Ladder HPF (inductors)

[Harry Bissell]

Harry Bissell writes: Here is a schematic of a HPF ladder using inductors. As
I posted last night, the inductor value is too small. Bode plot shows you
would want 50mH to get down to about 200Hz. The bigger, the lower you can go.
    Martin Czech and Jurgen Habile are right on involving inductor problems.
I'm using 50uH in series with 11 ohms and in parallel with 50pF. The
capacitance (parasitic) doesn't seem to hurt much, but DC resistance IS the
Q-killer as I guessed. 11 ohms was the lowest I've seen (Tamura QIL-50
series). Don't ask how much they cost, probably at least $20 a piece (maybe
$50, $100 ???)Hermetically sealed in metal case with teflon terminals
($200???). If anyone wants the EWB file to play with I'll post it. I WILL NOT
be building one of these anytime soon... 

Heresy: Hipass filters suck.  And Inductors suck even harder... ;_) Harry

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