Help modifying resistor values

Discussion in 'General Electronics Chat' started by Actionspa, Oct 7, 2012.

  1. Actionspa

    Thread Starter New Member

    Oct 6, 2012
    I have two identical thermistors. I will refer to them as sensor A and sensor B. Sensor A reports the vessel temp. while sensor B monitors the output of the heater. The original heater had just a 2 degree temperature differential. The new heater that must be used produces a temperature rise of 8 degrees F. on sensor B. What I am trying to do is automatically modify sensor B to read no more than 2 degrees hotter at any time than sensor A, using A as a reference through it's temp. range.
    An example of the resistance readings at two ends of the temperature range for this project is as follows: At 59F tank temperature sensor A is 48,840, heater is putting out 67 degrees so sensor B is about 40,000, difference of 8840. At 104F sensor A is reading 16,149 and sensor B is 112F @ 13,500 a difference of just 2,650. So I need a clever way to add 8000 ohms or so when colder and gradually reduce using A as my reference as temp. climbs to finally just 2500 when warmer.
    Thank you in advance for your suggestions.

  2. bertus


    Apr 5, 2008

    Could you make a table.
    You can put the temperature and the both resistor values in it.
    When using the code tags, the spaces in the table will be preserved
    The text all in one line is hard to read.

    Last edited: Oct 7, 2012
  3. Actionspa

    Thread Starter New Member

    Oct 6, 2012
    Here are a few reference points with the temp. and resistance relationship.