[Jon Yaeger]

I've got a PP output transformer that has a center tap but no ultralinear
taps, and two secondaries.

Is it possible to determine the correct phasing of the primary relative to
the secondary from the wire colors?

The secondary taps are known:

Yellow: 16 ohms
Blue: 8 ohms
Black: Ground

The Primary colors a

Yellow
Orange: B+ / center tap
Blue


Would it be likely that the Yellow wire of the primary is the "high" side,
and the blue wire the "low"?

Thanks in advance,

Jon

[Don Pearce[_3_]]

On Wed, 27 May 2009 01:11:01 -0400, Jon Yaeger
wrote:

I've got a PP output transformer that has a center tap but no ultralinear
taps, and two secondaries.

Is it possible to determine the correct phasing of the primary relative to
the secondary from the wire colors?

The secondary taps are known:

Yellow: 16 ohms
Blue: 8 ohms
Black: Ground

The Primary colors a

Yellow
Orange: B+ / center tap
Blue


Would it be likely that the Yellow wire of the primary is the "high" side,
and the blue wire the "low"?

Thanks in advance,

Jon

Possibly. The only way you are going to find out for sure is to put a
signal (doesn't need to be high power - straight off a signal
generator will do) into the yellow and blue primary, then see which
way round you need to connect the secondary to match the phase.

Is there a particular reason why you need to know? Like perhaps if you
intend to take some feedback from the speaker side of the transformer?

d

[Patrick Turner]

Jon Yaeger wrote:

I've got a PP output transformer that has a center tap but no ultralinear
taps, and two secondaries.

Is it possible to determine the correct phasing of the primary relative to
the secondary from the wire colors?

The secondary taps are known:

Yellow: 16 ohms
Blue: 8 ohms
Black: Ground

The Primary colors a

Yellow
Orange: B+ / center tap
Blue

Would it be likely that the Yellow wire of the primary is the "high" side,
and the blue wire the "low"?

Thanks in advance,

Jon

Probably you are right, but don't assume anything.
So test the OPT in an amp and with sec black to 0V, sec yellow to live
out.

Then with global FB connected the amp will either oscillate with the
wrong tranny phase for stability, or your level will drop due to FB
application and it will be stable with a resistance load. You can
reverse the anode leads to suit the wanted FB stability and gain
reduction.

Patrick Turner.
ythe y

[Lord Valve]

Don Pearce wrote:

On Wed, 27 May 2009 01:11:01 -0400, Jon Yaeger
wrote:

I've got a PP output transformer that has a center tap but no ultralinear
taps, and two secondaries.

Is it possible to determine the correct phasing of the primary relative to
the secondary from the wire colors?

The secondary taps are known:

Yellow: 16 ohms
Blue: 8 ohms
Black: Ground

The Primary colors a

Yellow
Orange: B+ / center tap
Blue


Would it be likely that the Yellow wire of the primary is the "high" side,
and the blue wire the "low"?

Thanks in advance,

Jon

Possibly. The only way you are going to find out for sure is to put a
signal (doesn't need to be high power - straight off a signal
generator will do) into the yellow and blue primary, then see which
way round you need to connect the secondary to match the phase.

Is there a particular reason why you need to know? Like perhaps if you
intend to take some feedback from the speaker side of the transformer?

d

Use a positive-going pulse, 10% on, 90% off, around 1 KHz.

Very easy to observe phase on the output with this kind of
input. If your sig generator is rated for a 600-ohm load,
this'll work fine.

LV

[Jon Yaeger]

in article , Patrick Turner at
wrote on 5/27/09 6:25 AM:



Jon Yaeger wrote:

I've got a PP output transformer that has a center tap but no ultralinear
taps, and two secondaries.

Is it possible to determine the correct phasing of the primary relative to
the secondary from the wire colors?

The secondary taps are known:

Yellow: 16 ohms
Blue: 8 ohms
Black: Ground

The Primary colors a

Yellow
Orange: B+ / center tap
Blue

Would it be likely that the Yellow wire of the primary is the "high" side,
and the blue wire the "low"?

Thanks in advance,

Jon

Probably you are right, but don't assume anything.
So test the OPT in an amp and with sec black to 0V, sec yellow to live
out.

