Tesla Bot

   Status: Available on App Store
   Price:  Free
   Compatibility: iPhone / iPad Universal App, requires compass

What is Tesla Bot?

Tesla Bot is a spin-off of the Geiger Bot project, and can be described as a "Geiger counter for magnetic fields".

Rather than relying on an external Geiger Counter as a sensor, Tesla Bot uses your device's built-in magnetometer / compass.

The main feature that sets Tesla Bot apart from similar apps is that it contains the Clickify sound synthesis model and produces Geiger counter-style clicks relative to the strength of the magnetic field vector.

It detects magnets. 
It clicks.
Really, what more do you want in life?

Why Would I Want That?

Mainly because it's somewhat novel and amusing; the clicking and manner in which you move the device around is the experience of using a Geiger counter, just with a different type of sensor.  As a developer, I can demonstrate the concepts of Geiger Bot without needing a Geiger counter, or allow someone else without one to experience something similar.

The practical application is finding magnets or ferromagnetic materials, including ones covered by something and which are thus not visible.  In my personal testing, the audio feedback makes this process more efficient and more rapid than relying on the display, though part of that may be due to previous experience with Geiger counters.

What Tesla Bot Will Not Do

1.  It will not detect ionizing radiation ("radioactivity")  Buy a Geiger or scintillation counter for that.
2.  It will not detect electromagnetic radiation (ie, radio waves).  It detects electromagnetic *fields*.
3.  It will not detect most steel, as most steel alloys are austenitic (300- series) and are not ferromagnetic.
    - Basically, during the forging process, austenite is heated past the curie point of iron
    - This causes a structural shift to the allotropic gamma phase of iron that is incapable of sustaining a net ferromagnetic alignment.
        - Another example of allotropes: graphite and diamonds are allotropes of carbon
    - Most cheap steels are 300 series (stainless steel silverware, etc).
    - Quality steel alloys and tool steels are usually ferromagnetic.
    - The most ferromagnetic alloy I've found is Crucible S30V, a martensitic powdered tool steel.
4.  It will not detect ghosts.  Ever.  Unless your ghosts like to carry neodymium magnets.

Tesla Bot: Features

If it looks like Tesla Bot mostly involved a lot of copy and paste from Geiger Bot, well, it did.

Tesla Bot has a very streamlined featureset compared to Geiger Bot, as most of Geiger Bot's features aren't really applicable.  Still, if anyone has any feature requests I'll be happy to implement them.

For the most part, you'll likely only use the default operating mode, and change nothing.

These are the features that Tesla Bot 1.0 provides:
  1. Sound Output - synthesized CDV-700 clicks
    1. From Geiger Bot's "Clickify"
    2. Output rate is CPM = uT * 10 (ie, 53.8 uT will sound like 538 CPM in Geiger Bot)
    3. The x100 / x10 sound range lets you multiply this by a further 10x for when the default sensitivity is not adequate (ie, in delta-uT mode)
  2. Units
    1. Microtesla - measurement of strength of magnetic field vector
    2. Delta-uT - measurement of change since last reading
    3. Degrees - 0 ... 360 degrees on a compass.  Sound model clicks at North.
  3. Axis
    1. * - root mean square function of all values - measures overall magnetic field strength
      1. ie, RMS = sqrt(x^2+y^2+z^2)
    2. x, y, z - individual magnetic field vector axis
      1. x: left/right of device
      2. y: top/bottom of device
      3. z: tilt of device
  4. Display
    1. in microtesla or degrees
    2. Blue box is shown when the device's compass is recalibrating itself (no data)
    3. NO COMPASS will be shown on the display if your device does not have a compass (all iPod Touch models and iPhones before the 3G, I believe)

NOTE: If your "*" reading in microtesla is unusually low (below 30-50 uT), you probably need to recalibrate your compass, as it was magnetized to a degree the auto-recalibration could not fix.  This is where you wave your device in the air in a figure 8.  I'll add an indication of this state in a future version, though you'll still have to wave it around in the air.  In my testing, this was required very rarely, even with quite powerful magnets.

Also, auto-recalibration happens more frequently after extended exposure to > 100 uT magnetic fields.  Strong fields can also slow down the data rate from the magnetometer sensor which you will notice as slower numerical updates.  This is not the app slowing down, it is just less frequent data from the sensor.

While this app really does detect something with a real sensor, and the sound feedback is directly relative to that, I personally consider this more of a novelty / science toy app than Geiger Bot.  But, it is amusing, and perhaps even rarely useful.

If anyone was wondering, the icon is the Unicode magnetic tape symbol.  It seemed fitting.