 Here is my new inductance & capacitance meter. I had took the analog oscillator part from a well know schematic found on the internet and adapt it for a AVR. It's impressive to have a very accurate result with a so small circuit. The way it's work is simple you chance a oscillator frequency with the part you want to find is value. The frequency is read and with some math you get the value. Here is how it's work, At power-up you read the oscillator frequency without any thing connected to you probe, we will call this value f1. After the calibration process via a relay put a very accurate capacitor of 1000pF, you read this new frequency f2. When the calibration is done you can place your unknown part value and read the frequency f3. Now we go in math…
For capacitor:
a = ((f1/f3)^2)-1
b = ((f1/f2)^2)-1
result = (a / b) * 0.001
For Inductor: a = ((f1/f3)^2)-1
b = ((f1/f2)^2)-1
c = 1000000000
d = (1/(2*pi*f1))^2
result = a * b * c * d
result = result * 1000000
Features: Inexpensive High acuarity Auto scale Auto calibration Can be use as a frequency meter with only small modification
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