12v to 5v buck converters

Bigwillystyle

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Dec 14, 2016
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Gold Coast
Hey guys, Weird question I've searched and can't really find anything solid..

Planning on running 5v pixels, My biggest concern now i'm planning my design is cable lengths and voltage drop for my power injection.. Mainly on my house outline.. 12v is superior for longer runs as far as voltage drop goes..

Why couldn't I use a 12v supply and some buck converters to reduce down to 5v at the injection point/ start of each string?? I know cost of the converters is going to be a factor that needs to be looked at because there is a cost vs reward if i'm using the cheap 5v pixels because i can get 80% more pixels for the same money as the 12v ones..

Am i just being silly and just use more power supplies closer to the roofline to reduce my cable lengths?? (its a 2 story house)

When I design car audio systems I have big current draw but a maximum 7m cable length (due to length of the car) so system design is pretty simple and I would normally just wing it with most of the design and make it up as I go breaking it all into sections with a focus on cable management over voltage drop in most cases.. This hobby requires much more thought in the design phase to get power injection done correctly to minimise the time I need to spend on the roof..

Am I over thinking this??
 

TerryK

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You can and there are already individuals that do exactly that. Running a higher voltage system and reducing it at the point of use will lower the effects of voltage drop in the supply cable. Put another way, depending upon cable length and gauge size, voltage drop will be regulated out by the 5 volt converter. And smaller gauge wire might be used be used.
Not weird, nor silly. But there are pros and cons to every or just about every approach. It also may or may not be cost effective but perhaps have advantages that override the cost/complexity.
 

David_AVD

Really old (now a Grandpa)
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I use 24V to 12V and 24V to 5V buck converters for a some of my props.

Some are Mean Well and some are no-name ones.
 

Bigwillystyle

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Thanks Terry, Good to see it isn't a completely crazy idea.. I may see how it goes just on some of the longer runs up to the furthest point of the displays.. Obviously need to be mindful of the higher voltage cables and not getting them confused during the install phase or during a repair phase mid season.. I suppose using a different type of cable from my 5v would ensure that I don't get them mixed up.. My plan this week is to go down to office works and get my house plans printed in A3 or bigger so that I can Draw all over them and get my measurements locked away..
 

Mark_M

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Nothing wrong with buck converters. It gives you the best of low cost 5v route and regulated pixels.
I went with (12v) regulated pixels for a constant brightness, even when the power supplies voltage is fluctuating under load. A buck converter would hopefully regulate it's 5v out and act like a regulator at the start of a string.

The only message of caution I can give, is to make sure the selected buck converter is of decent quality.
It's not common for one to fail but nothing is impossible. The fear of it failing should not deter you from it.

I know cost of the converters is going to be a factor that needs to be looked at because there is a cost vs reward if i'm using the cheap 5v pixels because i can get 80% more pixels for the same money as the 12v ones..
Whether 12v VS 5v is best for your roof line is another story.
If it's too much for a buck converter there's nothing wrong with a mixture of 12v and 5v in your display.

Is the roof line worth spending more money on, or is this possible solution worth it in the long run?
 

bpratt

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sounds like an interesting plan, just have to ensure the buck converters can provide enough current to drive the string of pixels that you want to plug in to them.
 

TerryK

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Nothing wrong with buck converters. It gives you the best of low cost 5v route and regulated pixels.
I went with (12v) regulated pixels for a constant brightness, even when the power supplies voltage is fluctuating under load. A buck converter would hopefully regulate it's 5v out and act like a regulator at the start of a string.
This hints at the similarity of 5 volt and 12 volt resistor strings. Both exhibit voltage drop along their lengths. At some point voltage drop is great enough to allow one to see visual discoloration. From another perspective each downstream node sees a supply voltage a bit less than the previous node. I'm not sure of the exact reason but I suspect that the higher voltage and resistors relative to the voltage drop from the previous node in combinatin of the LED characteristics delays the onset of the discoloration.

Regulated 12 volt strings on the other hand as mentioned need the voltage drop to lower to a level where the node regulator drops out of regulation. When that point is reached they start acting like a 5 volt or resistor 12 volt node.
 

TerryK

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... need to be mindful of the higher voltage cables and not getting them confused during the install phase or during a repair phase mid season.. I suppose using a different type of cable from my 5v would ensure that I don't get them mixed up.. My plan this week is to go down to office works and get my house plans printed in A3 or bigger so that I can Draw all over them and get my measurements locked away..
A good approach I think. It's rather difficult to have different connectors for everything. Can be done but doing so can also become confusing. I highly suggest labeling cables. Actually label everything that can be labeled. And make sure both cable ends are labeled. White heatshrink using a permenant marker is good. Plain stick on white paper labels work too and are weatherproof if covered with clear heatshrink.
 
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