--- On Mon, 6/15/09, Stephen A. Lawrence <[email protected]> wrote: > From: Stephen A. Lawrence <[email protected]> > Subject: Re: [Vo]:Jed's temporary ban... > To: [email protected] > Date: Monday, June 15, 2009, 8:22 AM > > > Interesting page. Here are some comments (yes, > they're just theory, I > don't have a 30K DC supply to start with and I'm not > getting one to test > this): > > -- It should work, but don't plan to disconnect from Edison > just yet, > because it's probably not going to produce much power.
Heh heh, I know. It's just something to try. Sometimes a surprise awaits the experimenter. > -- A careful reading of the page indicates to me that the > page author > hasn't got a clue what the thing actually does, nor why it > produces > volts. Take my word for it or don't, I'm not going to > pick apart the > details here. Again, I'm less interested in the theory behind it that he presents (which is kind of whacky), and more into the experimental apparatus itself. It's worth trying if only for its simplicity and cheapness. > -- Coax, when carrying a static charge (*not* acting as a > wave guide), > is just a rolled up parallel plate capacitor. Keep > that in mind, it > helps with understanding the thing. I know that. Coax cables are sometimes used in pulse forming networks. I'm just speculating that there might be something oddball going on here. > -- The setup procedure with the oven and the 30K supply > puts a permanent > *polarization* on the dielectric, NOT a permanent > *charge*. I guess what he was wanting to do, for whatever reason, was make the coax into an electret or something similar. I've made and played with electrets before, fun little gizmos. Used carnauba wax and rosin, with a little beeswax added to keep it somewhat less brittle. > Now let's look at that cable again. It's been abused > -- it's been > cooked and chilled, and its plastic sheath has been > stripped off. It's > probably not all that tightly bound together any > more. So, as it flexes > in the wind, and particularly as it vibrates, you'll get > some variation > in the radius; the distance from the shield to the central > conductor > will vary somewhat chaotically at various places along the > cable as it > wiggles. And when that happens, because of the > polarization of the > dielectric, you'll get current flowing to the places where > the > dielectric is compressed, and away from places where it's > stretched a > bit or the shield is separating from the dielectric, and > overall you'll > see a random AC voltage coming out the end. > > With a 30,000 volt polarization in the dielectric the > voltage coming out > the end could be substantial. > > And that, I'm pretty sure, is what is going on, and all > that's going on. > It's a big microphone, and the energy > being harvested is coming from > the "sound" of the wind. If that's it, it isn't that useful. Though for some reason, this is sounding interesting enough to do on its own. Maybe one could use it to charge a cap and run a tiny beacon transmitter for...well...for no good reason other than to do it. > Note the "OR" in this more complete quote -- a continuous > arc, OR one > that is eight feet. No hint here that the 8' arc was > continuous, and in > fact it sounds like the 8' arc occurred when something > nearby was hit > with lightning (could also have been a brush discharge, of > course, which > could be called "continuous"). Well, yeah, you can > see stuff like that > when there's a lightning strike, but I wouldn't depend on > it to power my > house. > And, of course, you've also got the usual confusion between > voltage, > energy, and power -- an 8' arc indicates there were a > wicked lot of > volts. How much *power* was it, averaged over some > reasonable period of > time? Can't say. If it was a single flash, then > maybe not much. If it > was a brush discharge, then once again, probably not much. What do you want from a page that has in its title the word "Diatribe"? :) The 'collector supply' for the thing is built. It looks really stupid, but that makes it fun. Now I have to find my coax that I thought I knew right where it was...or pilfer some from someone. --Kyle
