Max voltage for RAMPS

Hi all,

I have been looking at the circuit diagram for RAMPS. Currently I have a Sanguinololu and it is run from a 19V supply. I know that the Mega can accept up to 20V so if I put 19V I am assuming the RAMPS board will send the 19V to the Arudino and pull back the 5V to run on.

Am I even close?

okay, reading further it says on the wiki "The 1N4004 diode connects the RAMPS input voltage to the MEGA. If your board does not have this diode soldered in, you can safely input as much as 35V. (The pololus can do up to 35V)" but there are two 1n4004's. I belive it is refering to D1 and then I think would need to power the Arduino with a seperate 5V supply.

From [reprap.org] :

D1, D2 - Diodes

These must be placed in the proper orientation. The band on the diode must be turned the same way as the mark on the board.

Definitely solder D2 in. D2, F1, and F2 are shown installed here.

D1 should only be installed if the 5A rail is powered by 12V. It can be omitted and the Arduino will be powered from USB. You will want D1 installed if you add components to print without a PC. To reiterate, D1 MUST be omitted if you are powering the 5A rail by more than 12V.

According to [arduino.cc] the power supply limits for a standard Arduino Mega are as follows:

Operating Voltage 5V
Input Voltage (recommended) 9V
Input Voltage (limits) 7-18V
...
The board can operate on an external supply of 5.5 to 16 volts. If supplied with less than 7V, however, the 5V pin may supply less than five volts and the board may be unstable. If using more than 12V, the voltage regulator may overheat and damage the board. The recommended range is 7 to 12 volts.

My understanding is that the Arduino can safely handle up to 12V incoming power via its own on-board power regulator. If you include D1 it will route the 12V supply from the RAMPS board to power the Arduino, allowing you to run without a USB connection to your PC - e.g. if you install SDRAMPS to print "computer-less", or go one step further to print completely wirelessly as I have set up: [julianh72.blogspot.com]

The only limitation is that you need to limit your power supply to 12V to avoid overloading the Arduino's built-in power regulator. You MIGHT get away with running a 19V power supply to your RAMPS and connecting diode D1, but you would run the risk of over-heating the Arduino's power regulator.

If you omit D1, you don't connect the RAMPS power supply to the Arduino, so you need to have the USB (or an alternative suitable DC power supply) connected to power the Arduino, and the USB will power just the Arduino (and hence the 5V jumpers on the RAMPS), but the steppers and hot end / heated print bed circuits will draw their power from the beefier RAMPS power supply.

Hope this helps!

Edited 1 time(s). Last edit at 01/17/2012 06:25PM by julianh72.

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Follow my Mendel Prusa build here: [julianh72.blogspot.com]

Cool, thanks for the reply

I want to make it totally standalone so I can do without the computer being involved at all (aside from gcode creation). I currently use a bluetooth dongle on my Sanguinololu which works really well, but the Sangi doesn't have enough pins for complete autonomous operation. As I have the powersupply from the Sangi, at 19V, I can supply that for the ramps and I'll regulate it down for the arduino.

If the D1 diode is not used, and a computer is not connected to the USB connection on the RAMPS 1.4, can the Arduino Mega be powered using the power connection on the Arduino?

How high 12v is recommended? Mine is adjusted at 12.2 when idle, I guess it drops some when drawing more amps from the MW 350W psu.

Quote
Donald King
If the D1 diode is not used, and a computer is not connected to the USB connection on the RAMPS 1.4, can the Arduino Mega be powered using the power connection on the Arduino?

There is no USB connector on the RAMPS - it is on the Arduino. To answer the question, if you do not have the diode in place, you MUST provide separate voltage to the arduino. If it is not via the USB connector, it must be via the on-board barrel connector.

jbernardis, I think your a bit late, was posted February 09, 2012!!!!!!!

Edited 1 time(s). Last edit at 11/15/2014 10:11PM by Dust.

Stigern, the mega is only rated to 12v so if you powering the mega from the ramps via D1. 12 volts. Some have gone as high at 19 without frying things. but I cant recommend this. Your generating 5v from this, so you if applying 19v it have to turn 14v into heat! 12.2v is no issue

from [arduino.cc]
"The board can operate on an external supply of 6 to 20 volts. If supplied with less than 7V, however, the 5V pin may supply less than five volts and the board may be unstable. If using more than 12V, the voltage regulator may overheat and damage the board. The recommended range is 7 to 12 volts."

If you remove d1 from your ramps and power your mega separately, the ramps itself can have more voltage, depending on a few things.
1) the capacitors, some boards have 16v some have 35v caps, with 16v caps, you should stick to 12v, for 35v caps you go use up to 30v no issue (most use 24v)
2) the polyfuse, the 11amp poly fuse is only rated for 16v. So you must replace that if you use more.

Edited 1 time(s). Last edit at 11/15/2014 10:12PM by Dust.

Quote
Dust
jbernardis, I think your a bit late, was posted February 09, 2012!!!!!!!

This is what happens when someone resurrects an old thread. I didn't even notice the date ☺

I appreciate people replying... even in 2019