Amplifiers 101, The Magnetic Field
/Welcome to home-brew science! Above is a quick overview of how I spent a weekend, below is the director's commentary.
Determining RMS
Didn't think I'd leave you hanging for months did you? Remember that a square wave has the same peak and RMS voltage. Get hold of a low frequency square wave and hook up your multimeter, switch to VDC mode (yes direct current) and get a read on the voltage, if you've got a min/max function use it. Switch to VAC mode and if your meter has the same voltage readout, congratulations! You've got an RMS meter.
Holding it together
The test apparatus I made is wood shims, a railroad spike and hot glue. The only real critical material is the wire: 22ga solid core PVC insulated wire. Wrap the nail tight and often, I got about 100 turns on my rig. It takes a bit of handiwork to get a stable working platform but... I mean look at the build quality of this thing. Quick & dirty.
Regarding the Bolt
The story is actually not that much more than what I said. I was working at a city event that had a stage, we started pulling everything apart when lo and behold, there's a nut stuck on a bolt. Ordinarily when this happens late at night you toss the whole thing, truss and all on the truck and get on with life but this was holding a few very awkwardly shaped bits of truss that wouldn't fit unless we got everything apart. With my background in aviation maintenance of course I get tasked with getting this thing moving. Well after a good 15 minutes of aping the wrench I give one final mighty heave and snap! Truss is now free, and the nut managed to put scorch marks on the wooden stage with all the friction it had gone under.
What's a Gauss?
Gauss is a somewhat archaic unit for magnetic flux density, which is to say it measures the strength (and direction) of the magnetic field the phone sits in. If the name sounds familiar old CRT TV's and monitors had to be routinely degaussed to relieve color smear. The process moves the built up magnetic energy away from the screen, restoring the image.
Cheat Sheet
Just in case, Ohm's law looks like this
And two very useful equations for power look like this
V - Voltage
I - Current (amps)
R - Resistance (ohms)
P - Power (watts)