5v amps?

[Typefighter01]

I need to supply 5v to the breakout board on my CNC router and I have a question about amps. I see alot of breakout boards shipped with a USB header that supplies 5v to the board and it looks like 5v USB delivers 500ma. In the interests of simplicity, I was going to use the 5v from one of the molex connectors from the computers PSU to power my board as it does not ship with the USB header, however, it looks like the 5v from a PSU delivers upto 11amps. I Googled 5v PSU to power CNC breakout board and I can not find anything, is it because of the large amp capacity? What would you guys do:

1.Connect a generic USB cable from an old PC case to one of the extra USB headers on my MOBO and the just cut and strip wires?

2.Use the 5v from one of the Molex wires off of the PSU (red and black wire)?

3.Hack up one of those 5v cell phone wall chargers (this I have seen used in quite a few CNC builds)?

[PL1]

I need to supply 5v to the breakout board on my CNC router and I have a question about amps.

What breakout board are you running?  (Link?)

Do the specs list the current draw?

I see alot of breakout boards shipped with a USB header that supplies 5v to the board and it looks like 5v USB delivers 500ma.

The USB spec limits an individual unpowered USB connection/header to 500 mA IIRC.

Manufacturers often allow current in excess of the spec, but drawing too much can fry your motherboard.

Powered hubs can provide more amperage, but you might as well cut the USB out of the loop to preclude any possible damage to the motherboard.

3.Hack up one of those 5v cell phone wall chargers (this I have seen used in quite a few CNC builds)?

Of the three options listed, I'm leaning toward this, but you need to know how much current it will draw to make an informed decision.


Scott

[Typefighter01]

Hey Scott, this is the best link I can find if you can believe it http://www.nbglin.com/download/cnc25.pdf . Lots of info out there if you speak Russian or Spanish. I have now stumbled onto at least one example of each where someone has used the 5v from the PSU molex and/or the cell phone charger. I have this http://www.amazon.com/Music-Power-0900-70-Solo-Charger/dp/B000QFKDJ2, what do you think about using it for my 5v power? I think keeping the USB ports from my MOBO out of the equation is a smart idea, I am leaning in this direction.

[BobA]

Easy way would be to use the molex red and black wires from your power supply to power your interface.   Why limit the amps when you do not have the amp requirement in black and white.  You could have less then required amps if you power from a USB plug or USB power adapter.

[PL1]

I was hoping to find something that would indicate the current draw, but no such luck.   

Looks like this is one for the CNC gurus.


Scott