LED Strip for visual effect project

Hi everyone,

Ive purchased 1m of LED strip - it has 32 LED and from some research it seems like it uses 10 watts per meter.

At 5v

P = VI , I = P /V

10 / 5 = 2 AMPS

Now, Essentially, I'm going to connect them on a circular plate type thing and put surface which diffuses light over the top of the strips.

I want to use the Arduino, but imagine just from a USB connection alone i can't get the 2Amps i need.

Do i just buy an adapter which outputs 5V and can give 2 Amps?

Im a bit confused how to run the strip if I'm not connecting it to the Arduino - I mean..I would have software to control each individual LED.

The strip ill be using is

http://www.ebay.com.au/itm/1M-32LEDS-32-IC-WS2801-5050-RGB-LED-Strip-Individual-Addressable-5V-Black-PCB-NP-/261548833293?pt=AU_Lighting_Fans&hash=item3ce5867a0d

Yes you need a power supply to give you 5V at at least 2A. You connect the + to the strip, the - to the strip and also to the ground of the Arduino.

There is a data input pin that you connect to the arduino and then run a libary designed for those chips which is a WS2801.

hmmp, honestly im a bit confused by the connections.

To keep it simple, say before i separate it in to multiple segments

ill keep it as one strip.

So i go from the wall adapter:

  • to V+ on the strip, and - to GND on the strip

and the D1 and C1 to the arduino?

My apologies. Having a hard time visualising

Yes, the 5V 2A power supply goes to V+ and GND on the strip, while CI (Clock In) and DI (Data In) and GND of course, connect to the Arduino.

If your 5V 2A power supply is guaranteed to be regulated, you can use it to power the Arduino via its 5V terminal.

How can that be guaranteed?

OK i think I get it now

Arduino by USB, GND connects to GND (obviously), Power supply to + and Gnd on the strip.

Clock In and Data In into the Arduino UNO. Id imagine they would be into the Digital Pins?

MrDropsy: How can that be guaranteed?

You measure the power supplie's output with nothing else attached. It should be 5V. If it is higher you have not got a regulated supply and so can not use it.

Yes the clock and data are digital output pins, the ones you use are told to the library. You should find a libary to use first before wiring it up.

MrDropsy: Clock In and Data In into the Arduino UNO. Id imagine they would be into the Digital Pins?

All port pins on the UNO - and most Arduinos - are digital pins.

Including the "Analog" pins. (The Pro Mini has just two Analog-only pins.)

As Mike mentions, you use whatever pins suit the library you propose to use.

You measure the output on DC setting and see 5.0V +/- 0.2V, you measure it again on AC setting and see ~0.0V, then you know its regulated. These values shouldn't change under load either.

Most of the time your strip won't be taking all that current (unless you leave it at full intensity white), it will have a rapidly fluctuating current demand, so I'd recommend adding extra supply decoupling where the power connects to the stip. 1000uF or so if poss.

If you have long runs of strip apply power at both ends with thick wires to avoid voltage droop - otherwise you can get noticable drop in brightness along the strip due to the resistance of the flexible PCB traces carrying the supply current. For very long runs you will need to add power at regular invervals.