Re: TI-H: LED Backlight

To: <ti-hardware@lists.ticalc.org>
Subject: Re: TI-H: LED Backlight
From: "David Knaack" <dknaack@geocities.com>
Date: Thu, 28 Jan 1999 18:10:49 -0600
Delivered-To: ti-hardware-outgoing@towerguard.unix.edu.sollentuna.se
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Reply-To: ti-hardware@lists.ticalc.org


From: Grant Stockly <gussie@alaska.net>
>>From: Grant Stockly <gussie@alaska.net>
>>>There realy aren't plans needed.  Get the enable line from the onboard
ram.
>>>It goes low and another high when the sram is pumping power.
>>
>>I wouldn't be comfortable drawing 30+mA (and noisy at that) directly from
>>the board, I don't know how much those components can source, and I
wouldn't
>>want to hook up the noisy inverter directly to it.
>
>Transistors don't source 30ma from the input...
>

Huh?  You said no plans were needed, I inferred from this that you
were suggesting hooking the inverter directly to the 'enable line from
the onboard ram'.  Since I don't know how much current can be safely
drawn from the enable line I would not attempt this.

I would be concerned about the noise that the inverter would cause on the
enable line, its already clear that it can bring a TI-86 to a crawl
connected
directly to the power supply, I have no clue what it would do if connected
to the chip.

I don't know what your response means, what transistor are you referring to?
Are you suggesting using the enable line as input to my auto-switch?  In
that case plans ARE needed for those who don't know how to design such
a circuit.

DK

Follow-Ups:

Re: TI-H: LED Backlight

From: Grant Stockly <gussie@alaska.net>