Simple Power Supply

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Simple Power Supply

Postby bdring » Sun Mar 04, 2012 10:00 pm

I bought a 350 watt micro ATX power supply at Fry's a while back. I think it was about $20. I trimmed back all the wires and put some banana jacks on the side for the 12V and Gnd. I also added a switch, because micro ATX power supplies generally do not have one. This switches the enable circuit.

I wanted a clean, small and portable power supply. This can easily be disconnected and moved about.

I documented the wiring on the wiki.

uATX_mod.jpg
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Re: Simple Power Supply

Postby AndrewR » Mon Mar 05, 2012 1:24 am

FYI, some power supplies won't turn on without a load so a power resistor may need to be used. I've converted a few old PC PSUs to lab bench power supplies following these directions:

http://www.wikihow.com/Convert-a-Comput ... wer-Supply
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Re: Simple Power Supply

Postby butterfingers » Mon Mar 05, 2012 1:35 am

I was thinking about something like this...

http://www.goodluckbuy.com/12v-15a-180w ... urity.html

...mounted in a ventilated plastic enclosure with "bench" style outputs and an IEC socket in. Would this be workable? I like the idea of not having a fan.
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Re: Simple Power Supply

Postby Halfdead » Mon Mar 05, 2012 1:45 am

I ordered http://www.newegg.com/Product/Product.a ... 6817341050

It arrived a couple days ago, it's completely modular so I just modified the Molex connector a little bit and now I have a nice looking PSU with 45A on the 12V rail.
It's also silent and comes with a 5 year warranty.
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Re: Simple Power Supply

Postby bdring » Mon Mar 05, 2012 2:27 am

The modular power supplies are sweet. Some are not 'modular' on the motherboard connector, so watch out for that.

won't turn on without a load


I checked for that, and it measures 12.00V exactly (well according to my fluke meter last calibrated about 5 years ago). The fan is a little louder than my std ATX because it is smaller, but I like the small size.
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Re: Simple Power Supply

Postby canadianavenger » Mon Mar 05, 2012 4:36 am

Your OC voltage may be good, but under load it may fall severely out of regulation. Most AT/ATX power supplies require a minimum load on the 3.3V or 5V line in order to maintain regulation on all rails.
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Re: Simple Power Supply

Postby awesomenesser » Mon Mar 05, 2012 7:35 am

I am using a very similar setup. I documented it in my buildlog here.

I am using a $30 380 watt micro atx power supply that produces 19A@12V. I decided to build the power switch wiring into the connector so that a power switch on the 3d printer will be able to control the power supply.

I checked the open circuit voltage and it is spot on 12 Volts. Then as a test I attached a few feet of led strip (1.5A@12V) and the 12V line reads 11.75 Volts which is well within the ATX specification of +or- 5%. (My multimeter is a cheap Chinese ripoff of a Fluke... it should be quite accurate for everything but RMS current)

P1020278.JPG
LED strip load test.
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Re: Simple Power Supply

Postby Enraged » Mon Mar 05, 2012 6:00 pm

I took apart an old 380W ATX power supply yesterday (free!), desoldered all of the 3.3V and 5V wiring, as well as all of the unused ATX motherboard connector wires.

I'm either going to use http://www.sparkfun.com/products/9739 or http://www.sparkfun.com/products/10474 to connect to my Hadron. I like the XT60 because it would make connecting everything easier. I'm also using the same on my Shapeoko
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Re: Simple Power Supply

Postby Enraged » Thu Mar 29, 2012 4:04 am

Turns out my power supply was on its way out, so I picked up one of these 12V 30A supplies that are pretty popular in the reprap community: http://www.ebay.ca/itm/140662404070?ssP ... 1497.l2649

at 30A it should be more than powerful enough for my Hadron, with lots of room for future upgrades like dual extruders and heated beds.
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Re: Simple Power Supply

Postby butterfingers » Thu Mar 29, 2012 6:09 pm

Enraged wrote:Turns out my power supply was on its way out, so I picked up one of these 12V 30A supplies that are pretty popular in the reprap community: http://www.ebay.ca/itm/140662404070?ssP ... 1497.l2649

at 30A it should be more than powerful enough for my Hadron, with lots of room for future upgrades like dual extruders and heated beds.


That's my plan too. Would you mind sharing your enclosure/mounting ideas?
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