Hello, I am a beginner experimenting with Arduinos and have just made a DC motor speed controller with a MOSFET and saw a video from Great Scott! about using MOSFETs with Arduinos and how switching a MOSFET on and off can cause a current spike higher than the digital pin of my controller is rated for. I don't want to mess up my board as I just got it. I read some other forums about putting a resistor in series between the gate and the pin so I did that. I made a schematic on how I made my circuit below. Can someone explain why MOSFETs have such high current spikes and if what I did is enough to protect my arduino? Thanks!
Inductive loads, like motors, produce high voltage spikes which can kill many electronic parts all around. Place a freewheel diode over the load to kill such spikes, cathode to battery +.
It might work but it is not the best. Always put the pull down resistor on the port pin. Putting on the gate as you show it forms a voltage divider decreasing the drive to the MOSFET. If you look at the Vgs curve you will see that the voltage drooped by the divider will have a big impact on the MOSFETs capacity.
You picked a good part and you are correct it is an avalanche rated device so yo do not need a fly back diode.
Needed to prevent noise on other circuit components in the project.
You can add it but the MOSFET will quench the fly back as it generally turns on at a lower voltage depending on the diode.
It depends on the output protection of the PSU, whether it will allow current to flow also in instead of only out.
If I am not mistaken, optocoupler provides isolation in these circuits, it is safer.
If you are using a powerful mosfet to drive another transistor solid state junction mosfet, always use a circuit to turn on the switch. promise. hold the fire with tongs
small powers trigger big powers
THX @jim-p correct and correct. I was getting motion sickness trying to rectify the OP's schematic.
a7
I didn't realize that I had drawn the Mosfet as a p channel. There are many applications that are the opposite of this.
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