History & Topics
　
Digital Dip Meter
Conventional dip meters have multiple frequency scales that correspond with a set of plug-in coils. No other coils can be used. Digital Dip Meters are also sold with a set of plug-in coils but without frequency scales. You can operate them even with a coil tweaked by yourself, big or small, round or square so long as the Dip Meter oscillates. The counter displays "your" frequency digitally.
　
Dip meters have been the universal instrument for amateur builders. Their original purpose was to sniff-out or adjust the local resonant circuit in a narrow space. It is why plug-in coils are so small and slender like a little finger.
　
Today, very few people enjoy making their own electronic gears so the dip meters are retiring from workbenches. But their ability to locate the resonant circuit remotely is recognized again at the research of the non-contact data exchange system such as "SUIKA" card at train's ticket gate. There are no needs the plug-in coils should be small.
　
When the coil is big, the size of magnetic fluxes induced by the current flowing through the coil is also big. The small coils are the lumped components, which generate the induction field in a limited narrow area. The big coils are a kind of distributed components, which generate radiation field as well like a transmitting antenna and the long sniff distance is obtained. The average sniff distances of the small plug-in coils are few centimeters (half an inch) at most, while the coil shown above is sensible as far as 50cm (1.5feet).
　
Since Digital Dip Meters are consisted of LC Colpitts oscillator generated waveform is pure sine* and the frequency is smoothly adjustable (unlike a synthesizer). Good news for purists but small frequency drift is unavoidable. The real frequency for each moment, however, is displayed on the counter in an accuracy of better than ±0.005%. You will have a standard marker generator.
*Pure sine wave is obtainable only when batteries or genuine AC adapter are used. Don't use "wall wart" sold on the market.
　
The coil shown above is not on sale so you have to make it if you need. Prepare insulated copper solid wire of 1.8mmφ～2.2mmφ(AWG13～11), wind on coffee can and bind with plastic tape to avoid kick back. Remove insulator and bend at both ends to fit with the socket then plug in. The above coil is 3 turn 115cm in diameter, oscillates between 11MHz and 20MHz.
　
Enjoy home brewing and experience the wide variety of applications of the Digital Dip Meter, but we owe no responsibility with the result of your experiments.
　
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