Shoving 3 pin single row header (long) into a Conductive Foam for a Pressure se

Ezsynn

Would That Work?

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Post Edited (Ezsynn) : 2/5/2009 10:20:07 AM GMT

Mike Green

You're not giving much in the way of information. If you want a useful answer, you need a clear question.

Would what work? "Shoving 3 pin single row header (long) ... sensor"?

You can shove something into a block of Jello. Whether that will do something useful is another question. What are you trying to accomplish?

Depending on the header pins and the conductive foam and how you're shoving it, you can break or bend the pins, tear the foam, or successfully get the pins into the foam without damage. Depending on how you hold the thing, you might damage the sensor or not.

Zoot

Ezsynn -- if you are thinking about the conductive foam pressure sensor hack (using "anti-static" IC foam), generally that technique involves putting two very thin metal plates (or even aluminum foil) on either side of the foam. Wires are attached to the metal. Then the whole thing acts like a variable resistor when squeezed/pressed.

Two issues you have to take into account:

- the amount of resistance changed can be small; you need to be able to measure it reasonably accurately (RCTIME with solid components)

- the foam will not return to it's original state completely, so your code will need to take that into account and essentially look for rapid "change" in resistance as indicative of pressure, not absolute values, i.e.

pseudocode:

do

-> measure resistance
new "steady" state = resistance
wait
-> measure resistance
if ( ABS (new - old) / old ) > .25  then  ' basically a change of more than 25% from whatever it was is "pressure"
    under pressure
endif
' or
pressure =  ( ABS (new - old) / old ) * 100 ' pressure "value" 0-100


loop

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Phil Pilgrim (PhiPi)

Ezsynn,

Here is a thread that may help you.

-Phil

Ezsynn

Phil Pilgrim (PhiPi) said...
Ezsynn,

Here is a thread that may help you.

-Phil

I know that but Would the title of this thread work?

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Phil Pilgrim (PhiPi)

I have no idea. Why don't you try it and see for yourself?

-Phil

Beau Schwabe

Ezsynn,

Try it and see. Report back with your results.


If your talking about the action of inserting the 3 pin single row header into the foam to cause a change in resistance, it will probably be a very small change due to series-parallel resistor effects within the foam at the point of insertion. See attached image. The resistance change will be most noticeable near the peripheral but quickly decay as you move inward.

If your talking about compressing the foam near the area of where the 3 pin single row header is inserted, it might give more resistive range, but the mechanical wear and tear of the foam compressing around the 3 pin single row header will eventually destroy the foam.

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Beau Schwabe

IC Layout Engineer
Parallax, Inc.

Ezsynn

Beau Schwabe (Parallax) said...
Ezsynn,

Try it and see. Report back with your results.


If your talking about the action of inserting the 3 pin single row header into the foam to cause a change in resistance, it will probably be a very small change due to series-parallel resistor effects within the foam at the point of insertion. See attached image. The resistance change will be most noticeable near the peripheral but quickly decay as you move inward.

If your talking about compressing the foam near the area of where the 3 pin single row header is inserted, it might give more resistive range, but the mechanical wear and tear of the foam compressing around the 3 pin single row header will eventually destroy the foam.

Ah I get you. But still the Idea stands.

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