Some real world experience and practical measures tell us that if you wind them up to 4.8v then in general you will be fine if your powered 5v pixels.I found a bunch of 40a and 60a power supplies for free but they are 4.2v. I played around with the voltage adjustment and they can go up to 4.8v, would I be able to use these power supplies for my pixels?
sort of surprised you got down to 4.8 as that is under the voltage for proper regulation of a 78L05, spec sheets says line regulation from 5.3v to 20v so anything under 5.3 wasn't regulatedThey'll just light up 5v pixels.
Although I guess you will have a a lot more power injection (ACL 101 manual states what power injection is).
My video from 2019 tested a 12v pixel with the lowest voltage it could go.
12v pixels are basically 5v pixels with a voltage converter inside. Lowest stable operation I got was exactly 4.8v, after that it wouldn't work.
5V gets bagged a lot (same with strip) but has some benefits, yes you have to wire more, but in most of my props that's just attaching the beginning power to the end. Not a major drama. The benefit is more lights per Power supply, and less power supplies to run my show.
That's good to hear, I will probably power inject every 50 pixels. I'm going to make extensions with ethernet cable meaning 0.75mm2 cable from the power supply to the prop (max distance 5 metres) would that cause problems?Just have the PSU close to the prop and it will be fine, power inject every 100 pixels to keep the power up.
Hi Terry, I'm curious were the 5.1v limit comes from. The common WS2811 IC actually calls for a Vdd of 6v to 7v with Vin +-0.5v from Vdd. 10% hot on the voltage is well within limits ie 5.5v.As was mentioned in another post, set them as high as possible. If by chance any can reach higher, stop at 5.1 Volt. 5 Volt pixels can handle the extra 0.1 Volt and it will give a bit of added 'cushion' against voltage drop. The lower supply voltage may require either shorter or larger gauge size wire depending upon your design's physical structure.
Also as previously mentioned, the number of pixels between the points of power injection will need to be decreased. A bit of testing should give you an idea of how many.
Always good to prove the theory with tests, glad you will be able to use themSo I have done some experimenting:
Luckily, these power supplies don't have much voltage sag under load, under no load I measured 4.82v, and under around 30a of load, I measured 4.75v. For testing I used an Arduino Nano, running FastLED outputting full brightness white, and on its own 5v power supply. The pixels I am using are the super cheap ones, similar to Ray Wu's "Promotion" pixels.
With a 50 pixel string, the last few pixels are noticeably orange, but when injecting power at the end of the string, there is no visible difference between the middle pixels and the end/beginning pixels. Just for fun, I tried with 100 pixels, the last 30 or so pixels were extremely orange, and the last 5 pixels were flickering red.
Most of my props are only 50 pixels, and it won't be an issue to inject power for the props with more than 50. I have ordered some cat5e solid core cable to make some extensions, but since I am in lockdown, it could take a while to arrive. I will update with voltage drop tests once I get the cable.