Unlabelled and disconnected mains primary wires

[N_Cook]

About year 1999, USA make, for export
In line , not 2 or more separate primary windings, DC ohms to nearest 0.1
ohm. I'm assuming same gauge wire throughout
Labelled by me as A,B,C,D,E crossplot (message souce maybe equispaced font)

--- A B C D E
A --- 9.2 8.5 12.5 1.5
B 9.2 --- 0.6 3.6 7.6
C 8.5 0.6 --- 4.2 7.6
D 12.5 3.6 4.2 --- 11.1
E 1.5 7.6 7.6 11.1 ---


Would D-E / D-A be 220/240Vac or 230/250V ac?
what would likely be the 110 or 130V interconnctions option ?
Other than checking using a variac , any other tips ?

 

[Gerard Bok]

On Tue, 1 Jun 2010 10:37:06 +0100, "N_Cook" <diverse@tcp.co.uk>
wrote:

About year 1999, USA make, for export
In line , not 2 or more separate primary windings, DC ohms to nearest 0.1
ohm. I'm assuming same gauge wire throughout
Labelled by me as A,B,C,D,E crossplot (message souce maybe equispaced font)

--- A B C D E
A --- 9.2 8.5 12.5 1.5
B 9.2 --- 0.6 3.6 7.6
C 8.5 0.6 --- 4.2 7.6
D 12.5 3.6 4.2 --- 11.1
E 1.5 7.6 7.6 11.1 ---


Would D-E / D-A be 220/240Vac or 230/250V ac?
what would likely be the 110 or 130V interconnctions option ?
Other than checking using a variac , any other tips ?

Assuming the beast also has a secundary, --possably even marked
with a voltage-- I would apply that voltage (from another
transformer) and measure the voltages on the primary terminals.

--
met vriendelijke groet,
Gerard Bok

 

[Arfa Daily]

On 01/06/2010 10:37, N_Cook wrote:

About year 1999, USA make, for export
In line , not 2 or more separate primary windings, DC ohms to nearest 0.1
ohm. I'm assuming same gauge wire throughout
Labelled by me as A,B,C,D,E crossplot (message souce maybe equispaced font)

--- A B C D E
A --- 9.2 8.5 12.5 1.5
B 9.2 --- 0.6 3.6 7.6
C 8.5 0.6 --- 4.2 7.6
D 12.5 3.6 4.2 --- 11.1
E 1.5 7.6 7.6 11.1 ---


Would D-E / D-A be 220/240Vac or 230/250V ac?
what would likely be the 110 or 130V interconnctions option ?
Other than checking using a variac , any other tips ?

Look for single wires, indicating winding ends, rather than taps ?

Arfa

 

[N_Cook]

Gerard Bok <bok118@zonnet.nl> wrote in message
news:4c04ef34.3464695@News.Individual.NET...

On Tue, 1 Jun 2010 10:37:06 +0100, "N_Cook" <diverse@tcp.co.uk
wrote:

About year 1999, USA make, for export
In line , not 2 or more separate primary windings, DC ohms to nearest 0.1
ohm. I'm assuming same gauge wire throughout
Labelled by me as A,B,C,D,E crossplot (message souce maybe equispaced
font)

--- A B C D E
A --- 9.2 8.5 12.5 1.5
B 9.2 --- 0.6 3.6 7.6
C 8.5 0.6 --- 4.2 7.6
D 12.5 3.6 4.2 --- 11.1
E 1.5 7.6 7.6 11.1 ---


Would D-E / D-A be 220/240Vac or 230/250V ac?
what would likely be the 110 or 130V interconnctions option ?
Other than checking using a variac , any other tips ?

Assuming the beast also has a secundary, --possably even marked
with a voltage-- I would apply that voltage (from another
transformer) and measure the voltages on the primary terminals.

--
met vriendelijke groet,
Gerard Bok

I hadn't actually thought of that but problem is which crosslink/s? for 110
or 130 V operation. From the deformation set into the leads it was probably
D-E used in the UK so D-A probably 250V. The others can stay disconnected if
need be , as unlikely to ever be used outside the UK

 

On Tue, 1 Jun 2010 10:37:06 +0100, "N_Cook" <diverse@tcp.co.uk> wrote:

About year 1999, USA make, for export
In line , not 2 or more separate primary windings, DC ohms to nearest 0.1
ohm. I'm assuming same gauge wire throughout
Labelled by me as A,B,C,D,E crossplot (message souce maybe equispaced font)

--- A B C D E
A --- 9.2 8.5 12.5 1.5
B 9.2 --- 0.6 3.6 7.6
C 8.5 0.6 --- 4.2 7.6
D 12.5 3.6 4.2 --- 11.1
E 1.5 7.6 7.6 11.1 ---


Would D-E / D-A be 220/240Vac or 230/250V ac?
what would likely be the 110 or 130V interconnctions option ?
Other than checking using a variac , any other tips ?





