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yanito
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« on: February 10, 2012, 06:51:31 am »
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Afternoon all,

Trying a simple analog read on an arduino uno analog pin 2 from a potentiometer, and then using the Serial.print to display this input, the problem I have is the reading keeps fluctuating  when the pot is stationary, I have changed the pot and still the same issue.
Any ideas what could be causing the issue? Tried a resistor on the wiper but no improvement.

Thanks,

Mark
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Runaway Pancake
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« Reply #1 on: February 10, 2012, 09:00:04 am »
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How much is is fluctuating?
Could be coupling noise (AC - it's all around us)...
Tried shorter leads?
A 0u1 bypass?
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yanito
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« Reply #2 on: February 10, 2012, 12:52:46 pm »
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Hi runaway_pancake,

The values keeps jumping from 150 to 134 then 161 then back again, the leads I'm using are short breadboard connector leads, but there were close to the laptop at the time, I will set it up again and try it.
"A 0u1 bypass?" - Sorry totally lost me there  smiley-eek

Many thanks for your help.

Mark
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« Reply #3 on: February 10, 2012, 01:11:51 pm »
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Quote from: yanito on February 10, 2012, 06:51:31 am
Trying a simple analog read on an arduino uno analog pin 2 from a potentiometer

Schematic?
And how much is it fluctuating?
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liudr
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« Reply #4 on: February 10, 2012, 01:29:04 pm »
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What is the value (total resistance) of the pot? Do you have a multimeter to measure it? Maybe the contact inside is bad.
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retrolefty
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« Reply #5 on: February 10, 2012, 01:31:40 pm »
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If the value of the pot is too high then it can effect the stablity of the reading. No higher then a 10k ohm pot is recommended. And any noise on the voltage feeding the pot will also be seen as noise on the measurement.


Lefty
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MarkT
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« Reply #6 on: February 10, 2012, 02:52:52 pm »
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Computers put out oodles of interference.
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Daanii
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« Reply #7 on: February 10, 2012, 03:32:09 pm »
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Just to give you a benchmark, I've been working with a 5k pot using analogRead, and if I don't move the pot wiper it stays on a value, sometimes flipping between two values (like from 243 to 244 and back). I've never seen the sensed values moving + and - over 1% like you are seeing.

My pot is hooked to a breadboard about six inches from the Arduino, and the Arduino is on a six-foot USB cable from my computer.
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