How does one calculate the type/gauge of wire to use in a small electronics project?
Specifically, I’m thinking of ordering a hundred or so solar cells to play with (hook up to a little motor, perhaps put together a trickle charger for some battery-powered Zigbee-type sensors). They’re rated at 4V and 0.5uA each.
Am I right that any wire from AWG40 (link is to a chart showing AWG ratings) down could be used (that is, max amps for AWG40 is 0.0137; a single cell only transmits 0.005A)? Can I use twisted pair cabling? Is shielding necessary for power transmission (no data transfer)? What effect will the length of the wires have (if any)? What is required to increase the output current (i.e., hook a bunch of cells up in parallel)?
This is my first foray into developing/constructing hardware devices (I’m a software guy and just bought my first soldering iron), so I’m pretty ignorant as to practical details. While I’ve done some reading, none of it has sunk in enough to become intuitive…which is part of the reason I’m doing this in the first place. So, any information would be greatly appreciated!
Yeah, I realize it’s a teeny amount. So, for instance, I could take a phone line, take off the jack ends, and use it? What about hooking a bunch of cells up in parallel?
Where are you getting the 0.5 uA number from anyway? The linked page lists devices ranging from 25 to 100 uA.
Though that’s still a tiny amount. Yes you can connect them in parallel to increase current, but wouldn’t it be easier to just use a larger cell to begin with?
I regularly put several hundred milliAmps through phone cord, so that should work fine. As you parallel the cells, your current is going to increase, but you’ll need a million of them in parallel to get to 1/2 Amp…
D’oh! :smack: My error in confusing mA and uA in my head during composition and o’er-hasty posting. Let’s call it a short-circuit somewhere between my keyboard and chair.
It depends on what I do with them. In some cases, I think it would be neat to have them “strewn about” on a framework of some sort, with wires “tying” them together at an endpoint. (They’re kinda neat looking as they are, and I definitely don’t plan on putting them in standard SOIC mounts.) In other cases, that’s not appropriate in the slightest. Since I’m approaching this as a learning experience, I don’t know yet where I’m going to go.
Where were you planning to find #40 wire other than cracking open some microchips and using the bonding wires that connect the die to the pins?
In practical use, #30 “wrapping” wire is probably the smallest wire you’ll easily find and still have any chance of being able to manipulate it without having it snap from the force of your breath.
As pointed out by scr4, I had the amps wrong. I admit I experienced quite some confusion in trying to reconcile your “million” point with a blog post I saw somewhere that said the person “put 50 cells in parallel to yield 2.5mA”.
At any rate, thanks for the info about phone cord. I wasn’t sure what the practical current limits were, and now I can strike one more thing off my “look up list”.
Actually, I hadn’t planned on using any particular gauge of wire yet. Rather, I wasn’t even sure that I was putting the numbers together correctly, although it seems like I am.
Thanks for the tip about #30 (or below) wire; I think you just helped me avoid much frustration in the not too distant future.
The thicker the wire (in other words, the lower the American Wire Guage (AWG) number), the more current it can carry, the lower the resistance per unit length, and the lower the voltage drop along it. All other things being equal, thicker wires will have less resistance and will lose less energy to heat as current passes through them.
So if you’re using a large number of solar panels with many wire runs between them, they should be as thick as possible to ensure the least amount of energy is lost to resistance. This is especially important if you are using low voltages.
I used to work around electric resistance welders that used five volts to weld the steel. Five volts… and 20,000 amps. Their conductors were slabs of copper with the cross-section of a large book. The largest actual wire I’ve ever dealt with was “four-ought” (AWG 0000), which is about the diameter of my thumb.
I think it’s more than likely that I’ll be posting another question about small electric motors in the near future. I’ve looked at the motors available in the Mouser, Jameco, and other catalogs, and am kinda lost as to what exactly I’m looking for (or at) and what the specs mean (practically speaking). But I think I have to do some more reading first before I can even phrase a coherent question…
It’s readily available as magnet wire. At a previous job, we wound several types of current transformers with it; it’s a little fussy to work with and will break if you look at it wrong, as you might imagine.
I like overthinking my projects as well, it’s half the fun…
But having said that, the practical answer to your question is that the current produced by these cells is at fergeddaboutit levels for any reasonable size of wire (and by reasonable I mean, thick enough to be practical to solder and play with), even if you parallel a large number, and even if you have fairly long cable runs.
Yes you can use twisted pair (not what it was designed for, not necessary, but will work), and no shielding isn’t necessary. I think your other questions have been answered.
