Omnimaga
Calculator Community => Other Calculators => Topic started by: Iambian on January 20, 2012, 09:48:34 pm
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Since what I'm doing with my calculator will eat too many batteries across what it's doing (it's a secret), I strapped my calculator down to a breadboard and hooked in a spare stripped cellphone charger to supply it with the juice that it needs for the fraction of the price. And so, I leave this with you:
(http://img.removedfromgame.com/imgs/ExternalPowerCalc2.png)
The tape probably wasn't necessary but I wanted it strapped in good. Also, this makes operating the calc a bit more difficult. Whatever works, I guess. The voltage source is probably 5V. Not sure. Most likely. It's a cellphone charger after all. Doesn't really matter to me. Just as long as the calc powers on and doesn't complain to me about low batteries. Which it did when I had a 5V regulator in the circuit (leftover from a previous project). That's what the capacitors were in for, but I guess they might help keep the calc going long enough to reach a place where it can shut down if the power cuts. I haven't tested that one. Should I?
And no, my calc isn't trying to call out for help... yeah. Let's go with that. I was just... um. Too lazy to shoot another photo? Right, right, exactly! That'll be my story. It's believable, right?
EDIT: Quick 15-30 minute project. Most of that time spent was in locating the supplies.
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Well, that's pretty nice what you did there Iambian.
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I had a random piece that I found once that had a USB tip on one end and a charging tip on the other (round). I use that often to keep my calc operating when I need to charge my batteries and still use my calc. All I do is cram a wire inside and wrap another wire on the outside and those go to the two terminals on my calc.
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What has science done???
On a more serious note, I can't wait to find out what your secret project is ^^ My best guess is something to do with overclocking, as a backlight and wifi would need *more* power, not just a reliable source of the same power.
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I saw this earlier on irc, pretty cool stuff. ^^ No idea what mad science you're cooking up, but I can't wait to see! =)
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Look at the calc screen. ^^
EDIT: To make this post worthwhile:
That is a neat thing you did there! I've been looking for a way to power my calc like that.
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XD Yes, the calc screen is quite lovely :)
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Wow, I thought I had a lot of the keys worn off, yet then I look at this one.. 0.o
Sounding pretty good, tho.
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Wow, that's impressive
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Cool!
I wonder if you can plug it into USB and draw the 5V from that...
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Cool!
I wonder if you can plug it into USB and draw the 5V from that...
Do you mean like from the USB port on your calc?
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Cool!
I wonder if you can plug it into USB and draw the 5V from that...
Do you mean like from the USB port on your calc?
Yeah, if you plug it into the computer and draw the five volts from the calc's USB port.
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Hmm, that would probably require more hardware modding, but I am sure it is possible to do. Add a gate that switches which power input to use. If there is energy coming from the USB, use USB energy, otherwise, just use batteries. I've been thinking about making it charge my rechargeables, too :D
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After hooking my calc up to the cellphone charger, which ought to be outputting 5V, I was thinking about trying to wire up something that would draw power from the 5V line of the USB port if the power was available. Just scrape off a little bit of the green stuff and solder a wire to it, then right on over to a small circuit board that deals with the batteries.
I did the scrape-y thing before with a Super Gameboy cartridge after some of its smaller contacts corroded right off. My granddaddy bought me that thing from a garage sale once, but it didn't work so yeah. Didn't really know how to repair a PCB at the time, so that was the only logical solution I had at the time. Took my dad a helluva lotta convincing to buy me that soldering iron.
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lol at the calc screen XD
It is awesome indeed. :)
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doesn't 4 batteries at 1.5 volts each make 6 total?
anyways, i tried this before as well, on a whim, but decided against using it after that for fear of making something explode.
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Well, anything less than 6 volts won't make anything explode. You have to watch out the amperage though, I think.
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I've had 8.1 volts going to it before at about 1.5 amps and it worked fine. I did this to the gameboy as well except I used 9 volts and the amps may have been slightly higher. I know on the gameboy, after a certain amount of voltage, it just refused to work. I don't think you will harm the calc much, but I would not suggest over 9.6 volts (8 rechargeable batteries).
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fyi,
if i remember cellphone chargers dont give the specified voltage, it will give out in accordance of the amps it is using more amps lower volt , less amps more volt..
thats what i remember being told lol.
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You trying to bring it to life Dr. Frankenstein style?
Brute force code breaking?
Portals?
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Time to tell us what in the world this is for :D
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For the record, the TI-84+/SE's maximum current draw without USB is about 30 mA, which happens during flash write/erase operations; the typical current draw is 16 mA max in other circumstances, 5-12 mA typical, and 2 mA on the homescreen with no hooks. For comparison, when a USB device is initially connected, it can draw up to 100 mA, and up to 500 mA if authorized by the computer. The USB port on the TI-84+SE is a USB-On-the-Go port, and supplies a maximum of 100 mA to a connected peripheral.
The TI-83+/SE/84+/SE family of calculators test the batteries by reading the voltage with the CPU in a busy-loop (which raises the current draw). The TI-83+ was originally based on 5.0 V logic, and the CPU specifically tests for voltages around this level. The newer TI-83+s and the SE/84+ series of calculators are based entirely around 3.3 V logic, but the OS still expects at least 5.0 V, even though the hardware (except for the USB port +5 V power rail) technically does not need it.
The calculators use linear voltage regulators, which convert the extra voltage supplied by the batteries into waste heat. Consequently, the calculators are fairly flexible with respect to the voltages they can accept. The maximum voltage you can supply to your calculator is dependent upon the load and design of the regulators TI uses. We experimentally know they will accept up to 9 V; the maximum is probably between 12 to 15 volts. Because the OS specifically looks for around 5.0 V, you should not supply less than 5.0 V. Due to various issues like voltage losses in the USB cable, a USB port might actually supply slightly less than 5.0 V. Alkaline batteries supply 1.5 V for between 250 and 1200 mAh; rechargeable batteries typically supply 1.2 V, with a similar capacity range, though usually lower. Because rechargeables supply a lower voltage, they can easily fail to meet the OS's voltage expectations.
Generally, it is perfectly acceptable to run a calculator from a generic power supply. However, a poor-quality power supply may permit excess AC noise to reach the calculator, causing stability issues. Adding a capacitor may help filter out noise. For a USB port, a capacitor may stabilize the voltage output, as changes in the calculator's load can cause transient voltage drops with a poor-quality USB power supply.
Edit: I created an official power-related Wiki page (http://wikiti.brandonw.net/index.php?title=83Plus:OS:Power_Usage).
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Yeah this is why I always avoided rechargeable batteries for my calcs, even though everyone kept telling me I should use them to save on the monthly Duracell battery package. All rechargeable batteries available around here were 1.25 volts and I feared it might not be enough for the calc, especially while running programs.
By the way wasn't it the Richfiles that had a tutorial on how to use AA batteries with a TI-83 Plus instead of the more expensive AAA's?
EDIT: Nvm it was: http://richfiles.solarbotics.net/BatteryExpander.html
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The only good option for using rechargeables in your calculator are rechargable alkaline batteries (https://en.wikipedia.org/wiki/Rechargeable_alkaline_battery). The only other option I can think of would be lithium-based batteries, which operate at around 3 V, and so would either require using specially shaped batteries or dummies.