The first step is to rearrange the chart so it makes sense.

The highest resistance is A-D. so A and D are the ends.
A-E is the lowest resistance, so the top line of the chart should now
read

--- A E C B D
A ---1.5 8.5 9.2 12.5

But a better way to look at is is the increments

A-E = winding a = 1.5
E-C = winding b = 7.0
C-B = winding c = 0.7
B-D = winding d = 3.3

NOW let's relabel, and assume that the maximum input voltage is 250
volts (because it's a convenient multiple of 12.5). So the voltage
across each segment (and the taps for each segment) becomes:

A
a = 30
E
b = 140
C
c = 14
B
d = 66
D
Which doesn't make sense for a dual voltage supply UNLESS you assume
multiple gauge wires were used. Which is not unreasonable, factoring
in a desire to save $.02 per device.

Suggestion: A variac (turned down to a very low voltage) would work,
but just about any transformer with an output voltage of 10 -15 volts
should do it. Feed the low voltage AC into the end wirings and
measure the voltage at each tap. Calculate from there.

PlainBill

 

[Gerard Bok]

On Tue, 1 Jun 2010 14:12:36 +0100, "N_Cook" <diverse@tcp.co.uk>
wrote:

Gerard Bok <bok118@zonnet.nl> wrote in message
news:4c04ef34.3464695@News.Individual.NET...
On Tue, 1 Jun 2010 10:37:06 +0100, "N_Cook" <diverse@tcp.co.uk
wrote:

About year 1999, USA make, for export
In line , not 2 or more separate primary windings, DC ohms to nearest 0.1
ohm. I'm assuming same gauge wire throughout
Labelled by me as A,B,C,D,E crossplot (message souce maybe equispaced
font)

--- A B C D E
A --- 9.2 8.5 12.5 1.5
B 9.2 --- 0.6 3.6 7.6
C 8.5 0.6 --- 4.2 7.6
D 12.5 3.6 4.2 --- 11.1
E 1.5 7.6 7.6 11.1 ---


Would D-E / D-A be 220/240Vac or 230/250V ac?
what would likely be the 110 or 130V interconnctions option ?
Other than checking using a variac , any other tips ?

Assuming the beast also has a secundary, --possably even marked
with a voltage-- I would apply that voltage (from another
transformer) and measure the voltages on the primary terminals.

I hadn't actually thought of that but problem is which crosslink/s? for 110
or 130 V operation.

Crosslinks ?
From your original message I read that all primary connections
connect to one continuous winding.

Transformers designed for minimal copper use contain 2 identical
sets of windings. Those get connected in parallel for use on 115
volt and in series for 230 Volt.

As long as there is DC continuity I wouldn't attempt any cross
wiring ;-)

--
Kind regards,
Gerard Bok

 

[Phil Allison]

<PlainBill47@yahoo.com>

But a better way to look at is is the increments

A-E = winding a = 1.5
E-C = winding b = 7.0
C-B = winding c = 0.7
B-D = winding d = 3.3

** OK - let's assume two gauges of wire ARE being used and the 3.3 ohm
tapping B-D is 100V for Japan.

Then by ratio of resistance, the 0.7 ohm tapping C-B is 20 volts making C-D
120 volts for the USA etc.

Similarly, E-C is another 100 volt tapping ( using thinner wire) making E-D
220 volts for Europe.

Again, A-E is another 20 volt tapping making the whole winding 240 volts.


..... Phil

 

[N_Cook]

Gerard Bok <bok118@zonnet.nl> wrote in message
news:4c054944.6350870@News.Individual.NET...

