Measuring High Voltage with Influence

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Discussion Overview

The discussion focuses on methods to measure the voltage of a Kelvin Water Dropper, particularly in the context of high voltage and low charge. Participants explore various techniques, including measuring by influence and using electric fields, while addressing the challenges posed by the specific characteristics of the device.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests measuring voltage by influence due to the high voltage and low charge of the Kelvin Water Dropper.
  • Another participant proposes several methods, including building an electroscope, using an electro field meter, and measuring force between capacitor plates.
  • A different approach involves constructing a generating voltmeter that uses a rotating fan to alternately cover and uncover capacitor plates, which could provide a proportional AC signal to a high impedance meter.
  • There is a question raised about the applicability of the generating voltmeter method for Van de Graaff generators, which produce DC power.
  • A response clarifies that the rotating fan method can produce an AC signal through capacitive coupling, despite the DC nature of the voltage source.

Areas of Agreement / Disagreement

Participants present multiple competing views on the methods for measuring voltage, and the discussion remains unresolved regarding the effectiveness and applicability of the proposed techniques.

Contextual Notes

Some methods proposed depend on specific configurations and assumptions about the devices used, and there are unresolved questions about the nature of the signals produced by different measurement techniques.

triac
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Hi!
I am looking for a way to measure the voltage on a Kelvin Water Dropper that I've built. This is quite problematic since the charge is small and the voltage is high. The only way to do it, as it seems to me, is to measure by influence. Any suggestions?
 
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You could also use the field. Some suggestions:
- build a simple Electroscope with an arm that moves up if the device is charged (some have a scale)
- buy an electro field meter
- attach your buckets to a plate capacitor and rotate a coil inside
- measure the force between two capacitor plates
- do something with a cathode ray tube
 
triac said:
Hi!
I am looking for a way to measure the voltage on a Kelvin Water Dropper that I've built. This is quite problematic since the charge is small and the voltage is high. The only way to do it, as it seems to me, is to measure by influence. Any suggestions?

Build a generating voltmeter. This is a rotating "fan" that alternately covers and uncovers capacitor plates. Feed the plates behind the rotating part to a high impedance scope or other High Z AC meter. AC signal will be proportional to the high voltage without contact. These are commonly used to sense the voltage on Van de Graff generators.
 
Ok, thanks for your help!
 
bjacoby said:
Build a generating voltmeter. This is a rotating "fan" that alternately covers and uncovers capacitor plates. Feed the plates behind the rotating part to a high impedance scope or other High Z AC meter. AC signal will be proportional to the high voltage without contact. These are commonly used to sense the voltage on Van de Graff generators.

How can this work if Van De Graff generators produce DC power?
 
taylaron said:
How can this work if Van De Graff generators produce DC power?

The rotating "fan" alternately shields and exposes the voltage on the target, producing an AC signal via capacitive coupling.
 

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