Power (cont’d)

At this moment, I appeared to have
  1) A dose-response relationship to line noise
    a. When line noise was high, the system was unstable.
    b. When line noise was minimal, the system was stable.
  2) Measurable reductions in line noise with line conditioners.
  3) Spontaneous resolution of the AC line noise from the wall

So the question is why the change in line noise from the wall? Well AC line noise can be caused by anything that is plugged into the grid, and EMI noise has effects over distance because all cables act as antennas. In my apartment, that means something my neighbor has can affect the quality of my own power. EMI noise can be caused by motors such as refrigerators.

At this point, I contacted Monster Cable to ask them if they could send me the “AC line noise generator” they used at hi-fi shops to demo their equipment. I wanted to see if I could generate system crashes with it. You know what they sent?

Also known as an unmodified off-the-shelf generic Nokia cell phone charger

I didn’t get any sort of exotic component designed to add ridiculous amounts of AC noise – they sent me a generic Nokia cell phone charger with a little Avery label stuck on, noting that it was a “Noise Source.” I couldn’t believe it! I independently tested another cell phone battery charger and indeed it too added AC line noise. This means that even common electrical components can add significant amounts of line noise!

So how can we really know that line noise is the source of the system crashes? In medicine, there are these things called Koch’s Postulates; if bacteria are found everywhere, how do you know if a bacterium you find in a sick person is the cause of their illness, or if it’s just a bacterium that’s hanging out? That’s what Koch’s Postulates are for. They are the rules that, if true, tell you definitively that a bacterium is a source of disease. The four rules are:

   1) The specific organism should be shown to be present in all cases of animals suffering from a specific disease but should not be found in healthy animals.
   2) The specific microorganism should be isolated from the diseased animal and grown in pure culture on artificial laboratory media.
   3) This freshly isolated microorganism, when inoculated into a healthy laboratory animal, should cause the same disease seen in the original animal.
   4) The microorganism should be re-isolated in pure culture from the experimental infection.

In other words, you have to find something in all of the animals that are sick, but absent from animals that are healthy. Then after isolating those bacteria, you should be able to give it to a healthy animal and cause it to be sick and then be able to recover the same bacteria in the new animal. (See, you always learn something random from a FiringSquad.com article.)



Going back to our power issues, we did find something in the systems that crashed – noisy power. All of our stable systems were those running with clean power. When we increased the AC line noise to a stable system (by removing the conditioner), it caused crashes. It did not matter if the power was clean from the wall, or clean from the conditioner.