Then with global FB connected the amp will either oscillate with the
wrong tranny phase for stability, or your level will drop due to FB
application and it will be stable with a resistance load. You can
reverse the anode leads to suit the wanted FB stability and gain
reduction.

Patrick Turner.
ythe y

* * *

I thought that method would be fool-proof, but being a bit lazy I was hoping
for something simpler.

Thanks for your help!!

Jon

[Jon Yaeger]

in article , Lord Valve at
wrote on 5/27/09 9:46 AM:

Don Pearce wrote:

On Wed, 27 May 2009 01:11:01 -0400, Jon Yaeger
wrote:

I've got a PP output transformer that has a center tap but no ultralinear
taps, and two secondaries.

Is it possible to determine the correct phasing of the primary relative to
the secondary from the wire colors?

The secondary taps are known:

Yellow: 16 ohms
Blue: 8 ohms
Black: Ground

The Primary colors a

Yellow
Orange: B+ / center tap
Blue


Would it be likely that the Yellow wire of the primary is the "high" side,
and the blue wire the "low"?

Thanks in advance,

Jon

Possibly. The only way you are going to find out for sure is to put a
signal (doesn't need to be high power - straight off a signal
generator will do) into the yellow and blue primary, then see which
way round you need to connect the secondary to match the phase.

Is there a particular reason why you need to know? Like perhaps if you
intend to take some feedback from the speaker side of the transformer?

d

Use a positive-going pulse, 10% on, 90% off, around 1 KHz.

Very easy to observe phase on the output with this kind of
input. If your sig generator is rated for a 600-ohm load,
this'll work fine.

LV



LV,

Thanks for your suggestion.

Last night (before I wrote the post) I tried the square wave function using
a Heath signal generator, but it really wasn't up to the task. It did not
generate useful positive-going pulses, and one channel of my Tek 60 Mhz.
scope isn't up to par, so I gave up.

I guess it's time for an equipment upgrade . . .

I appreciate your help.

Jon

[jim greg]

"Jon Yaeger" wrote in message
...
I've got a PP output transformer that has a center tap but no ultralinear
taps, and two secondaries.

Is it possible to determine the correct phasing of the primary relative to
the secondary from the wire colors?

The secondary taps are known:

Yellow: 16 ohms
Blue: 8 ohms
Black: Ground

The Primary colors a

Yellow
Orange: B+ / center tap
Blue


Would it be likely that the Yellow wire of the primary is the "high" side,
and the blue wire the "low"?

Thanks in advance,

Jon

In the absence of having a dual-chnl scope...
Use two balanced (preferably) inputs of a sound mixer,
Connect sig gen giving around 0.5V @ 800Hz and the xfrmr primary [CT and one
of the push-pulls] into first chnl at -Line- level, and arrange for any sec
(one at a time) to feed into next input at -Mic- level.
Then pre-adjust each chnl gain pot, but solo, to give -6dB.
Now open both pots: if the inputs sum, they are in phase and will give 0dB
at mixer; but, if cancelling and ergo out of phase, invert the sec's wires.
Make a note of the 'hot' colours of each set.
End of guesswork!
Jim

use this wheeze for analysing phase of any unmarked audio transformer, if
around 10:1 to 1:1, set both chnl sensitivities to Line.
Jim

[[email protected]]

On May 27, 10:07*pm, Jon Yaeger wrote:
in article , Lord Valve at
wrote on 5/27/09 9:46 AM:



Don Pearce wrote:

On Wed, 27 May 2009 01:11:01 -0400, Jon Yaeger
wrote:

I've got a PP output transformer that has a center tap but no ultralinear
taps, and two secondaries.

Is it possible to determine the correct phasing of the primary relative to
the secondary from the wire colors?

The secondary taps are known:

Yellow: * 16 ohms
Blue: * * *8 ohms
Black: * * Ground

The Primary colors a

Yellow
Orange: * B+ / center tap
Blue

Would it be likely that the Yellow wire of the primary is the "high" side,
and the blue wire the "low"?

