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:



EDIT: 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?

EDIT2: Shrunk the image down further to be more friendly on smaller screens. And maybe bandwidth.

Haha, nice dialog on the calculator!

Nice! Now you just have to build in that it's wireless

Do I also see at least one AAA acting as a shim underneath that calculator? I caution you against running it on unfiltered power from the adapter, and at 5V, but it's not the worst thing you could do to your calculator. Kudos for a respectable hack.

The battery that you see underneath the calculator was taped down as part of an older setup. It's one of those 12V batteries that you can get from the specialty battery section of stores that have 'em, and that battery was used to test a circuit that was supposed to be powered by a solar panel to ensure that I hooked a voltage regulator (5V) up to it correctly. I tried leaving that component in the circuit but the input was just not enough and the calculator freaked. So out it went. I was just too lazy to remove them capacitors that was nearby.

If I did my math right, this circuit should be putting out a higher voltage than say a pack of NiHM rechargeable batteries (1.2 * 4 = 4., which isn't much of a circuit since all I did was stick an already torn apart cellphone charger into the breadboard, using the breadboard as more of a thing to secure the setup in.

My calc has been running like this since my first post and nothing bad has happened yet. Now that I've shown that the calc will run on 5V, I plan on seeing if I can get the calc to take its power supply off the USB port if it's available, but that wasn't the original point of this hack. I just wanted to save $12 on the batteries I would've used for the duration of the unnamed experiment. So hooray for unintended ideas.

EDIT: The cellphone charger doesn't filter the 5V input enough?

Iambian, it probably does filter it enough; I just wouldn't trust a very delicate $120 piece of equipment to a $5 charger. It sounds like it works fine to me, so it's probably nothing to worry about. Hooray for unintended ideas for sure, and I love to see this sort of a necessity-mother-of-invention hack in action.

I'm probably gonna go ahead and make the internal modifications, since the setup came unglued about 15 minutes ago, which caused data loss and a setback of about a day or two. Had I taped the calc down from the other end, this might've been avoided, but I suppose this hack needed to have been done anyway.

After I play a round or two of Touhou Soccer (it's easy to forget that they're even playing soccer), I'll see what parts and plans I can pull together. Mostly plans as I probably have all the parts I need stashed away somewhere in the house. I could probably use a new soldering iron, tho...

Side note: I clicked on all of those, and almost froze my computer. haha.

As an aside, the reason it probably didn't work with the 5V regulator is that is that linear regulators have a certain drop-out voltage, which translates to requiring an input voltage somewhat higher than the output voltage. A typical 7805 will have a drop-out voltage of a couple of volts, meaning the input voltage should be higher than 7V for it to work.