[Bob F]

The schematic here seems completely wrong to me.
http://www.mcmelectronics.com/conten...ts/50-7725.pdf

http://canada.newark.com/mcm-custom-...eld/dp/96K0889

[Don Pearce[_3_]]

On Sun, 5 May 2013 09:44:40 -0700, "Bob F"
wrote:

The schematic here seems completely wrong to me.
http://www.mcmelectronics.com/conten...ts/50-7725.pdf

http://canada.newark.com/mcm-custom-...eld/dp/96K0889

Looks OK to me. It's configured as a series common mode stopper.
What's the problem?

d

[Bob F]

Don Pearce wrote:
On Sun, 5 May 2013 09:44:40 -0700, "Bob F"
wrote:

The schematic here seems completely wrong to me.
http://www.mcmelectronics.com/conten...ts/50-7725.pdf

http://canada.newark.com/mcm-custom-...eld/dp/96K0889

Looks OK to me. It's configured as a series common mode stopper.
What's the problem?

Will this design eliminate ground loop problems? My concept of baluns was that
they isolated the two ends by placing them on opposite windings of a
transformer. I am no expert, which is why I asked.

[Don Pearce[_3_]]

On Sun, 5 May 2013 10:26:13 -0700, "Bob F"
wrote:

Don Pearce wrote:
On Sun, 5 May 2013 09:44:40 -0700, "Bob F"
wrote:

The schematic here seems completely wrong to me.
http://www.mcmelectronics.com/conten...ts/50-7725.pdf

http://canada.newark.com/mcm-custom-...eld/dp/96K0889

Looks OK to me. It's configured as a series common mode stopper.
What's the problem?

Will this design eliminate ground loop problems? My concept of baluns was that
they isolated the two ends by placing them on opposite windings of a
transformer. I am no expert, which is why I asked.


That is a different thing. You need a transformer to kill a ground
loop entirely, but yes, provided there is enough inductance in the
coils this will still make a good job of getting rid of hum from a
ground loop.

The downside of the transformer method is that lower bass response is
usually somewhat compromised.

d

[isw]

In article ,
(Don Pearce) wrote:

On Sun, 5 May 2013 10:26:13 -0700, "Bob F"
wrote:

Don Pearce wrote:
On Sun, 5 May 2013 09:44:40 -0700, "Bob F"
wrote:

The schematic here seems completely wrong to me.
http://www.mcmelectronics.com/conten...ets/50-7725.pd
f

http://canada.newark.com/mcm-custom-...n-rca-plug-rj4
5-shield/dp/96K0889

Looks OK to me. It's configured as a series common mode stopper.
What's the problem?

Will this design eliminate ground loop problems? My concept of baluns was
that
they isolated the two ends by placing them on opposite windings of a
transformer. I am no expert, which is why I asked.


That is a different thing. You need a transformer to kill a ground
loop entirely, but yes, provided there is enough inductance in the
coils this will still make a good job of getting rid of hum from a
ground loop.

If there's enough inductance to attenuate 60 (or 50) Hz from the power
line, why won't it do the same for similar frequencies in the desired
signal?

The downside of the transformer method is that lower bass response is
usually somewhat compromised.

For any sort of well-designed and properly terminated transformer, the
lower 3dB point will be well below the frequency of any "musical note"
you'll ever want to pass through it. So, no, bass response won't be
compromised at all.

Isaac

[Don Pearce[_3_]]

On Sun, 05 May 2013 23:04:35 -0700, isw wrote:

In article ,
(Don Pearce) wrote:

On Sun, 5 May 2013 10:26:13 -0700, "Bob F"
wrote:

Don Pearce wrote:
On Sun, 5 May 2013 09:44:40 -0700, "Bob F"
wrote:

The schematic here seems completely wrong to me.
http://www.mcmelectronics.com/conten...ets/50-7725.pd
f

http://canada.newark.com/mcm-custom-...n-rca-plug-rj4
5-shield/dp/96K0889

Looks OK to me. It's configured as a series common mode stopper.
What's the problem?

Will this design eliminate ground loop problems? My concept of baluns was
that
they isolated the two ends by placing them on opposite windings of a
transformer. I am no expert, which is why I asked.


That is a different thing. You need a transformer to kill a ground
loop entirely, but yes, provided there is enough inductance in the
coils this will still make a good job of getting rid of hum from a
ground loop.

If there's enough inductance to attenuate 60 (or 50) Hz from the power
line, why won't it do the same for similar frequencies in the desired
signal?


No, because of the way the windings are arranged their inductances
cancel each other out for the audio signal, but not for the induced
hum.

The downside of the transformer method is that lower bass response is
usually somewhat compromised.

For any sort of well-designed and properly terminated transformer, the
lower 3dB point will be well below the frequency of any "musical note"
you'll ever want to pass through it. So, no, bass response won't be
compromised at all.

