Stupid question about replacing 1 pot with 2 for fine and course adjustment ohm totals

Discussion in 'General Electronics Chat' started by born2dive00, Jun 14, 2017.

  1. born2dive00

    Thread Starter Member

    Oct 24, 2016
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    I know that this is going to be a stupid question, but I don't want to burn my circuit out.
    I want to replace one 500k pot with 2 pots one for fine one for course and a 200k pot, again with 2 pots one for fine one for course.
    Here is the question. On the circuit board they have a 500k and a 200k so would the total ohms of the 2 pots have to equal the output of the single pot.
    I.e. replacing a 500k with one 450k and a 50k= 500k
    i.e. replacing a 200k with one 180k and a 20k = 200k

    Here is the next question. which way do I connect the 2 pots.
    replacing the 200k does the 180k go on the left and the 20k on the right? or viceversa?
    Replacing the 500k does the 450 go on top and the 50k on the bottom or viceversa?

    LTC3780_WD2002SJ_AdjustableCurrentLimit.jpg
     
  2. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
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    It doesn't matter which side you put the pot and resistor, as long as the resistance will vary to your needs,. The 500k pot should be wired with wiper to to output VoSense, and its end terminals in place of the R9,like a Volume control.
     
  3. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    20170614_082705.jpg
     
    born2dive00 likes this.
  4. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    I am still not sure what you want to do, but if you try to power any current hungry circuit you will burn the pots.
     
  5. born2dive00

    Thread Starter Member

    Oct 24, 2016
    285
    6
    Thank you DoggyDave I was worried about this and burning the circuit.
    Thank you kermit2 for the drawing of the 500k. I am removing the pots on a ltc 3780 buck boost converter (see photo below,)and mounting them remotely, one for fine one for course.

    Now that we have the 500k circuit done And thank you very much for the drawing!!!!

    How do I replace the 200k pot (VR2 on the diagram) with 2 pots, (should i use one 200k and one 2k)??? it appears to be a different type of connection than VR3???



    LTC3780_WD2002SJ.jpg

    LTC3780_WD2002SJ_AdjustableCurrentLimit.jpg
     
  6. born2dive00

    Thread Starter Member

    Oct 24, 2016
    285
    6
    Kermit

    What is the functional difference between your drawing and this one???

    Do they do the same thing? or is one better or does something different?
    I know that the ones in my drawing are in series but do they function the same? which design is better for the 500k?

    as for the 200k VR2 would the one in my drawing top right work? or is there a better way?

    20170615124332.jpg
     
  7. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
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    Both the same, just make sure the wipers are linked together.
     
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