This blog is about new inductivity meter based on a NE555.
For my experiments with switch mode converters, I needed a simple way to compare inductivities of coils.
Since I don't have a multimeter which can do inductivity measurement (but I have a really great multimeter, more infos perhaps in the next blog), I decided to build one.
And this is the schematic of it:
A NE555 works in its most simple rectangle osciallation configuration.
In this mode, the duty-cycle should be around 50%, but this depends on the load on pin 3.
Over the amplifying transistor Q1 the AC is given on an LC circuit.
It oscillates a freqency given by the equation:
This oscillating waves are amplified by Q2 and frequency is converted into a voltage by the RC-network of C3 and the ampmeter.
Due to the capacity of both C3 and C2 being constant, the current through the ampmeter is defined by the inductivity.
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