Will this power supply work

[lboucher]

Hi All

Typically I would do more of my own research, but right now I don't have much of any free time and just got this power supply given to me and I am excited to know if it will work for my smart strings.

I know smart strings are 12 volts, this supply is 13.8 volts.

Will this work? Or would i have to regulate it to 12 volts.

Thanks

[tbone321]

I would adjust it back down to 12V if possible. 

[lboucher]

So, never having dones something like this before....

Whats the cheapest way to get this down to 12V. (And is it worth it, or should i go get an ATX)

I was thinking 9 of these in series??
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But i really don't know what I am talking about.

Thanks

[taybrynn]

I don't know, but looks like a decent supply, but voltage may be the problem.

I see a lot of SS stuff potentially moving towards a optional de-centralized power model ... with the passive hubs and option 12v option on the hub.  Maybe the passive hubs aren't required if you just hook up the power properly just before the SSC (?) .  I may get embarrassed p for the dumb suggestion, but just thinking.

Those waterproof 5a 12v power supplies from ray (about $11.68 each) could be used for a lot of stuff.

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And then for smaller stuff, the 3.75a PS is popular.
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Anyways, understand we all have to work on a budget, so many its worth trying to retrofit, maybe not.

[lboucher]

Thanks for the thoughts.

I have been mulling this on my drive.
Electrical design is my weak point so excuse me if I am thinking of stupid ideas.

Is what I really need as simple as a diode to drop the voltage 1.2 volts?

[chrisatpsu]

why not look for a 12volt regulator?  trying to just drop the voltage will give you a problem BC if the 13 volts dips then will your modified 12 volts. a regulator will try to give you 12 volts no matter if the source fluctuates.

[RJ]

I would not run them on over 12volts regulated DC.

The problem with the little power supplies is cost. They look cheap to you because the base price but lets look at it for real world.

to get 40 amps I need 8 of them costing = $170.19 including shipping or $4.25 per amp.
one 40 amp Atx supply can be purchased on deals = $40 and free shipping or $1 per amp.

I can do more light with the ATX than all the 5 amp units because my power is pooled.   I can only run 128 nodes on 5 amps but I have a little left over. This is not in the pot for other lights to use like it is with the power central from an ATX.

So it comes down to put power at the hub and run cat5 to the ssc. Or pay 4 times as much for power supplys and put power at the SSC.

I designed for the cheaper route. With the flexibility of doing the other if really needed.
So in the end the users should do it the way they want or need but this is why it is the way it is. 

I will be running 100 amps in the yard this year. That would be real expensive with the independant supplys it's reasonable with the ATX units.

RJ

[tbone321]

Thanks for the thoughts.

I have been mulling this on my drive.
Electrical design is my weak point so excuse me if I am thinking of stupid ideas.

Is what I really need as simple as a diode to drop the voltage 1.2 volts?

Yes, running it thru a diode will drop it 1.2V.  The problem is you are still at 12.6V which is still over half a volt higher than what is expected.  Another issue is finding a diode that can pass the current you need.  While high current diodes do exist, they are large and expensive.  Unless the powwer supply has a method to control its internal regulator, I would probably just go with an ATX supply.  Trying to save a few dollars doesn't help if you blow out a controller, hub, or nodes due to over voltage, especially if it happens during the season and your display is either crippled or shut dowwn by it.

[lboucher]

Talked to a guy at work who does a bunch of HAM stuff. He told me that lots of times the old fixed power supplies have a trim pot inside.

So i (Very Carefully) opened err up, and kinda glad I did...  Found a loose paperclip bouncin around inside, yikes...

I did find a trim pot, and was able to lower the voltage to 12.88
Looking at it, it seems like a fairly easy process to desolder the existing trim pot and replace it with one with a bit more range.

In theory I should be able to get down to 12V.

Is there any reason i shouldn't do this?

Thanks

[lboucher]

Hi All

Finally figured out how to lower this to 12V and only used 1 resistor.
Here is a little write up with links/pics.
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