Hi Tim
you wrote.
----------
> Hi people,
>     Does anyone now how i can get a negative voltage to drive the
> contrast of the 16x1 LCD display, FROM a single supply of +13.5
>
> Thanx
>   Tim
>

Have you tried the Si7660 or Si7661.
These chips are 8 pin devices, the 7660 will give you a up to a -10 from a +10 supply while the 7661 will give you up to -20 from a +20 volt rail.
All thats required is a 10uf Electro between pins 2 and 4 with the + toward pin 2.
Pin 3 in ground
Input is pin 8
pins 1, 6 & 7 not connected.
output is pin 5.
On pin 5 have a 10uF electro to ground + toward ground
NOTE + toward ground, output on pin 5 is negative.

All thats required is a Si766x and 2 x 10uF electros.

cheers Norm
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