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What type of power supplies?

Discussion in 'LOR DC' started by Bevo, Dec 30, 2010.

  1. Bevo

    Bevo Let your Light Shine before men

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    Hi I am new to the DC world of controllers and I am trying to find out which DC power supplies other people are using and where they got them from?

    Any help on this topic will be greatly appreciated.

    Thanks
     
  2. XDU

    XDU Full Time Elf

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  3. fasteddy

    fasteddy I have C.L.A.P Global Moderator Generous Elf

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  4. aussiexmas

    aussiexmas Sinnamon Lights

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    I also use these 350W power supplies (or at least ones that are similar) and they are available from other suppliers, Asia Engineer, Eparts138, etc.
    I have bought several from both these suppliers, the Asia Engineer ones being better priced at my last purchase. Their EBay store includes detailed specifications covering all the voltages available - see http://stores.ebay.com.au/Asia-Engineer/_i.html?_nkw=power+supply+350w&submit=Search&_sid=149380788

    I've been happy with the delivery and response from both suppliers.
    While I intially bought some 24 & 36V supplies, I now buy 27V supplies as these are typically adjustable between ~24V and ~31V which covers the majority of voltages required by OTS LED strings.

    Regards Geoff
     
  5. ryanschristmaslights

    ryanschristmaslights Senior Elf Administrator Generous Elf

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    I originally had a 'Meanwell lookalike' 350W 24v PSU from eBay but it had big problems with generating electrical interference that would kill connection to the internet and display lines on screens using analog connections (VGA monitors, etc).

    I now use an official Meanwell 320W 24v PSU (SP-320) that does not have these problems.. 2011 I will need a 2nd PSU so will stick with an official Meanwell as my problems put me off trying any generic copy cat brands.
     
  6. darkeyrie

    darkeyrie Light-O-Rama User

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    Another option you can consider (although they are harder to find) is to go for the big high current switchmode supplies sometimes found in telephone PABX and commercial radio installations. I have managed to source mostly at amateur radio junk sales some 60A 24V supplies (~1.5kW) and have a couple of these driving my display.

    However, if you go down this route, and wish to remote your dimmer boards from your power supplies, you then need to carefully consider the resistance of your feed cables. Otherwise as you switch one channel on and off on your dimmer, you can modulate the brightness of all other channels on the same board. This is because the input voltage on the end of say a 20m run of cable will vary with the amount of current flowing through it (basic ohm's law). It is particularly noticeable if you mix LED and incandescent lights together on the one master power supply (which I do).

    The solution - use very heavy cable (I run 8G and 4G cable to overcome this for controllers delivering around 20A/controller over 20m runs).

    Why do I do this? Well, I have mounted the controllers out in the yard to reduce the amount of individual circults I need to bring back the whole distance to the rectifiers in the garage. I saved myself 2400m of 2 core wire for the cost of 2x20m of 8 gauge cable.

    Running the smaller power supplies, you are likely to only run one PSU per 1-2 DC boards so the chances of having the volt drop problem are reduced - but a consideration still remains that you may want to keep your controllers mounted in waterproof enclosures closer to your lights, and keep your PSUs relatively close to your controllers, just to keep better control of the spaghetti factory of cable you end up with otherwise :)
     
  7. Silvo

    Silvo New Elf

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    Grant,

    If i wanted to mount my power supplies close to my controllers, but mount my controllers in a single location (garaged), would the max achievable distance from the controller to the string just be dependent on the cable thickness of the lead to the string?

    so if i mount everything central, and want to run a string 10 metres away i would likely use heavier cable to the string to not lose current.

    i would really prefer not to run my controllers in the yard.

    thanks
     
  8. mrpackethead

    mrpackethead Full Time Elf

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    General rule would be to put your power supplys as close as possible to your load. Thats not always possible of course.

