SERIES BUCKING was Re: SeriesII Gecko210 voltage people use

Hi Alan
Have use Variacs many times and understand what you mean but what do
you do with the primary of the "bucking" transformer to control the
output of the main transformer?

Many thanks, Paul

-- In CAD_CAM_EDM_DRO@y..., Alan Marconett KM6VV <KM6VV@a...> wrote:

> Hi Lee,
>
> Yes, 88V is a little high. What you can do is find a 12V (or as
> desired) filament transformer with a secondary current the same or
> greater then the PRIMARY current needed by your transformer.

Connect it

> in SERIES BUCKING, and you can drop the resultant secondary voltage

as

> required. This sounds similar to what your "control transformers"

might

> have been doing! But simpler, smaller!
>
> Kinda like a "fixed" VARIAC!
>
> HTH
>
> Alan KM6VV
>
>
> studleylee wrote:
> >
> > Hi Alan,
> > My DC supplies are 88vdc or so, which is alittle high for the

G210's

> > They are the original seriesII supplies (x3)run from 110vac vs the
> > 220vac. Basically just a big transformer, bridge rect. and cap.
> > This yields a healthy 88vdc output ( down from the original

unipolar

> > bi-level drive of 160vdc/12vdc ).
> >
> > I removed the original primary-side 'control' transformers which
> > controlled the primary drive to the output transformer. These

control

> > transformers acted as a 'variac'-like element to drop the voltage
> > after the stepper coils slewed up to 10amps or so. Then the

voltage

> > was dropped to a holding level about 12vdc. This was the circa

1978

> > way of increasing speed. Its funny how convoluted the original
> > controls look at 1st, then after dissection, how simple
> > it really was.
> >
> > Right now the variac is to bring the primary side down to 100vac

or so

> > to get the output side to a more usable voltage.
> > -Lee
> >
> > --- In CAD_CAM_EDM_DRO@y..., Alan Marconett KM6VV <KM6VV@a...>

wrote:

> > > Hi Lee,
> > >
> > > You don't need to regulate the motor voltage, just rectify and
> > filter
> > > it! And please use ISOLATION (a transformer)!
> > >
> > > Alan KM6VV
> > >
> > > studleylee wrote:
> > > >
> > > > Thanks Tim and Peter.
> > > > I'm working on a big regulator to use on my supplies
> > > > vs. the variac I'm currently using to bring the mains down so
> > that my
> > > > vdc out doesnt exceed 70vdc.
> > > > -Lee
> >
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