19 Sep
2002
19 Sep
'02
8:35 a.m.
Is it normal for a Variac to hum when it's plugged in?
If not, any ideas why one would do so?
Sellam Ismail Vintage Computer Festival
------------------------------------------------------------------------------
International Man of Intrigue and Danger http://www.vintage.org
* Old computing resources for business and academia at www.VintageTech.com *
19 Sep
19 Sep
8:52 a.m.
If not, any ideas why one would do so?
Vibrations induced by the changing magnetic fields created
as a result of the cyclic nature of alternating current.
At 05:36 AM 9/19/02 -0700, you wrote:
Is it normal for a Variac to hum when it's plugged
in?
If not, any ideas why one would do so?
Sellam Ismail Vintage Computer Festival
------------------------------------------------------------------------------
International Man of Intrigue and Danger http://www.vintage.org
* Old computing resources for business and academia at www.VintageTech.com *
8:58 a.m.
A non-text attachment was scrubbed...
Name: not available
Type: text
Size: 826 bytes
Desc: not available
Url :
http://www.classiccmp.org/pipermail/cctalk/attachments/20020919/98eaf4aa/at…
11:54 a.m.
On Thu, 19 Sep 2002, Tony Duell wrote:
It depends on how loudly!
It's quiet. But I left it plugged in and when I was going to bed at night
and the house was quiet it was noticeable enough that I went to
investigate and determined that it was the Variac, so I unplugged it. I
noticed also that the enclosure was warm, which bothered me.
All Variacs -- in fact just about every
mains-frequency transformer --
will hum a little. The hum will get louder when you increase the load. A
Variac with no load should hum pretty quietly, but you may still hear it.
At the time I noticed it there was no load on it. I'd never heard it hum
before (or at least never noticed). I plugged it in today just to see if
it hummed off the bat and it does.
On variacs, the moving contact brush will effectively
short-circuit a
couple of turns. The variac is designed to handle this, but if you're not
using the original brush then you might have problems. Have you replaced
the brush?
Nope. Where would I get a replacement brush if it needs it?
Sellam Ismail Vintage Computer Festival
------------------------------------------------------------------------------
International Man of Intrigue and Danger http://www.vintage.org
* Old computing resources for business and academia at www.VintageTech.com *
20 Sep
20 Sep
8:38 a.m.
A non-text attachment was scrubbed...
Name: not available
Type: text
Size: 1134 bytes
Desc: not available
Url :
http://www.classiccmp.org/pipermail/cctalk/attachments/20020920/1d33d556/at…
5:41 p.m.
On Fri, 20 Sep 2002, Tony Duell wrote:
Cool.
It's
quiet. But I left it plugged in and when I was going to bed at night
and the house was quiet it was noticeable enough that I went to
OK< that sounds about normal, actually... A worn brush is _not_ the cause of the humming. But if
somebody had
replaced the brush with one of the wrong type then it could cause problems.
Often, replacement brushes are available from the manufacturer (at least
I've seen them listed in catalogues over here). It's rare to need to
replace one, though.
M'kay.
Thanks very much for the information, Tony!
Sellam Ismail Vintage Computer Festival
------------------------------------------------------------------------------
International Man of Intrigue and Danger http://www.vintage.org
* Old computing resources for business and academia at www.VintageTech.com *
8:47 p.m.
A Variac is a kinda transformer. Transformers often
hum. Especialally when the iron laminates in the core
start to come loose. So it's a bit of an old age phenomenon. Even small HF
ferite-based transformers
can squeek (arghhh yuck) if the frequency (product) comes into the hearing
range..........
Sipke de Wal
-------------------------------------------------
http://xgistor.ath.cx
-------------------------------------------------
----- Original Message -----
From: "Sellam Ismail" <foo(a)siconic.com>
To: "Classic Computers Mailing List" <cctalk(a)classiccmp.org>
Sent: Thursday, September 19, 2002 2:36 PM
Subject: Humming Variac?
Is it normal for a Variac to hum when it's plugged in?
If not, any ideas why one would do so?
Sellam Ismail Vintage Computer Festival
------------------------------------------------------------------------------
International Man of Intrigue and Danger http://www.vintage.org
* Old computing resources for business and academia at www.VintageTech.com *
8128
days inactive
8130
days old
7 comments
5 participants
participants (5)
-
ard＠p850ug1.demon.co.uk -
foo＠siconic.com -
geneb＠deltasoft.com -
mail.list＠analog-and-digital-solutions.com -
sipke＠wxs.nl