| | Inductance Measuring Circuit (Site not responding. Last check: 2007-11-02) |
 | | Other advantages to using a series inductance as a calibration inductance is that the circuit is guaranteed to oscillate for any value of test inductance (Ltest) and that the inaccuracies resulting from finite op-amp slew rate are cancelled out, even if the positive going slew rate differs from the negative going slew rate. |
 | | The 220 ohm resistor is necessary to discharge the inductor during reversals in the polarity of the output voltage, otherwise a spike appears in the output voltage causing inaccuracies in the measured value of inductance. |
 | | For a desired inductance, l, the designer should calculate the number of turns, N, then wind an inductor with a few more than N turns, and gradually back off the number of turns, by measuring the inductance with the test circuit below until the exact inductance is achieved. |
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