Cheap measurement for R, C and L.

[Guest]

Any hints for this project?

Want to make a small and cheap measurement for R, C and L.

I think using a opamp for interface to the pic. And a fet to discharge the C or L.

Measure for C can be "3*tau" = 95% of the input. And for L the same but reverse.

Start to make sure the L or C is discharged then disconnect the fet, now the current will grove in the circuit. Start the A/D and wait for the U to be 95% of the Ui. There i got my 3tau.

R=1k / C=1u /Ui=5 -> 3*1k*1u*2*3,14=18,84ms

Will this simple method work?

[SherpaDoug]

Check out Microchip application note AN512 for a glimpse at how much can be done with how little hardware. AN512 can measure R or C. Measuring L with take a little thought.
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[Guest]

Is there any hints for this?

[crystal_lattice]

Create a oscillator circuit with RCL combo, with the L or the C as the variables and measure the frequency. There is a circuit diagram here: http://electronics-diy.com/lc_meter.php

Edit: Here is a more complete link:http://ironbark.bendigo.latrobe.edu.au/~rice/lc/index.html