DC-DC converters and pixels.. getting your feet wet?

[plasmadrive]

I got asked a lot about using DC to DC converters because that is how I powered my Plasma Icicles last year. I think the converters are the way to go for many of us..

anyway, here are my thoughts.. hope they are of some help to others.
https://www.dropbox.com/s/5yxqw7q2p7...%20rev%201.pdf

BTW, I used these because they are waterproof and they regulate very well.
http://www.prodctodc.com/dc-step-dow...l#.U7MWYbHzKot

Craig

 

[Superman]

Thanks Craig they look very good. most i have seen are very under-rated

 

[David_AVD]

I have some of those modules in my eBay watch list and was wondering how good the IP rating was.

 

[plasmadrive]

I have some of those modules in my eBay watch list and was wondering how good the IP rating was.

Well the point of my post was not to show the converters but rather the information.. But if something is useful that is a good thing.. :

But... since you asked.. they are 100% potted and they work just fine.. They are waterproof.

 

[SmartAlecLights]

do they handle the full 5amps they say?
i have some of the 3amp ones, an they start complaining after 2amps

 

[algerdes]

Craig, In your paper you don't discuss the inefficiencies of the converters. Do you know how much "energy cost" they present to the overall picture?

 

[plasmadrive]

do they handle the full 5amps they say?
i have some of the 3amp ones, an they start complaining after 2amps

I ran my test converter at a bit over 4 amps for 24hrs without much in the way of heating and the voltage drop was about .1volts from start to finish of my test. On the Plasma Icicles last year they needed to run at about 3.3amps when I called for white and they handled that easily.

 

[plasmadrive]

Craig, In your paper you don't discuss the inefficiencies of the converters. Do you know how much "energy cost" they present to the overall picture?

Actually I did, kind of... The very last line. My goal was not to make this too math intensive but rather just informative for those testing the waters with converters. These round numbers are good enough to get anyone started with converters.

"**These are all round number calculations and do not take into account conversion efficiencies, PCB and wire voltage drops other than in general.In general I would add a 6-10% minimum safety margin for power supplies and converters."

I found during testing of the converters I used that the conversion was very efficient. a few percent lose at most up to 4 amps. I didn't test all the way to 5amps since I didn't need them to work up there. My suggested safety margin should be plenty using good supplies and converters..

 

[algerdes]

Thanks.
I think it is a great idea. Having a 12 or 24 volt Power Supply would allow for longer runs. I really like knowing I have 5 volt at the site of the strips/pixels, and not having to worry about voltage drop. I also like keeping my 110v AC based Power Supplies in "safe" areas, away from curious ones. Sending low voltage DC is so much safer.


Just needed to know how much of a hit the converters add so that the Power Supply can be properly sized for the setup.

 

[David_AVD]

I'd probably only count on a efficiency of 85% max when calculating input power requirements. The efficiency will also vary of the range of current draw and well as input voltage.

 

[JPB]

I have a few 12v-5v converters on my strings that are furthest from the power supplies and are happy with them. From memory I got them from Suzie Ma on Aliexpress.
They are cheap enough that you can have a few extra and not drive them at their max, same as we do with power supplies.
In saying that, if I had a large concentration of lights in one area I would put a proper power supply there.
Jon

 

[BundyRoy]

So when these convertors say they can transform 12/24V to 5V does that mean it needs to be 12 or 24V for it to work or does it mean that they will convert any voltage in the range of say 7V to 24V back to 5V.

 

[David_AVD]

So when these convertors say they can transform 12/24V to 5V does that mean it needs to be 12 or 24V for it to work or does it mean that they will convert any voltage in the range of say 7V to 24V back to 5V.

The input voltage can be anywhere in the range specified by the module supplier. A higher voltage in means lower current draw on the input side and the possibility of using thinner cables. This is assuming we're talking about "switching regulators" and not simple linear types.

 

[plasmadrive]

I'd probably only count on a efficiency of 85% max when calculating input power requirements. The efficiency will also vary of the range of current draw and well as input voltage.

Actually the ones I tested were closer to 94-96%. I was amazed. Spec is 90%. It could be that I just got a good one to test with but there was almost no loss at all.

Remember, they don't have the front end losses that AC/DC supplies have. And like any electronics, they have their sweet spot..

 

[plasmadrive]

So when these convertors say they can transform 12/24V to 5V does that mean it needs to be 12 or 24V for it to work or does it mean that they will convert any voltage in the range of say 7V to 24V back to 5V.

Usually they put those specific voltages on ads to make it easy for those that have no electronics background to pick what they need. However, the truth is that most have a range of input voltage. For example, the ones I posted about, I tested them down to 10v input with no issue. Keep in mind the current draw on the primary goes up with the lower voltages.. Not counting circuit losses in the converter, it is proportional like my paper says.