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Sunday, October 16, 2016

How to test the pf range of a Variable Capacitor with an arduino uno or any atmega328 boards [beginner]

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Variable capacitor for a simple loop antenna for receiving
A variable capacitor is useful in various projects like magnetic loop antennae, crystal radio and in making antenna tuners. It is often necessary to know the range (max and minimum pf value) of the capacitor for designing its application and to choose optimal coils for covering the suitable area of the rf spectrum.

The solution is a capacitance meter. But for a pure diy enthusiasist, it may be often useful to measure it with our own tools and i used an arduino uno to do the job. See attached video




The basic circuitry and principles are the same as in my previous post on quick and dirty way to measure inductance and capacitance.

In this article i used a arduino uno hoocked to a i2c lcd and the capacitance measurement happens between pin A0 and A2

Schematic/Wiring

Connect the i2c lcd to i2c pins on the uno (A4 (sda) and A5 (clock)) and connect the test capacitor with a small wire to A0 and A2  and load the firmware



Firmware for the capacitance tester  (download)

Source code details (read here)

More on air variable capacitor (toy demo)



A simple video showing some application of the capacitance meter for learning how a split stater capacitor functions. See video







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