Re: TI-H: EL Backlights? A LA TI-92

To: <ti-hardware@lists.ticalc.org>
Subject: Re: TI-H: EL Backlights? A LA TI-92
From: "Kevin Buck" <mckbuck@coastalnet.com>
Date: Sun, 31 Oct 1999 11:52:08 -0500
Reply-To: ti-hardware@lists.ticalc.org

Hey David, you may not remember me, but a long time back, I purchased one of
your EL backlight kits, and remember when we were working so hard to try and
figure out why the calc always slowed down with new batteries and the EL was
on?  You said you never figured out how to conteract it...

Well, I went and got me a variable potentiometer and placed it inside the
calc, cut a small hole right next to the battery casing, and above the
switch to make it flush, then after a little adjusting, I had a dimmer knob
for the backlight.  And get this, since the pot was place before the
inverter, even with brand new batteries, the calc doesn't slow down
anymore!!


-----Original Message-----
From: David Knaack <dknaack@rdtech.com>
To: ti-hardware@lists.ticalc.org <ti-hardware@lists.ticalc.org>
Date: Friday, October 29, 1999 3:12 PM
Subject: 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
>
>
>