RadioBanter - View Single Post - power supply hums when electric blanket on

Stray Dog · January 2nd 09, 09:01 PM posted to rec.radio.amateur.equipment

On Wed, 31 Dec 2008, wrote:

Date: Wed, 31 Dec 2008 21:51:08 +0000 (UTC)
From:
Newsgroups: rec.radio.amateur.equipment
Subject: power supply hums when electric blanket on

When I dare to use an
A) electric blanket, or a electric frying pan set on "low",
at the same time when there is a
B) UPS computer power supply, or Ham radio power supply
also turned on anywhere in the house, the power supplies hum most
worryingly. One must make a choice: A) food, warmth, or B) fun.

What is the name of this waveform resonance with the current limiters
of A phenomena? Is there some kind of filter I can apply?

You can think about so-called power filtering or power conditioning
transformers or voltage stabilizing transformers. They are not cheap
and can get heavy, too, but come in at least three versions: i) low end,
ii) mid range, and iii) fancy-schmanzy high end, all
with various kinds of specifications on max output harmonic content,
voltage regulation plus/minus, etc. Some use
transformer-capacitor-inductor networks, some use an unusual core geometry
to exploit a curiosity in electrodynamics of transformers to get the
effect. But they are all designed to take out spikes, harmonics, and
weirdo waveform problems. Some of these are offered by high-end computer
backup-PS companies since some computer installations experience funny
glitchy-buggy problems from their power lines.

Can't help you with search terms and I know the proper term will give you
magic results (lots of hits on what you want). Good luck, but our modern
world is hooking up all kinds of weirdo electronic crap to the power grid.

For ham radio, you might want to think about a 12 volt deep cycle marine
battery and charger to give you clean power.