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Author Topic: SOLVED: Wiring of 6 pots to Arduino  (Read 154 times)
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Hi all,

I'm making a control box with 6x10k linear potentiometers. I have checked that they are all 10k and working.

I have daisy chained them together with all + legs and all - legs connected. The problem is now that when I check the resistence over the plus and minus leg of any pot, the resistance is only 2 kOhm. And the value from minus to signal leg varies in a parabola starting from 0 going to 3.2 kOhm and down to around 2 kOhm.

I have a hard time understanding why this is and I don't think that this setup would give the desired result...

I have attached a picture of the soldering. I checked all connections for continuity and all is good.

I would of course then attach a single + and - wire to the arduino and the signal wire form each pot to the analog inputs.


* foto.JPG (114.69 KB, 640x480 - viewed 12 times.)
« Last Edit: August 04, 2014, 03:19:51 pm by zenseidk » Logged

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I have a hard time understanding why this is
No problem just google resistors in parallel.
It will work fine.
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I have daisy chained them together with all + legs and all - legs connected. The problem is now that when I check the resistence over the plus and minus leg of any pot, the resistance is only 2 kOhm.

That's because you're measuring them when they're all connected together in parallel.

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When you connect them to +5 & Gnd, they all still return the desired Voltage reading tho, yes? That's all the analog input cares about.
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Hi all,

Yes, I realise that resistors in parallel is not 10kOhm, but 1/(1/R1+1/R2+1/R3+...1/Rn), but when I measure from GND to signal I also don't get 10 kOhm, but rather the parabola I wrote about before. And that is what I don't understand... I would expect to still have 0 to 10 kOhm when measuring from GND to signal.

Or am I mistaken on that?
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And that is what I don't understand... I would expect to still have 0 to 10 kOhm when measuring from GND to signal.
Your expectations are wrong.

Forget measuring resistance, power it up and measure the voltage on the wiper they will all go from 0 to 5V.

In fact the value of the pot does not matter all that matters is that they go between the rails. I often use 24K pots because they were the cheapest when it came to purchasing them in bulk.
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Using that many pots, dont forget decoupling caps.  smiley Will allow you to use higher resistance pots and all.
« Last Edit: August 04, 2014, 02:43:08 pm by iyahdub » Logged

10 LET Loop=Infinite
20 GO TO 10

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How can you get 10K when you have the equivalent of a 2K resistor (from the other 10Ks in parallel) across the legs of your 10K resistor?
You have the equivalent of this:
-------------------
|        |
> 2K     > 5K
<        <
|        |
|        |---
|        |
|        > 5K
|        <
|        |
--------------
with your pot at mid scale.
So measuring between junction of the 2 5K pots and a leg is like
measuring a 5K in parallel with a 7K
= 1/(1/5000 + 1/7000) = ~2.9K
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Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
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All right, I give :-)

I have connected it up and everything works... Thanks!
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