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Author Topic: Negative Contrast Voltage to Run LCD at 3.3V  (Read 1172 times)
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I'd like to experiment with running various 5V LCD displays at 3.3V. From what I can gather, many 5V units will actually work if you provide a negative contrast voltage, say -1V, at pin 3. Is there an easy way to produce this negative voltage in a typical Arduino or Arduino clone circuit? Could this be done by adding a small battery to the circuit with the battery's positive terminal attached to the ground of the main circuit, and a contrast pot across the small battery to provide an adjustable negative voltage?

Thank you.
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Could this be done by adding a small battery to the circuit with the battery's positive terminal attached to the ground of the main circuit, and a contrast pot across the small battery to provide an adjustable negative voltage?
Yes, this technique will work.  You have to do this for some 5v LCD modules as well, usually extended temperature varieties.

Don
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It is also not difficult do create a 5V supply with a switched-capacitor
converter. See the schematic in my LCD interface datasheet --

http://wiblocks.luciani.org/ZB1/ZB1-LCD-CHAR-index.html

(* jcl *)
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