UNO board - external 12v OR on board VIN 12v

Hi gang, may sound like a stupid question, In my research on connecting stepper motors to my UNO board via a stepper driver, some of the diagrams posted on the net, I have seen, show the 12v power connected to the VMOT/GRD pins of the driver board, directly to an exterior 12v power supply with a 47µF resistor bridged between them.
But I see that you can obtain 12v via the VIN/GRD pins if you have a 12v power supply connected in the DC power jack on the uno board.
What is the best / safest way of doing this ??????
Ta mucly

Not exactly following you but for the stepper use the external power supply. You can also use the same 12V power supply to power the Vin of the Arduino. The best thing is not to conduct any of the stepper power through the Arduino in any way. Be sure the grounds are connected, best at power supply.

zzrblokey:
But I see that you can obtain 12v via the VIN/GRD pins if you have a 12v power supply connected in the DC power jack on the uno board.

Under no circumstances should you draw the motor power through the Arduino board. The PCB traces are designed for currents of a few milliamps - not the sort of current that a motor requires.

And note that the pin is labelled VIN not VOUT

...R

Thanks Robin2, but you have miss read my post,

"I have seen, showing the 12v power connected to the VMOT/GRD pins of the driver board"

I will as advised power via a external 12v.

zzrblokey:
Thanks Robin2, but you have miss read my post,

"I have seen, showing the 12v power connected to the VMOT/GRD pins of the driver board"

These are the words that caught my eye

But I see that you can obtain 12v via the VIN/GRD pins if you have a 12v power supply connected in the DC power jack on the uno board.

That still reads to me as if power would be supplied to the DC power jack and taken from the VIN pin

However I note that that is not what you intended to say.

...R

There is a reverse polarity prevention diode between the barrel jack and VIN pin that will drop 0.6 volts from your supply AND is only rated 1 Amp, bad idea. As @Robin2 said, it's a VIN pin.

If you connect 12V to the barrel jack the current that the 5V regulator can supply is limited to about 150 mA. The Uno uses about 50mA of that leaving around 100mA for peripherals. You need to take care not to draw too much more from the regulator. A better way to power the Uno is a 12V to 5V switch mode converter connected to the 5V pin. That will bypass the (weak) 5V regulator.

So to sum this up, for those of us that are mentally challenged, in your world of electronics and programming.

Powering the VMOT/GRD on the stepper drivers, to power the step/motor, with an external 12v source = "GOOD"

Powering up the DC jack and trying to draw 12v from the UNO VIN/GRD to do the same thing above = "VERY BAD"

Got it. many thanks

1 Like