>   That diode solution will alter also the logic input levels, so I
> will not use it. Obtaining -Vlc by rectifying and inverting a square
> wave generated by one pic pin, sound to be the better choice. Up to
> -6...-8V can be easily obtained using a voltage doubler.
>
> Vasile

The Shottky diode will put the input voltage (Vil) for the LCD to
-0.3-0.4V which is within spec. Normal (not extended temperature) LCDs
accept 0..5V on Vlc, not -2.5V. -6..-8V can NOT be obtained by running a
voltage doubler in inverting mode from +5V. -4V is about the limit with
Shottky diodes and no load. Maybe Ge diodes will increase it a little bit
more but it will be less than -5V in any case.

Peter

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