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09-23-2015, 04:19 PM
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Join Date: Nov 2008
Location: Shreveport, LA
Posts: 1,002
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How to wire this linear potientometer?
I bought this linear pot thinking I could use it for a DIY pitch trim position indicator. Now that I have it, I can not understand how to wire it up. Can someone explain it? I would think the red wire would go to my position light on my panel and either yellow or green would go to +12v and ground respectively?? The wiring diagram in the photo is what came with the linear pot. Its sad I can become so confused over 3 wires...
Last edited by blueflyer : 09-23-2015 at 04:25 PM.
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09-23-2015, 05:13 PM
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Join Date: Jul 2005
Posts: 1,341
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What exactly are you driving? And, what is the total value of the pot?
__________________
Mike W
Venice, FL
RV-6A. Mattituck TMX O-360, FP, GRT Sport EFIS, L3 Lynx NGT-9000
N164WM
N184WM reserved (RV-8)....finishing kit in progress. Titan IOX-370
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09-23-2015, 05:24 PM
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Join Date: Dec 2011
Location: Livermore, CA
Posts: 6,767
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My guess is that you've swapped the yellow and red on the diagram. But it's just a guess. Put an ohmeter on 2 leads at a time, move the end, then you'll know for sure. As already asked, what is the device driving, and what is its total resistance?
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09-23-2015, 05:56 PM
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Join Date: Apr 2008
Location: Riley TWP MI
Posts: 3,068
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Applying 12 volts directly to a pot will likely burn it up when the pot is adjusted to one extreme or the other. Do you have any documentation for the position indicator?
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Joe Gores
RV-12 Flying
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09-23-2015, 06:00 PM
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Join Date: Nov 2008
Location: Shreveport, LA
Posts: 1,002
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Its a 50K pot. Its going to drive the position indicator on my D120. Thank you both for asking. That made me go to the Dynon D120 install manual and it shows you how to connect the pot. That wouldn't have struck me to do that for several days otherwise.
Here is the data sheet: https://www.bourns.com/pdfs/3046.pdf
uh oh, I better get with dynon to see if a 50K pot will work. The D120 manual only lists up to 20K.
Last edited by blueflyer : 09-23-2015 at 06:10 PM.
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09-23-2015, 06:02 PM
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Join Date: Dec 2011
Location: Livermore, CA
Posts: 6,767
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Quote:
Originally Posted by Mich48041
Applying 12 volts directly to a pot will likely burn it up when the pot is adjusted to one extreme or the other.
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Only if it's mis-wired or wrong for the application. It's very common to have 12 volts on one end. |
09-23-2015, 06:18 PM
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Join Date: Jul 2005
Posts: 1,341
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Yellow to 5V excitation pin on D120
Green to Ground pin of choice on D120
Red to General Purpose input pin on D120.
50k should be fine. It's just a voltage divider. The D120 input impedance should be pretty high, but you can calibrate the error out regardless.
__________________
Mike W
Venice, FL
RV-6A. Mattituck TMX O-360, FP, GRT Sport EFIS, L3 Lynx NGT-9000
N164WM
N184WM reserved (RV-8)....finishing kit in progress. Titan IOX-370
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09-23-2015, 06:29 PM
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Join Date: Nov 2008
Location: Shreveport, LA
Posts: 1,002
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Thank you Mike.
Quote:
Originally Posted by fl-mike
Yellow to 5V excitation pin on D120
Green to Ground pin of choice on D120
Red to General Purpose input pin on D120.
50k should be fine. It's just a voltage divider. The D120 input impedance should be pretty high, but you can calibrate the error out regardless.
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09-24-2015, 01:20 PM
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Join Date: Mar 2008
Location: Dublin, CA
Posts: 1,259
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Use your multi-meter to measure the resistance. It should be fixed between the two terminals and variable relative to the third. When measuring from the third terminal to one of the other two the resistance will go to zero at one extreme of motion. As you push it in the resistance will get high between two of the terminals and lower between the other two. Or vice versa.
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Ray Tonks
2020 Donation Paid
Titan IOX-370, Dual PMAGs, 9.6:1 Pistons, FM-150
RV-7 Fuselage in progress
* Cabin Interior - In progress
RV-7 SB Wings
* Both Wings fully skinned
* Fuel Tanks Complete - No leaks finally
* Ailerons Complete
* Flaps Complete
RV-7 Empennage - Complete (a little fiberglass work left)
Vans Training Kit # 2 - Complete
RV-7 Preview Plans
Vans Training Kit #1 - Complete
EAA Sheet Metal Class - Complete
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09-24-2015, 01:26 PM
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Senior Curmudgeon
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Join Date: Sep 2005
Location: Dayton Airpark, NV A34
Posts: 15,408
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Quote:
Originally Posted by rapid_ascent
Use your multi-meter to measure the resistance. It should be fixed between the two terminals and variable relative to the third. When measuring from the third terminal to one of the other two the resistance will go to zero at one extreme of motion. As you push it in the resistance will get high between two of the terminals and lower between the other two. Or vice versa.
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Yes, this is correct.
If your indicator reads backward to the surface travel, reverse the input power to the other end of the fixed resistance.
__________________
Mike Starkey
VAF 909
Rv-10, N210LM.
Flying as of 12/4/2010 
Phase 1 done, 2/4/2011
Sold after 240+ wonderful hours of flight.
"Flying the airplane is more important than radioing your plight to a person on the ground incapable of understanding or doing anything about it."
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