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One main 12V supply vs lots of bricks?

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#1 rimcrazy


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Posted 11 January 2013 - 09:56 AM

I'm setting up a remote controlled observatory and I've got a quick question on setting up my main 12V DC Supply. One school of thought is to simply use all of the wall bricks and hook them up to either an IP controlled AC outlet ( Data Loggers IP AC Switch ) or something like the remote controlled outlet you can slave to a RoboFocus. ( HomeDome Remote AC Outlet )

Another way is to simply get a fairly robust 12V DC Supply ( 150W 12V DC Power Supply ) and use something like a simply Arduino board ( Arduino Boards ) and program it up with a relay board to switch separate 12V connections to the respective accessories.

I've been an electrical engineer for 30+ years so programming up an Arduino for me is a relatively simple task. That being said, I've never been one to reinvent the wheel if a reasonable solution already exists.

My thinking is using a 12V supply with the Arduino is probably both the most robust and most programmable. While my AC supply is through a heavy duty Tripp Lite UPS that regenerates a perfect sine wave, the regulation on a dedicated DC supply like I showed is far better than your average brick, which is many cases is not much more than a diode bridge with a cap. That being said, I lack real time experience in this application so I am quite interested in solutions and problems others have overcome and solved.

Thanks much!

#2 stmguy



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Posted 11 January 2013 - 10:16 AM

I think I'd rather have one good power supply . I used a used hot swap power supply from a server and it puts out lots of amps with separate 12 volt taps. I didn't even have to open it up to convert it, just shorted 3 pins together and nice stable power. If you go this route look up how to do it for the power supply that you are going to buy first as they are all a little bit different, mine was from a X-series IBM 236 server

#3 Alex McConahay

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Posted 11 January 2013 - 10:54 AM

I run all my 12 volt devices off of one large power supply......Salvaged from an old ham radio setup. Works fine.


#4 rimcrazy


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Posted 11 January 2013 - 11:07 AM

Maybe to clarify my point. I'm not questioning if a single DC will work or not. With a properly scaled supply it is a moot point. My question really centers on what people have found most useful in a remote control environment. The IP AC switch outlets I've seen, while accessible over your private observatory network can be switched, they don't appear to be a very script-able controlled asset. A single regulated DC supply switched with a micro-controlled relay bank OTOH to me seems far more controllable. I'd be interested to know what others are using in a remote controlled environment.

#5 JAT Observatory

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Posted 11 January 2013 - 11:36 AM

I use these:

They are RS-232 controlled via this crude GUI I wrote in Visual Basic
This is an older version of the GUI it looks a little different now but I think you'll get the idea.

#6 rimcrazy


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Posted 11 January 2013 - 12:08 PM

AH! Now that is outstanding. I should have posted this question earlier. I picked up a Telco/IP switch for my main server room with my DSL Modem and Tomato Router earlier but it was more expensive than this model and probably not nearly as programmable. This looks to be pretty sweet. My observatory is located up in the White Mts. in Arizona and our local ISP, Frontier, manages to lock up their DSL modem about once every 2 or 3 months. Short of a 3 hour ride up to my place there was no other way to reboot it. This ganged outlet looks to be pretty sweet. Looks like you have a very nice control panel to boot. I want to be able to control a host of things, both unscripted and scripted. This looks to be a good way to handle some of those things.

I checked out your web page. Very sweet indeed. I'm just getting started and putting things together. This is item was one of the early ones on a list that looks to be, oh probably semi-infinite in length but fun none the less. Thanks for the input.

#7 Lorence



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Posted 11 January 2013 - 02:29 PM

I've got a combination of a big 12V power supply and a bunch of wall warts. I control the wall warts with two CPS switchs like the one JAT indicated and a Digital Logger IP switch. I prefer the IP switch. The CPS works well enough but has a small problem. It has no way to tell your software if a switch is off or on. If you have to reload your software mid session you may not know if a switch is off or on. Not critical on some devices but not good with others. There is also an occasional problem when the software I use forgets there are two switches daisy chained together. That's an easy fix but it's a hands on fix.

My observatory is only a few minutes away. Not a problem to go out there and fix something. I have the option to move it to an even darker site. I may do that someday. This is one option I would consider if I moved the observatory. The DSL line you use might be a trip saver for you. It works on a regular telephone (POTS) line. As long as the line is working you have dial tone and can dial into a modem. That modem can be used as a way to get into the system and control power to devices including your DSL modem when your high speed is out.

If you do go with a big 12V supply don't forget sub fusing. I was given a 45 amp supply out of an RV. More than enough power to turn wires into heating elements.

#8 Mary B

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Posted 11 January 2013 - 07:54 PM

Internet control DC power distribution http://www.powerwerx...005i-interne...

#9 rimcrazy


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Posted 11 January 2013 - 10:54 PM

Hmmm that is interesting. A bit on the pricy side but it is already done and the programmable current limits is a nice feature. I will have to noodle on it. The Arduino solution is significantly cheaper and I suspect more scriptable all be it at the expense of my time. Thanks for the link.

#10 frolinmod



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Posted 12 January 2013 - 12:08 AM

I use a Powerwerx 12V power supply along with a "Mount Hub Pro" to both distribute and remotely switch the power to various devices on-mount. My mount itself is a Paramount, so I switch that and the 12V power supply separately with a scriptable Ethernet switch.

#11 jmasin



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Posted 22 January 2013 - 08:57 AM

I think the RigRunner switchable is nice solution. I personally am not a big fan of wall-warts. Quality varies wildly, they are typically fairly cheap pieces. I've had more than one fail over the years (yeah, simple transformers failing... crazy).

So a dedicated 12V supply and switchable individual routes like the RR is a nice solution.

I'm not remote but I'm slowly setting up my setup as if it was (running from in the house as a dry run) in prep for later.

I also contemplated programming a simple MCU board (my company makes them) as a home-grown programmable switching solution, but decided it just wasn't worth the extra time required when turn-key solutions are there...

#12 Mr_T



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Posted 22 January 2013 - 08:48 PM

I use a CPS that is controlled with the foster ROR board The cps then turns on my mount cameras and a 12volt supply to a rig runner that is fused for each device

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