Re: TI-H: EL Backlight installed!
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Re: TI-H: EL Backlight installed!
From: Greg Hill <gregh@xmission.com>
>On Tue, 14 Apr 1998, David Knaack wrote:
>
>> Anyone know how the LCD is signaled to turn it on?
>
>I suppose I'll offer a guess here.. The power leads that go to the
LCD
>board are always powered because the LCD memory (located on the LCD
>board..?) needs power to "remember" what to show when the calc is
turned
>on. So there is probably some command sent over the data lines to the
LCD
>board which tells the LCD controller to bring the LCD back up.
The LCD requires AC to run, correct? Where is the AC power for the
LCD produced? (I don't have schematics).
>Try putting an ammeter on the positive power lead to the LCD board
and see
>if the current draw increases when the calc gets turned on.
I don't think I want to disconnect that ribbon cable, they are a bit
too hard to work with. At this point I'd prefer to just use the
switch.
>If it does,
>you can put a resistor there and put the base of the transistor on
one
>side and the emmiter (?) on the other side. Calculate the resistor
value
>such that the change in the current being drawn (between ON state and
OFF
>state) will produce a voltage big enough to turn the transistor on
and
>off.
Where exactly would the resistor go?
DK
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