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Topic: troubles with slide pots (Read 583 times) previous topic - next topic

edward11

Hi there,

I'm working on a project with slide pots. They have 115C-10KDX2 written on them and are 10 kohm. A couple of the pots seem to respond irregular to the movement of the slider. Sometimes they behave like expected, but on other times the pin i'm reading out gives nothing back when i change the position of the slider. Is this a sign of short circuit? Does anyone recognize this problem?

Thanks in advance.

Greets.

cyclegadget


Pots can have "opens" and "shorts" inside of them if they are old or of poor quality. I would use an Ohm meter to check their operation.

You can also post your code and perhaps your serial monitor results and we can check that for you too.

retrolefty

#2
Nov 20, 2012, 08:48 pm Last Edit: Nov 20, 2012, 08:50 pm by retrolefty Reason: 1
If they are older slide pots that have been hanging around for awhile then maybe they just need a contact spray applied to the inside and exercised a little. That is common problem with older vintage hi-fi equipment, noisy pots and intermittent switches, which in most cases can be fixed right up with a treatment of good quality contact cleaner. Don't use WD40 spray as some advice as it leaves a oil residue that will attract dust.

Good luck;

Lefty

edward11

thnx for the quick replies! I was rebuilding a old midi controller project with 32 turn knobs to a controller with 28 turn knobs and 4 slide pots. (So it actually is an audio project). I've build the whole thing on an old metal and coated dvd player. It turned out that the coating was scratched a little, so the whole thing was short circuited and the midi data went all over the place.. Fixed it now, and everything works fine! About the logarithmic pots: why would you want logarithmic pots for audio control specifically? I bought them by accident, while I was looking for linear ones. This will work out though, or I'll just fix it in the code.

retrolefty

#4
Nov 21, 2012, 02:16 am Last Edit: Nov 21, 2012, 02:18 am by retrolefty Reason: 1
Fixed it now, and everything works fine! About the logarithmic pots: why would you want logarithmic pots for audio control specifically?

Because it more closely matches the human hearing response curve. Log pots are almost always used for volume controls in audio equipment.

I bought them by accident, while I was looking for linear ones. This will work out though, or I'll just fix it in the code.

Here is a great article about pots from a audio site. It explains about the different audio 'tapers' that are used and why. Also at the end some nice pot application circuits for wiring pots up as volume/balance and other neat stuff:

Lefty


http://sound.westhost.com/pots.htm

John_S

Quote
Don't use WD40 spray as some advice as it leaves a oil residue that will attract dust.

dhenry will say WD40 is ok...  :smiley-roll:

Seriously though, I was in a pinch and used WD40 on the slide pots on my headset about 8 months ago. It's still working. YMMV.

retrolefty


Quote
Don't use WD40 spray as some advice as it leaves a oil residue that will attract dust.

dhenry will say WD40 is ok...  :smiley-roll:

Seriously though, I was in a pinch and used WD40 on the slide pots on my headset about 8 months ago. It's still working. YMMV.



I too have used it in a pinch, and it can work. But it does ensure you will have to redo it much sooner then if you use one of the better non-residue contact cleaners. The difficult part (with any spray cleaner) is that sometimes it's very difficult to get the spray into the part of the pot or switches that need the cleaning.  ;)

Lefty

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