In every tutorial of "Hello World" I can find it calls for a resistor on the #15 . When I do this the background dims to the point that it doesn't even appear to be on anymore.
Wondering if my (recommended) 220 ohm was just too much resistance, I hooked up the 15 to the potentiometer, and the screen only got bright when I turned it all the way up. So, assuming it needed the full 5V, I just hooked it up directly to the 5V source. It lit up fine, and seems to not be burning out or getting hot.
am I missing something or am I just using a LCD other people are'nt? Is this 5V going to shorten the life of my LCD?
LED backlights take quite a bit of current e.g. 20-50mA. Most 16x2 displays already have a series resistor on the pcb. 47R is a typical value of series resistor. If the pcb has only got a 0R installed, you need the external 47R. 220R would be too high a resistance.
If the LED looks too bright, you need a higher resistance. And vice-versa.
TFTs take very significant current. e.g. 50-200mA
Since most hardware is designed for 3.3V, you might need extra series resistance for 5V operation.
Your photo looks about right.
OK. Firstly I suspect you did not use a 220 Ohm resistor. What are the colour bands on it?
Next, look at resistor "R8" on the back of the board, you will almost certainly find it to be "101" or 100 Ohm, in which case you do not need any additional resistor. This will draw about 22 mA (I measured it once) and can just be switched directly by an Arduino pin safely.
You may also find a zero ohm resistor "R9". It is possible these could be exchanged as one is in series with the anode line and one in series with the cathode line. If R8 or R9 is not 100 Ohms, then my comments do not apply.