Effects strat becoming apparent well before you hit the 3dB point.

d

[Kevin McMurtrie[_3_]]

In article , "Bob F"
wrote:

Don Pearce wrote:
On Sun, 5 May 2013 09:44:40 -0700, "Bob F"
wrote:

The schematic here seems completely wrong to me.
http://www.mcmelectronics.com/conten...ts/50-7725.pdf

http://canada.newark.com/mcm-custom-...-rca-plug-rj45
-shield/dp/96K0889

Looks OK to me. It's configured as a series common mode stopper.
What's the problem?

Will this design eliminate ground loop problems? My concept of baluns was
that
they isolated the two ends by placing them on opposite windings of a
transformer. I am no expert, which is why I asked.

It will stop ground loop problems for the range of frequencies where the
transformers work. It's not clear what that is.

Transformers have a limited working range of frequencies. The ones you
posted have DC to MHz passthrough but limited common mode blocking. The
other wiring of isolators blocks DC to MHz common mode but only passes
through maybe 50Hz to 15 Khz; more or less depending on the quality.
Isolators can do weird things to the impedance too.

If this is pro-audio, the absolutely best fix is using balanced cables
with balanced connectors. The audio quality will be superior to any
other hack.
--
I will not see posts from Google because I must filter them as spam

[Jon Elson]

Bob F wrote:

The schematic here seems completely wrong to me.

http://www.mcmelectronics.com/conten...ts/50-7725.pdf


This datasheet shows it is a VIDEO balun.

Jon

[Don Pearce[_3_]]

On Mon, 06 May 2013 14:46:56 -0500, Jon Elson
wrote:

Bob F wrote:

The schematic here seems completely wrong to me.

http://www.mcmelectronics.com/conten...ts/50-7725.pdf


This datasheet shows it is a VIDEO balun.

Jon

So it needs a much wider bandwidth than just an audio one.

d

[Bob F]

Jon Elson wrote:
Bob F wrote:

The schematic here seems completely wrong to me.

http://www.mcmelectronics.com/conten...ts/50-7725.pdf


This datasheet shows it is a VIDEO balun.


Wow! I clearly didn't pay enough attention. It is the "datasheet" for what
claims to be"AUDIO BALUN, RCA PLUG-RJ45 SHIELD JACK". I guess Newark doesn't
have their act together.

[Don Pearce[_3_]]

On Mon, 6 May 2013 13:29:33 -0700, "Bob F"
wrote:

Jon Elson wrote:
Bob F wrote:

The schematic here seems completely wrong to me.

http://www.mcmelectronics.com/conten...ts/50-7725.pdf


This datasheet shows it is a VIDEO balun.


Wow! I clearly didn't pay enough attention. It is the "datasheet" for what
claims to be"AUDIO BALUN, RCA PLUG-RJ45 SHIELD JACK". I guess Newark doesn't
have their act together.

Just means you get some bonus performance - audio plus a load more.

d

[isw]

In article , "Bob F"
wrote:

Jon Elson wrote:
Bob F wrote:

The schematic here seems completely wrong to me.

http://www.mcmelectronics.com/conten...ts/50-7725.pdf


This datasheet shows it is a VIDEO balun.


Wow! I clearly didn't pay enough attention. It is the "datasheet" for what
claims to be"AUDIO BALUN, RCA PLUG-RJ45 SHIELD JACK". I guess Newark doesn't
have their act together.

Look again. There are several devices on that page. The 50-7725 *is* for
audio.

Isaac

[geoff]

"Bob F" wrote in message
...
Jon Elson wrote:
Bob F wrote:

The schematic here seems completely wrong to me.

http://www.mcmelectronics.com/conten...ts/50-7725.pdf


This datasheet shows it is a VIDEO balun.


Wow! I clearly didn't pay enough attention. It is the "datasheet" for what
claims to be"AUDIO BALUN, RCA PLUG-RJ45 SHIELD JACK". I guess Newark
doesn't have their act together.


Just to fudge things further (not really, well not for us at least)
audio/video-over-cat5 industry calls the tx and rx 'baluns' !

geoff

[Michael A. Terrell]

Bob F wrote:

The schematic here seems completely wrong to me.
http://www.mcmelectronics.com/conten...ts/50-7725.pdf


That is a VIDEO Balun for 75 ohm unbalanced to 100 ohm balanced. It
is not intended for audio. It is to use Cat5 wire for 75 Ohm video from
security cameras.


http://canada.newark.com/mcm-custom-...eld/dp/96K0889

Another link to the same part.

[Wild_Bill]

If these small transformers won't provide the characteristics you want/need,
you could look for an opto-isolation solution.

--
Cheers,
WB
..............


"Bob F" wrote in message
...
The schematic here seems completely wrong to me.
http://www.mcmelectronics.com/conten...ts/50-7725.pdf

http://canada.newark.com/mcm-custom-...eld/dp/96K0889