Hi. Total newb here. I want to power my Uno with a 12V power supply as that's what is need for the DC motor I am connecting. I read this on the net:
Another important thing to note is Vin pin is directly connected to on board voltage regulators which means Vin pin has no reverse polarity protection for current, as it bypasses the diode circuit attached with DC barrel jack. While connecting Arduino through Vin pin wires polarity must be taken into consideration otherwise a single wrong connection can burn the Arduino board.
How can I connect anything wrong as I understand all I am doing is connecting the red (+) wire from my 12V power supply to the Vin? I must be missing something here. How can there be polarity in a single wire?
You must also connect the ground from the power supply to the
Arduino ground. Connecting only the positive 12V wire only will not work.
What is going to be powered by the Arduino 5V?
Be careful when using the power plug or Vin. Powering through Vin or the power jack means that the Arduino and all peripherals that are on the 5V rail are powered by the onboard 5V regulator. The on board 5V regulator is not heat sinked so will supply limited current before it overheats and shuts down. Keep the total power dissipated by the on board regulator to less than 1W to avoid overheating. The amount of current depends on the voltage input to Vin or the power jack. The higher the voltage the less current can be supplied. I would use a buck converter to drop the higher voltage to 5V and connect that to the 5V on the Arduino, bypassing the, weak, 5V regulator if the 5V rail needs to provide much current. Then the rated current of the DC DC converter is available on the 5V line.
I want to use a 12V DC power supply to power a 12V DC motor that draws 300mA and am using a L293D in between. I can't plug the power supply into the barrel jack as it doesn't have that kind of connector.
OK, but if you use Vin you still have to connect the ground from the 12V supply if you want to power the Arduino with +12V into Vin.
I ask again, what is being powered by the Arduino 5V regulator?
Do you understand that the current available to any peripherals connected to the 5V regulator output is very limited when using 12V into Vin? Do you understand why?
Only a single 12V motor is getting powered but through a L293D so the 12V will power it directly. Arduino is just running the program. I am going to download Fritzing and post the schematic.
I use L298D for my toy car, and its has a 5V output.
So my main power (2 Li Ion battery for like 7V in output) is connected directly to the L298D input, and it powers the motor in 12V as powers the board in 5V.
If I am right, there is a jumper on the module to activate or not the 5V output (not to be done if the module is power with 12V according to datasheet).
So for my point of view, you already have everything needed for a clean and functionnal configuration.
EDIT: hmmm. looks like I made a mistake with the module, so for things to be clear here is what I make reference of
Because the Arduino needs to get powered too and I thought I could do it from the 12V power supply too as indicated using the VIN port by splitting the 12V cable to it.
Your question has been answered already. Connect positive to Vin, negative to GND. I highly suggest you also take the advice of using a buck converter. And anything with wires can be fitted with a barrel jack, they cost pennies on amazon
The question I asked was how to connect the 12V power supply to the VIN and what polarity in THAT situation means, not with respect to the barrel jack. Since there is apparently a way to do it using the VIN that is what I want to do. I know one can buy a barrel jack and connect it to the power but I don't want to do that and should not have to if using the VIN is possible.
If someone can answer the question that I actually posed I would really appreciate it.
It's hardly that. Sorry you feel that way. I'm a newbie. Please have some understanding instead of making such insulting comments. You were one too in the beginning and I don't think you would like people calling you a troll.
I'm an Arduino newbie too but I do have 40 years of electrical and electronic engineering experience. So, if I may, my understanding is, and I'm sure someone will correct me if this is not the case with an Arduino, the barrel jack is the Vin so you can connect your 12V to either. If you use the barrel jack you will connect a positive and negative as expected. If you take a 12V positive to the Arduino Vin connection you will also need to connect a negative from your 12V source to the an Arduino Ground pin. This is the reason polarity was mentioned. If you don't link the ground of the source, the ground of the Arduino and the ground of the motor then you will have problems.
Power supply positive (+) to Vin.
Power supply negative (-) to ground.
Does this make sense?
The power jack has a diode in series between the jack and the input of the 5V regulator so reverse connection will not kill the regulator. There is no diode between the Vin pin and the input to the regulator so connecting ground (-) to Vin and 12V to ground will destroy the regulator so polarity is very important in that case.
That is why it is recommended for a new user to use the power jack. There is reverse polarity protection.
And yet you haven't provided any information about this power supply you want to plug in other than that it's 12 volts, not a part number, not a data sheet, not what kind of connector it has, not a photo, nothing. This is how trolls act.
I didn't know that the type of power supply was required. If I did I would have provided that information, right? You are also the first person that asked. I am not a troll but am a newbie so please stop with that, ok? It's not very nice accusing people that just want to learn with insults like that.
My power supply is a Eventek 5-35V power supply that I can run at 12V. It has 2 wires: red (+) and black (-).
