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I'm new to the Raspberry Pi community and to working with electricity, so I'm looking for some advice.

I've brought the WS2801 LED strip from eBay (but I think it's the same as this: https://www.sparkfun.com/products/retired/11272). Using a computer PSU I've connected the LED strip power to my 5V molex rail and data to my Raspberry Pi. Everything seems to work as it should.

Similar to this, but power drawn from my PSU rather then a DC Jack: https://i.sstatic.net/T5bRL.png

After reading a bit more about this setup online, I found out that it might not be wise to connect the power directly to the GPIO. Apart from that I also don't want to use a bulky PSU to power this, but rather a smaller power brick if possible.

What I intend to do is to use a male molex connector and connect it to micro USB header and to the power pins of the same connector used by the power strip. This way I intend to power both the LED strip and my PI using the 5V provided. When it comes to the data connection I'm going to do the same as in the picture and use the GPIO as previously. Is it possible/a good idea to split the power between the LED strip and my RPi this way or is there something I should be aware of?

I think about using a Molex connector in the beginning, just to verify that everything works. Then trying to measure the current needed and replace my Molex and PSU with a DC Jack connector and suited power brick. I have one that says 5V/8A max (5V 8A 8000mA AC-DC Switching Adapter Desktop Power Supply YT-0508 PSU 2.5/2.1), but I'm not sure if that's ridiculous high amount of amps and if it's ok to be trusted...

Any suggestions on this or things I should be careful about would be awesome!

Edit: This is the micro usb connector I intend to use. I plan to just remove the red and black and replace it with my own from the molex power connector. I've that the usb connector has a connector on the side as well (Ground?). Do I have to connect this one to ground (the other black cable that already goes to the connector) as well or just leave it?

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2 Answers 2

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What you are suggesting sounds fine to me (but I'm not an electronics type so treat anything I say with caution).

As the Pi and LED strip will have a common ground you don't need to connect a Pi ground to the LED strip ground. If you ever use a separate power supply for the Pi and the LED strip you will have to join the grounds.

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    I've made the necessary cables and it worked perfectly. However I had to try two power supplies before I found one that could provide enough power from one single molex rail. The other ones just turned off once the LED strip was supposed to turn on.
    – NeoID
    Commented Aug 17, 2015 at 5:45
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Powering the Pi and the LED strip the way as shown in the schematics is possible. There is however one issue to consider: back feeding the supply voltage to the Pi via the GPIO pin connector bypasses the polyfuse of the Pi and might render the overvoltage protection (D16) non-operative.

Compare schematics, page 1, top left.

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