[sdiy] Leaded Ferrite Bead vs. Inductivity

[Jaroslaw Ziembicki]

> 1. Possible to use inductivity insted of ferrite beads? (my guess is: yes)
>
> 2. If Yes, what is the correct value (interval) of it (in mH / uH) (of
course the right ansver can be the: it's depends
> the circuit behind, but is there any common sense?)

A ferrite bead has only some hundred nH or some µH, but works effective
at frequencies up to 1 GHz (at least), whereas a typical 10µH EMC choke
behaves as an inductivity up to, say, 30 and 80 MHz, and then the
impedance decreases (stray capacitance effect). That means: you should use
ferrite beads if you want to supress frequencies above 200-300 MHz.
If you have to use chokes - try to get "EMC chokes" 1µH to 4.7µH.
Avoid using "storage inductors" which are dedicated for switching
regulators!

Regards,
Jarek