SERIES BUCKING was Re: Correct or Max voltage for Bridgeport Nema 42

Hi Alan,
I've come around to your thinking on the series-bucking connection
to simplify the setup. The regulators work, but its not
a simple setup. I found a good 2KVA autotransformer with a 240/208
or 120/104 ratio that is perfect. Later I played with the contol
transformers that I removed and have found that by seperating the
mirrored cores and removing the outer control winding( common around
both cores), there's plenty of room to add 20-30 turns of heavy
secondary windings. This makes possible
to get 2 usable autotransformers from one of these SeriesII control
transformers. This may be a good trick for people with these seriesII
supplies laying around. The power transformers are overbuilt and
heavy wound, so Just run them at 110vac (vs 220) and make take
2 of the control transformers and wire them as mentioned.

Picture of the control transformers:
http://www.users.qwest.net/~indigo_red/files/xfer/bptransCtrl.jpg

-Lee

--- In CAD_CAM_EDM_DRO@y..., "studleylee" <indigo_red@q...> wrote:
> Hi Matt,
> I've got the origianl SeriesII triple set of transformers, of which
I
> removed the control transformers. This leaves the 3 supplies main
> tranformers,bridges,caps. I'm running those at 110 volts (vs th e
> original 220) which gives about 88vdc each. Then I went nuts and
> made 3 regulators which can span about 20V at 10amps and can be
> adjusted, to create the final 75vdc. The regulators have current
and
> device SOA protection that trips a master supply relay when
exceeded.
>
> Alan Marconett KM6VV proposed a neat simpler alternative:
> >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
>
>
> --- In CAD_CAM_EDM_DRO@y..., "Matthew King" <mattking@k...> wrote:
> > What sort of power supply are you using? A pre-built 75vdc
supply?
> Or did
> > you build your own?
> >
> > Thanks,
> >
> > Matt
> >
> > -----Original Message-----
> > From: studleylee <indigo_red@q...>
> > To: CAD_CAM_EDM_DRO@y... <CAD_CAM_EDM_DRO@y...>
> > Date: Monday, February 11, 2002 11:09 PM
> > Subject: [CAD_CAM_EDM_DRO] Re: Correct or Max voltage for
> Bridgeport Nema
> > 42? + mo...
> >
>