12v into the Arduino UNO R3, USB port

Official Hardware UNO Family UNO R3
1

Is it safe to supply Arduino power with 12v through USB-B port?

2

No.

3

Hi @rafa-akbar. You can use the barrel jack for that purpose.

4

Okay, thanks for the reply.

5

I had a 12v fan for my arduino project and i want to use only 1 adaptor, and my fan using an 5v to 12v step up. So, my Arduino will be using the 5v to 12v, or just the regular usb to jack (5v), or just usb-a to usb-b. Sorry for my bad english

6

You might use 12V for power with a step-down converter to 7V to feed the barrel jack and make less heat. Some Arduinos won't let you power them 5V to the 5V pin.

Why is to not power the fan through the Arduino at all but turn the fan on/off through a FET (field effect transistor) connected to a pin or just fan always on with 12V.

The hardware gurus here know more than I do about this.

7

This might help:
Gil's Crispy Critter Rules for Processor Hardware:

  1. Rule #1: An Arduino is NOT a Power Supply!
  2. Rule #2: Never connect anything inductive (motors, speakers) directly to an Arduino!
  3. Rule #3: Avoid connecting or disconnecting wires while the power is on.
  4. Rule #4: Do not apply power to any pin unless you are certain of what you're doing.
  5. Rule #5: Do not exceed the maximum voltage ratings.
  6. Rule #6: Many Arduinos cannot power transmitters directly.
  7. Rule #7: Before powering your project, take a break and double-check the wiring.

LaryD’s Corollaries:

  1. Coro #1: When starting out, add a 220Ω resistor in series with both input and output pins to protect against shorts.
  2. Coro #2: Invest in a Digital Multi-Meter (DMM) to measure voltages, currents, and resistance.

Note: Violating these rules can turn your Arduinos into crispy critters. For optimal performance, keep your wires under 25 cm (10 inches).

Additional Tips:

  • The L293 motor driver, though common, is inefficient as it can lose around 3V as heat when driving both legs of a motor. Consider using a motor driver with MOSFET outputs to reduce heat loss and conserve battery power.
  • For more on powering Arduino boards, explore this guide: Powering Alternatives for Arduino Boards.
8

Do you understand what to do?

9

Hi better use USB-B Port to develop code and If u want to test voltage 12 volt to arduino is not "really good" bcz usally it´s use to work to 5V.

Also If u use a battery try to use the battery-port i think that it has a voltage regulator