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Equipment Discussions >> Equipment

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Ira
Carpal Tunnel
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Reged: 08/22/10

Loc: Mitzpe Ramon, Israel
Basic electrical power question new
      #5610718 - 01/07/13 06:52 PM

I have a computer monitor that I want to run in the field with DC power from a Power Tank. It has a DC input power jack that says 12v 4.5Amp. Can I just find a plug that fits the power jack and plug it directly into the DC jack of my power tank, or do I need something special to power it?

Thanks,
Ira


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Midnight Dan
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Reged: 01/23/08

Loc: Hilton, NY, Yellow Zone (Bortl...
Re: Basic electrical power question new [Re: Ira]
      #5610738 - 01/07/13 07:02 PM

You should be able to connect it directly to the power tank. Be sure you have the polarity correct though. If you reverse the + and - leads, you could damage the computer.

-Dan


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Eddgie
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Re: Basic electrical power question new [Re: Ira]
      #5610749 - 01/07/13 07:09 PM

If the monitor has will run on 12 Volts you should be able to do this, but the 4 amp draw will be a lot. Most powertanks only have 15 amp hours of power, so this will suck it down pretty fast if you are running other things off of it.

But if it has a 12 vdc jack, it may work.

Radio Shack and Amazon sell different power jacks with changeable tips. Get one with a cigerette ligher plug on one end and match your power tip. Be sure to observer the polarity.


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Ira
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Reged: 08/22/10

Loc: Mitzpe Ramon, Israel
Re: Basic electrical power question new [Re: Eddgie]
      #5610795 - 01/07/13 07:38 PM

It's a Shuttle XP17 monitor. The specs only say 12V DC power in. No mention of polarity.

/Ira


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neotesla
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Re: Basic electrical power question new [Re: Ira]
      #5610810 - 01/07/13 07:52 PM

That would be 12V from a AC power brick. I run electronics like this using a power pack with a built in inverter, so the AC plugs directly into the unit. Straight DC power may be variable enough to damage the monitor.

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Midnight Dan
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Re: Basic electrical power question new [Re: neotesla]
      #5610820 - 01/07/13 07:57 PM

Neotesla:
If the monitor says 12VDC next to the connector, then it needs DC voltage, not AC.

Ira:

The polarity is often shown in a small symbol either printed next to the jack, or embossed in the plastic next to it. The symbol looks like this:
http://www.stagebeat.com/power-supply-voltage-and-polarity/

The certral circular part is supposed to look like the connector. If the dot in the middle is connected to the + symbol, then it means that the pin in the middle of the connector must be positive.

-Dan


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Ira
Carpal Tunnel
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Reged: 08/22/10

Loc: Mitzpe Ramon, Israel
Re: Basic electrical power question new [Re: Midnight Dan]
      #5610844 - 01/07/13 08:16 PM

Yes, it originally ran from an AC power brick that provided DV output. I've lost the power brick. That probably had the polarity on it. I've checked the monitor again. It does not have a power polarity symbol on it. I wrote a note to Shuttle tech support asking them. In the mean time, now what? Should I get a power brick and run it off an inverter plugged into the power tank? This is getting expensive. I may just go back to the idea of getting a DC powered TV instead of messing with this computer monitor.

/Ira

Edited by Ira (01/07/13 08:18 PM)


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evil16v
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Reged: 08/18/12

Loc: N.E. Kansas
Re: Basic electrical power question new [Re: Midnight Dan]
      #5610865 - 01/07/13 08:30 PM

I wouldn't recommend powering your monitor straight off the battery. It needs to be regulated.

If you do it anyway... or find a method to regulate (might be able to find something one ebay), get a voltmeter and test polarity of your 120v power pack at the tip while plugged into the wall. Note the polarity, then go to radio shack and get the plug that fits the monitor (if they have it). Add wiring, wire to your power tank with a 4-5 amp fuse. Then check the polarity at the tip again with your volt meter. Correct if needed.

Lower brightness settings should drop power draw considerably. I bet it doesn't draw 4 amps anyway.

a slightly less efficient method may be just to go buy a cigarette lighter 12V to 120v inverter at wally world.


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Pauls72
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Re: Basic electrical power question new [Re: evil16v]
      #5611295 - 01/08/13 01:38 AM

Yes the monitor is 12VDC.
The odds are the center tip is + positive. The vast majority or 12V components and power supplies are polarized this way.
It should work just fine off the power tank.
The main concern is the amount of power that the monitor requires, it will use up the power tank fairly quickly.