Thanks in advance,

Jon

Possibly. The only way you are going to find out for sure is to put a
signal (doesn't need to be high power - straight off a signal
generator will do) into the yellow and blue primary, then see which
way round you need to connect the secondary to match the phase.

Is there a particular reason why you need to know? Like perhaps if you
intend to take some feedback from the speaker side of the transformer?

d

Use a positive-going pulse, 10% on, 90% off, around 1 KHz.

Very easy to observe phase on the output with this kind of
input. *If your sig generator is rated for a 600-ohm load,
this'll work fine.



Thanks for your suggestion.

Last night (before I wrote the post) I tried the square wave function using
a Heath signal generator, but it really wasn't up to the task. *It did not
generate useful positive-going pulses, and one channel of my Tek 60 Mhz.
scope isn't up to par, so I gave up.

I guess it's time for an equipment upgrade *. . .

Without a fully and correctly working 2 channel scope I would simply
not work on anything, but that's because I am spoiled. Scopes are not
expensive. THAT SAID you can do this whole job with nothing but a
sine wave generator, limited for safe voltage and current, and a
voltmeter. You first determine what the groups of wires are as far as
their respective windings and where they are on the winding and then
you series them together and see if they series-boost or series-buck.
This whole procedure is called "phasing out".

[jim greg]

"Jon Yaeger" wrote in message
...
I've got a PP output transformer that has a center tap but no ultralinear
taps, and two secondaries.

Is it possible to determine the correct phasing of the primary relative to
the secondary from the wire colors?

The secondary taps are known:

Yellow: 16 ohms
Blue: 8 ohms
Black: Ground

The Primary colors a

Yellow
Orange: B+ / center tap
Blue


Would it be likely that the Yellow wire of the primary is the "high" side,
and the blue wire the "low"?

Thanks in advance,

Jon

i wrote a useful reply XMFR phasing question - answered yesterday but
it has not yet been published by newsgroup's scrutineer.
sincerely
Jim

[Patrick Turner]

Jon Yaeger wrote:

in article , Patrick Turner at
wrote on 5/27/09 6:25 AM:



Jon Yaeger wrote:

I've got a PP output transformer that has a center tap but no ultralinear
taps, and two secondaries.

Is it possible to determine the correct phasing of the primary relative to
the secondary from the wire colors?

The secondary taps are known:

Yellow: 16 ohms
Blue: 8 ohms
Black: Ground

The Primary colors a

Yellow
Orange: B+ / center tap
Blue

Would it be likely that the Yellow wire of the primary is the "high" side,
and the blue wire the "low"?

Thanks in advance,

Jon

Probably you are right, but don't assume anything.
So test the OPT in an amp and with sec black to 0V, sec yellow to live
out.

Then with global FB connected the amp will either oscillate with the
wrong tranny phase for stability, or your level will drop due to FB
application and it will be stable with a resistance load. You can
reverse the anode leads to suit the wanted FB stability and gain
reduction.

Patrick Turner.
ythe y

* * *

I thought that method would be fool-proof, but being a bit lazy I was hoping
for something simpler.

Thanks for your help!!

Jon

There is something simpler than trying the OPT out in an amp. But I
thought perhaps you'd have an amp to try the OPT.

The simpler method is as foillows.

Connect a sig gene with low Rout (say 1k ohm or less, 600 ohms etc )
with 0V connected to the CT, ) orange wire, and active lead to the
yellow end of the P winding.

Set the sig gene for say 3.0Vrms at 500Hz.

You should be able to measure 0V to the other blue end of the P to give
3.0Vrms or 6Vrms across the whole P, blue to yellow.

Now connect the black Sec end also to the CT+0V. Measure the voltage
between 0V and yellow S end, 16 ohms and 0V, and record the voltage.
Do the same between 0V and the blue sec and record the voltage.

Now measure the voltage between the yellow Sec and the yellow Pri. If it
is less than 3.0Vrms, then the voltages are in phase, if it is more than
3.0Vrms, it is oppositely phased.

Suppose the OPT was 20:1 TR, then with 6V across the whole P you's have
+3V and -3V at each end measured from 0V.
Assume the yellow is +3V, and blue is -3V, because your signal generator
is connected to between CT and yellow.

