Re: PWM and dither

In article <vr0Bj.4811$e52.3303@trndny01>, Martin Riddle says...

"Pasquale" <desmomito@xxxxxxxxxxxx> wrote in message news:47d48b6a$0$16039$5fc30a8@xxxxxxxxxxxxxxxxxx
Hi,
I need to control a solenoid valve using PWM but I have also some
specifications about "the dither" in order to reduce friction etc.. I now
what the dither is able to do in theory. I now how to built an electronic
circuit concerning PWM (I'd do that using a micro plus a MOSFET etc.) but
I don't have any idea about "the dither". Should I sum another PWM with
lower frequency to the higher frequency PWM which control the valve
position ? Do you have any example or links in order to clarify this
aspect ?

Thank you in advance,
Pasquale

A 'dither' technique typically increases the PWM reolution by one or two bits depending upon your tolerance for dither
ripple.

I think he's suggesting an actual dithering of the valve position. IE
the valve actually vibrates around its setpoint. Possibly to overcome
stiction?

Robert

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