Re: TI-H: EL Backlight installed!
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Re: TI-H: EL Backlight installed!
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.
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. 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.
--
Greg Hill
greg-hill@bigfoot.com
www.comports.com/link
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