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Guest

Thu Dec 20, 2018 7:45 am   



I looked, didn't find much.

Audio, high quality like a good ass old tube amp, they had them 5 - 100,000 Hz with less than a percent THD. That level of quality, however the specs are different.

I don't need a primary. "Primarily" what I need is a center tapped choke, but if I can just get a 1:1 audio transformer it would work given one thing - the primary and secondary must be identical.

In fact is it has to be a custom wind I want them wound bifilar but of course not twisted. An E/I core is fine as long as there's enough of it.

I know it is not going to be cheap. I think off the shelf I might be looking at a hundred or more, especially when they hear what wattage I want to pump through it. At least 100 watts.

Anyone had to do this, actually make them make you a transformer ? Anyone got an idea what shit like this would cost ?

Or if you know of something off the shelf I would have to grease you somehow. Anything but firearms, this is Usenet after all.

bitrex
Guest

Thu Dec 20, 2018 7:45 am   



On 12/20/2018 01:01 AM, jurb6006_at_gmail.com wrote:
Quote:
I looked, didn't find much.

Audio, high quality like a good ass old tube amp, they had them 5 - 100,000 Hz with less than a percent THD. That level of quality, however the specs are different.

I don't need a primary. "Primarily" what I need is a center tapped choke, but if I can just get a 1:1 audio transformer it would work given one thing - the primary and secondary must be identical.

In fact is it has to be a custom wind I want them wound bifilar but of course not twisted. An E/I core is fine as long as there's enough of it.

I know it is not going to be cheap. I think off the shelf I might be looking at a hundred or more, especially when they hear what wattage I want to pump through it. At least 100 watts.

Anyone had to do this, actually make them make you a transformer ? Anyone got an idea what shit like this would cost ?

Or if you know of something off the shelf I would have to grease you somehow. Anything but firearms, this is Usenet after all.


I like Edcor, if you can't find what you need from a distributor I
believe they can custom wind what you want. Made in da USA and prices
are pretty reasonable might not cost as much as you expect. downside is
long delivery times, custom winding looks like 8 weeks.

<https://www.edcorusa.com/>

Martin Riddle
Guest

Thu Dec 20, 2018 12:45 pm   



On Thu, 20 Dec 2018 01:40:16 -0500, bitrex <user_at_example.net> wrote:

Quote:
On 12/20/2018 01:01 AM, jurb6006_at_gmail.com wrote:
I looked, didn't find much.

Audio, high quality like a good ass old tube amp, they had them 5 - 100,000 Hz with less than a percent THD. That level of quality, however the specs are different.

I don't need a primary. "Primarily" what I need is a center tapped choke, but if I can just get a 1:1 audio transformer it would work given one thing - the primary and secondary must be identical.

In fact is it has to be a custom wind I want them wound bifilar but of course not twisted. An E/I core is fine as long as there's enough of it.

I know it is not going to be cheap. I think off the shelf I might be looking at a hundred or more, especially when they hear what wattage I want to pump through it. At least 100 watts.

Anyone had to do this, actually make them make you a transformer ? Anyone got an idea what shit like this would cost ?

Or if you know of something off the shelf I would have to grease you somehow. Anything but firearms, this is Usenet after all.


I like Edcor, if you can't find what you need from a distributor I
believe they can custom wind what you want. Made in da USA and prices
are pretty reasonable might not cost as much as you expect. downside is
long delivery times, custom winding looks like 8 weeks.

https://www.edcorusa.com/


Thats interesting they have steel laminations availble. Seems
resonable too, last time I had gone to Temple Steel to get a small
quantity of laminations.

Cheers

Jon Elson
Guest

Thu Dec 20, 2018 8:45 pm   



On Wed, 19 Dec 2018 22:01:03 -0800, jurb6006 wrote:

Quote:
I looked, didn't find much.

Audio, high quality like a good ass old tube amp, they had them 5 -
100,000 Hz with less than a percent THD. That level of quality, however
the specs are different.

I don't need a primary. "Primarily" what I need is a center tapped
choke, but if I can just get a 1:1 audio transformer it would work given
one thing - the primary and secondary must be identical.

In fact is it has to be a custom wind I want them wound bifilar but of
course not twisted. An E/I core is fine as long as there's enough of it.

I know it is not going to be cheap. I think off the shelf I might be
looking at a hundred or more, especially when they hear what wattage I
want to pump through it. At least 100 watts.

