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strange readings of pot — Parallax Forums

strange readings of pot

fabricefabrice Posts: 3
edited 2004-11-13 02:35 in Learn with BlocklyProp
Dear all,
I am using a stamp in class and followed the instructions of the tutorial on chapter 5, etc. however, the potentiometer are giving me readings that range from 1 to an increasing huge value up to the mid section of the range and then abruptly fall to 0 for the rest of the range.
Any suggestion? I used a 10K pot with a 220 resistor and a 0.1mF capacitor.
Thanks a bunch

Comments

  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2004-11-11 22:33
    You didn't specify which unit you were doing the experiment, so I will assume it's the WAM tutorial.· From the sounds of things you're using much too small of a value capacitor...I would use a 2200uF or 3300uF capacitor and see what happens.



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  • Andy Lindsay (Parallax)Andy Lindsay (Parallax) Posts: 1,919
    edited 2004-11-12 03:43
    It may also be that you are using too large of a capacitor or too large of a resistor. If you are working on Chapter 5, Activity 3, and if you are really using a 0.1 mF capacitor, it is 1000 times too large. This would in turn account for large values, then zeros due to overflow in the RCTIME command when the potentiometer is turned beyond a certain point. Make sure of the following:

    That your potentiometer has 103 printed on the underside. That's a 10 k potentiometer.

    That your 220 ohm resistor is color coded red red brown.

    That your 0.1 uF capacitor is labeled 104.
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2004-11-13 02:35
    Andy, don't those experiments in that chapter use larger caps?· I could be wrong, but my boy went through that section and I thought he was using larger values, not smaller ones.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Chris Savage

    Knight Designs
    324 West Main Street
    P.O. Box 97
    Montour Falls, NY 14865
    (607) 535-6777

    Business Page:·· http://www.knightdesigns.com
    Personal Page:··· http://www.lightlink.com/dream/chris
    Designs Page:··· http://www.lightlink.com/dream/designs
    ·
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