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Midnight Dan
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Re: Basic electrical power question new [Re: Pauls72]
      #5611433 - 01/08/13 07:13 AM

Hi Ira:

Like Pauls72 says, the majority of items use tip positive connections. So you could just take a chance with that. But, if you're wrong, and if the monitor is not reverse-voltage protected, then you could damage it.

Also, as Paul and Edgie both mentioned, a big consideration here is the power draw. At 4.5 amps, it will drain a standard power tank in just a few hours all by itself. If you add on powering your mount, dew heaters, and a computer (I assume the monitor is for a computer?), you'll be out of juice pretty quickly.

Maybe it would help if you described what you want to do with the monitor and what all of your power needs are.

-Dan


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Ira
Carpal Tunnel
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Reged: 08/22/10

Loc: Mitzpe Ramon, Israel
Re: Basic electrical power question new [Re: Midnight Dan]
      #5611550 - 01/08/13 09:09 AM

I will be using this monitor with a Mallincam Extreme, no computer. So my power tank will be running:

XP17 Monitor
Mallincam
S-video to VGA converter
Mini-LCD screen for adjusting the scope and camera
Ioptron MT Pro mount

Nothing for dew control yet, but I need to buy something.

/Ira


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Midnight Dan
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Re: Basic electrical power question new [Re: Ira]
      #5611944 - 01/08/13 01:23 PM

Hmmm ... hard to say without knowing all the power requirements for the equipment, but I'm guessing that with a 17amp Celestron Power Tank (the larger model) you'll probably only get a couple of hours of power, especially if you need dew heaters.

Keep in mind that to keep the battery in good shape you should not drain it completely. So a 17 amp hour battery can probably safely deliver on the order of 12-14 amp hours. I'm guessing your power needs will be around 6-7 amps so that's a couple of hours. If that's all you need for a session, and if you have the 17 amp hour Power Tank, then you're good to go. Otherwise, you should consider a larger battery.

-Dan


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Ira
Carpal Tunnel
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Reged: 08/22/10

Loc: Mitzpe Ramon, Israel
Re: Basic electrical power question new [Re: Midnight Dan]
      #5613167 - 01/09/13 05:49 AM

So, here is the very helpful answer I received from Shuttle tech support regarding the polarity of the power plug:

"Dear Sir/Madam

Thank you choosing Shuttle.

Regarding your concern about XP17 issue, yes, the power cable connector is the + and -.

Thank you very much.

Best Regards,
Shuttle Inc.
Technical Support"



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Midnight Dan
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Re: Basic electrical power question new [Re: Ira]
      #5613210 - 01/09/13 07:17 AM

Yeesh!

-Dan


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tecmageModerator
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Reged: 01/13/10

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Re: Basic electrical power question new [Re: Ira]
      #5614159 - 01/09/13 05:49 PM

Quote:

So, here is the very helpful answer I received from Shuttle tech support regarding the polarity of the power plug:

"Dear Sir/Madam

Thank you choosing Shuttle.

Regarding your concern about XP17 issue, yes, the power cable connector is the + and -.

Thank you very much.

Best Regards,
Shuttle Inc.
Technical Support"






Wow.


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Ira
Carpal Tunnel
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Reged: 08/22/10

Loc: Mitzpe Ramon, Israel
Re: Basic electrical power question [Re: tecmage]
      #5633921 - 01/20/13 08:52 PM

So...I looked all over for a regulated DC-DC power supply. Hard as the dickens to find online to match my needs. Not that there aren't any. Problem is there are too many, most of them industrial strength. Just when I was about to give up I walk into the little variety store in my tiny desert town where you can't even buy a pair of shoes and what do I see hanging on the rack but a really nice, consumer-grade, dc to dc power regulator with an assortment of tips to match different devices. I actually heitated to buy it since I thought the price was outrageous, about $60, but I finally gave in and took it home today.

Tonight I tried it out on my XP17 monitor, held my breath, plugged it in, turned it on, and...worked perfectly connected to my battery and laptop. I had it running for over two hours and there was still juice left in the battery. I am good to go.

Now I am just waiting for my video to VGA converter to arrive and I'll be cooking with grease! Unbelievably, the DC to DC power adapter even has a USB plug that I can use to power it!

/Ira

Edited by Ira (01/20/13 08:56 PM)


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