So I have an arduino driving a motor by switching a mosfet.the problem is the motor is severely weaker when I switch it with a lower voltage. Say I switched the mosfet with a 9v battery I get more amperage to the motor and more torque. The motor and battery are about 9v and arduino is 5v. I need help designing a circuit to switch the n type mosfet with the voltage from the battery to conserve the torque while still controlling it from arduino

 

Please post your circuit so we can see it.

 

Guessing ahead, use a logic-level MOSFET. A normal MOSFET won't turn full on with just 5V on the gate.

A schematic eliminates guessing.

 

There are hundreds of modern logic-level FETs which will turn on hard with only 3.3V on their gates... You must be using something like an old IRF530...

 

Actually I'm using an irf520 but I think your right do you have any suggestions for mosfets that are easily arduino compatible and at least 25v switching. If possible name something off mcm electronics because it's local and I can pick it up

 

Actually I'm using an irf520 but I think your right do you have any suggestions for mosfets that are easily arduino compatible and at least 25v switching. If possible name something off mcm electronics because it's local and I can pick it up

There are >425 through-hole NFETS which can be turned on with 5V with a Vds>=25V in stock at Digikey.

I'll let you figure out which ones you can buy locally. Have fun!