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Carbon comp resistors - shifting value

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  • #16
    I would have to think that your meter is doing 'something' to the carbon that the resistance reading always goes up.

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    • #17
      Originally posted by Jazz P Bass View Post
      I would have to think that your meter is doing 'something' to the carbon that the resistance reading always goes up.
      I'm in agreement. After considerable pondering and experimenting I reckon that the voltage passed by the meter causes the value to shift. Probably comes back to R.G.'s "voltage coefficient of resistance".

      The act of observing (measuring) changes the observed event. Carbon Comp Quantum Resistors!

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      • #18
        Originally posted by Mick Bailey View Post
        ...I reckon that the voltage passed by the meter causes the value to shift. Probably comes back to R.G.'s "voltage coefficient of resistance"...
        Mick,
        That seems unlikely to me because the Voltage Coefficient of Resistance of a carbon comp resistor is negative. Therefore, your observed drift is in the wrong direction. I’d also expect the voltage coefficient effect response time to be faster than the slow drift that you observe.
        I’d say that the next test would be to move the resistor to another known good meter.
        Tom

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        • #19
          Old CC read steady on both my meters, don't have any new ones atm though.

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