HD44780 24x2 backlight inverter

riverdan

What and at what voltage do use for a "HD44780 24x2 backlight" can't seem to find it by internet search.

Thank You
Riverdan

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RDL2004

The HD44780 chip is really not relevant (edit: well, if you add +hd44780 to a google search it does help narrow things down). What is important is whether it's an LED or EL backlight.

If it's an LED type you need a current limited voltage - anything from a few volts on up will work.

If it's an EL type it's more complicated. The ones I've seen use around 100 volts AC over a pretty wide frequency range - up to several hundred Hz..

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- Rick

Post Edited (RDL2004) : 10/27/2007 10:45:08 AM GMT

riverdan

Great i just found a site that has these displays and they sugest 90 to 120vac 60Hz i'll burn one.



Thanks

riverdan

The 115vac house power works just fine for the HD44780 2x24 LCD EL backlight "Light Green" (make sure to cover the slodered leads with tape as it is 115 Volts AC!) Looking for more projects using these displays as·I have several to play with.

Great trick using the "+" sign search.

Thanks

Post Edited (riverdan) : 10/27/2007 12:08:31 PM GMT

RDL2004

Using AC right out of the wall outlet will work, but (as you realize) it isn't the safest way to do it. You can run EL lighting off DC using inverter circuits. There are companies that make chips specifically for driving these lights. Here is an app note from one that I'm posting mostly because it contains a lot of useful info about EL lighting in general.

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- Rick