FPV LC filters

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Filter Basics

A simple LC filter is known to reduce noise going towards the video system, mainly through its power input. Recommended values: 1mH inductor and 470uF capacitor

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Source: Sander's filter

The Capacitor

The capacitor can be broken up like this:

Lc-lowpassfilters2.gif


Using e.g. two 220uF capacitors. Be careful, the Voltage rating of the caps must be much higher than the involved voltages (usually lipo). A small (tantalum?) capacitor can be added in parallel to the big ones to filter out higher frequencies. 0.1 uF is a starting point according to Wayne.

Source: Recommended values


The Inductor

Looking around for enamel cable, and reading through comments about CAT5 wires, I figured I could use one of those $1 MicroUSB cables to source wire... Hobbyking ferrite rings (here or here) will also be used:

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The results:

140524 LCfilter3.jpg140524 LCfilter4.jpg

1mH is very good! Additionally, using the green rings yields inductors of almost 2mH using the same wire. The current capacity of the cable is not so great though... caution.


In contrast, the one used in Hobbyking's filter is only 0.25mH.

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