100 W at 5 Hz? Yikes, that is going to be a real problem! Or, 100 W at
100 KHz, and same voltage at 5 Hz - maybe that is doable with a big pot
core. Bifilar winding should be quite easy to do on a pot core bobbin.
But, that bifilar winding has HUGE capacitance, as I found out some time
ago. I had a 1/2" pot core with 80 turns of quadrifilar, ENTIRELY for
ease of winding, and ended up with a staggering 500 pF between wires.

Quote:
Anyone had to do this, actually make them make you a transformer ?
Anyone got an idea what shit like this would cost ?

There certainly are outfits that will design and make such things. I
just bought the cores, bobbins and clamp, and made my own, but it was a
much smaller unit.

Jon

speff
Guest

Fri Dec 21, 2018 12:45 am   



On Thursday, 20 December 2018 01:01:07 UTC-5, jurb...@gmail.com wrote:
Quote:
I looked, didn't find much.

Audio, high quality like a good ass old tube amp, they had them 5 - 100,000 Hz with less than a percent THD. That level of quality, however the specs are different.

I don't need a primary. "Primarily" what I need is a center tapped choke, but if I can just get a 1:1 audio transformer it would work given one thing - the primary and secondary must be identical.

In fact is it has to be a custom wind I want them wound bifilar but of course not twisted. An E/I core is fine as long as there's enough of it.

I know it is not going to be cheap. I think off the shelf I might be looking at a hundred or more, especially when they hear what wattage I want to pump through it. At least 100 watts.

Anyone had to do this, actually make them make you a transformer ? Anyone got an idea what shit like this would cost ?

Or if you know of something off the shelf I would have to grease you somehow. Anything but firearms, this is Usenet after all.


Hammond supplies high quality tube style transformers and chokes, not at all cheap. I think they're still made in Guelph, Canada.

--Spehro Pefhany

Steve Wilson
Guest

Fri Dec 21, 2018 12:45 am   



speff <spehro_at_gmail.com> wrote:

Quote:
On Thursday, 20 December 2018 01:01:07 UTC-5, jurb...@gmail.com wrote:
I looked, didn't find much.

Audio, high quality like a good ass old tube amp, they had them 5 -
100,000 Hz with less than a percent THD. That level of quality, however
the specs are different.

I don't need a primary. "Primarily" what I need is a center tapped
choke, but if I can just get a 1:1 audio transformer it would work
given one thing - the primary and secondary must be identical.

In fact is it has to be a custom wind I want them wound bifilar but of
course not twisted. An E/I core is fine as long as there's enough of
it.

I know it is not going to be cheap. I think off the shelf I might be
looking at a hundred or more, especially when they hear what wattage I
want to pump through it. At least 100 watts.

Anyone had to do this, actually make them make you a transformer ?
Anyone got an idea what shit like this would cost ?

Or if you know of something off the shelf I would have to grease you
somehow. Anything but firearms, this is Usenet after all.

Hammond supplies high quality tube style transformers and chokes, not at
all cheap. I think they're still made in Guelph, Canada.

--Spehro Pefhany


I used to use 6V6's driving old filament transformers from the 1940's. They
worked great with the pre-war speakers I had at the time. This was back in
the early 50's. I soon learned there was a limit to how much amplification
you could use. The tube microphonics would make the amplifier howl when you
turned the gain up.

The old transformers are hard to find now. Everyone considers them
collectors items and wants a fortune. If you are lucky, you might find a
scrap wallwart with the right characteristics.

Tim Williams
Guest

Fri Dec 21, 2018 1:45 am   



For what purpose? Literally just audio? Refine your spec -- what impedance
and (3dB) bandwidth? How much balance either side of CT? DCR?

Does it in fact need to be so precisely balanced that a mere CT choke won't
cut it? Do you need a CMC afterwards, or a Guanella style TLT, or a special
balanced and shielded design (probably some combination of all of these)?

Can you not solve the problem without a transformer?
etc.

Curious, how would you even know that it's bifilar vs. twisted pair? Say
it's been potted in tar. X-rays? Actually digging it out? How committed
are you to knowing/verifying it..?

Tim

--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Design
Website: https://www.seventransistorlabs.com/

<jurb6006_at_gmail.com> wrote in message
news:a04a7851-3b35-4912-9572-000c3587a74e_at_googlegroups.com...
Quote:
I looked, didn't find much.

Audio, high quality like a good ass old tube amp, they had them 5 -
100,000 Hz with less than a percent THD. That level of quality, however
the specs are different.