You would have 6/20 = 0.3V between 0V and the 16 ohm yellow tap. But is
it +0.3V, or -0.3V?

If you measure between the 16 ohm tap and the sig gene/yellow P at +3V,
then you will either get 3V -0.3V, or 3V +0.3V, which means 2.7V is same
phase, and 3.3V is opposite phase, savvy?

The measurements I have asked you to take and record will give you the
vital info about the TR and hence the ZR, and exactly what impedance
matches are available.

Make a label and glue it to the OPT with phase info so that in 5 years
when you have forgotten all about what I said, you'll still have the
info.

Patrick Turner.

[Patrick Turner]

Jon Yaeger wrote:

in article , Lord Valve at
wrote on 5/27/09 9:46 AM:

Don Pearce wrote:

On Wed, 27 May 2009 01:11:01 -0400, Jon Yaeger
wrote:

I've got a PP output transformer that has a center tap but no ultralinear
taps, and two secondaries.

Is it possible to determine the correct phasing of the primary relative to
the secondary from the wire colors?

The secondary taps are known:

Yellow: 16 ohms
Blue: 8 ohms
Black: Ground

The Primary colors a

Yellow
Orange: B+ / center tap
Blue


Would it be likely that the Yellow wire of the primary is the "high" side,
and the blue wire the "low"?

Thanks in advance,

Jon

Possibly. The only way you are going to find out for sure is to put a
signal (doesn't need to be high power - straight off a signal
generator will do) into the yellow and blue primary, then see which
way round you need to connect the secondary to match the phase.

Is there a particular reason why you need to know? Like perhaps if you
intend to take some feedback from the speaker side of the transformer?

d

Use a positive-going pulse, 10% on, 90% off, around 1 KHz.

Very easy to observe phase on the output with this kind of
input. If your sig generator is rated for a 600-ohm load,
this'll work fine.

LV


LV,

Thanks for your suggestion.

Last night (before I wrote the post) I tried the square wave function using
a Heath signal generator, but it really wasn't up to the task. It did not
generate useful positive-going pulses, and one channel of my Tek 60 Mhz.
scope isn't up to par, so I gave up.

I guess it's time for an equipment upgrade . . .

I appreciate your help.

Any audio amatateur can work it all out with nothing more than a volt
meter and a low Z signal source.

I've assumed you'd have a low Rout sig gene but a heater supply 6.3Vrms
at 60Hz will do fine.

CAUTION AND WARNING...

Always use the low voltage testing signal connected to the ***high
voltage** winding which is usually the high dc resistance winding.

If you have a 20:1 OPT, and you have 6.3V across the sec, then you have
126Vrms across the P. But say you had a 40:1 OPT, then the P voltage
would be 252V and quite deadly!!!!!

If you have trouble measuring the dc resistance of a P winding of an OPT
with a DMM, it is because of the inductance, so while measuring dc
resistance, connect a temporary shorting lead across the sec, and it
shorts the inductance that fools the DMM.

Any cheap DMM costing $20 should be OK to use, and most read down to mV
fairly accurately, ie, within 5% for anything you will read in this
case.

Patrick Turner.

Jon

[Don Pearce[_3_]]

On Fri, 29 May 2009 12:34:46 GMT, Patrick Turner
wrote:



Jon Yaeger wrote:

in article , Lord Valve at
wrote on 5/27/09 9:46 AM:

Don Pearce wrote:

On Wed, 27 May 2009 01:11:01 -0400, Jon Yaeger
wrote:

I've got a PP output transformer that has a center tap but no ultralinear
taps, and two secondaries.

Is it possible to determine the correct phasing of the primary relative to
the secondary from the wire colors?

The secondary taps are known:

Yellow: 16 ohms
Blue: 8 ohms
Black: Ground

The Primary colors a

Yellow
Orange: B+ / center tap
Blue


Would it be likely that the Yellow wire of the primary is the "high" side,
and the blue wire the "low"?

Thanks in advance,

Jon

Possibly. The only way you are going to find out for sure is to put a
signal (doesn't need to be high power - straight off a signal
generator will do) into the yellow and blue primary, then see which
way round you need to connect the secondary to match the phase.

