help with comparator 2

Discussion in 'The Projects Forum' started by tibbles, Jul 17, 2014.

  1. tibbles

    Thread Starter Active Member

    Jun 27, 2008
    249
    3
    hi
    thought id start a new thread on my comparator query as i messed up the original of trying to desensitise the trigger point with waffle, sorry.
    i like the idea of a fine and a coarse pot but it dosent seem to work as all the resistance is only on one leg of the divider,taking the input from the junction of the pots does not work either, ive tried adding a new resistor in the bottom leg also without success
    im sure ive come accross this before in an earlier life, but if anyone can shed some light i'd be very grateful.
    regards
    doug
     
  2. DickCappels

    Moderator

    Aug 21, 2008
    2,647
    632
    If all you need is a variable resistance, that should work "fine" :)

    Tell us about the circuit and what kind of behavior you are experiencing.
     
  3. tibbles

    Thread Starter Active Member

    Jun 27, 2008
    249
    3
    hi
    the problem is that the slightest touch on the VR when using one vr ,changes state,
    this would normally be ok, but i would like to 'soften or spread' the trigger point slightly so its not too sudden.
    ive put a resister in each divider leg this has improved it a bit,a multi turn pot would probably be ok but a bit a bit fiddly as the project may need occasional adjustment, i wonder if anyone makes them with a knob instead of screwdriver adjustment?
    just out of curiosity i might try the two VRs but in paralell.
    but to get back to my initial point i couldnt see how two VRs- a coarse and a fine on one leg of the divider could work.
    regards
    doug
     
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