Talk:Fessenden oscillator

Merge to Reginald Fessenden
It has been suggested to merge this article away.


 * Oppose Another crap suggestion by User:Wtshymanski to delete an article because he has never heard of it, and if he can't manage that, to merge it so that it goes away quietly. Andy Dingley (talk) 14:36, 27 June 2011 (UTC)
 * It looks like the device actually had some practical application, and there's literature on it. --Wtshymanski (talk) 14:47, 27 June 2011 (UTC)
 * Oppose because we do not merge articles about inventions into articles about their inventors (hence Internet, telephone, television, wheel, fire, the Garden of Eden). No reason to make an exception in this case has been put forward. ╟─ Treasury Tag ►  constablewick  ─╢ 15:05, 27 June 2011 (UTC)
 * It's been untagged. Non-notable inventions may not have any context aside from their (otherwise notable) inventor. Internet and telephone have reliable sources. How are folktales applicable to this case? --Wtshymanski (talk) 15:10, 27 June 2011 (UTC)
 * You're not saying that this is a non-notable invention, are you? ╟─ Treasury Tag ►  sheriff  ─╢ 15:18, 27 June 2011 (UTC)
 * See above. No, I'm not saying that. I'm thinking of things like Tesla's speedometer, which is unimportant by itself, but is noted on the list of Tesla patents. --Wtshymanski (talk) 18:10, 27 June 2011 (UTC)


 * Oppose as clearly a notable invention which has significant coverage in its own right. Some 780 hits on Google Books, 82 on Google Scholar.  The following scholarly articles are entirely about this invention:,  and .  Why on earth would it not be the subject of its own article?  Sergeant Cribb (talk) 19:30, 27 June 2011 (UTC)
 * In all the excitement of blood in the water, the school has failed to notice a couple hours ago. Not till the scent of chum has completely faded will these relentless predators cease to strike. It's terrifying and in a way strangely magnificent.
 * Not everything that anyone invented is notable; certainly earlier this morning there was no indication if this was just a toy or if it actually got used in the real world. Notice that I've added the history and operatino sections that were missing. You are welcome to contribute to the article, too. --Wtshymanski (talk) 20:32, 27 June 2011 (UTC)
 * In that case, I've tagged it as resolved, as the originator could have done. Sergeant Cribb (talk) 20:37, 27 June 2011 (UTC)
 * Bully for you. Whatever would we do without the masters of template-fu? --Wtshymanski (talk) 20:41, 27 June 2011 (UTC)

Tubes?
The Fessenden oscillator didn't oscillate of itself. What was it driven with? An MG set or some kind of tube oscillator? Did they listen to the "voice coil" output directly with headphones or was there a tube amp involved? --Wtshymanski (talk) 21:33, 27 June 2011 (UTC)
 * According to Rolt it was "electrodynamically driven". Sergeant Cribb (talk) 06:14, 28 June 2011 (UTC)
 * Well, yes, that's how it works - but what makes the circa 540 Hz AC that powers it? The picture in the submarine book shows a big rack of electronics gear in a wire cage, but my retinas can't resolve if there are tubes peeking through the panel behind the wire mesh. --Wtshymanski (talk) 13:15, 28 June 2011 (UTC)
 * That would be an alternating current generator rotating 540 times per second, actually not that fast. User:Fred Bauder Talk 13:09, 29 June 2011 (UTC)
 * Think about this. That's 32,400 RPM, faster than an unloaded Dremel rotary tool. Better wear your safety googles, and it's hard to hear echoes from the ocean floor with that MG set roaring away next to you. --Wtshymanski (talk) 13:15, 29 June 2011 (UTC)
 * Multiple poles. Andy Dingley (talk) 13:39, 29 June 2011 (UTC)

carbon microphone
As I understand the operation of a carbon microphone (primarily used in telephone mouthpieces) it is not a bidirectional transducer, that is, it modulates a current in response to sounds but does not generate sound. Unless I am wrong, the application section that says that a carbon microphone was used as a "receiver" in a depth sounder must be incorrect. On the other hand, a dynamic microphone, such as used in telephone earpieces, could be a good impedance match to the 50 ohm armature coil. --AJim (talk) 16:09, 29 June 2011 (UTC)
 * The microphone doesn't have to be bidirectional. The Fessenden transducer can be used to make a sound in the water, then the carbon microphone can be used to listen for the echo (or listen to the sound coming from another ship or shore installation). A descrption of T/R switching would be interesting. If they used a carbon microphone, possibly there was no electronic amplification at all. --Wtshymanski (talk) 16:45, 29 June 2011 (UTC)
 * Duh! Yes. I think I may have misinterpreted the meaning of "receiver". I was thinking that the Fessenden transducer was switched to listening mode; using it for sound pickup is described in the patent. But I wonder why another hydrophone would be needed? It is not obvious to me that a carbon microphone would be a better receiver. In the patent (1,167,366), page 4, lines 17-21. Fessenden writes: "To such an extent is this true that the device here shown is more sensitive, for equal motions, than any carbon microphone. It will detect motions of less than one per cent. of those which a carbon microphone will detect." I guess I need to see more of a description of the depth sounder device; I would like to know how the time interval was measured and displayed anyway. --AJim (talk) 04:55, 30 June 2011 (UTC)
 * One of the advantages of Fessenden's device was that it was reversible - though I still haven't seen a schematic and I don't know if he used tubes. A carbon microphone has the advantage of producing a pretty good level with no external amplification. I would imagine the fewer holes you made in a submarine hull, the better off you were. I have run across references to using a  stopwatch in the early iceberg detection experiments, and the fathometer evidently had some kind of paper record, too. --Wtshymanski (talk) 14:05, 30 June 2011 (UTC)
 * Right, a device like Fessenden's can be used as a motor or as a dynamo. The patent shows a generalized schematic as Figure 4. There are no tubes in that drawing. If there were a paper recorder, the recorder pen would ordinarily be driven by a galvanometer mechanism, which would be a good impedance match to the Fessenden device acting as a dynamo. I agree that minimizing hull penetrations is a major design goal, really for any boat. But as to the commercial fathometer, I think we need to see a manual to know what they were doing. --AJim (talk) 20:25, 30 June 2011 (UTC)