Hello,
I'm currently trying to familiarize with my 28BYJ-48 motor with my Arduino Uno.
When the motor is plugged into the 5V pin, it perfectly work whereas when it's plugged into the pin 3 and I put this pin HIGH, the motor is too weak to turn.
Is it normal ?
Thank you for your help and sorry for my english, I'm french.
Rémi
Is it normal ?
Yes, but very bad for the Arduino. NEVER try to power a motor or servo from an output pin. You will destroy the pin and/or the Arduino.
Motors and servos should also not be powered by the 5V pin, as it is not designed for such a heavy load. Use a separate motor/servo power supply and connect the grounds (negative leads).
An output pin can be used to switch on a motor power supply using a transistor or a relay, as shown in this diagram.
Any inductive load like a motor, relay, solenoid, etc will kick back large voltages on turning off the
current abrubtly.
You always need to design protection components into any circuit driving such a load, and microcontroller
pins do not have enough protection typically.
Also they cannot supply enough current for a heavy load like a motor.
So directly connecting a motor to Arduino pins is likely to not work at all and to damage the Arduino.
Hi,
Welcome to the forum.
Please read the first post in any forum entitled how to use this forum.
http://forum.arduino.cc/index.php/topic,148850.0.html.
Have you googled 28BYJ-48 Arduino Uno
It is a stepper motor, not a motor.
Can you tell us your electronics, programming, Arduino, hardware experience?
Thanks.. Tom.. 
