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Topic: Making electrical connections to a carbon fibre tube? (Read 851 times) previous topic - next topic

mikb55

This is for a capactive sensor application.
Ideally the connection will be less than 100 Ohms and unaffected by high humidity.

I looked at silver loaded epoxy, but the smallest size that I can find on Ebay is $60 for 14g.
Silver loaded paint is available in smaller quantities, but has no mechanical strength.
Screws etc. cannot be used because the carbon fibre is brittle and has no strength across the grain.

At the moment I'm heatshrinking multistrand tinned copper wire against the carbon fibre surface, appying a drop of silver loaded paint which wicks by capillary action. Once that is dry I spray PCB lacquer over the lot. Not very elegant and I have no idea if this will be reliable in the long term.

What do othe people use, spring fittings, custom connectors?

M




DVDdoug

I'm just guessing, but it sounds like some kind of spring or clamping device is the way to go.


How big is this thing?  Can you explain a bit more about the application?  Do you need to connect to the ends?

mikb55


I'm just guessing, but it sounds like some kind of spring or clamping device is the way to go.
How big is this thing?  Can you explain a bit more about the application?  Do you need to connect to the ends?


It's a vertically mounted fluid level sensor consisting of a 12mm carbon fibre outer electrode with a 1.5mm wall thickness, with a concentric 5mm insulated inner electrode separated by a gap which is filled by air or water.
The electrical connection to the outer electrode can be anywhere on the outside surface, or the end, providing there is clearance for the inner electrode to pass through.


DVDdoug

#3
Mar 06, 2012, 06:29 pm Last Edit: Mar 06, 2012, 07:47 pm by DVDdoug Reason: 1
How does this sound?

Drill a hole for a small nut & bolt, and use a ring (or spade) lug.   Bend a couple of flat washers to the radius of the tube so that tightening the screw distrubutes the stress evenly.

Oops!  Nevermind... I'm thinking cm instead of mm...

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