro.
 
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sassyness77

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Hello, again :) I am just wondering if there are any tricks on wiring these together? I know how to make the circuit but I dont like doing the point to point with wires. I thought about making my own PCB, but it seems like this circuit should be so much easier but I just can't see how!

Also I don't think the strip board will work because the LED's need to be in a single file line, slimmest line of LED's possible. I have them all on perf board and just did the point to point with wires to connect all the negatives and positives. Just trying one more time to see if anyone has any ideas?

This is what I have done so far...
IMG_20120321_201353.jpg

IMG_20120321_201402.jpg
 

bshanahan14rulz

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Yep. regular strip board (perf board, but with each row of holes electrically connected) would look better, i.e. it would get rid of the need to use those wires, but at the cost of having to allow for a + and - rail, adding width to the strip. You'd also ahve to cut the copper strips in the right places for the strips that run under the LEDs. I think what you have is probably the best solution that doesn't involve a custom PCB. Not to mention, the extra wiring may help heatsink a few of the LEDs. Superflux package LEDs conduct their heat into the circuit traces, and theoretically should be heatsinked that way. I think all you do is lose a tiny bit of efficiency and some overall lifetime.
 
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