I don't need a primary. "Primarily" what I need is a center tapped choke,
but if I can just get a 1:1 audio transformer it would work given one
thing - the primary and secondary must be identical.

In fact is it has to be a custom wind I want them wound bifilar but of
course not twisted. An E/I core is fine as long as there's enough of it.

I know it is not going to be cheap. I think off the shelf I might be
looking at a hundred or more, especially when they hear what wattage I
want to pump through it. At least 100 watts.

Anyone had to do this, actually make them make you a transformer ? Anyone
got an idea what shit like this would cost ?

Or if you know of something off the shelf I would have to grease you
somehow. Anything but firearms, this is Usenet after all.


boB
Guest

Fri Dec 21, 2018 6:45 am   



On Wed, 19 Dec 2018 22:01:03 -0800 (PST), jurb6006_at_gmail.com wrote:

Quote:
I looked, didn't find much.

Audio, high quality like a good ass old tube amp, they had them 5 - 100,000 Hz with less than a percent THD. That level of quality, however the specs are different.

I don't need a primary. "Primarily" what I need is a center tapped choke, but if I can just get a 1:1 audio transformer it would work given one thing - the primary and secondary must be identical.

In fact is it has to be a custom wind I want them wound bifilar but of course not twisted. An E/I core is fine as long as there's enough of it.

I know it is not going to be cheap. I think off the shelf I might be looking at a hundred or more, especially when they hear what wattage I want to pump through it. At least 100 watts.

Anyone had to do this, actually make them make you a transformer ? Anyone got an idea what shit like this would cost ?

Or if you know of something off the shelf I would have to grease you somehow. Anything but firearms, this is Usenet after all.


So it's an auto-former then ?

Any DC bias or just the 5Hz --- 100 kHz AC ?

5Hz means it's going to be pretty big, depending on the voltage

boB
Guest

Fri Dec 21, 2018 6:45 am   



On Thu, 20 Dec 2018 14:48:50 -0800 (PST), speff <spehro_at_gmail.com>
wrote:

Quote:
On Thursday, 20 December 2018 01:01:07 UTC-5, jurb...@gmail.com wrote:
I looked, didn't find much.

Audio, high quality like a good ass old tube amp, they had them 5 - 100,000 Hz with less than a percent THD. That level of quality, however the specs are different.

I don't need a primary. "Primarily" what I need is a center tapped choke, but if I can just get a 1:1 audio transformer it would work given one thing - the primary and secondary must be identical.

In fact is it has to be a custom wind I want them wound bifilar but of course not twisted. An E/I core is fine as long as there's enough of it.

I know it is not going to be cheap. I think off the shelf I might be looking at a hundred or more, especially when they hear what wattage I want to pump through it. At least 100 watts.

Anyone had to do this, actually make them make you a transformer ? Anyone got an idea what shit like this would cost ?

Or if you know of something off the shelf I would have to grease you somehow. Anything but firearms, this is Usenet after all.

Hammond supplies high quality tube style transformers and chokes, not at all cheap. I think they're still made in Guelph, Canada.

--Spehro Pefhany


I've seen the work that Hammond does. It's very good.

Jasen Betts
Guest

Fri Dec 21, 2018 11:45 am   



On 2018-12-21, boB <boB_at_K7IQ.com> wrote:
Quote:
On Wed, 19 Dec 2018 22:01:03 -0800 (PST), jurb6006_at_gmail.com wrote:

I looked, didn't find much.

Audio, high quality like a good ass old tube amp, they had them 5 - 100,000 Hz with less than a percent THD. That level of quality, however the specs are different.

I don't need a primary. "Primarily" what I need is a center tapped choke, but if I can just get a 1:1 audio transformer it would work given one thing - the primary and secondary must be identical.

In fact is it has to be a custom wind I want them wound bifilar but of course not twisted. An E/I core is fine as long as there's enough of it.

I know it is not going to be cheap. I think off the shelf I might be looking at a hundred or more, especially when they hear what wattage I want to pump through it. At least 100 watts.

Anyone had to do this, actually make them make you a transformer ? Anyone got an idea what shit like this would cost ?

Or if you know of something off the shelf I would have to grease you somehow. Anything but firearms, this is Usenet after all.


So it's an auto-former then ?

Any DC bias or just the 5Hz --- 100 kHz AC ?

5Hz means it's going to be pretty big, depending on the voltage


5Hz and 100VA, it's going to be a foot-breaker if you drop it and miss
the floor not quite microwave oven transfromer size (because single
winding), but that ballpark.


