----- Original Message ----- 
From: "Spehro Pefhany" <speff@interlog.com>
Subject: Re: [PIC] 10 ohm pot to control contrast on a 16 char x 2 line LCD?


> The requirement for a negative contrast voltage is typical of wide
> temperature range LCD character displays.

In fact, "extended temperature" is pretty much synonymous with "needs a
negative supply".  Fortunately, the negative supply requires very little
current, so a charge pump as you used is fairly simple to cobble together.

Not all Seiko displays are extended temperature.  Seiko, like most
suppliers, provides both extended temperature and "normal" displays.

And yes, 10 ohm seems way too low to me.  I generally use whatever I happen
to have, but never less than 1K.  Sure they didn't intend 10K?

--McD


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