Sorry about the super low level question but I am very curious about an outcome I arrived at.
I recently purchased a super cheap LED strip from walmart. I never got around to using it for its intended purpose so I decided to hook it up to my arduino to see what I can do with it (Im more of a code guy than electronics). I looked at the strip and Saw 5V, R,B,G. When I wired everything I ran the 5V from the 5V out on the Arduino to the power strip on my bread board, RBG to their own rows, then linked each of the rows to the power row (initially confused the G as ground but thats neither here nor there). Long story short it worked. I wrote up some quick code (by copying and pasting lol) and in a few moments the led strip was blinking and changing colors...AWESOME. I got bored of that quickly and started to take it apart when i realized something....I never ran a ground. Since no ground was run, should it have worked?? Im kind of confused as to how it worked without grounding. Was the ground necessary? What negative impact would I have with this configuration (burnt LED, blown board, apocalypse?)
YIKES, very concerned makes me nervous lol. Ok, I looked up info on the LED strip. Per the instructions:
DC 5V 0.5A~2A
Power Consumption 2.5w~10w
60 LED lights
(ignore this. The battery was for the remote contriol unit, not the LEDs itself. If hooked up the way it was meant to be (out of the box) it would be running on a CR2025 cell battery. )
Not sure to tell what kind of resistors are on the strip.
I modified the spec post. When bringing up the battery I completely forgot that there is a remote control receiver in the original out the box setup. Obviously that's what the battery is for, not for powering the LEDs.
that's where I'm confused......why did it work? There was no ground and per this thread I shouldn't have been able to get the power I needed yet there I was with an LED strip cycling from red to blue to green in a lovely rhythmic fashion. Was it just a matter of time before the arduino gave out? Was the LED strip on but just not operating optimally?
Yes, that's the point. So far we have no idea of what you actually did. Our guess is that you wired Arduino pins to the LED strip, but your description is not really clear at all.
Take your arrangement out in daylight and take a picture of it for us please. Quicker than trying to put it in words
And yes, I intended to alarm you so that you would not persist and quite possibly damage the Arduino.
larryd:
We would really need to see an image of the wiring to determine the ‘why’.
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Fair enough. Does this help?
BTW sorry for any confusion. I promise I'm not trying to be confusing. Thanks to everyone whose taken time to respond.
If I need to take a pic of the actual wiring I can but I'll have to break it all out and put it back together. I took it apart immediately because this wasn't an application idea....Plus it was clearly wrong lol. It was just an off the cuff learning experiment. Hopefully I didnt ruin my board.
Yes, that makes it clear. Not the way to do it - you need driver (MOS)FETs (and these days, we don't use "bipolar" transistors because the FETs just do the job properly) to switch each of the three lines to ground.
You want to know how much current the strips draw, generally 20 mA per LED, but if you use generously rated "logic level" FETs, you should be fine.
Let's make it 0.5A
