Power alternative.

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Power alternative.

Unread postby JLM » Thu Jul 11, 2013 12:28 am

Hi. I looked that project: viewtopic.php?f=11&t=89
It´s great and i´ve want to do so.
My problem is the power supply. I don´t like the idea of 200 power adapters.

So, i could imagine two solutions and i need some help:
1- UART. Can be use to plug an standard4-pin molex? I´ll not use it.
2- Desolder DC jack. This is a trouble proof option. The question is, jack has four pins, will be compatible (my idea is to use an standar 4 pin molex but only connect to 5V)?

Did somebody try this or i more insane than i thought?
Thanks!!!
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Re: Power alternative.

Unread postby mdrjr » Thu Jul 11, 2013 12:32 am

1. You can't power the ODROID off the UART port.

2. Them buy a single PSU with enough amps to power it up..
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Re: Power alternative.

Unread postby JLM » Thu Jul 11, 2013 12:50 am

mdrjr wrote:1. You can't power the ODROID off the UART port.

2. Them buy a single PSU with enough amps to power it up..

So, Option 2 could work.
I thought buy a modular PSU with a lot of 4-pin plugs (between 8 to 12).

Do you have some data about DC JACK looks like?
There is four pins or something in the back. I think they are only to hold.
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Re: Power alternative.

Unread postby odroid » Thu Jul 11, 2013 12:06 pm

4 pins are tied to GND and 1 pin is connected to 5volt.

Note that you must have a good power supply which has very stable output voltage for heavy load variation (lower voltage drop).
Output range must be 4.8V~5.2V (well regulated and stable)

dc-jack.jpg
dc-jack.jpg (22.18 KiB) Viewed 456 times
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Re: Power alternative.

Unread postby JLM » Thu Jul 11, 2013 9:16 pm

odroid wrote:4 pins are tied to GND and 1 pin is connected to 5volt.

Note that you must have a good power supply which has very stable output voltage for heavy load variation (lower voltage drop).
Output range must be 4.8V~5.2V (well regulated and stable)

dc-jack.jpg

Ok. So The single pin is +. I´d like to use an standard PSU.
I think the best choice is solder a Red wire to the single pin and a Black wire to one of 4 other pins...
All in a 4-pin standard molex.
Do you agree?
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Re: Power alternative.

Unread postby mdrjr » Thu Jul 11, 2013 9:55 pm

I don't see why use a 4pin molex while a 2pin can solve.. Are you trying to use a computer PSU ?
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Re: Power alternative.

Unread postby JLM » Fri Jul 12, 2013 12:57 am

mdrjr wrote:I don't see why use a 4pin molex while a 2pin can solve.. Are you trying to use a computer PSU ?

Yes. I use the 4-pin, but only with 5V cables. Easy, standard. Computer PSU is an standard power supply and simplify power. I don´t like the idea of 200 small trafos...
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Re: Power alternative.

Unread postby mdrjr » Fri Jul 12, 2013 1:01 am

Just make sure that the 5V rails is fine...
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Re: Power alternative.

Unread postby Matt » Fri Jul 12, 2013 6:30 pm

If you are going to use an ATX/EPS power supply by itself, then you may have to do some work to get it to provide power without all the other rails plugged in. Most modern PSUs will not start unless there is a load on the 12V rail and the 5V rail. You should be able to find some how-tos online that go over what you have to do to make it work... look for articles on using an ATX power supply as a "benchtop" or "bench" PSU. Also keep an eye on exactly how much current that PSU can actually supply on the 5V rail. Most of the wattage from an ATX supply is provided to the 12V rail. The 5V rail is used to power some parts of the motherboard, USB ports, the controller board on hard drives (the spindle is 12V), and usually the full solid state drive (they don't usually use the 12V lines).

You might have to spend a lot of money on unused 12V power capability to get enough 5V juice to power all the U2s that you want to use.

BTW, I pointed out some little DC-DC converter boards on aliexpress.com to mdrjr that take a range of input voltages from like 4-40V and can output 2.5-38.5V at up to 3A. You could use a 12V source at 40A to power almost 90 U2s (correcting for efficiency). Just search for "LM2596 DC converter regulator". They are just boards using a circuit diagram right out of the datasheet for the TI Simple Switcher line of LM2596 switching regulators. He ordered a few of them, and hopefully he can give us a report on how well they work whenever he gets them.
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Re: Power alternative.

Unread postby mdrjr » Fri Jul 12, 2013 9:26 pm

I'll ;) They are already on the way to my house.. I'll review them and post my tough of running a ODROID off it.
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Re: Power alternative.

Unread postby JLM » Fri Jul 12, 2013 9:41 pm

Matt wrote:If you are going to use an ATX/EPS power supply by itself, then you may have to do some work to get it to provide power without all the other rails plugged in. Most modern PSUs will not start unless there is a load on the 12V rail and the 5V rail. You should be able to find some how-tos online that go over what you have to do to make it work... look for articles on using an ATX power supply as a "benchtop" or "bench" PSU. Also keep an eye on exactly how much current that PSU can actually supply on the 5V rail. Most of the wattage from an ATX supply is provided to the 12V rail. The 5V rail is used to power some parts of the motherboard, USB ports, the controller board on hard drives (the spindle is 12V), and usually the full solid state drive (they don't usually use the 12V lines).

You might have to spend a lot of money on unused 12V power capability to get enough 5V juice to power all the U2s that you want to use.

BTW, I pointed out some little DC-DC converter boards on aliexpress.com to mdrjr that take a range of input voltages from like 4-40V and can output 2.5-38.5V at up to 3A. You could use a 12V source at 40A to power almost 90 U2s (correcting for efficiency). Just search for "LM2596 DC converter regulator". They are just boards using a circuit diagram right out of the datasheet for the TI Simple Switcher line of LM2596 switching regulators. He ordered a few of them, and hopefully he can give us a report on how well they work whenever he gets them.

Amazing. I´ll search and keep thinking. Thanks!!!!
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