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Re: Undamped oscillations

Original poster: "Gary Peterson" <g.peterson@xxxxxxxxxxxx>

. . . the firing time would have to be correct within perhaps a couple of percent of the period. . . . Ed

To do this the interval between each successive firing has to be nearly identical. Once this is achieved, synchronization with the transmitter's resonator is simply a matter of tuning. Tesla could have used the alternator with, "a certain small number of [widely spaced] poles" that was rotated at "an enormous speed" and generated "sudden impulses which would produce the same effect as [a primary] arc discharge," but there was a problem with the machine in that it, "failed to give isochronous impulses."

The solution to this problem was an isochronous mechanical oscillator that was used in place of the usual governor to control the inlet valves of a 10 H.P. double compound reciprocating steam engine. "Boiling water was employed to keep the temperature of the air spring perfectly constant and the oscillations isochronous." [NTAC, p. 39] The steam engine was attached to an electrical generator. This machine was built in 1893. After destruction of the 35 S. 5th Ave. lab he built an improved apparatus that is mentioned in an earlier post (Re: Wire Length, Jan, 16, 2007). This machine had four vibrating parts instead of just one and furnished, "isochronous currents of desired wave frequencies, phases, and beats." [p. 45] This source of nearly constant frequency alternating current was available to power a high-speed rotary break used in conjunction with a high-voltage DC power supply.

"This is a form of break which I developed in working with alternators. I recognized that it was of tremendous advantage to break at the peak of the wave. If I used just an ordinary break, it would make and break the current at low as well as high points of the wave. Of this apparatus I had two forms; one in which I drove the break right from the shaft of the dynamo and the other in which I DROVE IT WITH AN ISOCHRONOUS MOTOR. . . ." [pp. 56-58]


Original poster: Ed Phillips <evp@xxxxxxxxxxx>

I don't believe that the
technology existed in Tesla's era to time spark gap firings with the
phase of a ringdown.

Gary Lau

What would be so hard about that?    If your coil is ringing down at
10kHz? and you fired it a 1000 pps......It would easily be done. I would assume the coil would be built suck that you get more than 20 cycles before the logrithmic decrement tookl it to zero. All you would need is a very well controlled rotary gap motor. heck....even up to 100kHz it could be done. If you have an even number of sets of stationary gaps hooked up on a ring....all paralleled..and an odd number of electrodes on the rotor, you can
v>> get quite a multiplier compared to a simple rotary gap with just one
set of stationary gaps.
Each set of stationary gaps would run cooller besides. Imagine four sets of stationary gaps...and three rotary electrodes. You'd get how many firings per rev? 12? next imagine 8 sets of stationary electrodes and nine rotary electrodes. I'll stop now....lol

You missed the point. The issue is setting the firing time so that successive wave trains added IN PHASE. That means that the firing time would have to be correct within perhaps a couple of percent of the period - say a microsecond for a 10 kHz coil (pretty low frequency). Objective was not a train of damped waves but a more or less constant wave "reinforced" with each sparking.