My brother Paul, W6PR, after chatting with some of you last Sunday, reports 
that the April 2013 QST, on pages 39 through 42, has a description of an 
updated auditory gimick circuit by Bill Gerrey, WA6NPC, of Smith-Kettlewell 
Institute fame.  I don't know what's different about this circuit, but we'll 
find out.  The entire run of the Smith-Kettlewell Technical File from 1980 
to 1998 can be found at  http://www.ski.org/Rehab/sktf/techfiles.html .

For anyone who doesn't know, the auditory gimick is a voltage-controlled 
audio oscillator; the pitch is varied by the voltage at the input terminals. 
The first design I know of was the "transistorized auditory gimick" designed 
and described by Robert Gunderson, W2JIO, in a 1956 issue of the Braille 
Technical Press magazine, which he published.  Many, many versions of this 
circuit have appeared since that time, in the pages of the BTP and sometimes 
in print ham magazines.  This analog circuit was commonly used to tune up 
transmitters, by connecting it across meter movements or other low-voltage 
sources.  A modern incarnation, if he is still making them, is inside the 
ATOM, described on Mike Keithley's web page www.blind-ham-products.com .

A V C O function has been simulated digitally in devices such as the late, 
lamented LDG talking wattmeters, as well as other devices.  I use this 
function in a TW-1 for tuning up my 42-year-old FL2500 amplifier, insuring 
that the transceiver doesn't drive it excessively.


Lloyd Rasmussen, Kensington, MD
http://lras.home.sprynet.com