Re: running calc on AC adaptor . . . . . SOUND? :)

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Re: running calc on AC adaptor . . . . . SOUND? :)

Modem Boy,

Power jacks are available that break the battery connection when the cord from the AC adapter is plugged in.  Try a Switchcraft N112A available from Digikey for $2.37 (1-800-344-4539)  Also, you may find one at your local Radio Shack.  They won't know other people's part numbers, so see if Switchcraft has a web page that you can download a datasheet from.  

This kind of jack connects the battery to the calculator until you plug in the AC adapter.  When you insert the connector, the tip pushes two metal pieces apart, breaking the battery connection.  Be careful of the polarity when you solder the wires.  You could destroy your calculator if you hook it up backwards.   The safest thing to do is use a voltmeter to check it before you make the connection.  Also, make sure your AC adapter is the correct voltage.

If you are interested, I can send a schematic for the circuit that Thomas was talking about, but the connector is the most reliable way to handle the task.

-----Original Message-----
From:   Thomas J. Hruska [SMTP:thruska@TIR.COM]
Sent:   Wednesday, October 29, 1997 9:49 PM
To:     CALC-TI@LISTS.PPP.TI.COM
Subject:        Re: running calc on AC adaptor . . . . . SOUND? :)

At 04:59 PM 10/29/97 -0800, you wrote:
>>
>> I don't think that would work without taking the batteries out every time
>> you want to use the adaptor.  Would someone correct me if I'm wrong.
>>
>> Donald McKay
>> donmckay@juno.com
>>
>> "Carpe diem" - Horace
>
>Lets assume you used some little jack on the calculator (eek, would
>require drilling a big hole), a male jack for plugging in an AC
>adaptor... perhaps you could make/purchase some sort of device that
>automatically switches the battery connection since the AC is kicked in.
>Dunno, (for sure, I won't try it). The "headphone adaption" thing will
>be my next hardware creation piece. (okay sarcasm, just gotta find one
>of dem jacks. ehehehe)
>
>-(: Modem Boy :)-

Actually, since circuitry follows the less resistent path, transistors and
resistors should do the job nicely.  Transistors act something like a
switch, and when used in combination with resistors, you can "detect" when
the AC adapter is plugged in.


                 Thomas J. Hruska -- thruska@tir.com
Shining Light Productions -- "Meeting the needs of fellow programmers"
         http://www.geocities.com/SiliconValley/Heights/8504
                    http://shinelight.home.ml.org
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