-1
\$\begingroup\$

wiring diagram

I understand that the circuit above will simply work, but what if the voltage input from the battery is significantly higher and the necessary voltage for the motor is high as well? Can you still connect the pins directly by soldering if it is not practical to connect everything by a breadboard?

I understand that the transistors have a voltage rating. It just doesn't seem practical to connect the transistors directly to their correlating wires.

\$\endgroup\$
  • \$\begingroup\$ Like how high voltage? And what amperage rating on the motor? \$\endgroup\$ – zeta-band Jun 11 at 19:47
  • \$\begingroup\$ You are using an N-Channel FET as a high-side switch. This will give you additional problems. Put the motor between drain and battery plus instead. \$\endgroup\$ – Janka Jun 11 at 19:51
  • \$\begingroup\$ Also, learn to draw proper schematics. It will help you and others understand the problem much better and quicker. \$\endgroup\$ – Janka Jun 11 at 19:54
  • \$\begingroup\$ @Janka , thanks for the help .The schematic isnt mine and i realised after that it didnt make sense. \$\endgroup\$ – Hamza Arshad Jun 11 at 22:19
  • \$\begingroup\$ The circuit will perform very poorly. The Pot will do nothing until the voltage on the Gate reaches VGS(th) which could be anything from 2-4V, the Pot will then result in voltage applied to the motor, up to the battery voltage minus approx. VGS((th). Lookup Source Follower to understand the operation. \$\endgroup\$ – Jack Creasey Jun 11 at 23:18
1
\$\begingroup\$

Read the datasheet of your MOSFET. Maximum Vds will be specified.

In the case of IRF540, the limit is 100 V

enter image description here

In this circuit you should also consider that the motor itself will produce a voltage when you try to turn it off. You can search for "flyback protection" circuits on this site or elsewhere to see examples of how to avoid this damaging your MOSFET.

but what if the voltage input from the battery is significantly higher and the necessary voltage for the motor is high as well?

In this circuit, that will mean the MOSFET must dissipate substantial heat. You'll need to determine the power consumed by the MOSFET, and then choose a MOSFET in an appropriate package and a heatsink that can dissipate the heat without your FET temperature rising above the rated value.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.