5v power for LEDs

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TTerBNZ

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#281571 26-Feb-2021 09:52

I'm having some trouble finding decent cheap PSUs in NZ..
I'm trying to get something between the 5-14A mark
Not fussed between the cage style or brick style...
These would be to power QuinLED Dig Uno's with some strips connected pulling around 30w on full RGBW

TTerBNZ

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#2663013 26-Feb-2021 09:59

one meanwell 5v 14A on jaycar but $55 seems steep

richms

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#2663015 26-Feb-2021 09:59

Meanwell. Getting from arrow and sent from the US seems to have got me the best deals in the past.

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Zeon

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#2663072 26-Feb-2021 11:12

Modify and use an old computer PSU?

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MarkM536

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#2663233 26-Feb-2021 19:21

As mentioned above; Meanwells are good.

Zeon:

Modify and use an old computer PSU?

I myself use computer power supplies and server power supplies (I'm 12v pixels).

This is my latest prop in my Christmas display with a computer power supply:

(If BB code is wrong; https://www.youtube.com/watch?v=L3pnPMD2zn8&ab_channel=MarkM, https://www.youtube.com/watch?v=kDdljeNrDlM&ab_channel=MarkM)

It draws a around 7.5A (12v) at full white.

Computer power supplies are great things because they're cheap and reliable.

Server power supplies pack a punch if you need 12v with an insane current draw.

neb

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#2663507 27-Feb-2021 21:45

TTerBNZ:
one meanwell 5v 14A on jaycar but $55 seems steep

Meanwell are good-quality supplies, and 14A is a pretty exotic power rating. OTOH Jaycar are also not the cheapest, you'll be able to get it cheapr from Element14 or Mouser or something.

richms

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#2663511 27-Feb-2021 22:02

MarkM536:

I myself use computer power supplies and server power supplies (I'm 12v pixels).

...snip...

Computer power supplies are great things because they're cheap and reliable.

Server power supplies pack a punch if you need 12v with an insane current draw.

PC power supplies dont do much on the 5v anymore, loading that up with nothing on the 12v seems to make some of the cheapies unhappy. Better ones seem to make 12v and then derive 5v and the other one from that with a DC to DC so there is good regulation all over.

Best IMO is to get a higher voltage PSU and then use small buck converters closer to the LEDs. I have had things not work on 5m of wire because of the voltage drop on the ground wire screwing up the data. Putting capacitors at the LEDs mostly sorted that, but there was some decent amount of ripple from the LED PWM on the ground.

Richard rich.ms

nash

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#2663656 28-Feb-2021 10:43

I second going for a meanwell unit, well made and you don't pay through the nose for them.

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MarkM536

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#2665913 28-Feb-2021 20:25

richms:

PC power supplies dont do much on the 5v anymore, loading that up with nothing on the 12v seems to make some of the cheapies unhappy. Better ones seem to make 12v and then derive 5v and the other one from that with a DC to DC so there is good regulation all over.

I use used power supplies off TradeMe and computer recycling places. I haven't noticed anything when loading one power rail or the other. I use one power supply just for standard lights running at 5v, it hasn't complained with 5A draw on 5v only.

But to compare to what you're mentioning; Power supplies I got have negative power rails. Shows how old they are, not many computers need negative 12v anymore.

richms:

Best IMO is to get a higher voltage PSU and then use small buck converters closer to the LEDs. I have had things not work on 5m of wire because of the voltage drop on the ground wire screwing up the data. Putting capacitors at the LEDs mostly sorted that, but there was some decent amount of ripple from the LED PWM on the ground.

Sounds like classic issues newbies on my Christmas lighting forum have. 🙂

It's always problems with 5v pixels and power!

Higher voltage and stepping down is basically my pixels above. They have a regulator inside taking 12v down to 5v for each LED and WS2811 chip.

Using DC step down converters is okay.... I do know for someone that was these using LED panels (P5 panels used in LED bill boards) and had one fail. His one failed by letting 12v straight through to the 5v device.

Data screw up will be from voltage drop over the cable and that pixel data doesn't do well over 3m length. A null pixel or pixel buffer solves this.

It's not just the data voltage dropping over the cable, but the ground floats above 0v with voltage drop. If ground is floating and data is degrading then this makes an overall lower voltage between them, the chip doesn't get triggered for a high/low in the signal.

Null pixels step the voltage between ground and data higher to the chip read level. Ground is still floating though.

Apart from nulls, ways around it is "power injection" But this is literally running another wire back to a power supply or second power supply, commonly in the middle of a string.

Have a look through xEssential videos that have been made in correlation to xLights software. There's tons of information on common pixel issues.

Someone did a great presentation on pixel data through different wires and about this floating ground. It's on AusChristmasLighting.com forum's Youtube account from the 2020 mini.

There's also the AusChristmasLighting 101 manual, it covers every single thing in an animated display. Parts for power will be of use to you.

As a side note (no offence to you); I get sick of these wifi pixel boards. People complain that it doesn't work and they're sending 200 universes over wifi with their home router.

richms

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#2665918 28-Feb-2021 20:38

I solved it by putting an ESP in each letter and it seems that the wled syncing is good enough, whereas the older sketches I was using with no sync would be a mess after a couple of mins. a D1 mini is cheaper than the hassle with the regeneration and other stuff.

Richard rich.ms