audio transformers

[John Larkin]

Who makes small (pc mount, signal-level) audio transformers these
days?

I need..

potted or decently varnished open-frame

3:1 stepup or so, maybe 60:600 ohms or such

50-100 mW

50 Hz-30 KHz, but maybe reduced voltage swing at low frequencies

0.6" cube or less maybe

Under $10 at 100 pieces

This will be used on the output of a multichannel wave/function
generator to boost the output from 20 v p-p (opamp levels) to 60 v p-p
floating. SSRs will kick in the transformer when it's needed, to
simulate VR speed pickups or engine-driven alternators in jet engine
test stands.

I looked at Triad and Tamura, and got some near misses. The catalogs
(Mouser, Digikey, Allied, Newark) have very little audio stuff these
days.

John

 

[Joerg]

Hello John,

Who makes small (pc mount, signal-level) audio transformers these
days?

I need..

potted or decently varnished open-frame

3:1 stepup or so, maybe 60:600 ohms or such

50-100 mW

50 Hz-30 KHz, but maybe reduced voltage swing at low frequencies

0.6" cube or less maybe

Under $10 at 100 pieces

This will be used on the output of a multichannel wave/function
generator to boost the output from 20 v p-p (opamp levels) to 60 v p-p
floating. SSRs will kick in the transformer when it's needed, to
simulate VR speed pickups or engine-driven alternators in jet engine
test stands.

I looked at Triad and Tamura, and got some near misses. The catalogs
(Mouser, Digikey, Allied, Newark) have very little audio stuff these
days.

I'll go through my lab bins to see who made the ones in there (but has
to me tomorrow night, got to run). Meantime, maybe try Murata. You might
also try Muxlab in Canada. They usually sell modules with connectors but
at 100+ might be willing to sell the innards.

 

[Joerg]

Hello John,

Who makes small (pc mount, signal-level) audio transformers these
days?

I need..

potted or decently varnished open-frame

3:1 stepup or so, maybe 60:600 ohms or such

50-100 mW

50 Hz-30 KHz, but maybe reduced voltage swing at low frequencies

0.6" cube or less maybe

Under $10 at 100 pieces

This will be used on the output of a multichannel wave/function
generator to boost the output from 20 v p-p (opamp levels) to 60 v p-p
floating. SSRs will kick in the transformer when it's needed, to
simulate VR speed pickups or engine-driven alternators in jet engine
test stands.

I looked at Triad and Tamura, and got some near misses. The catalogs
(Mouser, Digikey, Allied, Newark) have very little audio stuff these
days.

Ok, I looked in the lab bin and here is the brand I used in the past:

http://www.triadmagnetics.com/subcategory/atmil.html

They also have non-mil versions. Down to 50Hz will be tough and you
might not exactly get 60ohms. Their web site is pretty messed up but
their products are nice.

Triad is located in Caleefohniah (Corona). Of course

 

[mw]

Who makes small (pc mount, signal-level) audio transformers these
days?

I need..

potted or decently varnished open-frame

3:1 stepup or so, maybe 60:600 ohms or such

50-100 mW

50 Hz-30 KHz, but maybe reduced voltage swing at low frequencies

0.6" cube or less maybe

Under $10 at 100 pieces

This is not exactly what you want but the price is good and they have
great mechanical documentation:

http://www.edcorusa.com/transformers/pc/pc.htm

I have bought a couple of individual parts from them and they were very
good quality. They offer custom runs.

 

[Eeyore]

Who makes small (pc mount, signal-level) audio transformers these
days?

I need..

potted or decently varnished open-frame

3:1 stepup or so, maybe 60:600 ohms or such

50-100 mW

50 Hz-30 KHz, but maybe reduced voltage swing at low frequencies

0.6" cube or less maybe

Under $10 at 100 pieces

This will be used on the output of a multichannel wave/function
generator to boost the output from 20 v p-p (opamp levels) to 60 v p-p
floating. SSRs will kick in the transformer when it's needed, to
simulate VR speed pickups or engine-driven alternators in jet engine
test stands.

I looked at Triad and Tamura, and got some near misses. The catalogs
(Mouser, Digikey, Allied, Newark) have very little audio stuff these
days.

