"Fuzzy" push button component

[Arne Harisson]

Hi im looking for a button, the harder you press it, the less
resistance will run through the circuit, in effect a potentiometer but
with a button instead if a turning knob.

Im a newbee to the components world and was wondering if some knows
how to find such a component and if there are any tutorial online on
how to get started finding the right component etc. If someone know
the cross reference code or whatever its called ill be very happy.

thanks

 

[Jacobe Hazzard]

Arne Harisson wrote:

Hi im looking for a button, the harder you press it, the
less resistance will run through the circuit, in effect a
potentiometer but with a button instead if a turning knob.

Im a newbee to the components world and was wondering if
some knows how to find such a component and if there are
any tutorial online on how to get started finding the
right component etc. If someone know the cross reference
code or whatever its called ill be very happy.

thanks

You can use black antistatic foam for this. Place a disc of the foam in
between two conductive plates, and it will conduct slightly. As you compress
the two plates (press the button) the resistance drops. You don't mention
what range of resistance or power handling capability you're looking for,
but this is a simple solution.

A strain guage is a flexible element that changes its resistance according
to how far it's flexed (strained). You could mount your button on a flexible
beam and attach a strain guage to the beam, although usually you will get an
increase in resistance when you press the button and strain the guage.

You might also try a linear (slide) potentiometer, with the shaft connected
to your button and a spring that returns the button to a high resistance
position. Just some ideas.

 

[Arne Harisson]

I liked the foam idea.
The button can not be more than 1-1.5 cm thick.
Do you know how much the resistance would vary from no push to pushing it
all the way?

how does the relation look like in terms of a formula?

thanks


"Jacobe Hazzard" <spamsink@ATeudoramail.DOTcom> wrote in message
news:3ODSb.64094$9Ce1.52083@news04.bloor.is.net.cable.rogers.com...

Arne Harisson wrote:
Hi im looking for a button, the harder you press it, the
less resistance will run through the circuit, in effect a
potentiometer but with a button instead if a turning knob.

Im a newbee to the components world and was wondering if
some knows how to find such a component and if there are
any tutorial online on how to get started finding the
right component etc. If someone know the cross reference
code or whatever its called ill be very happy.

thanks

You can use black antistatic foam for this. Place a disc of the foam in
between two conductive plates, and it will conduct slightly. As you
compress
the two plates (press the button) the resistance drops. You don't mention
what range of resistance or power handling capability you're looking for,
but this is a simple solution.

A strain guage is a flexible element that changes its resistance according
to how far it's flexed (strained). You could mount your button on a
flexible
beam and attach a strain guage to the beam, although usually you will get
an
increase in resistance when you press the button and strain the guage.

You might also try a linear (slide) potentiometer, with the shaft
connected
to your button and a spring that returns the button to a high resistance
position. Just some ideas.

 

[Jacobe Hazzard]

Arne Harisson wrote:

I liked the foam idea.
The button can not be more than 1-1.5 cm thick.
Do you know how much the resistance would vary from no
push to pushing it all the way?

how does the relation look like in terms of a formula?

thanks

You would have to measure I think. I might be able to make some measurements
later if I get time, and I'll post them if I do.

What are you trying to do?

 

[Arne Harisson]

Im trying to detect if something is over the thing im trying to make.
it has to be a device that gets pushed down. e.g. an optical solution
wouldnt work.

I guess a piezo electric solution would work since it can be made very thin.
I think smart houses uses this in floors that can detect how much the person
standing on it weighs and where he is going and where he as been. But i dont
need that advanced feature, basically on or off with a couple of steps in
between that could be adjusted electronically/programmatically for a
threshold , e.g detect when (some signal) more than x.
The range of weight is approx between 2-20 kg



"Jacobe Hazzard" <spamsink@ATeudoramail.DOTcom> wrote in message
news:U_ESb.64365$9Ce1.36974@news04.bloor.is.net.cable.rogers.com...

Arne Harisson wrote:
I liked the foam idea.
The button can not be more than 1-1.5 cm thick.
Do you know how much the resistance would vary from no
push to pushing it all the way?

how does the relation look like in terms of a formula?

thanks

You would have to measure I think. I might be able to make some
measurements
later if I get time, and I'll post them if I do.

What are you trying to do?

 

[Tim Wescott]

I've heard that the black plastic stuff doesn't have a long life, though --
do you have experience to the contrary?

You may be able to hack an air pressure sensor -- I think that it's a
straight shot from the tube to the diaphram; you could put a little plastic
rod in there and push on it for a reading. The only problem with this is
that an overload _would_ break the diaphram, unless you had some sort of
protective arrangement.

"Jacobe Hazzard" <spamsink@ATeudoramail.DOTcom> wrote in message
news:3ODSb.64094$9Ce1.52083@news04.bloor.is.net.cable.rogers.com...

Arne Harisson wrote:
Hi im looking for a button, the harder you press it, the
less resistance will run through the circuit, in effect a
potentiometer but with a button instead if a turning knob.

Im a newbee to the components world and was wondering if
some knows how to find such a component and if there are
any tutorial online on how to get started finding the
right component etc. If someone know the cross reference
code or whatever its called ill be very happy.

thanks

You can use black antistatic foam for this. Place a disc of the foam in
between two conductive plates, and it will conduct slightly. As you
compress
the two plates (press the button) the resistance drops. You don't mention
what range of resistance or power handling capability you're looking for,
but this is a simple solution.

A strain guage is a flexible element that changes its resistance according
to how far it's flexed (strained). You could mount your button on a
flexible
beam and attach a strain guage to the beam, although usually you will get
an
increase in resistance when you press the button and strain the guage.

You might also try a linear (slide) potentiometer, with the shaft
connected
to your button and a spring that returns the button to a high resistance
position. Just some ideas.