LC Meter
The core of design is a LC oscillator.
The system works in two phases: free runnig measure, and alterated free running measure.
First the system measure the free running frequency of an LC oscillator.
Then, in the second phase, a mechanism (a controlled reed-relay) apply a known capacitance to the unknown inductor (or capacitor) LC-resonator and another measure is performed.
After that, the system calculate inductance (or capacitance) using maths.
Also:
- An Smidth comparator is needed for adapt the analog signal of the
LC-resonator to digital logic (0-5V).
- A LCD for visualize the results and buttons for access to calibration
function or to switch between inductance or capacitance measure.
- A bias circuit for manage the 9V-DC battery power.
Sorry but at the mment in which I made the photos I had not a DC 9V battery at home (then the meter is off ... :( ).
When I have time I will make others.... more explicative.