hello all, being an almost total newbie i have some questions. I have recently dragged a leonardo out of storage, its been in a plastic tub for some years. plugged it in and it powered up and ran the blink program. So that part of the equation works at least. I bought 5 led rings of ebay (today), each is a different size and from what i can see they have joiners at each end and plug together.
My intention is to have each ring nestled inside the next biggest size and end up with a round graphical display. I envisage running a countdown sequence around the circle, each time i get to the end of a circle, i move to the next inner ring. This will all be mounted on a perspex board.
The leds are 5V WS2812B 5050 RGB LED Pixel Ring Panel Lights and are Individually Addressable
there's a total of 128 leds. I have a variable power supply 3-12v at 5 amps. I have some concerns that may not be enough. I read somewhere that 5v leds are about 1.5 amps, per 30 leds. So at 90 leds i might be at 4.5 amps which leaves me a bit short, i think.
I think for testing purposes, i can limit my output to less than full brightness or leave out a ring, so that i don't melt anything. I also plan on using the fastled library to run it. That seems like the easiest way to do things. Am i overlooking anything ?
For 128 ws2812 LEDs, the current could be up to 6.5~7.5A. That is with all 128 LEDs at full brightness white. Other colours, patterns and animations will probably use much less.
FastLED has a function which will, if you set it appropriately, automatically reduce the brightness to keep the current under a limit you specify should the patterns/colours displayed need more than that limit.
thanks for the quick reply. I will look into a bigger power supply in a couple of weeks. Can't do much till i get paid next. Thanks for pointing out fastled has some sort of current limiting. That may be pretty handy in the meantime. I probably will need full brightness eventually as i want to achieve a white out effect with all the leds at the end of a sequence, rather than faking it in video editing. although if i cant get a white out effect it should get me pretty close that i can transition to a fully white screen in post. Once i have some more progress i'll update the thread.
My pile of stuff is only 15 years old. Although i did find an old pc power supply stashed in a caravan that i lived in for a couple of years. Quite by accident i found a youtube on converting an old pc power supply, which was quite interesting. i did a bit of research and some of those conversions look pretty tricked out.
A 10 amp 5v power supply wasn't that expensive. Not sure why i had the impression they were pricier than i thought. I now have a beefier power supply, and bit smaller than i thought too. Although i think i need an inline switch and a power cord as it doesn't come with any extras. Just waiting on the arrival of the led rings. In the meantime i'm playing with some 12v leds i got of ebay a few weeks ago.
some what curious, as to where would i be likely to find a 5 ohm resistor ? which type of equipment is my best bet ?
Its probably just as easy to buy one of ebay however in the interests of learning something, i should probably keep my eyes open.
It is a Dale wire wound 5ohm 5% 50 watt. It was a surplus load resistor for a higher voltage supply, so the 50W is overkill for 5V. It has a protective cage around it - possibly to keep people from touching it.
Thanks for the info. I presume i'm only likely to find something like that in older electronic units. Newer mass produced items arent going to built quite like that i guess. I didn't actually intend it for 5v. i was thinking more along the lines of doing a pc power supply conversion after i finish messing around with leds.
Speaking of leds, my rings arrived today and i'm quite excited. Heres a couple of pics of what im working with.
ok, i have another question for the group...
i bought some 0.63mm enamel wire, which for the imperial users amongst us is 0.0248031496 inches if the online calculator is right. the last four letters on the packaging say 100g which i assume means 100 gauge wire which seems pretty thin to my untrained mind.
what I'm wondering is if that is thick enough to use for another multiplexing led project i'm building at the moment. i have 20 leds to multiplex but that could double. They are 12v leds if that helps.
Have you looked up the current capacity for 0.63mm wire? Make sure you know if your wire is 0.63mm diameter or 0.63mm² cross-section area.
The voltage is not relevant for the question. The current capacity of the wire does not depend on the voltage, it can be any voltage you like, up to the max rating for the wire, which will be much higher than 12V, I suspect.
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