Re: TI-H: EL Backlights? A LA TI-92
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Re: TI-H: EL Backlights? A LA TI-92
From: <IGGYBIG@aol.com>
> is it posible to run the backlight off of the main batts vs. the batt
> pak,also is that the ti-92 version?
If it will run off of 6 volts or less you can. One thing to watch out for
though is that sometimes an inverter can put enough noise into the system to
effect the system clock, and the calc will run really slowly. I'm not sure
exactly what the cause of this is, or if it will happen with inverters other
than the particular model I was using. It only happened on 2 out of about
30 calculators. One of them I could not find a fix for, the other was fixed
by including a 10 ohm series resistor in the inverter power lead.
Anyway, the external battery pack seperates the power supplies and
eliminates the possability for those problesm. 'Course, I'd hate to have to
carry around a battery pack.
If the inverter draws too much power it can cause the voltage to sag a bit,
which can make the LCD hard to see. Not a problem with fresh batteries tho.
Attempting to power the inverter off of two of the 4 batteries in the calc
would probably not be a good idea. It would drain the batteries unevenly
and result in shorter battery life. Instead put a voltage regulator on the
positive supply and draw your power from it.
***
Don't forget to use a FUSE, and INSULATE anything near the high voltage
wires. At least one calculator has been DESTROYED by a failed EL (I suspect
a flaw in the EL lamp itself was the cause), and one inverter failed
internally and melted down inside my calc. No damage that time, but both
incidents could probably have been prevented by a fuse and good insulation.
***
DK
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