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Topic: 12v / 6amps to arduino barrel jack (Read 384 times) previous topic - next topic

SteveMann

Thanks for the  confirmation. Very nice.

The external device That I will be using is a 12v cpu fan. 2-5pcs. of led lights 3v,  i2c lcd and an sd card module.
What is the total current requirement?

KyleFrancis

What is the total current requirement?
Ok this is the part that is confusing to me. I tried to google it and I'am not sure if I understand it correctly.

When you say current are we referring to the total amps?

I'am totally new to this. I don't know how to get the total numbers of current. Unless it is printed on the device itself :(




GaryP

Here's my little advice!

Measure the actual voltage of your power supply. Many times 12V is actually much higher, and that with capable of 6A current is making even more heat on the onboard regulator. Usually power supplies are build to to give more voltage which drops closer to given numbers under load. If the load is not enough, voltage stays high.

I don't know what is the maximum input voltage of your Arduino, but be sure you don't exceed that.

Multimeter is your friend. Measure first, plug in only if not too high voltage. Forget the current.

Cheers,
Kari

Measure...
The only law for me; Ohms Law: U=R*I       P=U*I
Note to self: "Damn! Why don't you just fix it!!!"

6v6gt

#18
Jan 12, 2020, 03:21 pm Last Edit: Jan 12, 2020, 03:24 pm by 6v6gt
To help make the points a bit more concrete, I've tried to draw a schematic based on my interpretation of what you have said.

If the fan has only a small power requirement (mA), this may work.  Does it look like what you want to achieve ?


Click to enlarge, depending on your browser:




KyleFrancis

Here's my little advice!

Measure the actual voltage of your power supply. Many times 12V is actually much higher, and that with capable of 6A current is making even more heat on the onboard regulator. Usually power supplies are build to to give more voltage which drops closer to given numbers under load. If the load is not enough, voltage stays high.

I don't know what is the maximum input voltage of your Arduino, but be sure you don't exceed that.

Multimeter is your friend. Measure first, plug in only if not too high voltage. Forget the current.

Cheers,
Kari

Measure...

Meaning 12V 6a is to much  if there is not much load on the board. Though it may work but it will generate more heat? Since there's so much of an excess current? Am I getting it right? Thank you so much for taking time to :)

KyleFrancis

To help make the points a bit more concrete, I've tried to draw a schematic based on my interpretation of what you have said.

If the fan has only a small power requirement (mA), this may work.  Does it look like what you want to achieve ?


Click to enlarge, depending on your browser:




Thank you so much for the effort. I really appreciate it. The schematic that's almost what want. Except for the vin part. I'm gonna need to borrow your schematic and edit something. Your schematic given me an idea on how the vin pin works :)

6v6gt

The Uno Schematic is here:  https://www.arduino.cc/en/uploads/Main/Arduino_Uno_Rev3-schematic.pdf

Just in case it makes a difference to you, my rough sketch wrongly shows  the input to the 5v regulator direct from the barrel jack (marked X1 in the official schematic - top right section ). The 5v regulator is (also) fed from the Vin pin.




SteveMann

#22
Jan 12, 2020, 11:46 pm Last Edit: Jan 12, 2020, 11:48 pm by SteveMann
Meaning 12V 6a is to much  if there is not much load on the board. Though it may work but it will generate more heat? Since there's so much of an excess current? Am I getting it right? Thank you so much for taking time to :)


There is no "excess current". It doesn't matter if the PSU is rated at 6 Amps or 600 Amps,

THE ARDUINO WILL DRAW ONLY THE CURRENT IT NEEDS!!!!

As long as your power supply can deliver the current needed, then you are OK.  That is why I keep asking what is the total current requirement of your devices.

You are conflating current with voltage.

KyleFrancis



There is no "excess current". It doesn't matter if the PSU is rated at 6 Amps or 600 Amps,

THE ARDUINO WILL DRAW ONLY THE CURRENT IT NEEDS!!!!

As long as your power supply can deliver the current needed, then you are OK.  That is why I keep asking what is the total current requirement of your devices.

You are conflating current with voltage.
Thanks so much Sir. "THE ARDUINO WILL DRAW ONLY THE CURRENT IT NEEDS!!!!" that's very clear.

Thank so much everyone for giving sometime. Got the Arduino running :)

Paul__B

It is often pointed out that my power points for example, are rated 240 V, 10 A which is 2.4 kW.  But when I plug in my 3 W Aldi lamp, it does not turn into a room heater because the power point has that rating.  :smiley-eek:  It actually draws - about - 15 mA (RMS AC, allowing for losses).

And you should not use the "Barrel jack" or "Vin" if you propose to connect anything other than two or three indicator LEDs drawing 15 mA apiece, to the Arduino.

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