Perhaps the safest route is to say "it measures whatever it is directly touching". If you're measuring air temp, make it touch the air, if you're measuring a server rack, stick that baby on the heat sink!

There's no time, unfortunately. I could accomplish my goals with resistors, caps, etc, but it would be messy and inefficient. And, for the most part, uncertain in reliability. I got this dropped on me by a researcher that's going out in the field in a couple weeks, and I've already got a ton of stuff going on... yadda yadda yadda.

I know, I know. I was hoping you guys knew a place

It's on a grant, so I guess a lot. Less than a hundred would be... much preferable, though.

Hey guys. I'm in a time crunch and need a power supply that takes in 12vdc and outputs anywhere from 0 to ~6vdc (up to 12 is preferable, but not necessary) at at least 4A. Voltage would have to be controlled with hardware, I think that that is standard. I've spent a lot of time on the net looking around, but I'm afraid that I don't know all the nooks and crannies. Right now my best option is:

http://www.current-logic.com/shop/index.php?main_page=product_info&cPath=22&products_id=217

But they're in china, so shipping will be time-consuming.

The most important part is that it can provide at least 4 amps continuously, 5 or 6 is preferable as it'll be going for hours at a time. I'd like it as efficient as possible as well, and quiet. I would sacrifice the last two for the voltage and amperage specs, though. Cheap would also be nice

Any links you can find are much appreciated!

Thanks a bunch!

"average computer user's computer" and sit around saying "fuck off i'm not doing that" "rebooting" all day...

"My computer is broken! It's being stupid! There's something wrong with it!"

In my short lifetime, I've learned that computers are almost never wrong- it's nearly always user error, which makes working out bugs infuriating. I know I can't use the excuse "stupid compiler's doing it wrong again" when I forgot to declare the variable outside the parens... 

The best thing about a boolean is even if you are wrong, you are only off by a bit.

 

Space permitting (it's only one byte), you could keep track with a variable for the state and just do

Code:

boolean state = false;
...
state = !state;
digitalWrite(pin, state);

when you return a value (true/false), you break out of the method completely. Any code below the return will not be executed.

Depending on the batteries, you could monitor the voltage with an analog input and once it gets below X volts, light a blinky or something.

Thanks!

Did you have a particular reason for using the VDIP1?

nope. I think there might have been more information on the internet at the time regarding the VDIP1, but I'm not sure.

I've seen a lot of SD card projects, but the datalogger wasn't for me and the flashdrive was considered more user-friendly. I wish I had gone with it now, but it's no big deal. I guess if I ever use USB storage in a future project I'll go with the VDRIVE2.

I'd actually like to clarify, once I found a bit of code that worked, it was very consistent as long as you gave it adequate time to boot up (which varies for some reason). It was just getting the code to work and then adapting it to my project that took a lot of effort. Sometimes it seemed like making a change in the code completely unrelated to the flash drive would cause it to lock up and I'd have to go through the process of unplugging power, transfer the flashdrive to the computer, look and see if it worked, and then reverse it all.

Thanks again!

right, thanks lefty!

Alright. I don't like it, but I guess that doesn't really matter.

On a slightly related note, if I have several separate units (heat pumps, say) connected to arduino inputs and they all have separate power supplies, connecting all the grounds together will not be bad at all and will in fact be necessary to measure voltage differences between each unit?

Because there isn't a complete  path between battery A and B for current to flow.

Precisely the answer I was trying to prevent with my original wording  

So is it a hardware limitation or something else? I'm really hoping it's not simply "that's just the way it is"

Edit:

A complete circuit would also require a conductive path from -A to +B. It's the same reason you can't just wire from the +A to one lead of a lamp and expect the lamp to conduct current.

But what IS that reason?

d'oh. Okay, I guess my question is now "why isn't the + from battery A to the - of battery B a complete circuit?"

[do]

Alright first off, I do understand the concept of a complete circuit and generally how electricity works. Just thought I'd get that out of the way.

What I don't understand is how a battery 'knows' the difference between its own negative and another negative. For instance, when I put the + of one AA to the - of a different battery, why doesn't it discharge? The only thing I can come up with is that the inside of a battery is comparable to a capacitor in that one side can't accept electrons without the other side donating them because they'd repel each other. Again, I know it has to have a complete circuit, so I'd appreciate it if that phrase was left out of any and all replies