ASCEL Electronic AE20204, Руководство по сборке и эксплуатации

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First, the frequency without C10 is measured (f1).
f1
=
1
2
⋅π⋅
√ L1
⋅
C9
Then, the frequency f2 is measured with C10.
f2
=
1
2
⋅π⋅
√
L1
⋅(
C9
+
1000pF
)
C9 can be obtained by equalizing both equations.
C9
=
f2
2
f1
2
−
f2
2
⋅
1000pF
Since C9 is known now, L1 can be calculated.
L1
=
1
4
⋅π
2
⋅
f1
2
⋅
C9
This self-calibration is performed on start-up. To measure
components, frequency f3 is obtained with the component
under test connected to the oscillator. The unknown
capacitance Cx or inductance Lx can be calculated as follows:
Cx
=[
f1
2
f3
2
−
1
]⋅
C9 Lx
=[
f1
2
f3
2
−
1
]⋅
L1
This method allows the measurement of very small values, for
example the capacitance of cables.
3