-
When I tried casting out nines I made a hash of it.


Guest

Sat Dec 22, 2018 3:45 am   



Here goes...

>"bitrex
Dec 20
- show quoted text -
I like Edcor, if you can't find what you need from a distributor I
believe they can custom wind what you want."

They look pretty good. Closed for the holidays but then I wasn't in a hurry much anyway.

>"Martin Riddle
Dec 20
- show quoted text -
last time I had gone to Temple Steel to get a small
quantity of laminations. "

I thought they were still used in a whole buncha stuff.

>"Jon Elson
Dec 20
On Wed, 19 Dec 2018 22:01:03 -0800, jurb6006 wrote:

100 W at 5 Hz? Yikes, that is going to be a real problem! "

I might have to settle for less, err more.

>"But, that bifilar winding has HUGE capacitance, as I found out some time ago. I had a 1/2" pot core with 80 turns of quadrifilar, ENTIRELY for ease of winding, and ended up with a staggering 500 pF between wires. "

Wouldn't a heavier gauge wire with thicker insulation help a bit ?

>" speff
Dec 20
- show quoted text -
Hammond supplies high quality tube style transformers and chokes, not at all cheap."

Is that the organ people ? Audiophiles do have those amps rebuilt.

>"Steve Wilson
Dec 20
- show quoted text -
I used to use 6V6's driving old filament transformers from the 1940's"

I used the secondary of a power transformer once and while it worked it didn't sound all that good.

>"Tim Williams
Dec 20
For what purpose? Literally just audio? Refine your spec -- what impedance and (3dB) bandwidth? "

I could be happy with 8HZ - 30KHz @ -3dB. The low end is slightly more important that the y high end, I THINK.

>"How much balance either side of CT? DCR?"

Bias on each side would cancel, so whatever minimal heat, which is for class AB audio amps would not be much. Fuck class A. Given that there is no hint of saturation except at high levels, and there is just heat because of the DCR.

>"Does it in fact need to be so precisely balanced that a mere CT choke won't cut it? "

A CT choke would be fine but every time I look for one I come up with a blank. And for this application, precise balance is important.

>"Do you need a CMC afterwards, or a Guanella style TLT, or a special balanced and shielded design (probably some combination of all of these)?"

Not sure what CMC is except for a type of connector, it is not a balun or going to drive anything you would call a transmission line because this is audio.

>"Can you not solve the problem without a transformer?"

No, the main principles depend on it.

>"Curious, how would you even know that it's bifilar vs. twisted pair? "

Wouldn't there be some strange inductive effects when NOT used strictly in parallel ? The inductances would add no ? The main inductances will add of course, why not the inductance of the twist when phased (polaritied ?) that way ?

>"Say it's been potted in tar. X-rays? Actually digging it out? How committed are you to knowing/verifying it..? "

Well by ordering it mainly. I don't have an Xray machine handy. I think it would probably be more expensive to twist than not to twist no ? As such they would want more money and call it a feature. Right now I am not even sure what benefits there are to twisting them.

>"boB
Dec 20 (21 hours ago)
- show quoted text -
So it's an auto-former then ?

Any DC bias or just the 5Hz --- 100 kHz AC ? "

Yes, auto or CT, whichever. Voltage equal. Impedance of the whole thing is 4X each half, accurately. The bias is only in the mA and is applied opposite to each half of the whole thing. Nothing residual at quiescence.

>"Jasen Betts
5:01 AM (16 hours ago)
- show quoted text -
5Hz and 100VA, it's going to be a foot-breaker if you drop it and miss the floor"

Yup. Even if I said 10Hz it will not be small. I can even go higher actually but not too much.
----
Cost wise, a hundred bucks each would be great. I only need four, for two prototypes. After that, if it is a go I'll burn that bridge when I come to it.


Guest

Sat Dec 22, 2018 6:45 am   



On Saturday, December 22, 2018 at 1:28:26 PM UTC+11, jurb...@gmail.com wrote:
Quote:
Here goes...

"bitrex
Dec 20


<snip>

Quote:
"Curious, how would you even know that it's bifilar vs. twisted pair? "

Wouldn't there be some strange inductive effects when NOT used strictly in parallel ? The inductances would add no ? The main inductances will add of course, why not the inductance of the twist when phased (polaritied ?) that way?