Is there a particular reason why you need to know? Like perhaps if you
intend to take some feedback from the speaker side of the transformer?

d

Use a positive-going pulse, 10% on, 90% off, around 1 KHz.

Very easy to observe phase on the output with this kind of
input. If your sig generator is rated for a 600-ohm load,
this'll work fine.

LV


LV,

Thanks for your suggestion.

Last night (before I wrote the post) I tried the square wave function using
a Heath signal generator, but it really wasn't up to the task. It did not
generate useful positive-going pulses, and one channel of my Tek 60 Mhz.
scope isn't up to par, so I gave up.

I guess it's time for an equipment upgrade . . .

I appreciate your help.

Any audio amatateur can work it all out with nothing more than a volt
meter and a low Z signal source.

I've assumed you'd have a low Rout sig gene but a heater supply 6.3Vrms
at 60Hz will do fine.

CAUTION AND WARNING...

Always use the low voltage testing signal connected to the ***high
voltage** winding which is usually the high dc resistance winding.

If you have a 20:1 OPT, and you have 6.3V across the sec, then you have
126Vrms across the P. But say you had a 40:1 OPT, then the P voltage
would be 252V and quite deadly!!!!!

If you have trouble measuring the dc resistance of a P winding of an OPT
with a DMM, it is because of the inductance, so while measuring dc
resistance, connect a temporary shorting lead across the sec, and it
shorts the inductance that fools the DMM.

Any cheap DMM costing $20 should be OK to use, and most read down to mV
fairly accurately, ie, within 5% for anything you will read in this
case.

Patrick Turner.

How does that help in determining the phase?

d

[Patrick Turner]

Don Pearce wrote:

On Fri, 29 May 2009 12:34:46 GMT, Patrick Turner
wrote:



Jon Yaeger wrote:

in article , Lord Valve at
wrote on 5/27/09 9:46 AM:

Don Pearce wrote:

On Wed, 27 May 2009 01:11:01 -0400, Jon Yaeger
wrote:

I've got a PP output transformer that has a center tap but no ultralinear
taps, and two secondaries.

Is it possible to determine the correct phasing of the primary relative to
the secondary from the wire colors?

The secondary taps are known:

Yellow: 16 ohms
Blue: 8 ohms
Black: Ground

The Primary colors a

Yellow
Orange: B+ / center tap
Blue


Would it be likely that the Yellow wire of the primary is the "high" side,
and the blue wire the "low"?

Thanks in advance,

Jon

Possibly. The only way you are going to find out for sure is to put a
signal (doesn't need to be high power - straight off a signal
generator will do) into the yellow and blue primary, then see which
way round you need to connect the secondary to match the phase.

Is there a particular reason why you need to know? Like perhaps if you
intend to take some feedback from the speaker side of the transformer?

d

Use a positive-going pulse, 10% on, 90% off, around 1 KHz.

Very easy to observe phase on the output with this kind of
input. If your sig generator is rated for a 600-ohm load,
this'll work fine.

LV


LV,

Thanks for your suggestion.

Last night (before I wrote the post) I tried the square wave function using
a Heath signal generator, but it really wasn't up to the task. It did not
generate useful positive-going pulses, and one channel of my Tek 60 Mhz.
scope isn't up to par, so I gave up.

I guess it's time for an equipment upgrade . . .

I appreciate your help.

Any audio amatateur can work it all out with nothing more than a volt
meter and a low Z signal source.

I've assumed you'd have a low Rout sig gene but a heater supply 6.3Vrms
at 60Hz will do fine.

CAUTION AND WARNING...

Always use the low voltage testing signal connected to the ***high
voltage** winding which is usually the high dc resistance winding.

If you have a 20:1 OPT, and you have 6.3V across the sec, then you have
126Vrms across the P. But say you had a 40:1 OPT, then the P voltage
would be 252V and quite deadly!!!!!

If you have trouble measuring the dc resistance of a P winding of an OPT
with a DMM, it is because of the inductance, so while measuring dc
resistance, connect a temporary shorting lead across the sec, and it
shorts the inductance that fools the DMM.

