At 05:04 PM 12/21/2005 +0100, you wrote:
> > Here's the problem...
> > (snip)
> > Bottom line for me.... Controlling *just* the voltage at Vo does not
> > control contrast.
>
>If I read your post correctly you made a bad voltage buffer, it did not
>work, and now your conclusion is that voltage driving does not work????
>
> > yet, to me this is pretty conclusive....
>
>It is, but conclusive of what excatly? That you need much more
>experience before you jump to conclusions?
>
>A free tip (as in free beer): Olin is not known for his subtle human
>interface, but I don't recall him being wrong on electrical matters.

Yes. Ideally you feed Vo a voltage V(T) which varies with temperature. The
function of temperature depends on the LCD type. You can add a BF
for the user to fiddle with the contrast depending on viewing angle, lighting
conditions and personal preference.

Sounds like he was using a bipolar op-amp for a buffer than would not swing
to the -ve rail, and further one that had the phase reversal "feature".


Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
->> Inexpensive test equipment & parts http://search.ebay.com/_W0QQsassZspeff


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