From: G.Penate (penate@home.com)
Date: 06/21/01-06:21:51 AM Z
----- Original Message -----
From: "Dave Rose" <photo@wir.net>
> FWIW - When I built my custom-made light box I used eight 24" BL tubes and
> four ballasts. A large piece of sheet metal (painted flat white) is
affixed
> immediately behind the tubes. This metal is grounded. Without it, the
> light box will not work. With it, no problems! Why? I don't know, I
can't
> explain it.
The grounded metal close to the tubes provides an electrical path with less
"resistance", this helps the lamp start by ionizing the gas in the lamp,
once the lamp is going, that grounded metal is not really needed.
The electrons of the gas inside the tubes resist to get ionized (charged
electrically) and therefore moving from one filament at the end of the tube
to the other filament at the opposite end. The ballast/starter combination
is not quite enough to take the gas out of its "rest electrical inertia"
easily. Anything that is connected to earth (grounded) and in close
proximity of the tube (sheet of metal, your hand or usually the same box in
which the tubes are installed) will help to start the gas ionization
process, once it is going, the ballast/starter becomes more than capable to
keep it going without any help, until the lamp is turned off and the gas
electrons get "lazy" once again.
Guillermo
This archive was generated by hypermail 2b30 : 07/12/01-11:41:55 AM Z CST