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Re: [APD] Fw: DIY reflector?

An advantage of an electronic ballast operating at 15k-80kHz is that the on/off cycling is in no way perceptible. Also, any man over 40 would be lucky to be able to hear a hum in that frequency range.  ;-)
And at the higher freqs of the electronic ballasts, much smaller coils are needed to proived the necessary impedance so, that makes them a little easier to manage, too.


----- Original Message ----
From: Donald Hellen <donhellen at horizonview_net>
To: S. Hieber <shieber at yahoo_com>; aquatic plants digest <aquatic-plants at actwin_com>
Sent: Thursday, July 20, 2006 2:07:32 PM
Subject: Re: [APD] Fw: DIY reflector?

On Thu, 20 Jul 2006 08:51:40 -0700 (PDT), "S. Hieber"
<shieber at yahoo_com> wrote:

>But know that you are getting simple magnetic ballasts that might audibly hum as the bulbs turn on and off 120 times per second (some folks claim they can perceive the flicker), narrow spectrum bulbs (probably using calcium halophostate as the "single phosphor" -- the plants won't care but the viewers might)

You're right on the perspective form the
plants--Walstad claims that the plants won't care. Some
of the cheap shop lights have the mounting of the
ballasts set up to prevent the hum from being audible.
That seems to be the case with mine. If they're
packaged well, they won't hum, at least not until they
are a few years old. That's when some of them become
audible. I think some of the cheap ones, though, do hum
even right out of the box. We've been fortunate so far
with the brand we've bought.

The phosphor in some bulbs seem to smooth out the
flicker also, but I've seen some that don't do a good
job of that. 

If these had a hum problem, I would take them back. I
do expect them to hum eventually, and that's when I'll
move them to the garage where I need more light. Then I
can buy some with electronic ballasts that will last
more than 5 or 10 years. 
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