I3 power question

I am building my first 3d printer. The one I picked out was the Prusa I3. I'm planing on using a moded atx power supply. My question is ismy power supply has a +12v1@18A, do I still need to run 2 power lines to the driver board? Or is one line enough? I do not want to over power the board and fry it.

If you are going with a PC supply, you want one that is rated at > 25A for a normal heated bed setup. You very much do *not* want to run out of power going to the board. You also do not want to run a PC supply right at it's maximum ratings for hours at a time. They are not designed to do that sort of thing. A typical modern PC uses power in brief bursts. If you are building a PC that runs high power all the time, you pay 2X (and maybe more) as much for the power supply. The other approach in a PC is to simply buy one thats twice as large as you really need.

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Voltage is what fries things in this case. You could connect a 1,000A 12V supply to the board and it would be fine. If you hook up a 1/10A 24V supply you will fry the board. Of course if you short the wires on your 1,000A supply that would be a bit exciting. Not so much for the board as for the wires to the supply.

Edited 1 time(s). Last edit at 12/26/2013 01:26PM by uncle_bob.

Ok thank you for the information. I get what you are saying. I am still learning but I pick up on things fast. My power supply is a 600watt. Looking at the chart on the side of it it looks like my 12v is split into 3 groups. I can upload a photo of it when I get home. But looks like I have 2 12v@18am and 1 12v@15a = 450w then the other 160w at 3.3v and 5v.

I will need to do some more reading on the repreap wiki when I get home. If I need to buy a mother power supply that is find. Just will slow ny build down.

you can use that temporary to get thing moving and calibrate.
and if you have to buy a new power, suggest to go for a regular on instead of ATX. people use ATX power supply cause most have spare laying around the house.

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augus
you can use that temporary to get thing moving and calibrate.
and if you have to buy a new power, suggest to go for a regular on instead of ATX. people use ATX power supply cause most have spare laying around the house.

Yep. lol that is why I was using one.

A proper industrial supply that will put out 12V at 29A all day long is only $45. A good quality ATX supply of adequate power level will cost you more than that. The only reason to go with an ATX supply is if you have scrapped it out of a big PC and it's free.

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uncle_bob
A proper industrial supply that will put out 12V at 29A all day long is only $45. A good quality ATX supply of adequate power level will cost you more than that. The only reason to go with an ATX supply is if you have scrapped it out of a big PC and it's free.

I see that now. I will be ordering one tonight. Is there any brands to look for or stay away from?

A lot of us have used:

[www.trcelectronics.com]

Name brand, big distributor, quick shipping, nice people. (Yes I'm a happy customer of theirs).

I would avoid any of the eBay ones that look like the one on the link but are not *very* specific about exactly what it is. There are lot of clones out there. Many of them have issues.... Much easier to just buy it from a licensed dealer.

I was reading over the posts in this thread and I am a little surprised with the info.
because I was under the impression I could use a power supply from an older HP tower that I rewired so it supplys 2 ground wires and 2 - 24v wire to
the ramps 4.1 control board it puts out a constant 24v I also did this with another power supply for a CNC router.

I am a little ways away from finishing up, do you think I can use this power supply for my PRUSA i3 3D printer or not?