"Say it's been potted in tar. X-rays? Actually digging it out? How committed are you to knowing/verifying it..? "

Well by ordering it mainly. I don't have an Xray machine handy. I think it would probably be more expensive to twist than not to twist no ? As such they would want more money and call it a feature. Right now I am not even sure what benefits there are to twisting them.


Probably not more expensive. Bifilar windings are normally twisted - you do have to twist the wire before you wind it on, but that's never been a problem.

The main benefit is that the two twisted wires see almost exactly the same magnetic field, and - because of the twisting - any tiny differences are equal and opposite and cancel out almost perfectly.

https://www.amazon.com/Coaxial-AC-Bridges-B-Kibble/dp/0852743890

Rayner and Kibble point out that carefully wound multi-wire ratio transformers give successive taps that are equal to one part in about ten million, but in a bifilar wound transformers the two windings can be equal to one part in a billion.

The Kibble in the author list is the same Kibble remembered in the "Kibble balance" that now replaces the kilogram standard mass.

--
Bill Sloman, Sydney

Tauno Voipio
Guest

Sat Dec 22, 2018 10:45 am   



On 22.12.18 04:28, jurb6006_at_gmail.com wrote:

Quote:
Any DC bias or just the 5Hz --- 100 kHz AC ? "

Yes, auto or CT, whichever. Voltage equal. Impedance of the whole thing is 4X each half, accurately. The bias is only in the mA and is applied opposite to each half of the whole thing. Nothing residual at quiescence.


The impedance level and low-frequency limit are absolutely crucial,
the required inductance of the windings depends on those. The
upper end of the usable frequency range depends on the leakage
inductances (L1-M and L2-M) and windong capacitances, together
with the impedance level (again).

In 1:1 transformer equivalent circuit there is a series branch
consisting of primary resistance, primary inductance minus
mutual inductance, secondary inductance minus mutual inductance
and secondary resistance. From the connection between the
series inductances, there is mutual inductance to the common
voltage. See the LTSpice model below.

If a transformer has some other transformation ratio, it is
modeled as an ideal impedance transformation connected to
a 1:1 model.

LTSpice:

Version 4
SHEET 1 880 680
WIRE 64 240 -32 240
WIRE 208 240 144 240
WIRE 336 240 288 240
WIRE 384 240 336 240
WIRE 544 240 464 240
WIRE 736 240 624 240
WIRE 336 304 336 240
WIRE 336 432 336 384
WIRE 336 432 -48 432
WIRE 752 432 336 432
WIRE -48 448 -48 432
WIRE 752 448 752 432
FLAG -48 448 0
FLAG 752 448 0
FLAG -32 240 In
IOPIN -32 240 In
FLAG 736 240 Out
IOPIN 736 240 Out
SYMBOL res 160 224 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R1
SYMATTR Value ""
SYMBOL res 640 224 R90
WINDOW 0 -3 55 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R2
SYMATTR Value ""
SYMBOL ind 192 256 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 5 56 VBottom 2
SYMATTR InstName L1-M
SYMATTR Value ""
SYMBOL ind 368 256 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 5 56 VBottom 2
SYMATTR InstName L2-M
SYMATTR Value ""
SYMBOL ind 320 288 R0
SYMATTR InstName M
SYMATTR Value ""

--

-TV

Tim Williams
Guest

Mon Dec 24, 2018 6:45 am   



<jurb6006_at_gmail.com> wrote in message
news:9014427d-1c41-40c7-a5b8-ec5ee38beaa8_at_googlegroups.com...
Quote:
"But, that bifilar winding has HUGE capacitance, as I found out some time
ago. I had a 1/2" pot core with 80 turns of quadrifilar, ENTIRELY for ease
of winding, and ended up with a staggering 500 pF between wires. "

Wouldn't a heavier gauge wire with thicker insulation help a bit ?


Again, depends on specs. With high capacitance, you also get staggeringly
low leakage. More generally speaking: the impedance is lower. Which gives
you more bandwidth at a given system bandwidth.

I'm guessing your impedance is quite low, but again, without specs...


Quote:
"Tim Williams
Dec 20
For what purpose? Literally just audio? Refine your spec -- what
impedance and (3dB) bandwidth? "
?
I could be happy with 8HZ - 30KHz @ -3dB. The low end is slightly more
important that the y high end, I THINK.


Okay but there were two questions there?


Quote:
"How much balance either side of CT? DCR?"

Bias on each side would cancel, so whatever minimal heat, which is for
class AB audio amps would not be much. Fuck class A. Given that there is no
hint of saturation except at high levels, and there is just heat because of
the DCR.