On Tue, 1 Jun 2010 14:12:36 +0100, "N_Cook" <diverse@tcp.co.uk
wrote:

Gerard Bok <bok118@zonnet.nl> wrote in message
news:4c04ef34.3464695@News.Individual.NET...
On Tue, 1 Jun 2010 10:37:06 +0100, "N_Cook" <diverse@tcp.co.uk
wrote:

About year 1999, USA make, for export
In line , not 2 or more separate primary windings, DC ohms to nearest
0.1
ohm. I'm assuming same gauge wire throughout
Labelled by me as A,B,C,D,E crossplot (message souce maybe equispaced
font)

--- A B C D E
A --- 9.2 8.5 12.5 1.5
B 9.2 --- 0.6 3.6 7.6
C 8.5 0.6 --- 4.2 7.6
D 12.5 3.6 4.2 --- 11.1
E 1.5 7.6 7.6 11.1 ---


Would D-E / D-A be 220/240Vac or 230/250V ac?
what would likely be the 110 or 130V interconnctions option ?
Other than checking using a variac , any other tips ?

Assuming the beast also has a secundary, --possably even marked
with a voltage-- I would apply that voltage (from another
transformer) and measure the voltages on the primary terminals.

I hadn't actually thought of that but problem is which crosslink/s? for
110
or 130 V operation.

Crosslinks ?
From your original message I read that all primary connections
connect to one continuous winding.

Transformers designed for minimal copper use contain 2 identical
sets of windings. Those get connected in parallel for use on 115
volt and in series for 230 Volt.

As long as there is DC continuity I wouldn't attempt any cross
wiring ;-)

--
Kind regards,
Gerard Bok

This is what was confusing me , I don't often come across USA transformers ,
they must have plenty of copper to waste and unnecessarily larger
transformers. Only ever seem to see 2 separate primaries in the UK , in the
main, maybe some 10 or 20 V taps in addition.
For this continuous one and generally for this sort of mains transformer.
The"240V" ends cannot be returned to form one 110V connection and a mid
point the other 110V connection for that option, as counter winding sense
for the two "halves" and so no secondary volts.
So part of the winding wasted and the 110V
section of primary perhaps a larger gauge. I suppose measuring inductance
may have helped

 

[PeterD]

On Wed, 2 Jun 2010 08:46:56 +0100, "N_Cook" <diverse@tcp.co.uk> wrote:

Gerard Bok <bok118@zonnet.nl> wrote in message
news:4c054944.6350870@News.Individual.NET...
On Tue, 1 Jun 2010 14:12:36 +0100, "N_Cook" <diverse@tcp.co.uk
wrote:

Gerard Bok <bok118@zonnet.nl> wrote in message
news:4c04ef34.3464695@News.Individual.NET...
On Tue, 1 Jun 2010 10:37:06 +0100, "N_Cook" <diverse@tcp.co.uk
wrote:

About year 1999, USA make, for export
In line , not 2 or more separate primary windings, DC ohms to nearest
0.1
ohm. I'm assuming same gauge wire throughout
Labelled by me as A,B,C,D,E crossplot (message souce maybe equispaced
font)

--- A B C D E
A --- 9.2 8.5 12.5 1.5
B 9.2 --- 0.6 3.6 7.6
C 8.5 0.6 --- 4.2 7.6
D 12.5 3.6 4.2 --- 11.1
E 1.5 7.6 7.6 11.1 ---


Would D-E / D-A be 220/240Vac or 230/250V ac?
what would likely be the 110 or 130V interconnctions option ?
Other than checking using a variac , any other tips ?

Assuming the beast also has a secundary, --possably even marked
with a voltage-- I would apply that voltage (from another
transformer) and measure the voltages on the primary terminals.

I hadn't actually thought of that but problem is which crosslink/s? for
110
or 130 V operation.

Crosslinks ?
From your original message I read that all primary connections
connect to one continuous winding.

Transformers designed for minimal copper use contain 2 identical
sets of windings. Those get connected in parallel for use on 115
volt and in series for 230 Volt.

As long as there is DC continuity I wouldn't attempt any cross
wiring ;-)

--
Kind regards,
Gerard Bok

This is what was confusing me , I don't often come across USA transformers ,

If it is truely a USA only transformer, it will not have a winding
higher than 120 volts! USA makers were not export oriented, and the
few export units were typically fitted with different transformers,
but the run-of-the-mill domestic production was made with a 120 volt
primary (only). Export models were typically setup for 100/120/240
volts. (Japan, USA & and other countries with an approximate 120 volt
standard, and other countries with an approximate 240 volt standard.)

they must have plenty of copper to waste and unnecessarily larger
transformers.

Makers were (and still are) incredibly cheap, and will resort to all
kninds of tricks to save a penny. I don't see many (if any) who will
waste money on copper that will (in their opinion) never be used.