Any cheap DMM costing $20 should be OK to use, and most read down to mV
fairly accurately, ie, within 5% for anything you will read in this
case.

Patrick Turner.

How does that help in determining the phase?

If you had been following all the things I have said on the matter,
you'd have understood.

I don't like to see people getting an electric shock because they were
cavalier with voltage measurements.

Some ppl might assume a winding is the primary when it wasn't, then
connect 110V and for a second there's a big hum and huge voltage on some
other winding.

Patrick Turner.

d

[Don Pearce[_3_]]

On Sat, 30 May 2009 14:10:33 GMT, Patrick Turner
wrote:

How does that help in determining the phase?

If you had been following all the things I have said on the matter,
you'd have understood.

I don't like to see people getting an electric shock because they were
cavalier with voltage measurements.

Some ppl might assume a winding is the primary when it wasn't, then
connect 110V and for a second there's a big hum and huge voltage on some
other winding.


I've no idea how that answers my question.

d

[Patrick Turner]

jim greg wrote:

"Jon Yaeger" wrote in message
...
I've got a PP output transformer that has a center tap but no ultralinear
taps, and two secondaries.

Is it possible to determine the correct phasing of the primary relative to
the secondary from the wire colors?

The secondary taps are known:

Yellow: 16 ohms
Blue: 8 ohms
Black: Ground

The Primary colors a

Yellow
Orange: B+ / center tap
Blue


Would it be likely that the Yellow wire of the primary is the "high" side,
and the blue wire the "low"?

Thanks in advance,

Jon

i wrote a useful reply XMFR phasing question - answered yesterday but
it has not yet been published by newsgroup's scrutineer.
sincerely
Jim

As far as I am aware, this group don't have no scrootineer, or moderator
man. It be possible fo any one to type whatever an it jus gets posted
up. Otherwise it'd be kinda quiet around here.

So if there was a delay after posting off your post, then maybe its in
the ISP server or the route you have. In the past 9 years since i been
here there have been a number of ISPs I was with who could not give me a
reliable path to r.a.t.
They could always do alt.binaries.blondes, but could not provide links
to many other groups.

Patrick Turner.

[jim greg]

"Patrick Turner" wrote in message
...


jim greg wrote:

"Jon Yaeger" wrote in message
...
I've got a PP output transformer that has a center tap but no
ultralinear
taps, and two secondaries.

Is it possible to determine the correct phasing of the primary relative
to
the secondary from the wire colors?

The secondary taps are known:

Yellow: 16 ohms
Blue: 8 ohms
Black: Ground

The Primary colors a

Yellow
Orange: B+ / center tap
Blue


Would it be likely that the Yellow wire of the primary is the "high"
side,
and the blue wire the "low"?

Thanks in advance,

Jon

i wrote a useful reply XMFR phasing question - answered yesterday
but
it has not yet been published by newsgroup's scrutineer.
sincerely
Jim

As far as I am aware, this group don't have no scrootineer, or moderator
man. It be possible fo any one to type whatever an it jus gets posted
up. Otherwise it'd be kinda quiet around here.

So if there was a delay after posting off your post, then maybe its in
the ISP server or the route you have. In the past 9 years since i been
here there have been a number of ISPs I was with who could not give me a
reliable path to r.a.t.
They could always do alt.binaries.blondes, but could not provide links
to many other groups.

Patrick Turner.

so nowadays i can read off RAT but not write to the NG. sounds like there
is unwelcoming bias afoot.
often used to add to threads in the past.
anyway i am now corresponding with Jon Yaeger directly. a pity i can't send
my writings to NG.
Jim

[JP]

On Sat, 30 May 2009 21:08:32 +0100, "jim greg"
wrote:


"Patrick Turner" wrote in message
...


jim greg wrote:

"Jon Yaeger" wrote in message
...
I've got a PP output transformer that has a center tap but no
ultralinear
taps, and two secondaries.

Is it possible to determine the correct phasing of the primary relative
to
the secondary from the wire colors?

The secondary taps are known:

Yellow: 16 ohms
Blue: 8 ohms
Black: Ground

The Primary colors a

Yellow
Orange: B+ / center tap
Blue


Would it be likely that the Yellow wire of the primary is the "high"
side,
and the blue wire the "low"?

