Go to Post I have always gotten the answers I need. They're just not always the answers I want... - Alan Anderson [more]
Home
Go Back   Chief Delphi > Technical > Control System > Sensors
CD-Media   CD-Spy  
portal register members calendar search Today's Posts Mark Forums Read FAQ rules

 
Reply
 
Thread Tools Rate Thread Display Modes
  #1   Spotlight this post!  
Unread 12-02-2015, 21:42
rwodonnell rwodonnell is offline
Registered User
AKA: Rick O'Donnell
FRC #2876 (Devilbotz)
Team Role: Mentor
 
Join Date: Feb 2013
Rookie Year: 2011
Location: Burlington, MA, USA
Posts: 52
rwodonnell is a splendid one to beholdrwodonnell is a splendid one to beholdrwodonnell is a splendid one to beholdrwodonnell is a splendid one to beholdrwodonnell is a splendid one to beholdrwodonnell is a splendid one to beholdrwodonnell is a splendid one to behold
5K ohm 10 turn Potentiometer trouble

We have the AndyMark Bourns 5K 10 turn pot: 3590S-2-502L (datasheet: http://files.andymark.com/am-2619.pdf). When plugged into the roboRIO, we can't see any noticeable changes in the SmartDashboard when we turn the potentiometer, even manually. We've replaced it with a 270 degree 100K ohm potentiometer (and changed the settings appropriately with RobotBuilder) and see the results we would expect in SmartDashboard. We need more than a single turn potentiometer to execute our plan.

Is it possible to use a 5K pot, or do we need to get a higher resistance model?

We've confirmed the wiring and AI port, and don't believe it has anything to do with those types of errors.
Reply With Quote
  #2   Spotlight this post!  
Unread 12-02-2015, 21:48
GeeTwo's Avatar
GeeTwo GeeTwo is online now
Technical Director
AKA: Gus Michel II
FRC #3946 (Tiger Robotics)
Team Role: Mentor
 
Join Date: Jan 2014
Rookie Year: 2013
Location: Slidell, LA
Posts: 3,511
GeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond repute
Re: 5K ohm 10 turn Potentiometer trouble

Just to verify - do you have the red and black wires connected to the ends of the resistor, and the white to the "sweep"? (I'm assuming the usual 3-wire arrangement, black=0V, red=5V, white=signal.)

You can check this by unplugging the pot from the 'RIO and measuring the resistance between red and black with a meter - it should stay constant at about 5K no matter what position the knob is in.

Then, measure the resistance between white and either of the others - it should sweep from 0 ohms at one end to 5K at the other.

5K should work just fine. We're using a 10K 10-turn pot from Jameco, and 5V should work oh-so-slightly better for measurement purposes, at the trivial cost of drawing a full mA of current as opposed to a half mA.
__________________

If you can't find time to do it right, how are you going to find time to do it over?
If you don't pass it on, it never happened.
Robots are great, but inspiration is the reason we're here.
Friends don't let friends use master links.
Reply With Quote
  #3   Spotlight this post!  
Unread 12-02-2015, 21:51
GeeTwo's Avatar
GeeTwo GeeTwo is online now
Technical Director
AKA: Gus Michel II
FRC #3946 (Tiger Robotics)
Team Role: Mentor
 
Join Date: Jan 2014
Rookie Year: 2013
Location: Slidell, LA
Posts: 3,511
GeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond repute
Re: 5K ohm 10 turn Potentiometer trouble

This looks just like the Jameco pot we have. It is a bit unusual for a potentiometer in that the "sweep" on ours is at the back end - the farthest from the knob; usually the sweep is in the middle.

Confirmed from the data sheet - look at the diagram at the lower left of the second page. The back connector is the sweep.
__________________

If you can't find time to do it right, how are you going to find time to do it over?
If you don't pass it on, it never happened.
Robots are great, but inspiration is the reason we're here.
Friends don't let friends use master links.

Last edited by GeeTwo : 12-02-2015 at 21:54.
Reply With Quote
  #4   Spotlight this post!  
Unread 12-02-2015, 23:01
rwodonnell rwodonnell is offline
Registered User
AKA: Rick O'Donnell
FRC #2876 (Devilbotz)
Team Role: Mentor
 
Join Date: Feb 2013
Rookie Year: 2011
Location: Burlington, MA, USA
Posts: 52
rwodonnell is a splendid one to beholdrwodonnell is a splendid one to beholdrwodonnell is a splendid one to beholdrwodonnell is a splendid one to beholdrwodonnell is a splendid one to beholdrwodonnell is a splendid one to beholdrwodonnell is a splendid one to behold
Re: 5K ohm 10 turn Potentiometer trouble

Thank you GeeTwo! We are fixed! Our electrical guys feel a little sheepish, and I am hiding behind my "programming mentor" shield...

Thanks again!
Reply With Quote
  #5   Spotlight this post!  
Unread 12-02-2015, 23:24
GeeTwo's Avatar
GeeTwo GeeTwo is online now
Technical Director
AKA: Gus Michel II
FRC #3946 (Tiger Robotics)
Team Role: Mentor
 
Join Date: Jan 2014
Rookie Year: 2013
Location: Slidell, LA
Posts: 3,511
GeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond repute
Re: 5K ohm 10 turn Potentiometer trouble

Quote:
Originally Posted by rwodonnell View Post
Thank you GeeTwo! We are fixed! Our electrical guys feel a little sheepish, and I am hiding behind my "programming mentor" shield...

Thanks again!
My pleasure - and we probably would have gone through the same drill if I hadn't had a strange feeling as I looked at the arrangement of lugs and decided to put a meter on the pot rather than assume that the sweep was in the middle.
__________________

If you can't find time to do it right, how are you going to find time to do it over?
If you don't pass it on, it never happened.
Robots are great, but inspiration is the reason we're here.
Friends don't let friends use master links.
Reply With Quote
Reply


Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -5. The time now is 08:02.

The Chief Delphi Forums are sponsored by Innovation First International, Inc.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Copyright © Chief Delphi