Okay, so, a push-pull amplifier maybe?
Transistors?
Is that going to be, like, an ampere? Two? A hundred? Or one volt, ten or
a hundred? You've said 100VA but that's missing one more number.
What's wrong with complementary push-pull?


Quote:
Not sure what CMC is except for a type of connector, it is not a balun or
going to drive anything you would call a transmission line because this is
audio.


Common mode choke -- a real CT choke can't give perfectly differential
balance, but a CMC can clean it up.

You've said about nothing about the application so I have no clue where
you're actually going with this. :-\


Quote:
"Curious, how would you even know that it's bifilar vs. twisted pair? "

Wouldn't there be some strange inductive effects when NOT used strictly in
parallel ? The inductances would add no ? The main inductances will add of
course, why not the inductance of the twist when phased (polaritied ?) that
way ?


Which inductances? The winding inductance is the same, it's going around
the core the same number of times. (If it weren't, it wouldn't be a 1:1
transformer!)

The leakage inductance is more or less the same, because the distance
between wires, and wire length, is more or less the same. Or, more
accurately, inseperable from differences in wire/insulation diameter, or
variation in winding length.

Remember, if you can't measure it -- it doesn't matter!

Tim

--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Design
Website: https://www.seventransistorlabs.com/

Tauno Voipio
Guest

Mon Dec 24, 2018 2:45 pm   



On 24.12.18 06:49, Tim Williams wrote:
Quote:
jurb6006_at_gmail.com> wrote in message
news:9014427d-1c41-40c7-a5b8-ec5ee38beaa8_at_googlegroups.com...
"But, that bifilar winding has HUGE capacitance, as I found out some
time ago. I had a 1/2" pot core with 80 turns of quadrifilar,
ENTIRELY for ease of winding, and ended up with a staggering 500 pF
between wires. "

Wouldn't a heavier gauge wire with thicker insulation help a bit ?


Again, depends on specs.  With high capacitance, you also get
staggeringly low leakage.  More generally speaking: the impedance is
lower.  Which gives you more bandwidth at a given system bandwidth.

I'm guessing your impedance is quite low, but again, without specs...


"Tim Williams
Dec 20
For what purpose?  Literally just audio?  Refine your spec -- what
impedance and (3dB) bandwidth? "
?
I could be happy with 8HZ - 30KHz @ -3dB. The low end is slightly more
important that the y high end, I THINK.


Okay but there were two questions there?


"How much balance either side of CT?  DCR?"

Bias on each side would cancel, so whatever minimal heat, which is for
class AB audio amps would not be much. Fuck class A. Given that there
is no hint of saturation except at high levels, and there is just heat
because of the DCR.


Okay, so, a push-pull amplifier maybe?
Transistors?
Is that going to be, like, an ampere?  Two?  A hundred?  Or one volt,
ten or a hundred?  You've said 100VA but that's missing one more number.
What's wrong with complementary push-pull?


Not sure what CMC is except for a type of connector, it is not a balun
or going to drive anything you would call a transmission line because
this is audio.


Common mode choke -- a real CT choke can't give perfectly differential
balance, but a CMC can clean it up.

You've said about nothing about the application so I have no clue where
you're actually going with this. :-\


"Curious, how would you even know that it's bifilar vs. twisted pair? "

Wouldn't there be some strange inductive effects when NOT used
strictly in parallel ? The inductances would add no ? The main
inductances will add of course, why not the inductance of the twist
when phased (polaritied ?) that way ?


Which inductances?  The winding inductance is the same, it's going
around the core the same number of times.  (If it weren't, it wouldn't
be a 1:1 transformer!)

The leakage inductance is more or less the same, because the distance
between wires, and wire length, is more or less the same.  Or, more
accurately, inseperable from differences in wire/insulation diameter, or
variation in winding length.

Remember, if you can't measure it -- it doesn't matter!

Tim


Some time ago the OP posted a transistor amplifier with two
emitter followers in push-pull and the autotransformer as
the emitter feed choke. The speaker load was to be connected
between the emitters. The expected frequency range is simply
not realizable with audio transformers. Five decades is a
heavy challenge even with RF transmission line and magnetics
transformers.

I just do not understand him wanting all the troubles of the
transformer, as there is no such pressing need for it as in
tube amplifiers. But more than 50 years in professional electronics
has not given me an understanding of the audio things ...

--

-TV

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