my controller box

Heath-LightsOnTapley

Heath-LightsOnTapley

Senior elf
Joined
Aug 23, 2015
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Location
sheidow park
im posting this here to see what opinions people have (I am open to anything --- well not anything ;) )





Parts Used


Pixlite 16


This power supply
http://www.aliexpress.com/item/12V-350W-switch-mode-power-supply-LED-power-driver-AC90-260V-input-DC12V-350W-output-constant/1948832565.html

This fuse box
http://www.narva.com.au/pressreleases/press-releases/new-12-way-fuse-box-eliminates-messy-wiring

mains has inline 10 Amp glass fuse to supply




any pointer, opinions, flame sessions etc would be appreciated.
 
Other than the wire size as I mentioned in chat I have also developed a liking for mounting the controller and wires to the lid. It makes it easier to get the wires out of the enclosure and fitting off of the connectors is easier as it's not deep inside the box. The only issue is the lack of hinging. All you need from the back of the enclosure to the front is the power wiring and potentially the cat5 wiring. You can get away with mounting the power supply in the back of the box and the controller to the door.
 
thanks for the input AAH. would 12 awg wire be better? the awg to mm2 chart tells me that should be 2mm2
i think i have bootlace ferrules that would fit.


cheers
 
i am having trouble working out which cable is 14awg in the metric sizing...


for reference which one would i get from jaycar/bunnings/masters/autobarn ?


cheers
 
Keep in mind that we're typically trying to avoid voltage drop when choosing a wire thickness. The maximum current rating shouldn't really matter because it is usually higher than the currents at which voltage drop becomes a problem. The length of the wire is equally important. The 101 manual has quite a good section on wires and the resistance values are given so you can calculate the voltage drop with Ohm's law.
 
The cable voltage drop calculator that David put up on http://www.da-share.com/calculators/ is a handy calculator is you don't want to resort to finding data and punching it into ohms law. A 5% voltage loss total down both + and - is probably the maximum you should allow yourself at full load.
For example if you had a 12V 30A power supply with only 1 pair of wires coming from it to a fuse board 50cm away you'd have an allowable voltage drop per wire of 0.3V. Punching in some numbers you could get the required drop by using 1mm2 (17AWG) wire. This however is in contravention to the maximum rated current for 1mm2 cable which is about 10A.
It's always good to start with a minimum sizing of 1mm2 per 10A and then check to see if you need heavier cable.
 
so i calculated using the da thingo.


i got some 2.5mm2 single core power cable from masters, if i have about 450-500mm of wire from output on supply to input on controller (including distance through fuse block).


this gives me a result of 0.08 voltage drop each wire. this is using the method of 10a per 1mm2
(i assume this equates to 25A for 2.5mm2 cable)


is it correct i have 10 Amp fuses? or shall i use bigger/smaller value ones?


sorry in advance, but my math skills are crap.


cheers
 
What current are you planning on having? That's not an easy question to answer because the AliExpress listings generally have higher current values than the lights actually draw.
 
The fuses are primarily designed for protecting the wire. As long as the fuse rating isn't heavier than the wire you are using then you should be right. For instance the 2.5mm 25A wire you are using shouldn't be protected with a 30A fuse.

By the way Aliexpress numbers always have to be taken with a grain of salt. They are often cut and pasted from other sources and the specifications that they provide don't always match up with what you are looking at. That's kinda what happens when a sales person with no technical knowledge converts from Chinese to Chinglish.
 
 
Hopefully those pixel nodes are only 10mA per colour which is 30mA per IC. Sometimes the 12V ones are 18.5mA per colour which causes voltage drop problems the same as 5V plus you then have a higher power consumption. If they're 30mA per IC then your strings will draw 6 amps (ignoring the 8 pixels removed).

I don't know what current the stars draw but due to the two series branches (I expect) they're probably the same as a 6 LED section of your strip. Still it appears you only have 4 mini trees so the current drawn by 4 stars is insignificant. Ignoring these makes up for me ignoring the 8 pixels removed.

The strips probably run at 30mA per IC as well although I haven't measured them. I just suspect they do because I'd think they'd suffer from voltage drop along their length otherwise. You have 10 metres of the strip at 20 ICs per metre which is 6 amps as well.

Your show should therefore draw about 12 amps but it could be as high as 17.1 amps if your strings draw 18.5mA per colour. As you can see I'm really only estimating current draw here so it is always best to measure it for yourself and leave room in your design to allow for extra current draw such as the 17.1 amps.

Also a warning about those stars; they are not very good at passing on the 2811 signal over long distances so you might need a null pixel immediately after them if you plan on doing this.
 
i have 5 null pixels, was thinking about putting one after two trees, then after the next two trees and then one in between the arches.
and i as also thinking of injecting power at the same places.


cheers
 
here is my second attempt at wiring. opinions appreciated thanks.

2uqolll.jpg
 
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