Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.1 6/24/83; site watcgl.UUCP
Path: utzoo!watmath!watcgl!dmmartindale
From: dmmartindale@watcgl.UUCP (Dave Martindale)
Newsgroups: net.audio
Subject: Re: Linear with varying speeds
Message-ID: <2137@watcgl.UUCP>
Date: Fri, 17-Feb-84 13:23:42 EST
Article-I.D.: watcgl.2137
Posted: Fri Feb 17 13:23:42 1984
Date-Received: Sat, 18-Feb-84 02:21:40 EST
References: <1670@iedl02.UUCP>
Organization: U of Waterloo, Ontario
Lines: 12

It isn't necessarily that a turntable which uses a quartz oscillator
for its frequency reference needs an RC oscillator for pitch control.
Normally, the servo system will try to phase-lock the turntable's
rotation to a reference frequency which is the quartz oscillator's
frequency divided by an appropriate magic number.  To get variable
speed, you can either replace the quartz oscillator by an RC oscillator
(cheap but not stable) or you can change the "magic number" that the
reference oscillator is divided by.  If the frequencies involved are
chosen so that the "magic number" is large enough, then the frequency
can be changed in increments smaller than what you could possibly set
using an analog control while retaining the stability of the quartz
oscillator.