Article: 129361 of alt.peeves From: jsn@concentric.net (John S. Novak, III) Newsgroups: alt.peeves Subject: Re: Why Do I Live Here? Date: 28 Oct 1999 22:06:30 PDT Organization: Cynics Central Lines: 31 Message-ID: References: <7v7i2a$oqr$1@nntp6.atl.mindspring.net> <3817714b$0$215@nntp1.ba.best.com> <7vak2u$api$1@nntp6.atl.mindspring.net> <7vav9j$a9t$1@panix2.panix.com> Reply-To: jsn@concentric.net NNTP-Posting-Host: ts006d13.per-md.concentric.net X-Newsreader: slrn (0.9.4.3 UNIX) Path: news1.meer.net!news3.best.com!news2.best.com!news.maxwell.syr.edu!newspeer1.nac.net!news.lightning.net!newsfeed.concentric.net!global-news-master Xref: news1.meer.net alt.peeves:129361 On 28 Oct 1999 19:03:31 -0700, Kenneth Crudup wrote: >>While we're at it, what's the difference between a rheostat and a >>potentiometer? >I always assumed that "rheostats" got their variable resistance from a slider >on a core of wrapped wire, and "potentiometer" acheived variable resistance >from having its actuator slide across a carbon resistance fiom. Rheostats are two terminal devices, to be inserted into a circuit in series. Between the input terminal and the output terminal, there are small resistive elements in a linear array. A wiper, slider or other gadget selectively cuts out some or all of those resistive elements. A rheostat is, in every sense of the word, a variable resistor unit. A potentiometer, by contrast, is a three terminal device. It has two input terminals which should be attached to two different potentials. There are likewise resistive elements between these two terminals. The third (output) terminal is a wiper, slider, or other gadget which sweeps across the resistive elements, and delivers the appropriate divided voltage. A potentiometer is, in every sense of the word, a variable voltage divider unit. Similar, but not the same. -- John S. Novak, III jsn@concentric.net The Humblest Man on the Net