10/01/2011, 10:27:53
Le lundi 10 janvier 2011, Frédéric a écrit :
> Ok. Reste à comprendre comment ça fonctionne dans le détail.
Bon, j'ai trouvé une discussion intéressante :
"Most of these ballasts have a 10V internal reference connected through a
resistor to the "+" control line, designed to supply 0.6mA if shorted to
ground.
The "+" control line is also internally connected to the actual circuitry
which controls the brightness of the tubes.
The "-" control line is connected to ground. So when you have your resistor
connected between the two control lines, you drag the voltage down with
decreasing resistance. The internal resistor acts as the other half of the
potential divider.
If you supply an external voltage to the control lines, you just have to
make sure that they can sink greater than 0.6mA and overcome the effect of
the built-in resistor.
I think almost all of these ballasts are 1-10V rather than 0-10V, and you
cannot take the tube to 0% brightness without turning off the mains."
--
Frédéric
> Ok. Reste à comprendre comment ça fonctionne dans le détail.
Bon, j'ai trouvé une discussion intéressante :
"Most of these ballasts have a 10V internal reference connected through a
resistor to the "+" control line, designed to supply 0.6mA if shorted to
ground.
The "+" control line is also internally connected to the actual circuitry
which controls the brightness of the tubes.
The "-" control line is connected to ground. So when you have your resistor
connected between the two control lines, you drag the voltage down with
decreasing resistance. The internal resistor acts as the other half of the
potential divider.
If you supply an external voltage to the control lines, you just have to
make sure that they can sink greater than 0.6mA and overcome the effect of
the built-in resistor.
I think almost all of these ballasts are 1-10V rather than 0-10V, and you
cannot take the tube to 0% brightness without turning off the mains."
--
Frédéric