Re: TI-H: External Power Supply

To: ti-hardware@lists.ticalc.org
Subject: Re: TI-H: External Power Supply
From: Greg Hill <gregh@xmission.com>
Date: Thu, 2 Oct 1997 19:55:29 -0700 (PDT)
In-Reply-To: <msg235867.thr-e46358.2dc6e4@blackbox.at>
Reply-To: ti-hardware@lists.ticalc.org

On Thu, 2 Oct 1997, Andreas Braumann wrote:

> I have a big problem: The Ti-92 needs too much power and since
> ´batteries aren't too cheap and since I work a *lot* with the TI is
> there an external power supply for the TI. Kinda adapter like for the
> Gameboy and so on? 

As you know, in the TI-92 there are two battery stacks. The + of one of
those stacks is connected to the - of the other stack, effectively putting
all four batteries in series to make a total voltage of 6 volts DC
(optimally).

To use an external power supply (like a DC power brick) you'd need to get
one that puts out 6v at (probably) 150 mA or more. Contrary to popular
belief on this list, the current rating is *NOT* how much current is
actually going to be pushed through the calc. It is a maximum rating: the
power brick itself is not capable of providing any more current than that.
Anyway, to connect the external power to the calc, you'll need to fasten
the wires to the correct calc terminals (the pair of + and - that are NOT
connected to each other) and in the proper polarity (the + line goes on
the + terminal).

If the TI-92 is like the 85, you'll want to turn it off before
disconnecting power from the power brick or the memory will be erased.
Also, don't leave the batteries in the calc while running it from the
power brick. Without some special circuitry (a couple of well-arranged
diodes) bad things will happen.. like the batteries leaking or something
equally pleasing.

If anybody wants a clearer explanation of the process, don't hesitate to
ask..

-- 
Greg Hill
greg-hill@bigfoot.com
www.comports.com/link

References:

TI-H: External Power Supply

From: Andreas.Braumann@blackbox.at (Andreas Braumann)