PHXSYS wrote:
>
> Hello
>
> I have an application where I want to PWM a FET to drive a gauge. Is there any
> rule for the frequency PWM should be applied. I don't want to dedicate my
> 16F84 to a PWM task. Can I run at i.e. 50HZ and complete other tasks in
> between, kind of like a R/C servo? I suppose it really depends on the
> characteristics of the driven device, but I am looking for some general rules.
>
> Thanks
>
> Jon

Fuel guage example:
turn the ignition on and time full scale deflection(if tank full of
fuel). divide this time by minimum of 20 and PWM at this period or
smaller

many car guages use bimetalic strips with nicrome heater winding,
thermal inertia of this would take next to zero time overhead for a PIC

regards,
Graham Daniel.