0
\$\begingroup\$

So i ordered this cheap 100 ohm ten turn pot from ebay: Potentiometer

The problem is that it doesn't work as a normal pot (or it is broken).

When i check resistance from pin 2 to pin 3, everything is working fine, i can turn the wiper and the resistance is changing, however, if i check from pin 2 to pin 1, it shows 100 Ohms resistance all the time, no matter how much i turn the wiper. Is it supposed to do that or have i wired it wrong? Thanks!

enter image description here

enter image description here

\$\endgroup\$
8
  • \$\begingroup\$ Have you tried measuring the resistance between pins 1 and 3? \$\endgroup\$
    – John Dvorak
    Commented Sep 8, 2016 at 4:29
  • \$\begingroup\$ @JanDvorak Yes, everything is working fine there. When i turn the pot half the way it shows 50 ohms. \$\endgroup\$
    – Xane
    Commented Sep 8, 2016 at 4:30
  • \$\begingroup\$ So, is the pot working just fine except the pins seem mislabeled? \$\endgroup\$
    – John Dvorak
    Commented Sep 8, 2016 at 4:31
  • \$\begingroup\$ No.. I mean, if i check one of my other pots i have laying around. Resistance from pin 1 - 2, and from pin 2 - 3 should react the same way. It should not show the max resistance of the pot all the time right? \$\endgroup\$
    – Xane
    Commented Sep 8, 2016 at 4:32
  • \$\begingroup\$ In a 'normal' pot, you'd have variable resistance between pins 1-2 and 2-3, and the full resistance between pins 1-3. So apparently this does just what it's supposed to, with only the difference of the order of pins. \$\endgroup\$
    – chamod
    Commented Sep 8, 2016 at 4:57

1 Answer 1

Reset to default
10
\$\begingroup\$

Your pot is probably fine, but the terminal numbering is confusing you. Hopefully this image will make it clear:-

enter image description here

\$\endgroup\$
5
  • \$\begingroup\$ Why should the pins be numbered like that? \$\endgroup\$
    – John Dvorak
    Commented Sep 8, 2016 at 5:10
  • \$\begingroup\$ I just tried it! and you where right.. I feel so stupid.. damn ebay stuff who labeles things weird xD Thank you very much Bruce!! :D \$\endgroup\$
    – Xane
    Commented Sep 8, 2016 at 5:15
  • 1
    \$\begingroup\$ datasheet confirms: mouser.com/ds/2/54/590-776468.pdf \$\endgroup\$
    – Wesley Lee
    Commented Sep 8, 2016 at 5:16
  • 2
    \$\begingroup\$ The convention is to number from one end of the track to the other, with the wiper connection on pin 2. But physically this pot has its track spiraling around the inside wall of the body with the wiper in the center, so the wiper connection has to come out the back end rather than between other two terminals. i2.wp.com/www.scienceprog.com/wp-content/uploads/2014/07/… \$\endgroup\$
    – Bruce Abbott
    Commented Sep 8, 2016 at 5:22
  • \$\begingroup\$ This is my first time using multi-turn pots, Thank you for the detailed explination! Learned something new hehe \$\endgroup\$
    – Xane
    Commented Sep 8, 2016 at 5:24

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.