2
\$\begingroup\$

I'm trying to wire a 12v DC motor to a DPDT switch so I can control the spin direction (by inverting the polarity) it uses two digital pins, one of them to set the direction of the motor and another one to actually enable or disable the current flow to the motor. The design I came up is this one:

enter image description here

I'm not sure if the relay is wired correctly to achieve the desired functionality

\$\endgroup\$
  • \$\begingroup\$ You have no voltage source for the relay coil currently. \$\endgroup\$ – glen_geek Jun 29 at 23:08
  • \$\begingroup\$ Ups, you are right, updated the schematic with voltage source for the relay coil \$\endgroup\$ – Marc Jun 29 at 23:42
1
\$\begingroup\$

Unless you want possible excessive contact arcing on your relay I'd put diodes on like below: -

enter image description here

Of course, if you adopt the reasonable approach to deactivate the MOSFET first then you don't need them in ideal circumstances.

Due to stored mechanical energy in the motor, the catch diode on the MOSFET may dump excessive motor energy onto the 12 volt rail and you should have some form of over-voltage prevention scheme here like a big bulk capacitor to soak up excessive energy dumps on the rail or maybe a zener diode or some form of braking resistor. You don't want your 12 volt rail being driven upwards I would have thought.

| improve this answer | |
\$\endgroup\$
3
\$\begingroup\$

Looks okay. Of course you should turn off the current and wait until the motor is stopped before changing the relay state.

| improve this answer | |
\$\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.