Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!sol.ctr.columbia.edu!lll-winken!ames!skipper!rando
From: rando@skipper.dfrf.nasa.gov (Randy Brumbaugh)
Newsgroups: sci.electronics
Subject: Re: What is a triac
Message-ID: <950@skipper.dfrf.nasa.gov>
Date: 4 Jun 91 15:36:44 GMT
References: <035305.13208@timbuk.cray.com>
Reply-To: rando@skipper.UUCP (Randy Brumbaugh)
Organization: NASA Ames-Dryden, Edwards,CA
Lines: 30

In article <035305.13208@timbuk.cray.com> snowden@sequoia.cray.com (Jim Snowden) writes:
>I'm going to try running a CD-ROM player (US 110V) in the UK and someone told
>me I could use a transformer to convert the voltage, but not to use a triac.
>
>Could someone tell me what a triac is and why it wouldn't be suitable?
 
Well, . . . A triac is a solid state device which looks something like a
transistor, and works like 2 silicon controlled rectifiers, wired 
in opposite directions for swithing AC, etc.

But, . . . The triac has no application I know of in voltage conversion.
Maybe in switching power supplies or something.

However, there is a voltage conversion device called a Variac.  This is
a variable transformer -- I think Variac is a brand name.   It looks like 
a round (usually grey) can with a control knob on top -- to adjust the
voltage.  These are used for things like dimming lights.  Usually the 
output can be adjusted from something like 20% - 120% of the input voltage.
They come in various sizes, depending on the application.  I think this 
may be the device you were warned against using.

Yet, . . . I can't think of any reason this wouldn't work for voltage
conversion for a CD player.  (Disclaimer: just because I can't think
of a reason doesn't mean there isn't one).

Can anybody else think of a reason a Variac should not be used for 
converting voltages?

Randy Brumbaugh
rando@skipper.dfrf.nasa.gov