title: Getting Voltage from Magnetic Sensors
body: <p>This is most likely a very dumb question, so my apologies in advance.  </p>
  
  <p>I have a potential client that has had others make the claim that the values we receive from certain Android devices' magnetic sensor can be put through a formula (using Time) to actually calculate nearby voltage.  The idea is to test fairly small voltage amounts (around 5-7v) using the device when held near it.</p>
  
  <p>I have looked through documentation after documentation, and we have played around with existing calculations that some people have offered, but nothing seems to solidly work.  It does seem interesting that the X/Y/Z values do indeed change dramatically when held close to the voltage-producer (they seem to go into the negative for the most part), but there doesn't seem to be a solid way to convert the values to voltage, when I take into account what those x/y/z values are when held away from the source of voltage (they stay around the same, but only positive). </p>
  
  <p>I understand that the actual magnetic field can be found via the formula SQRT(x^2+y^2+z^2), but I have not found a solid algorithm for converting that to voltage.</p>
  
  <p>Sorry again for the dumb question, but is something like this even possible?  I figured this was the right place to ask.  Thanks so much in advance!</p>