Arduino power question

I am new to RAMPS, I have a RAMPS v1.4 as an upgrade to my 3D printer. My question / problem is I do not want to have a PC connected and running all the time since the setup I have has an SD card reader on full graphics LCD display board. I thought the Arduino was supposed to get power from the RAMPS shield but I guess I am wrong in that assumption. Can I power the Arduino with a wall wart plugged into the barrel connector? What ratings do I need to look for in a wall wart to power the Arduino? Can I safely use a 12 volt supply plugged into the barrel connector of the Arduino? Should I remove the D1 diode? Thanks, sorry for asking these questions if they have already been asked and answered,

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John Guenther
Anderson, Indiana
U.S.A.

"I thought the Arduino was supposed to get power from the RAMPS shield but I guess I am wrong in that assumption."

Correct, but it was never designed to drive a glcd, they suck to much power. (non ardunio mega2560 boards provide more current)
power is taken from the ramps to the mega threw D1 to the mega vin pin.

"Can I power the Arduino with a wall wart plugged into the barrel connector?"

Yes. But it wont help the most common power issue, voltage regulator on the mega is under rated and keep reading..
And you still need 12 into both sets of power plugs on the ramps to provide power for fans, heaters, steppers and heated bed.

" What ratings do I need to look for in a wall wart to power the Arduino? Can I safely use a 12 volt supply plugged into the barrel connector of the Arduino?"
7-12V is recommended to power a mega2560

" Should I remove the D1 diode?"
You have to remove D1 to use the DC barrel connector.

A better fix is a remove D1, get yourself a 5v 1.5amp or better regulated power supply. Connect the +5v to a free +5v pin on the ramps and gnd to gnd. Any unused endstop is good for this or aux 1. Don't use the 5v pins on the servos pins, those are not actually connected to the real 5v line.

Edited 3 time(s). Last edit at 05/08/2017 04:56AM by Dust.

Thank you for your detailed answers.

So removing the D1 diode will allow me to power the mega2560 directly using a 7-12V power supply.

I assume I can take 12V from the same supply I use to power the rest of the printer to power the ramps.

I will get a 12v to 5v converter and connect it to an unused endstop. I do not really understand the purpose of the additional 5V supply, is it to provide enough power to the display or the 5V rail in general.

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John Guenther
Anderson, Indiana
U.S.A.

"So removing the D1 diode will allow me to power the mega2560 directly using a 7-12V power supply."

yes.

"I assume I can take 12V from the same supply I use to power the rest of the printer to power the ramps."

yes. NB this is no different from the mega being feed from d1.. same 12v goes to same voltage regulator on mega.

" I do not really understand the purpose of the additional 5V supply, is it to provide enough power to the display or the 5V rail in general."
It replaces the current 5v power supply (generated on the mega) which has insufficient current for the job.

Thanks Dust,

I have decided to replace the mega2560 with another one I have that is currently not in use. I think then I will have time to replace the onboard requlator or I will be using it in a situation where it will always be powered through the USB port.

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John Guenther
Anderson, Indiana
U.S.A.

If you use a 9V wall wart to power the Arduino through the barrel jack, the regulator will dissipate around half the power that it does when powered from 12V, which will avoid the overheating problem.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].