Re: TI-H: TI Backlighting
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Re: TI-H: TI Backlighting
The Barkers wrote:
>
> John M Bishop wrote:
>
> > I believe I have new life for the backlighting thread... Over the
> > weekend, I went to Wally World and purchased two Indiglo Nightlights for
> > $5 apiece.
> >
> > Once I returned home, I took a knife and pulled the plastic casing apart.
> > Inside, there is a plastic sheet, containing (what I assume to be)
> > Indiglo. In front of this sheet, is a blue panel which protects the
> > Indiglo sheet.
> > - J. Bishop
>
> One question about these idiglo things. What sizes to they sell them
> in? And can they be cut to the right shape and size somehow so they
> would exactly fit the calculator screen? Or am I out of my mind...
>
> Eric Barker
I had an idea on how to get the ac needed to light these things. Hook
up the output of an oscillator circuit to the two leads of a
transformer, through a diode. Then connect the battery's opposite
terminal, through diodes again, to the same leads. This way you have a
square wave heading for the transformer. It would step the voltage up
to around 115V, and round the square wave out a little. The nightlight
I bought uses only .03W, or only .25 mA at 115V. This would put a heavy
drain on the batteries, but they should last for a decent time. You
could also use a 555 to create pulses to feed the transformer.
Andy Johnson <prjohnson@sisna.com>
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