extra power to mega2560

Hi, I ran into slight hitch on my 3d printer, using geeetech i3b, mega2560 and ramps 1.4. I have servo based auto bed leveling.

My printer somewhat doesn't want to print after probing all the 9 points of the bed and currently I need to power the mega by supplying a little bit of 5v through usb.

My question is, is it okay to add in another 12v to the black power input in the mega2560 and will it burn my board?

I was thinking of doing some kind of voltage divider to step down the 12v to 5v supply

Resistive voltage dividers won't work for actually powering anything. They only work for driving constant impedance loads and even then are not great unless the load is very high impedance (draws negligable current)

You in theory should be safe putting 12V into the DC jack technically, however, you are dropping a whole lot of heat with the on board regulator and it is likely already stuck under a hot RAMPS board and I have heard of them failing, frying the board.

Better would be to get an external regulator you can add a heat sink too, like a 7809 to drop it to 9V, then put that into the DC port, or a 7805 to drop it all the way to 5 and feed it back into the positive rail of the mega will also work, but I'd prefer the double protection of feeding in a lower voltage to the DC in. A LM317 tuned to 8V should be fairly robust.

I don't know how to make a voltage regulator to be honest, so far my electronic has print fan, extruder fan, servo connected on d9 output, 12v supply next to x axis stepstick and servo at the bottom next to reset button

... look here for a typical 7805 voltage regulator datasheet - [pdf1.alldatasheet.com]

You can wire from the existing 12V to the left input pin and connect the middle pin to GND and the right pin to +5V, so the 5V and 3.3V on the Arduino would be powered with your 12V PS too ...

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Viktor
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erm... how do I do that actually by supplying into the vin? it is blocked by the ramps

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sarf2k4
Hi, I ran into slight hitch on my 3d printer, using geeetech i3b, mega2560 and ramps 1.4. I have servo based auto bed leveling.

My printer somewhat doesn't want to print after probing all the 9 points of the bed and currently I need to power the mega by supplying a little bit of 5v through usb.

My question is, is it okay to add in another 12v to the black power input in the mega2560 and will it burn my board?

I was thinking of doing some kind of voltage divider to step down the 12v to 5v supply

You Can feed it 12v just fine. I've done it for the last year.

If you fint it gets too hot, you just ADD a fan to it.

Some People are always overcomplicating things and believes anyone actually knows what resistive voldtage dividers are, and also believes a link to datasheet is an answer to a question.

People should realize that the majority is not THAT much into Electronics and come here because datasheets makes no sense to most people.

Edited 2 time(s). Last edit at 12/19/2015 04:10PM by dintid.

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My Instructables - both total newbie instructables and some for intermediate users.
My Designs on Thingiverse
YouTube channel containing a few 3D printing videos - they are videos for my Instructables, and mostly not standalone.
Ultius / Tantillus Thingiverse Group

Quote
dintid
You Can feed it 12v just fine. I've done it for the last year.

If you fint it gets too hot, you just ADD a fan to it.

Some People are always overcomplicating things and believes anyone actually knows what resistive voldtage dividers are, and also believes a link to datasheet is an answer to a question.

People should realize that the majority is not THAT much into Electronics and come here because datasheets makes no sense to most people.

Thank you for your reply, it is still safe if I connect the usb to my computer right with the 12v connected to the arduino mega directly from the psu?

Quote
sarf2k4

Quote
dintid
You Can feed it 12v just fine. I've done it for the last year.

If you fint it gets too hot, you just ADD a fan to it.

Some People are always overcomplicating things and believes anyone actually knows what resistive voldtage dividers are, and also believes a link to datasheet is an answer to a question.

People should realize that the majority is not THAT much into Electronics and come here because datasheets makes no sense to most people.

Thank you for your reply, it is still safe if I connect the usb to my computer right with the 12v connected to the arduino mega directly from the psu?

Yes. You can connect everything at the same time.
I have mine powered from PSU so no need for USB, but I do connect USB when updating firmware or similar and it doesn't disrupt the arduino when plugging in USB

To the Electronics people: I know you think you help, but it's really doing the opposite. Confusing the heck out of the person asking the question by answering in technical terms.
Consider this: If my dad ask why his Wireless doesn't Work, I do not start by linking to or explaining the OSI model

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My Instructables - both total newbie instructables and some for intermediate users.
My Designs on Thingiverse
YouTube channel containing a few 3D printing videos - they are videos for my Instructables, and mostly not standalone.
Ultius / Tantillus Thingiverse Group

Thank you for your reply, now I don't have to wire my arduino to usb chargers, simply from the psu, I guess it was my first post in this thread ".... voltage divider from 12v to 5v..."

