power supply

[Lincoln Lights]

Up front disclosures.... spelling correct optional, proper jargon optional, and I know enough to be dangerous...

Back ground: rookie season, and this will be my first cristmas display. I did a small V-d display (16 channels) and a St Pat display, 16 channels and 10 RGB spots. Built up some confidence, and I have rolled up the sleaves and I am elbow deep in to Christmas. My front yard is small, and the longest run to any element would be 25-40 feet.

Here is where I am running into some road blocks. I have 100 (8 dollar) rgb controllers and they are all assembled the same way. I am using cat 5 cable to run the signal and power to each controller. solid orange, green and brown for + and striped for nuetral. Blue and Blue Strip are for dmx. on the input side I have madeapprox 6 inch sections of cat 5 cable with the male connector on one end, and soldered the appropite colors and connected to the controller. So each controller has 2 input conectors so I may daisy chain them.

I have all 100 of these controllers on 8 1x4 wood slats that fit into a heavy duty plastic storage container as shelves. I have a total of 12 slats that fit into this container. The other 4 are used to mount my 16 channel controller and power supplies, power strips, etc. Though, I am quickly rethinking this part due to heat build up.

After doing all of this, I am in the process of putting an order in for my "dumb strips" and continue fabrication. However, each strip is rated to use 72 W of power at full white. Here is where my ignorance is going to get me into trouble and I do not want to go back wards. (Only 6 weeks or so until Lights on and I have do do some sequnceing) And why did I wait until September to get back into this???

I understand the calculations of V=IR and all of that good stuff; however, my practical working knowledge is again enough to be dangerous. Lets say I need 4500 W of dc power to run my lights.

Should I buy 100 45w power supplies, or 18 250 W supplies... I will be running thepower over cat 5 cable and want to inject it to the controllers.

I want all controllers and power supplies to be set up at a central location..

http://www.aliexpress.com/store/product/12V-20A-250W-waterproof-power-supply-AC110-220V-input-CE-approved/701799_340448812.html

on this one, with the three outputs... does anyone know if that is 6.??? A per output????

[edvas69]

I prefer the 250 watt option personally for a few reasons.

1: Less maintenance and % chance of failures.

2: Reduce risk of any potential ground loops

3: Less cost and installation effort

But then it really depends on your layout and how far apart each controller is and the potential for voltage drop. You do say you want a centralised controller approach which i prefer to use less larger power supplies than more smaller ones for a centalized approach.

The other thing to take note of is that because each strip is rated at 72 watts then i would be at least getting a 100 watt power supply minimum so you can power each strip with its own power supply. I wouldnt use 100 45 watters as you cant just tie the +V together on these power supplies to get more watts.

You must also ensure that you rate the total power supply wattage down due to power supply inefficiencies. So 80 to 85% tops of your total load. So a 100 watt power supply you would put a maximum load of 85watts

Edited October 8, 2012 by edvas69

[Steven]

If you want a 12v power supply quick, I ordered a Mean Well model NES-350-12 350W (29A) supply from OnlineComponents.com for $47.24 (including shipping) on the morning of October 4th. It arrived on October 5th. And they're in a different state (albeit Nevada).

[Lincoln Lights]

I am using cat 5 run power and signal. how would i step down the amps???

[Steven]

I am using cat 5 run power and signal. how would i step down the amps???

Your fixtures require a certain current. The only way to "step down" the amps is to run them at a lower intensity, which is probably not what you really want to do.

According to this wire amperage page I found, 24-gauge (cat5) can transmit about 2/3 amp. Since you will be running 3 wires in parallel, you should keep your current to 2 amps. This rating is probably about limiting the heat damage to the wire, and since you're running outdoors in the Winter, and the duty cycle is much less than 100%, you can probably get away with more current.

So let's say you need to keep your maximum current below 5 amps. To keep the numbers simple, let's say you had 6 floodlights that each took 1.7A. If you add them all up, this would be about 10 amps, which would be too much for the cat5 cable. However, if you put your power supply in the middle of the Cat5 run, then you would be sending 5 amps through one cable, and 5 amps through the other.

Another option is to parallel the power wires. I have 4 fixtures at the end of a cat5 cable that is long enough that the voltage drop would be too much. So I'm going to run a length of SPT-1 wire in parallel with the cat5 cable to help carry the 12v power. I'll connect it to the power supply at one end and splice it into one of the fixtures at the other.

Another option is to use more, but smaller power supplies, and space them throughout your display to inject power where it is needed. The advantage is less voltage drop, but the disadvantage is that you have to get more power supplies and run more 120v wiring.

[Steven]

solid orange, green and brown for + and striped for nuetral. Blue and Blue Strip are for dmx.

By the way, it may be too late for you, but everyone recommends that you use pins 1 & 2 (orange solid & striped) for DMX, because this is specified in the DMX standard.

On the power side, I am pushing people to use pins 6, 7, and 8 for ground. (Pins 7 and 8 are specified as ground in the DMX standard, and pin 6 is what the LOR network uses for ground.) This leaves pins 3, 4, and 5 for power, which is at least consistent with LOR pin 3.

[edvas69]

I am using cat 5 run power and signal. how would i step down the amps???

I Think what may be asked here is how do you step down the amps so you can can supply more wattage of power down the same CAT5

People use things like 36 volt power supplies and then use a DC-DC step down converter at the end of the cat 5 run to then lower the 36 volts to 5 volts

For examplePower = Volts x Current

At 5 volts running 1 amp down the the cat 5 you could expect 5 watts of power to be able to run 16 pixels at 0.3 watts each

Now if you instead ran 36 volts down the Cat 5 at 1 amp and then converted that down to 5VDC at the element you would then get 36 watts of power to be able to drive 120 pixels at 0.3 watts each for the same 1 amp travelling down the same CAT5 at 5 volt.

This is how all electrical distribution is done because it means you can distribute your power over longer distances whilst using smaller diamter cables

So this may be the way the OP may be interested in

Edited October 9, 2012 by edvas69