Slide Pot

[Commanderbob]

I'm looking for a slide potentiometer that has a travel of at least 6". The longest one I've found was 100mm (about 4"). We need it to be able to tell where a pneumatic piston is.

[Soeren]

Hi,

You could get lucky searching among professional stage lightning sites, but be ready to pay through your nose if you do.

Alternatively, you could use a system like what's used on old radio scales, with a string where one point is moving with the piston and then driving a rotary pot with a pulley with a diameter made to match the length of travel to the around 270° travel of the pot.

There are other methods as well, but how precise do the readout need to be?

[z.s.tar.gz]

+1 for sting and pulley. I've never seen a 6" linear pot before.

[Soeren]

Hi,

Here's one for those with deep pockets

And here's a PDF with some

[duste83]

why don't you just use a lever action with a smaller linear pot.?  you have one end on a pivot and the other on the moving object and the shorter linear pot. in the middle.

[nottoooily]

Yea these are used in industry like what Soeren said, but you pay a heavy price for reliability and ruggedness.

You can also make you own from a straight or spiral length of electric heater wire/etc.

I'm looking for a slide potentiometer that has a travel of at least 6". The longest one I've found was 100mm (about 4"). We need it to be able to tell where a pneumatic piston is.

[galannthegreat]

I found one on this site that has 5 inch travel. It's motor driven though, but if you don't need the motor you can just remove it.

http://www.alltronics.com/cgi-bin/category.cgi?item=28P006