>-----Original Message-----
>From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] 
>Sent: 12 April 2006 16:29
>To: piclist@mit.edu
>Subject: [EE] Mosfet driver
>
>
>
>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 ?
>
>Dumitru Stama
>

You have wired up the MOSFET backwards.  Have a look at the diode symbol within the MOSFET symbol, as shown it will be forwards biased (and therefore conducting) when the MOSFET is switched off.  Swap the Drain and Source connections.

Regards

Mike

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