# Homemade Linear Potentiometer

What's the best materials to build a potentiometer ?

As I know I could use copper as a resistive material but what as a wiper ?

(deleted)

only copper?

Hi,
What value of resistance do you want the potentiometer to have??

To have any "reasonable" value you need to use some material with a lot more resistance than copper. Typically Nickle alloys like "NiChrome" are used for low values. For higher values, carbon or carbon-plastic compounds are used.

Do you have a multimeter to read resistance values? Make a dark pencil mark on a piece of paper about an inch long and read the resistance. Slide the probe along and see it change.

Do some searching on "make a potentiometer"...

Google "make a potentiometer"

I don't care about the value i will map it in the arduino later,

I already found some tutorials here is one of them :

http://memoir.okno.be/phys_comp_tutorial/ribbon4/ribbon4.htm

I'm not building this one but I'm building a specific one for a project that i need, if the copper will do the job
then it's fine with me no mater what value I get as I said im gonna map the value on the arduino code
and everything will work as I need.

D.60

Of course you care about the value; you more than likely do not want a 1 milliOhm resistor. Or if you want that, you do not want to end up with a 100 kiloOhm one.

Of course you care about the value; you more than likely do not want a 1 milliOhm resistor. Or if you want that, you do not want to end up with a 100 kiloOhm one.

well yea that's true, for that of curse i need to do tests, take the length of the copper and measure the
resistance if that's going to be fine for me that im gonna build with that length of the copper. I'm planning
to get a 10k that's a normal value for me and nice to work with.

D.60

Domino60:
i need to do tests, take the length of the copper and measure the resistance if that's going to be fine for me that im gonna build with that length of the copper. I'm planning to get a 10k.

I think you can skip the tests and drop copper right away.

http://www.circuitcalculator.com/wordpress/2006/01/24/trace-resistance-calculator

Copper 17 milliOhm / meter for a 1 mm2 wire. For 10 kiloOhm you need nearly 600 kilometer of wire

You can do the calculations for thinner wire.

Consider that you have to apply 5V DC to your potentiometer, if you want to read its value using analogRead().

I need +5V, Analog read and GND

Based on the picture above and how potentiometers work I need to have a copper "Resistive strip" but as well a "Wiper" which both may cause a resistance. One of the Voltage and 2nd of the strip that will be read.

The only way I'm thinking is to build the dimension of the pot. I need and after that measure the resistance, anyway on the arduino i will get from 0 to 1023.

If the resistance will be really really low then i will add an actual resistor between the pot and analog pin.

What do you think?

D.60

As a general rule it's not practical to make a pot. You can make one to demonstrate the principals but you're probably won't want to use it in a project. It's difficult to make a "good one" that operates smoothly and noiselessly.

Nichorme wire is in the ballpark of 1 Ohm per foot (depending on the gauge). You could make a 100 Ohm resistor/pot, but not a 10K.

By winding the wire you can make a [u]rhostat[/u] so the wiper travel-length can be shorter than the wire-length.

If the resistance will be really really low then i will add an actual resistor between the pot and analog pin.

Low resistance = high current ([u]Ohm's Law[/u]). Your power supply has to supply the current and the pot must dissipate the power (heat). That's why pots in the 1K - 10K range are typically used.