Re: Converting 3V to 5V
You can convert 3v to a higher voltage with this simple circuit if it is only for prototypes, you should really look at the earlier suggestion for production runs.
1. Use a small NPN transistor
2. Connect the emitter to the 3V circuit (the one you want to convert FROM)
3. connect the base to the 3V supply through a resistor of 10KΩ.
4. connect the collector to the 5V supply through another 10KΩ resistor.
5. take the signal for the LCD from the collector.
How it works:
The transistor base is held at 3V potential, if the input (emitter pin) is logic 1 there will be no voltage across the B-E junction and the transistor will not conduct. The collector will therefore be pulled to 5V by it's resistor. If the input is logic 0, current flows in the B-E junction and the transistor conducts. As it's emitter is low, the collector voltage will drop to (Ve +VCEsat) which should be low enough to bee seen as a logic 0 at the collector.
Crude but for testing purposes, it works!
Brian.