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berlin
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I am about to work with 33 x 60 cm strips of this kind:
http://www.ladyada.net/products/digitalrgbledstrip/index.html

the strips will be connected in series and I am wondering how much power I will need

it states:

"Maximum 5V @ 120mA draw per 2.5" strip segment (all LEDs on full brightness) - about 2A per meter"

does that mean I need 2A x 20 Meter = 40A???

sounds like a lot...

Fubbi

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Manchester (England England)
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does that mean I need 2A x 20 Meter = 40A???
Yes

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sounds like a lot
20 Meters is a lot of lights.
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Switzerland
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Yep, your calculation is correct. You probably have to feed additional power somewhere in the middle of this string. I have 10 meters but with less LEDs, my consumption is about 5A. I have to feed in at two points else not all LEDs get enough current to show full brightness. 40A need quite a bit of a wire, the internal are not suited for such amounts.
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berlin
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So I need several smaller power sources along the way?

fubbi
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Manchester (England England)
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Yes, split them up as there is no way you can get 40A through the first strip.
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berlin
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Yes, split them up as there is no way you can get 40A through the first strip.

So how much can the strip take? I need to find a small outdoor power supply, or can I use a big one and somehow portion out the power?
Is there a way to divide a 20A output to 10x2A outputs?

thanks

fubbi
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Switzerland
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If you have a 20A 5V power supply (at payable costs you get these usually only in PC power supplies), you can just have multiple wires going to the feed points of your strip.
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Norfolk UK
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I am about to work with 33 x 60 cm strips
How are these 33 strips wired together? If they are paralleled and controlled independently then you could reduce power needs by scanning 
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then you could reduce power needs by scanning 
Assuming you mean multiplexing.

Yes but that also reduces the brightness.
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Well when you say series rather than parrallel then your drawing 1.2 amps but at 165 volts
which isn't that bad if you get/build a hv supply than with regular diodes and a few caps that can handle the voltage you can power them all nicely right from the mains ac(once rectified and filtered it comes out to 167ish volts), althouth I don't know how the results would be in series with those strips since there already in series/parrallel
This would help as I doubt you have 8 or 6 gauge wire in those strips to handle that 40 amps
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berlin
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 I won't run anything at 100% and never all LEDs at the same time.

would this do it?
5V 20A 100W, MeanWell SP-100-5
http://www.hed-radio.com/de/Netzteil-SP-100-5.html

Again, I have 33 x 60cm strips in series. So how often do I need to power them, every 5m? that would mean 4 or powerpoints.

fubbi
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Switzerland
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You do attach them serially but the power consumption is parallel because the strip contains the controlling chips, you just have to supply enough current and control the chips with a special kind of shift register.

If you're sure that never 100% of the LEDs are at full power you can go for the 20A power supply. 4 supply points are probably not enough. I'd go for at least 10 supply points giving 2A each which is probably more than enough for the flexible printed connections on the strip. I have real wires between my LED elements and with 2A per supply point the wires get remarkably warm but not hot.
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berlin
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Ok I have a plan, thanks!

fubbi
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