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3.5mm TRS as electro-mechanical interface

3.5mm TRS as electro-mechanical interface

3.5mm TRS as electro-mechanical interface

Hi all,

I am developing the mechanical aspects of a new product that requires some sort of locating pin interface for positive placement. At this interface there also needs to be a means of electrical communication, ground, power and 3 com lines.

I am considering using two 3.5mm TRS pins to do this, but can't find any examples of this in the past. Is there a reason this might not be a good idea? The product will be in a home with frequent user contact, but no severe vibration.

The other option would be something like a 6 pin molex connector and separate locating pins. Maybe something like these.

Thanks for your input.


RE: 3.5mm TRS as electro-mechanical interface

Welcome to Eng-Tips.

TRS pins? Do yourself a favor and don't abbreviate in here and/or maybe give an example picture or a link to one. There are engineers from all over the world here so abbreviations fall flat or mean radically different things to some.

As for the Molex battery connector you 'these'd to, I'd be a little concerned since you didn't specify your communications. I suspect you need gold contacts and don't believe 'these' are.

Say some more about your task. Are you trying to locate something against a circuit board or is this mating two circuit boards together? Is this a frequently done task or a once in a great while mating?

Keith Cress
kcress - http://www.flaminsystems.com

RE: 3.5mm TRS as electro-mechanical interface

Have you considered blind mate connectors? Like http://www.molex.com/molex/products/family?key=min...

These allow for some misalignment and the bevels guide the connector to the correct mating position.

In general, alignments pins serving as electrical connections would be bad for a number of reasons:
> they typically need to be rigidly mounted to maintain alignment, which means they're either bolted metal to metal or similar, so insulation would be difficult
> circuit damage from ESD -- exposed pins could get zapped by ESD
> contamination -- exposed pins are more likely to pick up dirt and contaminants and might interfere with electrical conductivity
> safety -- exposed power pins could result in electrical shocks

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RE: 3.5mm TRS as electro-mechanical interface

This product will replace your light switch on the wall, so you will not have to install or remove it frequently, but people will be poking at it many times each day.

The TRS acronym stands for Tip Ring Sleeve. Generally they are used for headphone jacks.

I was imagining the TRS connector acting as a guide between two circuit board connections upon installation.

RE: 3.5mm TRS as electro-mechanical interface

Ah. When they were 1/4" diameter, they were phone plugs.
Doubles existed, but they were not common, probably because it's difficult to get two cylindrical plugs parallel, and two cylindrical sockets parallel, and both assemblies at the exact same center distance.

That tolerance problem doesn't get easier when the pins get smaller.

How about an RJ45 or a derivative?

What voltage?
AC or DC?
What current?
How many mate/ demate cycles in the device's lifetime?
What's the nature of your comm signals?
How many millions will you need?

Mike Halloran
Pembroke Pines, FL, USA

RE: 3.5mm TRS as electro-mechanical interface

The voltage wont be more than 5 volts DC, including the power line, and the communication will be a similar 5V serial protocol. Current will be less than an amp through the power pin. I'm guessing these things wont go through more than 10 install/remove cycles.

Millions produced.

RE: 3.5mm TRS as electro-mechanical interface

I think I'd use something made for it. More like:

Digikey Example1

Mate with:
Digikey Mate

This way the connector body carries the mating forces instead of the electrical connections.

Because you are using 5V you really need to have gold surfaces (unlike the example above). You can get gold inexpensively in these types of connector while it can be hard to find in the classic TRS styles partly because they are considered to be fairly high mating count connectors which start to fail because the gold wipes off eventually where as the board-to-board connectors are expected to have low mating counts.

Keith Cress
kcress - http://www.flaminsystems.com

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