Emax

> Every 80s/90s EL system I've seen uses AC to drive the panel, hence the inverters (the things that whine a bit when the display is old). 
> 
> 

Indeed, and so does the Emax.  The whine is because of the oscillator that generates the AC (typically close to 100V) for the EL foil.  The small transformer that's in the inverter will vibrate in that frequency, causing the sound.  There generally isn't a rectifier after the inverter (and I doubt EL foil would even work on DC).

By the way, whine and display age are not necessarily related.  Mine was pretty silent with a dead backlight and has started whining significantly more since it got a new backlight...



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