I'm having problem related to circuit which is presented bellow. I try to calculate a resultant capacitance of such circuit in case, where C is equal to 10 uF. I've connected this circuit physically, and according to measurements - searched capacity between point A and B is equal to 8.3 uF.


I've tried to calculate this circuit according to this post: Calculating effective capacitance of a circuit because I noticed, that my circuit is similar (in some part) to the capacitance bridge. According to my calculations, such effective capacitance have (3/4)*C = 7.5 uF, so there is some value mismatch, and I don't know why... I suspect, that there could be some calculation mistake or some parasitic, additional capacitances in physical circuit... enter image description here
Could someone explain this mismatch ? I'll be quite greatful.

Regards, Y.T

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  • I calculate that the circuit should have a capacitance of (5/6)C = 8.333 uF, so I think that your measurement is correct. You can use symmetry to simplify your problem a lot. Let A be at -1V and B at +1V. Then the bottom plates of all 5 lower capacitors are at 0V by symmetry. Also, the top plate of the middle capacitor of these 5 is also at 0V by symmetry. That accounts for the voltages at all of the capacitor plates except for two sets of three plates each. You should be able to see that those two sets have to have voltages of +(1/3)V and -(1/3V). That essentially solves the problem. – Samuel Weir 2 days ago
  • I've calculated the capacitance according to your suggestion and now it's fine. Thank you. – Young_Electronic yesterday

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