Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!tut.cis.ohio-state.edu!purdue!iuvax!silver!commgrp
From: commgrp@silver.bacs.indiana.edu
Newsgroups: sci.electronics
Subject: Re: Galena Crystals
Message-ID: <7200046@silver>
Date: 8 Dec 89 18:58:00 GMT
References: <1835@naucse.UUCP>
Organization: Indiana University CSCI, Bloomington
Lines: 32
Nf-ID: #R:naucse.UUCP:-183500:silver:7200046:000:1186
Nf-From: silver.bacs.indiana.edu!commgrp    Dec  8 13:58:00 1989




>On page 27 of the current "Nuts and Volts" magazine, there is an
>ad by Yeary Communications of a "Cat Whisker" kit.  Copy says
>"Authentic Cat Whisker and Galena Crystal Detector and Stand with
>All Brass Mechanism and True Woods Metal Crystal Mounting"
>
>circular and oval forms available: $19.95 & $5 s&h.
>address is 12922 Harbor Blvd, #800 Garden Grove, Ca 92640
>
>- Bob Wier     Northern Arizona University

Galena crystals are available cheap at "rock swaps" (like hamfests for 
rock collectors; ask a geologist where to find one).  I bought a 
beautiful one-inch cube of it for about $1.50.  Rock shops in cities 
have them for 4x - 8x that price.

Some crystal-set plans use a metal tube with a setscrew to hold the 
galena.  It's better to embed the crystal in low-temperature alloy 
(e.g., Wood's Metal: Bi 50%, Pb 25%, Sn 12.5%, Cd 12.5% by weight; 
melting point 70C.  See CRC Handbook of Chemistry & Physics).

The "cat whisker" is any sharp-pointed metal needle, mounted with a 
spring to maintain tension.

If you do not insist on historical purity, a 1N34 point-contact 
germanium diode works much better.

--

Frank Reid     W9MKV     reid@gold.bacs.indiana.edu