Optimizing Voltage Measurement in High Resistance Circuits

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Discussion Overview

The discussion revolves around methods for measuring voltage in high resistance circuits, particularly when the circuit resistance exceeds the resistance of the measuring voltmeter. Various techniques and tools for accurate voltage measurement are explored.

Discussion Character

  • Technical explanation, Experimental/applied, Debate/contested

Main Points Raised

  • One participant suggests that using a higher impedance voltmeter may be necessary for accurate measurements.
  • Another participant proposes using a null method, balancing the voltage against a known variable voltage or employing a potentiometer.
  • A different approach mentioned involves creating a measurement circuit that alternates between a standard voltage and the voltage to be measured, comparing their effects.
  • One participant recalls historical methods, indicating that potentiometers were commonly used before high impedance voltmeters were available.
  • Another suggestion includes using a feedback circuit with a high gain operational amplifier to match the test voltage with a low impedance source voltage for measurement.
  • A more unconventional idea is presented, recommending the connection of a low-leakage capacitor to the circuit and measuring the voltage after a delay.

Areas of Agreement / Disagreement

Participants present multiple competing methods for measuring voltage in high resistance circuits, with no consensus on a single best approach. Various techniques are discussed without agreement on their effectiveness or applicability.

Contextual Notes

Some methods depend on specific circuit conditions and the nature of the voltage being measured, which may not be fully addressed in the discussion.

Idea04
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What is the best way to measure the voltage from a high resistance circuit?
The circuit resistance is higher than the resistance of the voltmeter.
 
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You haven't really provided much to go on.

It could be that your voltmeter is not very high impedance so you simply need to get a higher impedance one.

Depending upon the voltage you wish to measure, and the circuit it occurs in, one way is to use a null method. The voltage to be measured is balanced for a null against a known variable voltage or by means of a potentiometer.

Yet another method is to devise a measurement circuit where you switch alternately between a standard voltage and the one to be measured. Your measurement circuit then compares the effects of both voltages.

hope this helps

go well
 
In the 'olden days' when there just didn't exist high impedance voltmeters, people always used a 'Potentiometer.' (See above). Nowadays, you could use a feedback circuit with a high gain op amp to match the test voltage with another equal voltage from a low impedance source and then measure the value of this voltage.
 
i would connect a low-leakage capacitor to it, then come back tomorrow and read the voltage. ;)
 

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