Author Topic: How do you wire a pot?  (Read 1287 times)

tehfunk

How do you wire a pot?
« on: May 17, 2008, 07:39:47 PM »
No seriously, I have searched countless times, read the majority of the R.G.'s the secret life of pots, read diy wiki faq article. What I need is a reliable method for knowing what to wire to each lug of a pot, preferably a way that will allow me to know straight from a schematic because I have read that the 321 numbering system is not always true and that most schematics don't number the lugs. I've been "lucky" so far, I figure it out backwards, but every time I look at a schematic it seems like the orientation of the cw and ccw for the pots is different, etc. Thank you very much!

EDIT:  One thing to add, on one post I read something about R.G. saying all that he needs to know in order to do it is which way the wiper goes when he turns the pot physically. I don't know how to apply this, or what he means, can someone clear this up for me?
« Last Edit: May 17, 2008, 07:45:02 PM by tehfunk »
Carvin CT6M > diystompboxes.com > JCM800 4010

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ambulancevoice

Re: How do you wire a pot?
« Reply #1 on: May 17, 2008, 07:44:24 PM »
http://www.beavisaudio.com/techpages/Pots/

usually its always signal into pin 3, out pin 2 and ground pin 1 (or pin one is connected to pin 2) unless otherwise noted

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tehfunk

Re: How do you wire a pot?
« Reply #2 on: May 17, 2008, 07:49:29 PM »
Thanks for the resource, but since I have heard that not all pots follow the convention, so I was looking for the non-number based way.
Carvin CT6M > diystompboxes.com > JCM800 4010

The tools of the artist give you a chance to twist and bend the laws of nature and to cut-up and reshape the fabric of reality - John Frusciante

petemoore

Re: How do you wire a pot?
« Reply #3 on: May 17, 2008, 08:12:32 PM »
 Tha's how I do it:
  For purposes of expl> put a knob on the pot so it turns up to 5 oclock, and down CCW to 7 oclock, when the put is turned all the way down, CCw, the pointer will point to the Ground connection, signal path goes in to the other outside lug, wiper is output.
  I finally remember the # method because I just built a theremax, and it finally got drilled in far enough the one way to make a memorable impression...potshaft pointing away from you lugs up, left lug is #1.
Convention creates following, following creates convention.

earthtonesaudio

Re: How do you wire a pot?
« Reply #4 on: May 17, 2008, 09:47:54 PM »
I learned the numbering system, but I don't use it anymore.  I just look at the schem, and think to myself, "what do I want the control to do when I turn it this way or that?" and wire it accordingly.  It doesn't really matter what numbering system you use (if you use one at all), so long as you know which lug is the wiper, the taper of the pot, and which side the knob attaches to. ;)

I'd say if you're going to commit something to memory, then it should be a mental picture of the inner workings of a pot, not some arbitrary numbering scheme.




R.G.

Re: How do you wire a pot?
« Reply #6 on: May 17, 2008, 11:45:07 PM »
Numbering systems for pots stink. There's always the next one that doesn't fit.

To find out how to wire a pot:
1. Take your meter, set to ohms. Turn the pot to the middle of its travel. Measure the resistances between each pin and the others. The biggest resistance is between the clockwise/hot side and the counterclockwise/cold side. The one which is intermediate between them is the wiper.

2. Turn the shaft fully counterclockwise. Measure the resistance between the wiper and the two other lugs. The one nearest the wiper (i.e. the lowest resistance) is the CCW  or cold side.

3. Turn the shaft fully clockwise. Measure the resistance between the wiper and the two other lugs. The one nearest the wiper (i.e. the lowest resistance) is the CW  or hot  side.

4. Turn the shaft as nearly to the exact middle of its mechanical rotation as you can. Measure the resistance to the cold/CCW side. If this is about half the total resistance, the pot is probably linear. I say "probably" only because there are some weird S tapers that can do this too. But you'll probably never see one. If the resistance is about 10% of the total pot resistance, the pot is A or audio/log taper. Probably, again in the same sense. If it's 90%, it's a reverse log.

Now wire your pot. For volume/voltage divider use, put the cold side nearest ground, the hot side gets the signal and the wiper is the output.
R.G.

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