I'm trying to start working with this customer and want to solve some of
their problems. The reduced ripple is to avoid motor hum.

I'm not familiar with your suggestion on using the FETs, do you have a
source I can look up?

I think I don't have much more details. The basic idea is to have the ps
with the mentioned ripple to avoid motor hum (which the user can hear).
That's the main thing. All of the above must be done considering the space
constraint.

Regards,

> -----Original Message-----
> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On
> Behalf Of Apptech
> Sent: Thursday, January 31, 2008 10:04
> To: Microcontroller discussion list - Public.
> Subject: Re: [EE] Cheap power supply
> 
> > The LV supply is relatively easy to solve. The problem is
> > the HV supply with
> > the high current requirements and the required ripple.
> > What I'm trying to
> > avoid somehow is the large capacitor.
> 
> You are liable to run into regulatory issues with power
> factor and more. Why do you WANT to reduce the ripple? What
> is it doing that is bad (eg motor hum or vibration or ...?)
> 
> Ideally you need to give us as complete as a description as
> possible (and possibly some money from the 360,000 pa sales
> :-) ) for us to be useful.
> 
> A "preregulator" would probably help -  either a Triac or
> SCR or a FET in a bridge. The latter is very controllable.
> Power factor wise "lumpy DC" at 2 x mains frequency may be
> best. What does this do to your motor?
> 
> More details may lead to better solutions. And may not :-)
> 
> 
>         Russell
> 
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