One last thing, any specific wire can be used? Thinking of using just a mere 26-24ga solid core wire

Quote
sarf2k4
Thank you for your reply, now I don't have to wire my arduino to usb chargers, simply from the psu, I guess it was my first post in this thread ".... voltage divider from 12v to 5v..."

One last thing, any specific wire can be used? Thinking of using just a mere 26-24ga solid core wire

I just use standard (here in Denmark) 0,75mm2 to 1,5mm2 wire - depending on what I have lying around. The 1,5mm2 is the standard we use for electrical lamps and such.

Wire thickness really doesn't really matter for such short distances, and the Arduino is using pretty much no power at all in regards to need of wire-thickness. The arduino itself use like 0,2amp (somewhere around that figure) - add to it if you power things from Ramps AUX pins (which get 5v from arduino).

I personally do not like solid core for anything but installations.

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My Instructables - both total newbie instructables and some for intermediate users.
My Designs on Thingiverse
YouTube channel containing a few 3D printing videos - they are videos for my Instructables, and mostly not standalone.
Ultius / Tantillus Thingiverse Group

Thank you in advance, so I gonna find mains wire to wire up the arduino mega directly from the psu, cause I have a wire about 0.5mm in diameter lying around, solid core what's more, but I somewhat worried that it might burn

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sarf2k4
Thank you in advance, so I gonna find mains wire to wire up the arduino mega directly from the psu, cause I have a wire about 0.5mm in diameter lying around, solid core what's more, but I somewhat worried that it might burn

Feeding 12V directly to the Arduino is no better than feeding it via the RAMPS. The issue is that Arduino/RAMPS provides insufficient 5V power to drive a servo, or the backlight of a graphical LCD. If you are into electronics, you can fix this by adding an external 5V regulator. If not then I suggest you ditch the ancient RAMPS electronics and get something more modern with fewer drawbacks.

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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].

I tried last night on wiring extra rail directly to my mega 2560, made no difference at all, I guess I just power it up from usb then, I'm using the cheap chinese ch340 ftdi chip type, so far it is okay, no problem arise

If it doesn't work from 12v via the ramps, or 7V or more to the power connector, then the 5v regulator on the mega2560 is already broken. As David said, the mega2560 doesn't have enough 5V capacity to power servos along with everything else. You need to provide a separate 5V supply for the servo power. You're also going to need to fix/replace your mega2560 or continually supply it with 5V via USB or the 5V rail.

Edited 1 time(s). Last edit at 01/23/2016 07:16AM by JamesK.

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dc42

Quote
sarf2k4
Thank you in advance, so I gonna find mains wire to wire up the arduino mega directly from the psu, cause I have a wire about 0.5mm in diameter lying around, solid core what's more, but I somewhat worried that it might burn

Feeding 12V directly to the Arduino is no better than feeding it via the RAMPS. The issue is that Arduino/RAMPS provides insufficient 5V power to drive a servo, or the backlight of a graphical LCD. If you are into electronics, you can fix this by adding an external 5V regulator. If not then I suggest you ditch the ancient RAMPS electronics and get something more modern with fewer drawbacks.

I know, I know, we have had this before but the maturity (lack of) and available STUFF (lack of) for newer, modern controllers are the main drawback.
Most people find it easier to provide 5v seperately to attached STUFF, than being a firmware Ninja and make Said STUFF work on the new controllers.

That said, huge strides have been made. I think I might have seen a new display somewhere? And also Saw budding support for PT100 sensors, so say to go @DC42

Edited 2 time(s). Last edit at 01/30/2016 04:47PM by dintid.

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My Instructables - both total newbie instructables and some for intermediate users.
My Designs on Thingiverse
YouTube channel containing a few 3D printing videos - they are videos for my Instructables, and mostly not standalone.
Ultius / Tantillus Thingiverse Group

Quote
dintid
I know, I know, we have had this before but the maturity (lack of) and available STUFF (lack of) for newer, modern controllers are the main drawback.

Arduino/RAMPS looks very immature in comparison to Duet and Smoothieboard. Nobody should have to contend with inadequate voltage regulators, lack of an easy means to set the stepper motors currents and know what they are, or having to recompile the firmware to reconfigure it. Granted, there are a few more options for connecting stuff in Marlin (if you can get it to compile with support for that stuff enabled), but a lot of it is stuff that is rarely used.

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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].