Hello,
On a project that i'm working on, we use an Arduino Mega with an ethernet shield. The all pilots a qrcode reader, RFID reader and a relay.
All components combined consumes 800 mA.
We tried to supply the Arduino Mega from the jack input using following power supplies: 9V 1.5A /12V 1.5A/ 12V 2A/ 9V 3A. Neither of those works.
Can you suggest me a suitable power supply for my system to work properly.
I tried from USB input it works perfectly, but i want a solution to power it from the jack input.
Thank you.
Don't.
Better take one of your other power supplies and get a buck DC-DC converter for it that makes 5V from our 9 or 12V. Then put that 5V directly to the 5V pin of your Arduino and to any other components that use 5V.
The onboard regulator that makes 5V from whatever you input on the barrel jack will NOT be able to handle your 800mA current requirement. If you feed it 9V, it will dissipate 9V-5V=4V*0.8A=3.2W which is WAAAAAAYYYY more than it can handle. So your requirement of powering this project through the barrel jack is technically impossible and will damage your board.
Only regulated 6.5volt on the DC socket could work, sort off, short time.
A higher voltage that that would put too much thermal strain on the 5volt regulator,
and you will be rewarded with periodic shutdowns/resets.
USB supply does not use the 5volt regulator, but it has a 500mA fuse inline,
so trying to draw 800 mA will also lead to problems.
You could power the Mega with a 5volt cellphone charger connected to the USB socket.
But you should power the relay module and maybe the QR code reader from a separate supply.
Post links to all components and a diagram if you want more help.
Leo..
Thank you for you reponse here is the diagram of the system.
Yeah, so like I said, just apply 5V from an external power supply to the red +5V line on your schematic. That'll work and it'll be by far the best (and practically, only) solution. Good luck.
Ok, i will try this solution, thank you so much for your help.
I have found a power supply of 6V 1.5A, i tried it but plug it throw the jack, for the moment it seems to work fine, i will update later the final result.
Uhm, ok...but why?
It's 6V, so too low for the jack, plus you still dissipate loads of power through the onboard regulator.
It's V, so too high for connecting to 5V line directly.
In short, it's just about the most inappropriate thing you could have tried.
Just get a DC-DC converter that gives 5V out and use one of your 9V or 12V supplies.
Anyway, third time I said it, now it's up to you to actually listen & comprehend.
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