You'll need something fairly special for those voltages. It certainly isn't '600
ohms' for sure.

Graham

 

[John Larkin]

You'll need something fairly special for those voltages. It certainly isn't '600
ohms' for sure.

Graham

Yeah, it may need to be a special. These guys...

http://www.precision-inc.com/

did some custom magnetics for us a while back, very nice work and good
pricing... USA design and manufactured in India. I guess I may have to
go the pita custom route if nothing stock shows up. All I really need
is 60 volts p-p, very low power, and maybe less voltage on the low
frequency end. Both the VR speed sensors and alternators tend to
produce voltage proportional to frequency.

John

 

[Eeyore]

Yeah, it may need to be a special. These guys...

http://www.precision-inc.com/

did some custom magnetics for us a while back, very nice work and good
pricing... USA design and manufactured in India. I guess I may have to
go the pita custom route if nothing stock shows up. All I really need
is 60 volts p-p, very low power, and maybe less voltage on the low
frequency end. Both the VR speed sensors and alternators tend to
produce voltage proportional to frequency.

What's the load ? How good does frequency and transient response need to be ?

Graham

 

[John - KD5YI]

Who makes small (pc mount, signal-level) audio transformers these
days?

I need..

potted or decently varnished open-frame

3:1 stepup or so, maybe 60:600 ohms or such

50-100 mW

50 Hz-30 KHz, but maybe reduced voltage swing at low frequencies

0.6" cube or less maybe

Under $10 at 100 pieces

This will be used on the output of a multichannel wave/function
generator to boost the output from 20 v p-p (opamp levels) to 60 v p-p
floating. SSRs will kick in the transformer when it's needed, to
simulate VR speed pickups or engine-driven alternators in jet engine
test stands.

I looked at Triad and Tamura, and got some near misses. The catalogs
(Mouser, Digikey, Allied, Newark) have very little audio stuff these
days.

John

http://www.mouser.com/search/refine.aspx?Ntt=838-MET-39

50:500 might work.

Cheers,
John

 

[Eeyore]

http://www.mouser.com/search/refine.aspx?Ntt=838-MET-39

50:500 might work.

No way any standard transformer is going to have the volt-second rating IMHO.

Graham

 

[Phil Allison]

"Eeyore"

No way any standard transformer is going to have the volt-second rating
IMHO.

** A Lo-to Hi Z mic transformer meets the basic spec.

Eg, one used in a Shure 545 outputs 60 volts p-p at 100 Hz into 47 k with
low THD.

Response is flat, -3dB at 50 kHz into the same load.

Dim: 26 x 14 x 18 mm.

Shame it is an auto.

Isolation ones must exist.




......... Phil

 

[Don Foreman]

Yeah, it may need to be a special. These guys...

http://www.precision-inc.com/

did some custom magnetics for us a while back, very nice work and good
pricing... USA design and manufactured in India. I guess I may have to
go the pita custom route if nothing stock shows up. All I really need
is 60 volts p-p, very low power, and maybe less voltage on the low
frequency end. Both the VR speed sensors and alternators tend to
produce voltage proportional to frequency.

John

I was going to suggest these guys. I've worked with them too. Doing
a custom design with them was incredibly painless; took about 10
minutes in a visit, then we spent a while talking about fishing! The
little transformers they made worked perfectly in my application.

Being less than five miles from them made a visit real easy to do.

 

[John Woodgate]

In message <[email protected]>, dated Wed, 30

Who makes small (pc mount, signal-level) audio transformers these days?

Jensen. www.jensen-transformers.com/

 

[Eeyore]

Who makes small (pc mount, signal-level) audio transformers these
days?

I need..

potted or decently varnished open-frame

3:1 stepup or so, maybe 60:600 ohms or such

50-100 mW

50 Hz-30 KHz, but maybe reduced voltage swing at low frequencies

0.6" cube or less maybe

Under $10 at 100 pieces

This will be used on the output of a multichannel wave/function
generator to boost the output from 20 v p-p (opamp levels) to 60 v p-p
floating. SSRs will kick in the transformer when it's needed, to
simulate VR speed pickups or engine-driven alternators in jet engine
test stands.

