Hi all
  The most interesting thing I found was that as the panel ages the capacitance
of the panel decreases. If the Driver Oscillator
uses the panels capacitance as part of it's resonant circuit then its output fre
quency will increase as the panel ages. And as
Donald said, as the driving frequency goes up so does the lamps brightness. If d
one right you can maintain lamp brightness at a
constant level, over the entire life of the lamp.

--------------------------------------------
Brian Whittaker SVSKITS.COM
Voice: 510-582-6602 FAX: 510-291-2218
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Donald L Burdette wrote
>
> I did some development a while back for a customer who wanted to sell
> advertising stuff with EL lighting.  I learned some things y'all may find
> interesting:
>
> 1.  There are several different kinds of phosphors, and many varieties of
> each.  Color, voltage and drive frequency vary.
> 2.  Voltages range from 30-40 VAC to as high as 800 VAC.
> 3.  Higher frequencies tend to make the colors more blue, lower
> frequencies, more green.  You can run some phosphors from 60 to as high
> as 1000 Hz.
> 4.  The lamps look like lossy (resistive) capacitors.  Thus the current,
> power dissipation, and light output are closely related to voltage and
> frequency.
> 5.  Phosphors degrade with time, and faster if you use them.  The harder
> you drive them the shorter the life.
> 6.  Phosphors degrade with moisture.  That's why most sheets should not
> be cut (it destroys the edge seal).  There are some materials that have
> micro-encapsulated phosphors.  These can easily be cut without affecting
> the reliability.
> 7.  Attaching electrodes may be the most problematic item for hobbyists.
> The thing is basically a capacitor with phosphor in the dielectric.  The
> back plate can be heavy and opaque, but the front plate needs to be
> transparent.  I don't know a lot about how they do it, but it ends up
> being a very thin metallic layer with a protective insulator over it.
>
> Hope this is helpful, or at least enlightening.  Time for some
> ZZZZZ's....
>
>
> Don
>