Only ever seem to see 2 separate primaries in the UK , in the
main, maybe some 10 or 20 V taps in addition.
For this continuous one and generally for this sort of mains transformer.
The"240V" ends cannot be returned to form one 110V connection and a mid
point the other 110V connection for that option, as counter winding sense
for the two "halves" and so no secondary volts.
So part of the winding wasted and the 110V
section of primary perhaps a larger gauge. I suppose measuring inductance
may have helped

About the best thing would be to measure the primary volts while
powering the secondary with its rated voltage. However, I suspect you
don't know the secondary specifications either, so that is difficult.

I'd probably look at the secondary and give it a known, low voltage
(say 6 v AC) and measure the ratio of the primary voltages. That would
be better than static DC resistance measurements which can easily be
affected by inductance and wire gauge.

 

[PeterD]

On Wed, 2 Jun 2010 15:57:16 +1000, "Phil Allison" <phil_a@tpg.com.au>
wrote:

PlainBill47@yahoo.com


But a better way to look at is is the increments

A-E = winding a = 1.5
E-C = winding b = 7.0
C-B = winding c = 0.7
B-D = winding d = 3.3


** OK - let's assume two gauges of wire ARE being used and the 3.3 ohm
tapping B-D is 100V for Japan.

Then by ratio of resistance, the 0.7 ohm tapping C-B is 20 volts making C-D
120 volts for the USA etc.

Similarly, E-C is another 100 volt tapping ( using thinner wire) making E-D
220 volts for Europe.

Again, A-E is another 20 volt tapping making the whole winding 240 volts.


.... Phil

Which makes sense!

 

[N_Cook]

I cannot see what the economic argument is in wasting copper , weight and
space. Both methods require a break in winding the primary. The 2 separate
coil system requiring a break and a pair of tails coming off. The continuous
system probably requires a break in gauge of wire and only one tail but 3
dissimilar wires joint at that point - surely not a cheaper option.

 

[Phil Allison]

"PeterD"

If it is truely a USA only transformer, it will not have a winding
higher than 120 volts! USA makers were not export oriented, and the
few export units were typically fitted with different transformers,
but the run-of-the-mill domestic production was made with a 120 volt
primary (only). Export models were typically setup for 100/120/240
volts. (Japan, USA & and other countries with an approximate 120 volt
standard, and other countries with an approximate 240 volt standard.)

** Japan does not have domestic 120 volt AC power.

The standard domestic voltage is 100 volts and may be as low as 90 volts in
some places.

The AC frequency varies too, 50Hz and 60 Hz being used in differing parts of
the country - means that most Japanese made products for domestic use
are designed to accept either frequency.


..... Phil

 

[Phil Allison]

"Nutcase Kook is So Full of Shit "

This is what was confusing me , I don't often come across USA transformers
,
they must have plenty of copper to waste and unnecessarily larger
transformers. Only ever seem to see 2 separate primaries in the UK , in
the
main, maybe some 10 or 20 V taps in addition.

** Wot a load of utter bollocks.

Most audio amps made in the UK between the mid 1960s and late 1990s had
multi-voltage, single winding AC transformers.

Check any old schem from Marshall, Vox or Sugden etc, et alia.

http://www.audiomisc.co.uk/JES/A21series2/A21series2.html

http://www.schematicheaven.com/marshallamps/jcm800_lead_mstvol_50w_2204.pdf

http://www.schematicheaven.com/voxamps/ac301960.pdf

http://www.schematicheaven.com/voxamps/ac151960.pdf




..... Phil

 

[hr(bob) hofmann@att.net]

On Jun 1, 4:37 am, "N_Cook" <dive...@tcp.co.uk> wrote:

About year 1999, USA make, for export
In line , not 2 or more separate primary windings, DC ohms to nearest 0.1
ohm. I'm assuming same gauge wire throughout
Labelled by me as A,B,C,D,E crossplot (message souce maybe equispaced font)

--- A    B    C    D     E
A  ---  9.2  8.5  12.5  1.5
B  9.2  ---  0.6  3.6   7.6
C  8.5  0.6  ---  4.2   7.6
D 12.5  3.6  4.2  ---   11.1
E  1.5  7.6  7.6  11.1   ---

Would D-E / D-A be 220/240Vac or 230/250V ac?
what would likely be the 110 or 130V interconnctions option ?
Other than checking using a variac , any other tips ?