Thanks in advance,

Jon

i wrote a useful reply XMFR phasing question - answered yesterday
but
it has not yet been published by newsgroup's scrutineer.
sincerely
Jim

As far as I am aware, this group don't have no scrootineer, or moderator
man. It be possible fo any one to type whatever an it jus gets posted
up. Otherwise it'd be kinda quiet around here.

So if there was a delay after posting off your post, then maybe its in
the ISP server or the route you have. In the past 9 years since i been
here there have been a number of ISPs I was with who could not give me a
reliable path to r.a.t.
They could always do alt.binaries.blondes, but could not provide links
to many other groups.

Patrick Turner.

so nowadays i can read off RAT but not write to the NG. sounds like there
is unwelcoming bias afoot.
often used to add to threads in the past.
anyway i am now corresponding with Jon Yaeger directly. a pity i can't send
my writings to NG.
Jim
USENET is not moderated for the most part. The problem almost surely
has to be with your computer/news reader or ISP..unless you have a
court order not to post or something ..

[Bret L]

On May 30, 9:10*am, Patrick Turner wrote:
Don Pearce wrote:

On Fri, 29 May 2009 12:34:46 GMT, Patrick Turner
wrote:

Jon Yaeger wrote:

in article , Lord Valve at
wrote on 5/27/09 9:46 AM:

Don Pearce wrote:

On Wed, 27 May 2009 01:11:01 -0400, Jon Yaeger
wrote:

I've got a PP output transformer that has a center tap but no ultralinear
taps, and two secondaries.

Is it possible to determine the correct phasing of the primary relative to
the secondary from the wire colors?

The secondary taps are known:

Yellow: * 16 ohms
Blue: * * *8 ohms
Black: * * Ground

The Primary colors a

Yellow
Orange: * B+ / center tap
Blue

Would it be likely that the Yellow wire of the primary is the "high" side,
and the blue wire the "low"?

Thanks in advance,

Jon

Possibly. The only way you are going to find out for sure is to put a
signal (doesn't need to be high power - straight off a signal
generator will do) into the yellow and blue primary, then see which
way round you need to connect the secondary to match the phase.

Is there a particular reason why you need to know? Like perhaps if you
intend to take some feedback from the speaker side of the transformer?

d

Use a positive-going pulse, 10% on, 90% off, around 1 KHz.

Very easy to observe phase on the output with this kind of
input. *If your sig generator is rated for a 600-ohm load,
this'll work fine.

LV

LV,

Thanks for your suggestion.

Last night (before I wrote the post) I tried the square wave function using
a Heath signal generator, but it really wasn't up to the task. *It did not
generate useful positive-going pulses, and one channel of my Tek 60 Mhz.
scope isn't up to par, so I gave up.

I guess it's time for an equipment upgrade *. . .

I appreciate your help.

Any audio amatateur can work it all out with nothing more than a volt
meter and a low Z signal source.

I've assumed you'd have a low Rout sig gene but a heater supply 6.3Vrms
at 60Hz will do fine.

CAUTION AND WARNING...

Always use the low voltage testing signal connected to the ***high
voltage** winding which is usually the high dc resistance winding.

If you have a 20:1 OPT, and you have 6.3V across the sec, then you have
126Vrms across the P. But say you had a 40:1 OPT, then the P voltage
would be 252V and quite deadly!!!!!

If you have trouble measuring the dc resistance of a P winding of an OPT
with a DMM, it is because of the inductance, so while measuring dc
resistance, connect a temporary shorting lead across the sec, and it
shorts the inductance that fools the DMM.

Any cheap DMM costing $20 should be OK to use, and most read down to mV
fairly accurately, ie, within 5% for anything you will read in this
case.

Patrick Turner.

How does that help in determining the phase?

If you had been following all the things I have said on the matter,
you'd have understood.

I don't like to see people getting an electric shock because they were
cavalier with voltage measurements.

Some ppl might assume a winding is the primary when it wasn't, then
connect 110V and for a second there's a big hum and huge voltage on some
other winding.

