TI-H: Re: EL Backlight Auto-Off


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TI-H: Re: EL Backlight Auto-Off



Ok, I found a place on the TI-85 and the TI-86 that can be used
to turn equipment of when the calculator goes off.
 
On the display board, on the lower right side are solder pads
for a capacitor.  This capacitor is not installed, and the lower
pad is at Vcc when the calc is off and Gnd when the calc is
on.  A transistor set up as an inverter driving a second transistor
that drives the load will allow devices to be controlled by the
calculator ON/OFF state.
 
On the Ti-85 the capacitor is c21, on the 86 it is c31.  These
numbers may vary with the hardware version, check around
with a multimeter to verify that you have the correct location.
 
YMMV 
DK