Post by thread:[OT] EL Backlit LCD

I have some of those too. Supposedly, they can be driven directly from 120Vac!, although that kind of makes me nervous. The LCD board would burn up real fast if the EL backlight terminals became shorted to the main LCD board. They act like a capacitor. I'm told that they like to operate around 400hz or so best. Electronics Now just did a write-up on them. For other than just experimenting, a proper EL driver is called for, but don't ask me about those... But you will get much better efficiency especially if driven from a battery. On Thu, 9 Sep 1999 08:10:14 +1000, Wesley Moore (Yallara) wrote: >Hi All, >I have just bought an LCD with EL backlighting. The datasheet doesn't seem to >mention anything about how to power the backlight, if it is switchable at all. >I was wondering if anyone knew anything about the functionality of EL >backlights on such LCD's. I haven't yet fired it up, so I'm assuming it's >not on all the time. > >Wesley >

Wesley Moore (Yallara) wrote: > I have just bought an LCD with EL backlighting. The datasheet doesn't > seem to mention anything about how to power the backlight, if it is > switchable at all. From Vorlac by any chance? Gotcha! The backlight connection is two pads, separate from the main ones (for protection). You need a power converter for the backlight, this is generally *extra*. How you switch it is your own determination. > I was wondering if anyone knew anything about the functionality of EL > backlights on such LCD's. I haven't yet fired it up, so I'm assuming > it's not on all the time. They work. They have a limited lifetime in the order of 1k hours. That's why on the alarm consoles and such, they are not on all the time. In practice, E-L backlights are more-or-less *obsolete*, if you want to make something serious you use LED backlit modules. Far cheaper, more durable and easier. -- Cheers, Paul B.

Thanks a lot, I'll have to check out those VFD's they sound interesting. Wesley On Thu, 9 Sep 1999, Paul B. Webster VK2BZC wrote: {Quote hidden}> Hello Wesley. > > > Yep, from Vorlac. > > I thought as much. I have from them the really nifty six-(separate-) > line by about 8 character display boards from awhile back, and the > latest, the thirty-dollar NEC 40-char by 2 line VFD display, plus a > couple of LCDs from Oatley. > > I haven't activated it just yet (looking for my 2-pin header sockets > from Vorlac) but let me tell you, you *must have* one or two of these > VFDs. They are magnificent! They are BIG. You can see them from a > distance, and they should be *bright*, exactly what I want for my > surgery door! Heavy, yes, and rated 0.8A at 5V (Max 1A running, 2A to > start) but worth it. > > They have an 8-bit parallel interface which talks ASCII, i.e., you > just connect them to a parallel port (OK, so you can do that with the > LCD too) and print straight ASCII to them. By ASCII, I mean with > control codes too, CR does exactly that, LF does what you might expect, > ESC allows cursor positioning and so on. You may need a monostable to > get the timing right to drive with pure LPR. > > I need to find (well I should have one, but where?) a UART to run them > down a long 4-wire cable from the PC. A PIC may have to do. > > Sigh! Back to you, just remember to order 1 or 2 VFDs! > > > I noticed those pads and assumed that's what they were for but I don't > > know how to 'drive' it. > > As per the other posting, 80-100V at a few hundred cycles. Not mains! > Like I said, they supposedly wear out faster the harder you drive them. > :-( > > > Do you know of any circuits for the purpose or even one of the > > manufacturer's power converter's. > > Not as I've seen recently, but one idea was the exciter from a > disposable camera flashgun. Put a capacitor (0.01µF 400V) in series to > avoid DC stress. I have a few of these but haven't tried yet. > > > Sounds like it's not really worth it though. Thought I might try it > > since the module had it. > > That's my gist. Complexity and lifetime, it's a pain. LEDs you can > leave on all the time if you want. I'd (do) avoid buying them in future > in favour of the LED-lit ones (from Rocom). > -- > Cheers, > Paul B. >