    The issue is one of voltage drop.. Copper cable has resistance, its not a perfect conductor. The smaller the cable, the higher the resistance per meter is. So for a given "load" a larger cable will drop less voltage than a smaller one. If you go too small your cable will get hot, and eventually melt.

    The numbers are all calculatable, and there are numerous web based tools for doing this.. As a rule of thumb, for low voltage things, don't exceed a voltage drop of 5%, and you'll be ok..
     
  9. Bridgette

    Bridgette Apprentice Elf

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    Where have u found the best place to buy your Meanwell PSU's

    Bree
     
  10. darkeyrie

    darkeyrie Light-O-Rama User

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    The cable thickness causing volt drop issue is only a visible concern within your rig up until the point where there are multiple channels worth of current flowing through one cable - i.e. between a power supply and the controller. After you have passed the controller, what happens on other channels will no longer be able to affect the voltage on any particular channel so you wont see the unwanted random dimming problems due to the load from other channels.

    In your case, if you are going to mount your power supplies and controllers together and then run individual channels out into the yard then you don't have a problem running light gauge wire out to the individual light sets.

    Typically then, you only need wire heavy enough to power the individual light string involved. That wire can be quite light and relatively long without being noticed for most modern lights such as LEDs. I have some runs that are 20-30m beyond a controller even with my controllers remoted. Those runs are using light duty speaker wire - and in one case I even used LAN cable (because I was short of wire at the time). In some cases I have used the same gauge wire as that which came with the light set originally once I was beyond the controller and it works fine.

    The case I was wishing to highlight which can be a trap for beginners was if you remote your controllers from your power supplies - which means you have the current from 16 channels all flowing over the one cable between the controller and the power supply. There, volt drop and as a result random channel dimming due to switching of other channels within the same board can become a pain.

    MrPacketHead is right to an extent - it is usually better to have your power supplies close to your controllers and for beginners it can be a good rule of thumb to follow. However, when you get to very high channel counts, distributing controllers and separating power supplies from DC controllers can be a worthwhile way to consider designing your rig, just to keep better controll of the birds nest of cables. At a certain point it can become cheaper too as you save a couple of km of wire (as in my case - where 20m saved with some heavy cable and controllers remoted from the power supplies translated to 2.5km less light gauge wire I needed).
     
  11. Beacy

    Beacy It's so much better on the dark side

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    Silvo this year I have had my power supply withing a few metres of the controller board and runs that are 20-25 mt from the controller to the light string and have been using 24/020 figure 8 cable (speaker wire) from Middy's at about $38 per 100mt roll. I haven't seen any obvious problems with voltage drop
     
  12. mrpackethead

    mrpackethead Full Time Elf

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    I use Meanwell in our commerical controllers exclusively now, primarly because i have had very little trouble with them, they functional well, they survive dead shorts on the output well, they shutdown nicely if they get overheated. Electrically they seem stable, and they dont' produce lots of RFI. Yes, they are a little more expensive than some of the so called "copies", but like everything "yous gets whats yous pays fors"
     
  13. Silvo

    Silvo New Elf

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    thanks for the response Grant, (and others), great information and inline with my understanding (woo :D )

    i see how running a controller closer to the display and running 1 single heavier wire between the PS and the Controller can benefit in a reduction of tangle.

    back to the drawing board to double check my plan.

    cheers
     
  14. fasteddy

    fasteddy I have C.L.A.P Global Moderator Generous Elf

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    The other advantage of getting the cheap power supplies from Ray Wu or other suppliers is that they are cheap enough to buy a spare or 2 and build in redundancy to your display. If you had the one power supply and it failed then it would be show over until you could source another one.
     
  15. darkeyrie

    darkeyrie Light-O-Rama User

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    Eddy,

    Yes - a central supply does have that drawback. Thats why I sourced N+1 worth to drive my rig :) I wouldnt advocate anyone do what I did unless you did have the redundant power supply on hand as it is game over if it fails.
     

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