Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!usc!elroy.jpl.nasa.gov!ames!amdahl!rtech!wrs!yuba!roger
From: roger@yuba.wrs.com (Roger Rohrbach)
Newsgroups: sci.electronics
Subject: need 50-300 uH RF coils
Keywords: coils, chokes, radio
Message-ID: <827@wrs.wrs.com>
Date: 12 Jan 90 23:24:12 GMT
Sender: news@wrs.wrs.com
Distribution: sci
Lines: 20

I am building a Theremin (an electronic musical instrument) from a
schematic published in a very old (1967) issue of "Popular Electronics".
The schematic calls for "50-300 uH RF coils".  I am told that this is
a very wide spread for adjustable coils by a mail-order house that carries
a very limited selection of same.  Furthermore, I can't find anyone locally
who stocks ANY coils whatsoever.  Does anyone know of a source,  or know
enough about the topic to suggest a substitution (I have to tune two RF
oscillators so that their difference frequency is audible)?

While I'm at it, the design also used "polystyrene capacitors", rated in
picofarads.  Can I substitute polypropylene, for which I have found a
source?  Any other substitutions?  (My, but there are a lot of capacitor
types out there;  ceramic, electrolytic, tantalum, Mylar... what's the
difference between them besides voltage rating?)

E-mail is appropriate.  Many thanks from an amateur.
Roger Rohrbach                                  sun!wrs!roger    roger@wrs.com
- Eddie sez: ----------------------------------------------- (c) 1986, 1990 -.
|   {o >o                                                                     |
|    \ ^) "I'm afraid of widths."                                             |