PROBLEM Mosfet/Transistor

Hi ! I start to electronics with arduino and i try to make a project: a car (IR) wich turn with a servomotor and move with a dc motor, so I have to use mosfet with an external electric source: 6 batteries in series(9V entire) to move the car that’s my code and my mounting.
The problem is that when I apply “HIGH” to mosfet ’ gate, it closed drain/source but the voltage transfer is very low compare to 9V waiting, I mean the motor don’t receive 9V but ~1V
It has been for 4 days i search why and i don’t understand very well how function precisely a mosfet/transistor so if anyone can answer my question and help me to solve the problem I will be happy.

RaceCarOne_script.ino (1.29 KB)

What Arduino and what MOSFET are you using? You really need a Logic Level MOSFET. Many others will not turn on fully with only 5V on the gate and hardly any work well with only 3.3V.


Oh, I use the IRF520 mosfet wich is include in the Arduino Starter Kit Multi Language and therefore the arduino uno, the mosfet is n channel but I’m not able to understand the datasheet and all of infos to know the Vmax and Vmin, etcc…
Thank you to answered !


How "big" is the motor? If you apply 5V to IRF520 gate, the maximum current @9V is approximately 1A. Is this enough? You can try a direct connection between the motor and the battery with you multimeter set on current measurements to see what the motor could adsorb @9V. Do you have, maybe, a transistor? You could use it to apply the 9V at the mosfet gate, so you'll have more than 10A (and in this case i guess that the battery will be the bottleneck).

The IRF520 needs at least 10V gate drive, its not logic level and has absolutely no place in an Arduino starter kit. Its also about the most hopeless MOSFET available, no doubt whoever put the kit together got them

But lets start at the basics - what is this motor? What is its stall current? Without knowing that
its impossible to judge what device is needed and what power supply is needed. It might
be a very high current motor for all we know, and that matters.