ok..
The motor that i am using does resonate at a particular freq frequency
so do you have any doc that is related to this??
the driver circuit i have produce a proportaional output voltage when the
motor is not connect but when i connect the motor, the output voltage remain
the same for several duty cycle. the different is very littlr about 1 volt
does this have some thing to do with the frequency that i am using??
thanks

regards
----- Original Message -----
From: Jinx <joecolquitt@CLEAR.NET.NZ>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Wednesday, November 24, 1999 8:03 PM
Subject: Re: Torque control


> From: soon lee <psln@CYBERWAY.COM.SG>
>
> > Hi    guys
> > got a question here
> > is there a standard for the value of PWM frequency for motors and how
you
> > determind it??
> >
> > thanks
> > regards
>
> I'm not too sure, but one factor to consider is the audible noise that
> comes from motor at the freq you drive the PWM at. Does a motor
> resonate at a particular freq, like a speaker ? If so, is this affected
> by the number of poles, or whether a motor is electro- or permanent
> magnet type ?
>
> I noted Russell McMahon's comments about the rotor losing touch
> with the magnetic fields as the frequency is increased. This would
> seem to imply that there's an optimum range of driving conditions.
>
> Jinx