In article <2uf4m6$7h5@lsi.lsil.com>, achien@lsil.com writes...
>I am looking for information on how to design a "Helical filter" . Any books, papers or design equations available for this kind of filters? I know "TOKO coil" make this kind of filters but I need to custom design my own filter.
>---
>Arthur Chien
Info on this type of filter is somewhat hard to find but I have spent *more*
than a little time searching so I think I can save you some time. Got a pen ?
As usual, the ARRL handbook touches on the subject.
Handbook of Filter Synthesis, A.I. Zverev ISBN 0-471-98680-1
Reference Data for Radio Engineers, Howard Sams (pre-seventh edition)
Filters with Helical and Folded Helical Resonators, Peter Vismueller
ISBN 0-89006-244-7.
There are a few more but these are the most common and should get you started.
BTW, the Zverev is out of print and is hard to find except in the reference
section of an engineering library (the copy at my library has been stolen by
some unscroupulous filter engineer). The Vismueller book *JUST* went out of
print a couple of weeks ago; at that time, the publishers had 2 copies left
which go for a hefty price (something like $70 CDN -Yeowch!).
-Good luck
Mark, VE2HVW
------------------------------
Date: Mon, 27 Jun 1994 12:09:50 GMT
From: wang!pvr@uunet.uu.net
Subject: PADS and single-point grounds
To: ham-homebrew@ucsd.edu
haymoree@newt.ee.byu.edu (Ed Haymore) writes:
$>I've been trying to get the shareware PADS to bring all grounds in my
$>circuit into a single point, without success. I don't seem to have any
$>control over which pins have the physical connections -- I can connect
$>all grounds to a single point on the schematic, but when it's imported
$>into PADS-PCB, that information is lost and PADS re-connects the pins in
$>a daisy-chain format.
You will have to hand route your ground traces. The trick is
that you must run one ground trace over top of other ground traces.
The copper will be correct but your layout under PADS will be more
complex. What you must do is to first route the trace from the
circuit ground point to the common ground point. Next, continue
from the common ground point to the point that PADS connected the
ground. This will complete the routing and make PADS happy. The
trace should be routed on top of the previous trace going to that
circuit ground.
How you draw the circuit has no bearing on how the netlist is
created. The netlist is only electrically correct. It is only
the netlist that controls how the routes are run.
Pete.
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