Re: twin transformer ?

Thank you guys,

I see there is a consensus that the dual set-up is constant voltage.
ROLM corp being involved with telecommunications, I can see the need
for such a device, I have never experianced the phone going dim when
the power dips.

Since I only need to run about 8 gecko's (not all at the same time) I
hope the other will offer me the power I am looking for.

Ray, I measured the steel and 6 3/8" 5 1/4" x 2" that is the
physical dimmentions of the laminations outside, the inside is one
inch less per side or 4.375 x 3.25. The core is wrapped in paper so
I have no idea of the number of wraps. I'm hoping the low voltage
test will give me voltage and ratios. I am anticipating it is
designed for either 220 or 110 as all the electrics were standard
commercial connectors.

Regarding the Ohmite brand resistor, it is clealy labeled 100ohm, I
will have to measure the resistance. 100K as a bleed for the cap
makes a lot more sense.

As for testing the voltages. I plan on baby steps.
check resistances on all leads to see what connects to what.
power a set with 24 vac from a wall transformer and record all the
readings. Then figure out the ratio's, then apply 110 vac to the
ones that will offer me the output in the range I hope to wind up
with. It's those muscle twitches that I get after touching 110 that
makes me wary of just jumping in too fast.

I'll keep you posted.

Dave

--- In CAD_CAM_EDM_DRO@y..., "Raymond Heckert" <jnr@a...> wrote:
> Sounds like the unit with two seperate sets of coils is a CV
(constant
> voltage) transformer. (There should also be a set of 'magnetic-
shunt'
> lamination stacks separating the two coils). They're commonly used
in
> 'brown-out' susceptable areas, where high reliability is necessary.
They
> usually construct the CV to be able to output rated voltage when
the input
> sags as much as 20 percent! Draws current like hell, though, under
those
> conditions... noisy, too!
> The other trx may just be to feed the power circuits the unit was
developed
> for. With no rating nameplates, it's hard to guess their actual
use. If
> you give me the dimensions of the core (height, width) and depth of
the
> laminatiion stack, I can calculate about how much power you could
handle
> with the regular transformer (but not the CV unit). Then, if you
could
> calculate the turns for me, I could probably tell you the
approximate
> voltage the unit was designed for. Wrap, say, ten turns of
insulated wire
> around the coil, connect those ten turns in series with another coil
> (making sure they 'add') and apply 1 volt across the ten turns. The
number
> of turns on the 'test-coil' should fit the ratio of 10 turns per
volt = 10X
> turns per volt of the test coil. eg 1 volt : 20 volts is 10 turns :
200
> turns. (Here is where a Variac comes in handy!) I'll go off-line,
if need
> be, but other DIY's may gain some insight here.
>
> RayHex
>
> ----------
> > From: dave_ace_me <davemucha@j...>
> > To: CAD_CAM_EDM_DRO@y...
> > Subject: [CAD_CAM_EDM_DRO] twin transformer ?
> > Date: Wednesday, April 03, 2002 8:34 PM
> >
> > Hi,
> >
> > I was lucky enough to get a junk yard transformer/cap/set of
diodes
> > from what I think was some sort of telecommunications unit. It
is
> > marked ROLM Corporation on the enclosure and is dated 1983.
> >
> > There are two large transformers, some model or part numbers, but
> > unfortunately no manufacturer name.
> >
> > One transformer has a 7" x 8" steel square frame and it has two
sets
> > of coils inside. One is a little over 5 inches in diameter and
one
> > and a half inches long, the other is also about 5 in dia and
about
> > 3.5 inches long.
> >
> > The main power is on the small coil and the output is on the
larger
> > one. The output goes to 4 diodes to get DC, and to a 68,000 uf /
75
> > volt cap and above the cap is a label 48 Volts RMS. There is
also a
> > 100 ohm 55 watt resistor across the cap.
> >
> > The smaller coil has 5 leads, 2 are connected to input power and
the
> > large coil had 4 leads. 2 go to a set of diodes, I am sure to
> > rectify the AC to DC. the other 2 leads on the large coil go to
a
> > small cap, 20uF 440 VAC. There is no connection between the two
> > coils so one must feed the other thru the frame.
> >
> > Can anybody shed light on this thing ?
> > Obviously, my first question is how much power would such a large
> > transformer have ?
> > and my second question is can I use it to drive a herd of
Gecko's ?
> > (a gaggle of Geckos?, flock...pack...)
> >
> > Then why the 100 ohm across the cap ?
> >
> > The other transformer is just a large unit, 5" x 6" on the frame
and
> > 4 inches dia on the coil and th coil is about 3.5 inches long. I
> > think I should be able to figure this one out. Just keep adding
load
> > until it gets hot (?) 8 wires so I will have some fun figuring
the
> > combinations out.
> >
> > If anyone would like to see a pic, I could post some or e-mail.
> >
> > Dave