"Powering things with Arduino"

You get everywhere the advice not to power things with Arduino. But there's the pin named VIN. This is direct connected to the barrel connector. So if I connect say 7.5 V 2 A power through the barrel connector of an Arduino Uno, I can use the VIN pin to power some servos, as long as there is power for the Arduino itself, right? This would not be "powering with Arduino", though I'd use the VIN pin, right?

What you describe would not be wise because the tiny metal traces on the Arduino board are not designed for carrying heavy currents.

Just connect your power supply directly to your Arduino and to your servos without going through the Arduino.

Is it safe to use 7.5v with the servos you have?

...R

For the servos, 7.5 V might be a bit too much, yes. But when there's a barrel connector and there's a VIN pin and they have direct connection, I assume that the VIN pin could be used for using the power connected through the barrel connector for external things. Of course, too many amps and something would get hot, but that something is just the tiny metal traces. And the VIN pin. No electronic components. And when getting too hot, damage happens not only to the VIN pin metal traces, but to things nearby.

Johan_Ha:
And when getting too hot, damage happens not only to the VIN pin metal traces, but to things nearby.

Feel free to experiment. You won't be damaging any of my Arduinos :slight_smile:

...R

If you have a power supply adequate for the Arduino and some other component it's perfectly reasonable to split that supply to the two things. Personally I'd think it really odd to use an Arduino PCB as a splitter rather than the more obvious bit of wire but you may see things differently.

Steve

Johan_Ha:
You get everywhere the advice not to power things with Arduino. But there's the pin named VIN. This is direct connected to the barrel connector. So if I connect say 7.5 V 2 A power through the barrel connector of an Arduino Uno, I can use the VIN pin to power some servos, as long as there is power for the Arduino itself, right? This would not be "powering with Arduino", though I'd use the VIN pin, right?

The concept, as presented by you, is sound but do some thinking about the whole idea. besides what has already been posted, have you thought about putting an inductive load onto your Arduino's VIN line? Have you given thought to the back-emf and the affect on the Arduino electronics? If you have and feel the risk is worth it, Arduino will appreciate repeat business, go for it.

slipstick:
If you have a power supply adequate for the Arduino and some other component it's perfectly reasonable to split that supply to the two things.

If I have a 5 V power bank (those used for cell phones) which provides 2 A, would this be considered a regulated voltage suitable for the 5 V pin for powering the Arduino? If I use the same power bank for the servos, too, could the servos cause harm through the 5 V pin?

Johan_Ha:
If I have a 5 V power bank (those used for cell phones) which provides 2 A, would this be considered a regulated voltage suitable for the 5 V pin for powering the Arduino? If I use the same power bank for the servos, too, could the servos cause harm through the 5 V pin?

That should work fine.

...R

Johan_Ha:
You get everywhere the advice not to power things with Arduino. But there’s the pin named VIN. This is direct connected to the barrel connector. So if I connect say 7.5 V 2 A power through the barrel connector of an Arduino Uno, I can use the VIN pin to power some servos, as long as there is power for the Arduino itself, right? This would not be “powering with Arduino”, though I’d use the VIN pin, right?

The voltage at VIN will not be the same as on the barrel jack. There an M7 diode between the two to prevent reverse polarity damage. It is a 1 amp diode so there is that limit and since it is a silicon rectifier diode, there will be a 0.7 volt drop across the diode.

The bottom line is that the VIN terminal is there to put voltage into, not pull it out.