Do you know the approximate secondary voltage? If yes. apply that
voltage to the secondary using a variac or some other transformer.
Then measure the various primary voltages. I have done that many
times when all else fails and I didn't want to take a chance on frying
the transformer. Should work just as well east of the big pond as on
the west side.

 

[Cydrome Leader]

N_Cook <diverse@tcp.co.uk> wrote:

About year 1999, USA make, for export
In line , not 2 or more separate primary windings, DC ohms to nearest 0.1
ohm. I'm assuming same gauge wire throughout
Labelled by me as A,B,C,D,E crossplot (message souce maybe equispaced font)

--- A B C D E
A --- 9.2 8.5 12.5 1.5
B 9.2 --- 0.6 3.6 7.6
C 8.5 0.6 --- 4.2 7.6
D 12.5 3.6 4.2 --- 11.1
E 1.5 7.6 7.6 11.1 ---


Would D-E / D-A be 220/240Vac or 230/250V ac?
what would likely be the 110 or 130V interconnctions option ?
Other than checking using a variac , any other tips ?

you never mentioned what you're even talking about, or what it's from.

Assuming it's something like an "international" linear power supply, there would be
windings for 100, 120 220 and 240 volts based off a combination of terminals. US made
transformers for domestic only use would generally max out at 3 or 4 terminals for
120/240 use.

here's a diagram of how these international transformers work:

http://www.slpower.com/Upload/Technical/20070404102642455201154_41-32512F_ML_Series.pdf

 

[PeterD]

On Thu, 3 Jun 2010 00:27:06 +1000, "Phil Allison" <phil_a@tpg.com.au>
wrote:

"PeterD"

If it is truely a USA only transformer, it will not have a winding
higher than 120 volts! USA makers were not export oriented, and the
few export units were typically fitted with different transformers,
but the run-of-the-mill domestic production was made with a 120 volt
primary (only). Export models were typically setup for 100/120/240
volts. (Japan, USA & and other countries with an approximate 120 volt
standard, and other countries with an approximate 240 volt standard.)


** Japan does not have domestic 120 volt AC power.

The standard domestic voltage is 100 volts and may be as low as 90 volts in
some places.

The AC frequency varies too, 50Hz and 60 Hz being used in differing parts of
the country - means that most Japanese made products for domestic use
are designed to accept either frequency.


.... Phil

Geeze Phil, read... Japan is 100, USA and other countries with
approximately 120 volts, and still other countries with 240 volts.
Completely clear to everyone else...

OK, for you:

(Japan at 100 volts, USA & and other countries with an approximate 120 volt
standard, and other countries with an approximate 240 volt standard.)

 

[Phil Allison]

"PeterDope"

"Phil Allison"

Export models were typically setup for 100/120/240 volts (Japan, USA
& and other countries with an approximate 120 volt standard, and other
countries with an approximate 240 volt standard.)


** Japan does not have domestic 120 volt AC power.

The standard domestic voltage is 100 volts and may be as low as 90 volts
in
some places.

The AC frequency varies too, 50Hz and 60 Hz being used in differing parts
of
the country - means that most Japanese made products for domestic use
are designed to accept either frequency.


Geeze Phil, read...

** What I read was misleading and * needed correction*.

It is a very common myth that Japan has 120 volt AC, 60Hz power ( like the
USA) when it does NOT !!

Your post repeated that myth.

Cos of eBay, second hand Japanese local market electronics is now being sold
to folk in all parts of the world to use - most of whom mistakenly think
that it can be used on 120 volts AC or with a 240 to 120 volts step down
tranny.



..... Phil

 

[N_Cook]

Cydrome Leader <presence@MUNGEpanix.com> wrote in message
news:hu6geg$qkj$1@reader1.panix.com...

N_Cook <diverse@tcp.co.uk> wrote:
About year 1999, USA make, for export
In line , not 2 or more separate primary windings, DC ohms to nearest
0.1
ohm. I'm assuming same gauge wire throughout
Labelled by me as A,B,C,D,E crossplot (message souce maybe equispaced
font)

--- A B C D E
A --- 9.2 8.5 12.5 1.5
B 9.2 --- 0.6 3.6 7.6
C 8.5 0.6 --- 4.2 7.6
D 12.5 3.6 4.2 --- 11.1
E 1.5 7.6 7.6 11.1 ---


Would D-E / D-A be 220/240Vac or 230/250V ac?
what would likely be the 110 or 130V interconnctions option ?
Other than checking using a variac , any other tips ?

you never mentioned what you're even talking about, or what it's from.

