[sdiy] inductor types and sizes for filters?

[Jerry Gray-Eskue]

Quick inductor intro:

An inductor is sort of like an inverse capacitor.
A capacitor resists Voltage changes, an Inductor resists Current changes.
These are both rather boring at DC, the capacitor acts like an open circuit
and the Inductor like a wire.

At AC they resist change in the form of frequency dependant Reactance.
=================================
Inductance is measured in henrys.
Reactive inductance is measured in Ohms.

	Xl = 2PIfL

Phase Shift - Current lags behind Voltage

Xl = Inductive reactance - ohms
f = frequency in hertz
L = Inductance in henrys
2PI = 2 times PI

	Q = Xl/R

Q = Quality of the inductor - no unit of measurement - Not the same as Q for
caps
R = DC resistance - ohms
=================================
=================================
Capacitor reactive inductance.

	Xc = 1/(2PIfC)

Phase Shift - Voltage lags behind Current

Xc = Capacitive reactance - ohms
C = Capacitance in farads.

	Q = CE

E = volts
Q = Charge in coulombs - Not the same as inductors
=================================
- Jerry

-----Original Message-----
From: synth-diy-bounces at dropmix.xs4all.nl
[mailto:synth-diy-bounces at dropmix.xs4all.nl]On Behalf Of Dan Snazelle
Sent: Tuesday, November 17, 2009 9:34 AM
To: sdiy
Subject: [sdiy] inductor types and sizes for filters?




the mysterious inductor.

in the past if i saw an inductor in a schematic, i would skip it.
but i want to get over that.

so can anyone recommend a few part types i could try out? one of the things
that has kept me from inductors is that i know nothing about which TYPE to
buy (choke, coil, power inductor, etc) or what size. mouser has around
50,000 inductors to choose from.

also i never know what a schematic is calling for when i look at it.

some schematics use upper case MH and some use mH and i know some types have
higher Q values, etc

so if anyone can help me out, i would really appreciate it (soon to make a
mouser order)


thanks!!!

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