>
> Hello guys
> I have a strange problem when trying to use the attached circuit as a
> small forward-only driver for a DC motor. The Mosfet is an IRF 540 and
> the PIC is 18F452. The pin RC2 in set as output from TRISC and i made
> a small program in C18 to issue a "zero-logic" for one second and then
> "one-logic" (+5v) for another second and so on.
> My problem is that the motor starts turning when the 1 is issued on
> RC2 but instead of stopping when i issue 0 it just turns a bit
> slowly... After 1 second the 1 is sent again on RC2 and the motor
> turns again fast.
> Can you guys help me with a suggestion ? What should i do ?

Hi Dumitru,

You have the source and drain reversed on the mosfet.

BTW, although the IRF540 has a fairly high breakdown voltage, it's good
practice to use a freewheel diode across the motor.

Another thing, the IRF540 is not a logic-level mosfet, so you will not be
getting full turn-on.

Cheerful regards,

Bob


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