Sliding pot does not read anything other than 0 or 1023

I am using this sliding pot for a project: Slide Pot - X-Large (10k Linear Taper) - COM-09119 - SparkFun Electronics

I used this simple tutorial to read the value off of the slider: http://arduino.cc/en/Tutorial/AnalogReadSerial

My wiring is all correct but nothing happens when I slide the potentiometer back and forth. It stays at 0 or 1023 if I reverse the 5v and GND wires.

Why doesn't the value change?

I tried it with a rotary pot I have and it worked fine. The wires could not be better soldered, so it's not a connection issue, like I said when I switch the +/- wires the value read by pin0 changes from 0 to 1023 but it does nothing when I slide the switch. Why? How can I fix it?

I'd check the pot with a multimeter.

And if the pot is OK, make sure that you have actually connected it, as it is in the tutorial.

I still have painful memories on how long it took me realizing that "it must be set up as a voltage divider to give anything useful" back when I first started playing with micro-controllers.

You have probably miswired it - set slider to mid-travel and measure the resistances
to identify the wiper.

Hi, from the datasheet, pin 1 is one end of the pot, pin3 is the other and pin2 is the slider.
So pin1 to gnd, pin3 to 5V, pin2 to arduino analog input.
What reading does the arduino give when you have the slide midway.?

Tom........ :slight_smile:

If it is wired up properly, the pot sounds like it could be burnt out, but even so as you adjust it, you would see voltage fluctuations .

Picture/schematic?

If you miss wired it by mistaking the wiper for one of the ends, then if the slider approaches the wrong end it will burn out the track and it will no longer work.

but even so as you adjust it, you would see voltage fluctuations .

No you wouldn't.

Grumpy_Mike:
If you miss wired it by mistaking the wiper for one of the ends, then if the slider approaches the wrong end it will burn out the track and it will no longer work.

but even so as you adjust it, you would see voltage fluctuations .

No you wouldn't.

Why not? Have you not had potentiometers when adjusting the resistance value goes mental? I had a couple of lm317's fry a few things because of a bad pot... (eg 1v.. 2v... 12v .. 4v ... while adjusting the pot) .

Why not?

Because if the pot is burnt out there is no voltage change as the wiper moves.

Have you not had potentiometers when adjusting the resistance value goes mental?

Yes but that is not caused by a burned out track. That is caused by dirt causing intermittent contact with the wiper thus connecting it to the wiper at one moment and leaving the wiper unconnected at the next.

With a burnt out track you would expect solid readings of 0 or 1023 for most of the travel until your wiper passed over the burnt bit when the reading will flip to the other extreme.

Hi, do you have a DMM to measure the resistance of the pot?
Set the slide about midway.
Measure between pins 1 and 2.
Measure between pins 2 and 3.
Measure between pins 1 and 3.
Tell us the values you have measured.

Thanks.

Tom..... :slight_smile:

Set the slide about midway.

Why?
If it is a linear device, that will tell you almost nothing.

Hi, it will tell you if and where the pot is burnt out and if it really is the device in the data sheet. Also if it is linear.

Tom...... :slight_smile:
ps I always test a pot about mid range.
I have had pots that have burnt out, or cracked track, at one end.
Turning the pot to that end, the wiper bridges the open circuit spot and the total resistance checks out as okay.