AC Wheatsone bridge equivalent impedance at AC

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The bridge circuit in post #19 can't be nulled due to phase shift between capacitive and resistive impedance. In so far it's unclear what you want to calculate.
 

Hi, thank you very much for this simulation. It seems my circuit is not working as I expected. I only have square wave oscillator for this setup.
But I found alternative methood to do good measure of capacitive probe with good results.



Any one could help with the simulation of this circuit?
How can I maximize voltage across AD8307? Oscillator ouputs square wave 3Vpp at 500ohms load

Thanks

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I'm also testing this setup's with good results.



One difference from A to B is probe range. When probe is connected to ground there is no range detection arround probe. But in schematic A probe has detection range about few cm's.
Don't know why this happening, but more range better measure.
 

vitoa said:
View attachment 129388

Any one could help with the simulation of this circuit?
Click to expand...

I adjusted some values. Current draw is 5-6 mA. The 'R' scope trace shows a response for both C values.



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View attachment 129389
Click to expand...

Your latest schematics can be simplified. The righthand one brings out the basic RC time constant. It resembles a schematic you previously posted.
 

Thanks for simulation. Bridge setup is not the best for this application ,so this circuit will fit better the propouses.
 

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