| History & Topics |
| Digital Dip Meter
checks Non Contact IC Card! |
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| For many years, radio amateurs have
been familiar with Dip Meters to measure the resonant frequency of the
L/C parallel (tank) circuit. Homebrewers, with their skills and experiences, used a Dip Meter as an universal measuring equipment for the adjustments of their receivers, transmitters as well as antennas. The recent sophisticated tranceivers took away the most of pleasures from those amateur craftsmen. The recent non contact IC cards contain L/C resonant circuit for the communication with gate machine (remote reading and writing) and the Digital Dip Meter got a new job for their factory adjustments. Digital Dip Meter is consisted of L/C Colpitts oscillator and the digital counter to read the oscillator frequency within the the accuracy of better than 0.005%. When Dip Meter's coil approaches and couples to the coil of the unknown L/C circuit within a few centimeters, a part of oscillation energy is absorbed by the unknown circuit and a dip is observed on the meter when the oscillator frequency is scanned across the unknown resonant frequency. The sharpness of the dip depends on the Q (Quality factor) of the resonant circuit to be checked, typically the resolution of 0.5% is attainable. The non contact measurement is a feature of the Dip Meter.
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