[sdiy] Noob Question: Passive Filter Design

[Ingo Debus]

Am 04.05.2010 um 21:53 schrieb Colin f:

> Ditto the Korg Minipops 7.
> PCB photo and schematics are here:
> http://www.colinfraser.com/mp7/index.htm
> Many of the sounds have no active components at all, or just a single
> transistor buffer.
> They are just resonant LC filters fed with trigger pulses.
> Count the inductors.

I count 15 on the schematic. Is this correct?
On the PCB I count 13 of the round brown things and two that look  
like little transformers. Which ones in the schematic are the two?  
The 250mH with the double line drawn next to them (upper half of the  
schematic)?

> Then think how long it would take you to wind them by hand.

Hm, four inductor have 4 Henries, that's hefty. But then, JH's filter  
bank has two with 5 Henries.

Ingo