"mystery" transformer---reverse engineering it
Christopher Zoeller
I've come across a transformer with multiple inputs (outputs) on
the primary (secondary). Some of these inputs (outputs) are
wired together internally {i.e.: multiple leads to the same node};
others are not.
Does anyone have any ideas on how I can determine if this
transformer is center-tapped or maybe "multiple" transformers
in one package.
I don't have a meaningful part number (meaningful to me, at least)
as this is a non-US part.
Thanks a million for any help!
P.Bennett
In article <51l900$m...@news-e2b.gnn.com>, CZoe...@gnn.com (Christopher Zoeller) writes...
>I've come across a transformer with multiple inputs (outputs) on
>the primary (secondary). Some of these inputs (outputs) are
>wired together internally {i.e.: multiple leads to the same node};
>others are not.
>
>Does anyone have any ideas on how I can determine if this
>transformer is center-tapped or maybe "multiple" transformers
>in one package.
If you find some connection between two or more leads, they will be part of the
same winding - If there are three or more leads in a group, using a low
resistance scale on an ohmmeter, you should be able to determine which leads
are the ends of that winding, and which are taps (and even the order of the
taps)
If it is a power transformer, a winding with black leads is probably the
primary. You could apply a low voltage AC (perhaps 12 V) to these leads, and
measure the voltages on the other leads to determine the turns ratios of the
various windings.
Peter Bennett VE7CEI | Vessels shall be deemed to be in sight
Internet: ben...@triumf.ca | of one another only when one can be
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TRIUMF, Vancouver, B.C., Canada | ColRegs 3(k)
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or: http://vancouver-webpages.com/peter/index.html
Douglas W. Jones,201H MLH,3193350740,3193382879
From article <51l900$m...@news-e2b.gnn.com>,
by CZoe...@gnn.com (Christopher Zoeller):
> I've come across a transformer with multiple inputs (outputs) on
> the primary (secondary). Some of these inputs (outputs) are
> wired together internally {i.e.: multiple leads to the same node};
> others are not.
> Does anyone have any ideas on how I can determine if this
> transformer is center-tapped or maybe "multiple" transformers
> in one package.
Get a variac or other source of a few volts AC. Don't use more than
a few volts!
Attach this across two terminals of the transformer (any two that you've
found to be connected) and measure the AC voltage across all the other
pairs and triples of terminals you've found to be connected.
This doesn't tell you which is the primary and which are the secondaries,
but the voltage ratios give you the turns ratios.
Suppose you have 4 leads, A B C and D, that your ohm meter says are
connected to each other inside the transformer and you get the following
pairwise voltages:
___________
| |
2.5V--- 0 -----5V |
| A | |
| | |
| | |
D 0 -- 2.5V --- 0 B |
| | |
| | 10V
| C | |
7.5V--- 0 ----10V |
|___________|
You can conclude the following structure for this winding:
B -------< --------
2.5 > | |
D -------< 5 |
2.5 > | |
A -------< --- 10
> |
5 < |
> |
C -------< --------
Hope that helps
Doug Jones
jo...@cs.uiowa.edu
Sam Goldwasser
> I've come across a transformer with multiple inputs (outputs) on
> the primary (secondary). Some of these inputs (outputs) are
> wired together internally {i.e.: multiple leads to the same node};
> others are not.
Are you sure they are just not very low resistance multitapped windings
that just appear to be shorted together? Are the leads color coded? If
so, post it.
> Does anyone have any ideas on how I can determine if this
> transformer is center-tapped or maybe "multiple" transformers
> in one package.
> I don't have a meaningful part number (meaningful to me, at least)
> as this is a non-US part.
Start with a good multimeter - DMM on the lowest ohms scale. This will
permit you to map the windings. Once you do this, applying a low voltage
AC input (from another power transformer driven by a Variac) will enable you
to determine voltage ratios. Then, you may be able to make some educated
guesses as to the primary and secondary.
Note: for safety, use the Variac and another isolated transformer for this.
--- sam