I looked at Triad and Tamura, and got some near misses. The catalogs
(Mouser, Digikey, Allied, Newark) have very little audio stuff these
days.

This will do ~ 60V pk-pk @ 50Hz. That'll be the tricky spec. Quite a bit bigger
than you want though.
http://www.lundahl.se/pdfs/datash/1588.pdf

Graham

 

[Eeyore]

"Eeyore"

** A Lo-to Hi Z mic transformer meets the basic spec.

Eg, one used in a Shure 545 outputs 60 volts p-p at 100 Hz into 47 k with
low THD.

Response is flat, -3dB at 50 kHz into the same load.

Dim: 26 x 14 x 18 mm.

Shame it is an auto.

Isolation ones must exist.

I've found a Lundahl that's good for 55V pk-pk @ 50Hz ( 1% THD )
http://www.lundahl.se/catframe.html LL1588
Quite a size though.

Graham

 

[John Woodgate]

In message <[email protected]>, dated Wed, 30

Who makes small (pc mount, signal-level) audio transformers these days?

I need..

potted or decently varnished open-frame

3:1 stepup or so, maybe 60:600 ohms or such

50-100 mW

50 Hz-30 KHz, but maybe reduced voltage swing at low frequencies

0.6" cube or less maybe

Under $10 at 100 pieces

This will be used on the output of a multichannel wave/function
generator to boost the output from 20 v p-p (opamp levels) to 60 v p-p
floating.

For those voltages and the size constraint, you need a special design.
But you probably don't need a nickel-iron core; a silicon-iron one will
do and that would be much cheaper. A COTS part will be bigger and more
costly than you want.

How low in voltage at 50 Hz can you go, and at what frequency do you
need to handle 7 V (+20 dBu, nearly) input? These are crucial in
determining core size.

 

[John Fields]

Who makes small (pc mount, signal-level) audio transformers these
days?

I need..

potted or decently varnished open-frame

3:1 stepup or so, maybe 60:600 ohms or such

50-100 mW

50 Hz-30 KHz, but maybe reduced voltage swing at low frequencies

0.6" cube or less maybe

Under $10 at 100 pieces

This will be used on the output of a multichannel wave/function
generator to boost the output from 20 v p-p (opamp levels) to 60 v p-p
floating. SSRs will kick in the transformer when it's needed, to
simulate VR speed pickups or engine-driven alternators in jet engine
test stands.

I looked at Triad and Tamura, and got some near misses. The catalogs
(Mouser, Digikey, Allied, Newark) have very little audio stuff these
days.

 

[Phil Allison]

"Eeyore"

I've found a Lundahl that's good for 55V pk-pk @ 50Hz ( 1% THD )
http://www.lundahl.se/catframe.html LL1588
Quite a size though.

** JL's naive size & cost and performance specs cannot be simultaneously met
by any practical design - which is completely consistent with his being
self admitted bi-polar sufferer.

Once the malicious, arrogant posturing ASS take his fist off his tiny cock
and relaxes ANY one of them - the task is dead simple.






........ Phil

 

[John Larkin]

"Eeyore"


** JL's naive size & cost and performance specs cannot be simultaneously met
by any practical design - which is completely consistent with his being
self admitted bi-polar sufferer.

I believe I mentioned that I don't need the full 60 volts p-p at low
frequencies, since I'm mostly simulating jet-engine alternators. My
customer is currently using a tiny and - no surprise - very expensive
Pico part to do this, and I have at least 5x the available volume to
work in. I would like to get the most voltage at 50 Hz as possible, so
I'd like to use all the iron that will fit.

But what's this fascination you have for the nether elements of male
anatomy?

John

 

[John Larkin]

This will do ~ 60V pk-pk @ 50Hz. That'll be the tricky spec. Quite a bit bigger
than you want though.
http://www.lundahl.se/pdfs/datash/1588.pdf

Graham

Yeah, that would work except for being huge. I have partisans for
using a dc-dc converter, a floating amp, and optical isolation to get
the hv floating output, 8 channels per board, and I must fight these
lunatics off.

John

 

[John Larkin]

Yeah, my customer is already using a Pico part, at about $40 a pop. I
don't want to spend anything like that, not with 8 transformers per
board.

John