Patrick Turner.



d

They should always use a current limited source for testing and work
with one hand. Get a piece of dry lumber and some tacks and solder the
wires to tacks for easy test if flying leads are what you have. Make
up a test cable with some grabbers on the ends so you can work one
handed easily with a scope probe. I'd wear a rubber glove as well in
HV situations.

I keep pushing everyone to get a HP 200CD for this work and lots
else. Unlike solid state units you can't hardly blow them up. Using a
lightbulb and a step down xfmr off a variac works too, but the
lunchbox is inherently safer-there is just not that much energy
available and you can work at 400 or 1000 hz instead of 60 or 50.

There is no UK or Euro equivalent to the 200CD or 200AB-get the real
thing. Later ones have multi standard power supplies. For earlier
ones, 2:1 transformers are cheap in the UK because they used 110V
drills for construction by law for years.

[Bret L]

Always use the low voltage testing signal connected to the ***high
voltage** winding which is usually the high dc resistance winding.

If you have a 20:1 OPT, and you have 6.3V across the sec, then you have
126Vrms across the P. But say you had a 40:1 OPT, then the P voltage
would be 252V and quite deadly!!!!!

If you have trouble measuring the dc resistance of a P winding of an OPT
with a DMM, it is because of the inductance, so while measuring dc
resistance, connect a temporary shorting lead across the sec, and it
shorts the inductance that fools the DMM.

Any cheap DMM costing $20 should be OK to use, and most read down to mV
fairly accurately, ie, within 5% for anything you will read in this
case.

Patrick Turner.

How does that help in determining the phase?

We need to understand the concept of the transformer here. When we
say "series boosting" and "series bucking" in terms of the voltage, do
you understand this issue?

We have a transformer with two separate windings. We call the four
terminals or wires, A,B, C, and D. A and B are one winding , C and D
the other. We put an AC voltage on one, and get another separate
voltage on the other.

Now if we put the windings in series, hooking C to B, leaving the
source on A nad B. and measure the voltage vrom A to D. Is the voltage
on A-D HIGHER or LOWER than on A-B? If it is higher, they are series
boosting. If it is lower they are series bucking.

Many good books on transformers exist. Read them, but also get some
real ones and play with them.

[Bret L]

Last night (before I wrote the post) I tried the square wave function using
a Heath signal generator, but it really wasn't up to the task. It did not
generate useful positive-going pulses, and one channel of my Tek 60 Mhz.
scope isn't up to par, so I gave up.

IOW someone gave it to you because one channel is dead and no one
will fix it for free.

[Patrick Turner]

Bret L wrote:


Always use the low voltage testing signal connected to the ***high
voltage** winding which is usually the high dc resistance winding.

If you have a 20:1 OPT, and you have 6.3V across the sec, then you have
126Vrms across the P. But say you had a 40:1 OPT, then the P voltage
would be 252V and quite deadly!!!!!

If you have trouble measuring the dc resistance of a P winding of an OPT
with a DMM, it is because of the inductance, so while measuring dc
resistance, connect a temporary shorting lead across the sec, and it
shorts the inductance that fools the DMM.

Any cheap DMM costing $20 should be OK to use, and most read down to mV
fairly accurately, ie, within 5% for anything you will read in this
case.

Patrick Turner.

How does that help in determining the phase?

We need to understand the concept of the transformer here. When we
say "series boosting" and "series bucking" in terms of the voltage, do
you understand this issue?

We have a transformer with two separate windings. We call the four
terminals or wires, A,B, C, and D. A and B are one winding , C and D
the other. We put an AC voltage on one, and get another separate
voltage on the other.

Now if we put the windings in series, hooking C to B, leaving the
source on A nad B. and measure the voltage vrom A to D. Is the voltage
on A-D HIGHER or LOWER than on A-B? If it is higher, they are series
boosting. If it is lower they are series bucking.

Many good books on transformers exist. Read them, but also get some
real ones and play with them.

My posts on the subject did try to explain that by measuring voltages
between relative terminals and by using powers of plain logical
thinking, one could soon work out the relative phasing of windings on
any Xfrmr.

But many cannot think at all....

Patrick Turner.