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Topic: Mega Power source (Read 3938 times) previous topic - next topic


Yes we know that, but have not received an explanation from the arduino designers on why that explicitly recommend not to power the board via the 5V pin. Do you know why they added the caution?

Probably because one time or another people forgets it's the 5V pin and applies more than 5V and destroy the board....

The datasheet for the Regulator on the UNO says this:

So it's only a possible problem if you power it from the 5V pin and Crowbar the input pin of the Vreg - You cannot crowbar the 'Duino from the DC-jack since a diode is wired in series with the input.

// Per.


Probably because one time or another people forgets it's the 5V pin and applies more than 5V and destroy the board....

Ok, we will put you down for that guess.



Jan 06, 2013, 07:44 pm Last Edit: Jan 06, 2013, 08:28 pm by Jantje Reason: 1
I used to power the Arduino on the 5 volt pin. I strongly advice against doing so now.
First of All I did have problems. I guess they were engine related which drove the voltage up but I never had a decent explanation.
More importantly though
If you supply power on the 5 volt and you plug in the USB or power the jack you (can?) get into problems.
That is why I advice to power with a modified USB cable. This way you have to remove the USB power plug to plug your USB cable in.

... or better use a switching regulator and power with a modified USB cable. The last option will make your solution run 2 times longer.

It costs an USB cable but it can save your arduino and your shields. So I think it is worth it.

Best regards
Do not PM me a question unless you are prepared to pay for consultancy.
Nederlandse sectie - http://arduino.cc/forum/index.php/board,77.0.html -


Thanks guys! Plenty of good ideas :)
Actually I have a few Esc's with built-in bec's spares from my planes and helis, so atm it could be the easiest solution.
However, since i    have few of Those batteries, (just found also one 6v like that) then external power connector will be my power delivery method atm.and with this, another question, im assuming that I'm safe to supply my mega with external power through the jack (either from my battery of wall-wart power adapter) and having usb from pc connected to it? (Im an user of ardupilot based on mega, and there were some issues with that if i remember correctly - also ardupilo was a reason for me diving deeper into arduino,did not wanted to be a user only.)

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