paai:
Let us not forget that there are many, many people like me who are good programmers and who are smart enough to connect the various wires and components, but who have absolutely no training in electronics. (Ohms law? Yes, I remember learning about that guy fifty years ago, when you needed a slide rule to compute anything complicated. I never understood slide rules).
Trust me, we know. That's why this forum exists for people like you to get help.
Also, the internet, marvellous as it is, contains a lot of information, some of which is useful, but other pages are misleading or just wrong. For instance, it is easy to find where you can by a 4x20 LCD screen, and whether it is an Euro cheap0er than the next one, but far more difficult to find the amount of power draw.
I hope that my question may help others. It certainly helped me.
Paai
Buy from a retailer or distributor that gives you an actual datasheet to download, and not just the cheapest of chinese ebay factory reject crap. I got one with my 20 x 4 serial LCD (think I got it from Mouser), and the supply current is right on page 5 of the datasheet: 229 mA typical.
NHD-0420D3Z-FL-GBW-V3-29857.pdf (576 KB)