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Jacobbus
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Joined: 20 Aug 2005
Posts: 106
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 Posted: 12 Dec 2005 10:54:02 am Post subject: |
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Yesterday I found an old transformator. (230V @50Hz to 5V 0,2 A)
My calc has 4 AAA's of (1,2V 0,8Ah) the batteries are placed after each other (as far as I can see) so totaly we have (4,8V 0,8Ah)
I thought the 4,8V and 5V are not so different form each other, but the calc works longer than 4 hours on one set of batteries, so the 0,2A is far to much.
So there is a resistor needed I gues.
Can this work? (I haven't tested cause I don't want to blow up my calc :hmpf: )
and if I (0,2A) is too high, does anybody know how much Amp the calc needs, or what the maximum is. so I can find a resistor.
(oh, its a TI84+)
Last edited by Guest on 12 Dec 2005 10:57:57 am; edited 1 time in total |
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Brazucs
I have no idea what my avatar is.
Super Elite (Last Title)
Joined: 31 Mar 2004
Posts: 3349
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| Posted: 12 Dec 2005 12:25:15 pm Post subject: |
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Yeah, I think people have done it before, too.
They've also changed them into 4 AA batteries. |
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Ray Kremer
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Joined: 16 Feb 2004
Posts: 237
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| Posted: 12 Dec 2005 12:53:31 pm Post subject: |
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| Aren't standard AAA and AA alkalines 1.5 volt? |
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Jacobbus
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Joined: 20 Aug 2005
Posts: 106
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| Posted: 12 Dec 2005 01:52:05 pm Post subject: |
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Ray Kremer wrote: Aren't standard AAA and AA alkalines 1.5 volt?
[post="64179"]<{POST_SNAPBACK}>[/post]
Yes probably the alkalines, but these are NiMH (Nikkel Metal Hydride) and they say 1,2 Volts.
but will I dammage my calc if I connect the wires. |
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Brazucs
I have no idea what my avatar is.
Super Elite (Last Title)
Joined: 31 Mar 2004
Posts: 3349
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| Posted: 12 Dec 2005 02:09:41 pm Post subject: |
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| Without a resistor, yes. With it, perhaps. |
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DigiTan
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Joined: 10 Nov 2003
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| Posted: 12 Dec 2005 06:22:51 pm Post subject: |
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Yeah, I've heard that large batteries have been a problem for some. You can also use a silicon diode to drop the voltage 0.7 Volts per diode. I'd try it with the diode/resistor first, see how the contrast looks, and go from there.
If you want to use AA's and AAA's at the same time, you have to isolate them with a Schotty Diode to keep them from back-charging each other. |
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kermmartian
Site Admin Kemetech
Calc Guru
Joined: 20 Mar 2004
Posts: 1220
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| Posted: 12 Dec 2005 06:38:00 pm Post subject: |
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| Someone has done this before. If you want, I'll try to find the link. |
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DigiTan
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| Posted: 12 Dec 2005 06:45:15 pm Post subject: |
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It was meeeeeee...
* EED1 Expander
This is actually sort of a coinsciendence because I was going to revamp the project and try to use smaller parts. I'll probably update that the page in a few days. |
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Jacobbus
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Joined: 20 Aug 2005
Posts: 106
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| Posted: 13 Dec 2005 08:01:51 am Post subject: |
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So you don't think that it does any harm to my calc if I connect the wires?
(you know I don't have the money for a new calc) |
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DigiTan
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| Posted: 13 Dec 2005 04:05:42 pm Post subject: |
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| It shouldn't, but just to be sure, connect the diode in series with your batteries to drop the voltage to 5.3 Volts. If the contrast is extremely (let's say it looks normal at level 0), that's probably a good indication to stay at that voltage. Otherwise, it should safe to leave that diode out. |
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Brazucs
I have no idea what my avatar is.
Super Elite (Last Title)
Joined: 31 Mar 2004
Posts: 3349
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| Posted: 14 Dec 2005 12:17:55 pm Post subject: |
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Jacobbus wrote: So you don't think that it does any harm to my calc if I connect the wires?
(you know I don't have the money for a new calc)
[post="64273"]<{POST_SNAPBACK}>[/post]
You're gonna try this on your only calc?! Good luck, my friend... |
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elfprince13
Retired
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Joined: 11 Apr 2005
Posts: 3500
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| Posted: 14 Dec 2005 01:02:21 pm Post subject: |
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| Digitan isnt the only who has tried it.....look under the modifications/hardware section on TiCalc.org |
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DigiTan
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| Posted: 14 Dec 2005 02:06:16 pm Post subject: |
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| Yeah there's one on the TI Richfiles site. The site is still maintained occaisionally, and they also have that ledgendary overclocking guide. |
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elfprince13
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| Posted: 14 Dec 2005 04:25:09 pm Post subject: |
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| that the one I was thinking of....got it saved on my hard disk |
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Jacobbus
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Joined: 20 Aug 2005
Posts: 106
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| Posted: 14 Dec 2005 05:09:24 pm Post subject: |
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| :biggrin: IT WORKS ! :biggrin: |
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DigiTan
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| Posted: 14 Dec 2005 05:41:24 pm Post subject: |
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| That's cool. Did you have to connect anything extra like a series resistor/diode, or is the direct connection working just as well? |
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Jacobbus
Member
Joined: 20 Aug 2005
Posts: 106
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| Posted: 14 Dec 2005 06:26:30 pm Post subject: |
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Nop, just connected the wires to place were the baterie's are used to be, works good, the contrast is a bit higher than normal but it works.
I had also the bateries installed and the external power on, but I don't know if that saves the batery's? |
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DigiTan
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| Posted: 15 Dec 2005 04:45:44 pm Post subject: |
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| Yeah, they'll share the load and the strongest supply will tend to do most of the work. |
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+ZERO+
Advanced Member
Joined: 28 Sep 2005
Posts: 289
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| Posted: 15 Dec 2005 05:27:59 pm Post subject: |
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You should post some pics of it!!!
Id like to make external power supply for myne..... |
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DigiTan
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| Posted: 15 Dec 2005 07:01:59 pm Post subject: |
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| I've got some grainy, low-res pictures from the Multi Ex thread. The resolution and lighting was so bad though, it's kind of hard to work off them. They might be sharp enough here. |
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Calculator Modifications => Calculator Hardware, Electronics, Robotics