Assuming it's something like an "international" linear power supply, there
would be
windings for 100, 120 220 and 240 volts based off a combination of
terminals. US made
transformers for domestic only use would generally max out at 3 or 4
terminals for
120/240 use.

here's a diagram of how these international transformers work:


http://www.slpower.com/Upload/Technical/20070404102642455201154_41-32512F_ML

_Series.pdf


That transformer type is the 2 separate primaries, not the subject of this
thread.
Does anyone have the generic name for these wasteful construction made in or
for USA , for export kit ? the ones with a (electrically) continuous single
primary winding

 

[Grant]

On Thu, 3 Jun 2010 08:27:03 +0100, "N_Cook" <diverse@tcp.co.uk> wrote:

Cydrome Leader <presence@MUNGEpanix.com> wrote in message
news:hu6geg$qkj$1@reader1.panix.com...
N_Cook <diverse@tcp.co.uk> wrote:
About year 1999, USA make, for export
In line , not 2 or more separate primary windings, DC ohms to nearest
0.1
ohm. I'm assuming same gauge wire throughout
Labelled by me as A,B,C,D,E crossplot (message souce maybe equispaced
font)

--- A B C D E
A --- 9.2 8.5 12.5 1.5
B 9.2 --- 0.6 3.6 7.6
C 8.5 0.6 --- 4.2 7.6
D 12.5 3.6 4.2 --- 11.1
E 1.5 7.6 7.6 11.1 ---


Would D-E / D-A be 220/240Vac or 230/250V ac?
what would likely be the 110 or 130V interconnctions option ?
Other than checking using a variac , any other tips ?

you never mentioned what you're even talking about, or what it's from.

Assuming it's something like an "international" linear power supply, there
would be
windings for 100, 120 220 and 240 volts based off a combination of
terminals. US made
transformers for domestic only use would generally max out at 3 or 4
terminals for
120/240 use.

here's a diagram of how these international transformers work:


http://www.slpower.com/Upload/Technical/20070404102642455201154_41-32512F_ML
_Series.pdf


That transformer type is the 2 separate primaries, not the subject of this
thread.
Does anyone have the generic name for these wasteful construction made in or
for USA , for export kit ? the ones with a (electrically) continuous single
primary winding

Autotransformer.

What results from driving the secondary with a low voltage?

Grant.
--
http://bugs.id.au/

 

[N_Cook]

Grant <omg@grrr.id.au> wrote in message
news:tkne06ltbli2a5aij6qc112iti0ed8tntp@4ax.com...

On Thu, 3 Jun 2010 08:27:03 +0100, "N_Cook" <diverse@tcp.co.uk> wrote:

Cydrome Leader <presence@MUNGEpanix.com> wrote in message
news:hu6geg$qkj$1@reader1.panix.com...
N_Cook <diverse@tcp.co.uk> wrote:
About year 1999, USA make, for export
In line , not 2 or more separate primary windings, DC ohms to nearest
0.1
ohm. I'm assuming same gauge wire throughout
Labelled by me as A,B,C,D,E crossplot (message souce maybe equispaced
font)

--- A B C D E
A --- 9.2 8.5 12.5 1.5
B 9.2 --- 0.6 3.6 7.6
C 8.5 0.6 --- 4.2 7.6
D 12.5 3.6 4.2 --- 11.1
E 1.5 7.6 7.6 11.1 ---


Would D-E / D-A be 220/240Vac or 230/250V ac?
what would likely be the 110 or 130V interconnctions option ?
Other than checking using a variac , any other tips ?

you never mentioned what you're even talking about, or what it's from.

Assuming it's something like an "international" linear power supply,
there
would be
windings for 100, 120 220 and 240 volts based off a combination of
terminals. US made
transformers for domestic only use would generally max out at 3 or 4
terminals for
120/240 use.

here's a diagram of how these international transformers work:



http://www.slpower.com/Upload/Technical/20070404102642455201154_41-32512F_M
L
_Series.pdf


That transformer type is the 2 separate primaries, not the subject of
this
thread.
Does anyone have the generic name for these wasteful construction made in
or
for USA , for export kit ? the ones with a (electrically) continuous
single
primary winding

Autotransformer.

What results from driving the secondary with a low voltage?

Grant.
--
http://bugs.id.au/

My understanding of the term autotransformer is primary and secondary
electrically continuous, ie no electrical isolation