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transformers



This has gotten so far from the "physics teacher" topic I decided to change
the subject line.

I just did a little survey to see what these power things are called in
various electronics catalogs. I have checked major parts suppliers such as
Newark Electronics, Mouser Electronics, Digi-Key Corporation, etc.

In many instances the companies are careful to distinguish between
transformers (AC to AC) and DC power supplies (AC to DC). Transformer is
clearly reserved for AC-AC when it comes to regular transformers (bare
transformers intended for incorporation inside an instrument). AC-DC power
supplies with a line-cord are typically called DC power supplies. There is
less agreement on what to call the plug-in devices (also called wall-mounted
devices).

Mouser Electronics frequently uses the words "power supply" and "adapter."
The things that plug into a wall outlet are called plug-in adapters. The
word "adapter" is mostly used for AC-DC but in one instance is used for an
AC-AC plug-in adapter. In another place the AC-AC device is specifically
called a plug-in transformer.

Newark Electronics calls it a plug-in "power source" and lists both AC-DC
and AC-AC devices under this heading.

Digi-Key is less rigorous and has a page titled "wall transformers" that
includes both AC-AC and AC-DC models. Within that page it sometimes calls
the AC-DC devices "power supplies" but also lists some AC-DC devices under
the "transformer" heading.

Jameco seems unpredictable. In some cases transformer means AC-AC and
power-supply means AC-DC, but in other cases transformer is used for AC-DC.

Hosfelt Electronics uses the word "adapter" for both AC-AC and AC-DC and
always makes it clear what the device does. When they use the word
transformer it always means AC-AC.

In this small survey I like what Mouser, Newark, and Hosfelt are doing. The
thing that plugs into the wall is a "plug-in adapter" or a "plug-in power
source." It can be either AC-AC or AC-DC. I think Digi-Key and Jameco are
being inconsistent and/or sloppy.

Additionally, today we also have relatively inexpensive ways to convert DC
of one voltage to DC of another voltage, and some of these methods do not
involve oscillation-transformation-rectification like the old ones always
used. In any case, these are called DC-DC converters.


Michael D. Edmiston, Ph.D. Phone/voice-mail: 419-358-3270
Professor of Chemistry & Physics FAX: 419-358-3323
Chairman, Science Department E-Mail edmiston@bluffton.edu
Bluffton College
280 West College Avenue
Bluffton, OH 45817