From obxwindsurf@yahoo.com Fri Oct 03 07:49:59 2003
Subject:Re: Vibrato

Dave,

Thanks for the info. I wondered about bleedthrough from the digital
to the analog side. I'm sure that this is a result of the switching
mechanisms inside the digipots being similar to analog switches.

I have found an article at: http://www.e-
insite.net/ednmag/archives/1998/031398/06di.pdf

describing a digital potentiometer design using micro relays and
resistors. (the resistor values table is incorrect and should be
reversed). But this achieves excellent isolation between digital and
analog side due to relays being used.

The only question which must be determined experimentally is: at the
speed at which the resistors need to be switched in and out are the
relays fast enough (412 equivalent scanner rotations per minute), and
do they settle quickly enough before the affected phase shifter needs
to be brought back online.

Thanks for sharing your experiences with a switched resistor phase
shifter network. It has saved significant time in conceiving an
alternate design.

Regards,
Kevin

> > V5.
> > >
> > > Enjoy,
> > >
> > > /Dave