Hi, am facing a strange issue. In brief, the objective is to measure di-electric constant of a varnish film (approx 30micron) applied to a copper plate. To achieve this, i have made a capacitance meter (using a CC Bridge method) where the electrodes are two brass plates of 11cm diameter, between these i keep a copper plate with varnish applied to one side.
1. Electrodes (11cm diameter)
2. Copper plate with one side varnished
3. Electrodes with plate in between
Based on theory – i should get a capacitance of around 3500 pf, however, what i get is only approx 600pf. I have tested the setup using paper as the dielectic (80 micron thickness) – again same problem, capacitance is much lower than expected.
I have tested the capacitance meter using various commerical capacitors in 470- 10000 pf range, the meter is accurate.
What am i doing wrong in either the electode setup or the measurement method itself? please advise...
1. Electrodes (11cm diameter)
2. Copper plate with one side varnished
3. Electrodes with plate in between
Based on theory – i should get a capacitance of around 3500 pf, however, what i get is only approx 600pf. I have tested the setup using paper as the dielectic (80 micron thickness) – again same problem, capacitance is much lower than expected.
I have tested the capacitance meter using various commerical capacitors in 470- 10000 pf range, the meter is accurate.
What am i doing wrong in either the electode setup or the measurement method itself? please advise...