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RJ-45 for instrument interface

For one reason, everybody assumes that an RJ45 is an Ethernet connector, so care is needed so that nothing gets blown up.

For another reason, they aren't the most reliable connectors in captivity, especially when daisy-chained.

For a third, there are a lot of different styles of Ethernet patch cords out there--especially crossover cords--and some squaddy is bound to use the wrong one. You'll get blamed for the resulting failure, as sure as God made little green apples.

I've often repurposed video cables (Displayport and HDMI) but not RJ45, thanks.

Cheers

Phil Hobbs

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Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net
Reply to
Phil Hobbs
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How's that going to happen?

As I see it with the coax isolated the only current flowing in the shield is the return of the current flowing in the core and that current will be drawn to the inside of the shield by the magnetic field of the core.

that's pretty much guaranteed to cause ground loops.

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Reply to
Jasen Betts

Unrelated to this request, but I ran across this from HP on using RJ45 connectors for analog instrumentation applications. They ended up using it for strain gauges, which, as most of you know, are rather low level devices.

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The combination of good electrical performance and cheap/reliable termination of shielded or unshielded twisted pairs is useful.

--sp

Reply to
Spehro Pefhany

Very much so!

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Les Cargill
Reply to
Les Cargill

Very interesting information. The connector is much more reliable than I thought. Excellent stability, 750 mating cycles, inexpensive and available everywhere. Pretty hard to beat.

Directly applicable to my request. Thanks, Speff

Reply to
Steve Wilson

On Mar 15, 2018, Jasen Betts wrote (in article ):

Yes. We use RF transformers to break ground loops in coax all the time. If it?s really critical, one uses shielded transformers, but if it?s low power, a transformer the size of a peppercorn is too small to radiate much.

Yep. For RF, what also works is to make the inputs to power-frequency ground loops.

See MIL-STD-461 method CS-109.

Joe Gwinn

Reply to
Joseph Gwinn

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