Talk:Spark-gap transmitter

Banned in the 1920's?

Should it be mentioned that spark-gap transmitters were banned for use in the USA? (Besides special allowances) TinyTimZamboni (talk) 16:09, 7 March 2013 (UTC)

Untitled

Model T magneto only delivered 30 volts; could this refer to the model T spark coil, the universal experimenters' high voltage source of past generations? Gzuckier 18:32, 22 November 2005 (UTC) . Yes, definitely. Gutta Percha (talk) 10:31, 25 July 2008 (UTC)

pic

Good addition. Doesn't it need a key (or switch)? Gzuckier 19:07, 21 December 2005 (UTC)

duplicate info

As far as I can see, the end of the Operation section is almost exactly the same as the Spark Gaps - Construction section. I do not understand why my edit to remove the duplicate paragraphs was reverted? StealthFox 00:17, 8 April 2006 (UTC)

legality?

http://www.amazon.com/gp/customer-reviews/discussions/start-thread.html?ie=UTF8&ASIN=0262082985&authorID=A70SVUQ397Q8Y&store=yourstore&reviewID=R5CL51KHLNJS6&displayType=ReviewDetail

According to this, and other websites, Spark gap tranmitters have been illegal since the '20s. should this be mentioned? --24.252.10.228 00:20, 20 July 2007 (UTC)

I've seen several in operation. I can't imagine why they'd be illegal or where that would be. — Preceding unsigned comment added by 108.202.113.201 (talk) 09:56, 5 April 2012 (UTC)

The radio waves emitted by spark-gap transmitters, called damped waves, are noisy and have a wide bandwidth, so they can interfere with other radio signals. In 1938 the International Telecommunications Union prohibited this type of emission (called "class B") to get the last spark-gap telegraphy transmitters off the air, and it is still prohibited in all nations. Title 47 of the FCC regulations has the prohibition in a footnote at the bottom. Radios are a lot better now, but hobbyists playing with spark-gap transmitters in their garage can still piss off neighbors by interfering with broadcast TV reception and perhaps other radio services. I'd guess the FCC is too busy to track down spark-gap transmitters unless someone complains. --Chetvorno^TALK 16:53, 5 April 2012 (UTC)

Crude Technology ?

The article claims that "Marconi's ... first transmitters were extremely crude". Well yes, they were crude by today's standard, but at the time they were quite literally "state of the art". I will re-word this section Gutta Percha (talk) 09:36, 25 July 2008 (UTC)

Other type transmitters?

The article states: "With the other types of transmitter, the carrier wave could not be controlled so easily, and elaborate measures were required both to modulate the carrier and to separate the receiving antenna from the transmitting antenna."

For the time-period cited, the only other type transmitters that I'm aware of were high-speed alternators. What other type transmitters of that period generated a constant carrier wave that needed to be modulated, as opposed to simply keying the carrier on-and-off?

Also, why would it be any more complicated to separate the receiving antenna from the transmitting antenna with the "other type transmitter" than with a spark-gap transmitter?

In short, the statement is extremely vague, and it lacks citation of a reliable secondary source.Ken (talk) 20:39, 7 March 2009 (UTC)

Upon re-reading the article, I realized that the phrase "other types of transmitter" was referring to an alternator or tuned-arc type transmitter. It's true that these type of transmitters generated a continous carrier; but regardless, the carrier was keyed/modulated in a fairly simple fashion via a telegraph key; albeit, not as simple as keying a spark-gap transmitter on-and-off.Ken (talk) 21:05, 7 March 2009 (UTC)

But how does it actually work?

This article has lots of history but doesn't actually explain the basic concept behind how does a spark gap create radio waves?

Modern high-school/grad physics will tell you about AM and FM but this is just alternating current in a wire - what is the discharge got to do with radio transmission? —Preceding unsigned comment added by 83.244.153.18 (talk) 14:50, 7 February 2011 (UTC)

One way to explain it, is that the spark gap doesn't create RF directly. Its main function is to discharge the capacitor through the tuned circuit, which oscillates on its natural frequency. SV1XV (talk) 16:53, 7 March 2013 (UTC)

I added the two below examples of freq vs antenna length; it seems to me the given frequencies of the illustrated transmitters are pretty far off from the expected values! Comments? "...The frequency of the waves was equal to the resonant frequency of the antenna, which was determined by its length; it acted as a half-wave dipole, which radiated waves roughly twice the length of the antenna (e.g. 15 MHz for 1 m, or 1.5 GHz for 1 cm)..." JdelaF (talk) 04:03, 12 December 2022 (UTC)

@JdelaF: I think you have a factor of 10 error in there. The frequency of a radio wave with a wavelength of λ is f = c / λ, where c = 3(10⁸) meters/second is the speed of light. A 1 meter half-wave dipole would generate a wavelength of approximately 2 meters. The frequency would be approximately

f = 3(10⁸) / 2 = 150,000,000 Hz =150 MHz

Similarly a 1 cm half-wave dipole would generate a wavelength of .02 meter and a frequency of f = 3(10⁸) / .02 = 15 GHz.

--Chetvorno^TALK 15:14, 12 December 2022 (UTC)

Tesla worship

Thanks, Fountains of Bryn Mawr, for scaling back the claims of the Tesla groupies and putting Tesla's contributions in better perspective. The fact that this article mentions Tesla and doesn't mention Oliver Lodge, Ferdinand Braun, Augusto Righi, Jagadish Chandra Bose, Adolf Slaby, Georg von Arco, John Ambrose Fleming, or Max Wien's contributions to spark transmitters is blatant WP:UNDUE. These gentlemen must be spinning in their graves. --Chetvorno^TALK 00:59, 4 November 2013 (UTC)

ty, Hunting down claims on Tesla turns up some real doozies, such as Tesla was Italian and invent AC[1] or that Edison invented DC and Tesla invented AC[2]. Radio cleanups have also been done by Martin Hogbin[3] although the "Tesla groupies" tend to revert them back without comment or rational. Fountains of Bryn Mawr (talk) 14:40, 4 November 2013 (UTC)

I am happy to help maintain due weight here if required. Martin Hogbin (talk) 15:09, 4 November 2013 (UTC)

Thanks. Wow, those examples are amazing! It's a difficult task, dealing with people who view history from such a single-issue (or single-person) perspective, kudos to you guys for taking it on. I know some editors are intimidated by the Tesla cult and avoid tangling with them, just because it is so time-consuming. This article has not seen their attention lately, the stuff Fountains of Bryn Mawr corrected was leftover from a while ago. In many articles, including this one, the problem is not so much false claims about Tesla but UNDUE weight because Tesla's contributions are the only ones mentioned; so the real solution is to write a proper history giving the contributions of others. --Chetvorno^TALK 07:28, 5 November 2013 (UTC)

Re:"others", I agree, just fact checking claims gives me a whole new appreciation of the people you listed. They should be added into the space being freed up from bloated UNDUE. Fountains of Bryn Mawr (talk) 14:18, 5 November 2013 (UTC)

Followed on with further cleanups after cleanups by User:LaurentianShield re:noticed UNDUE. I think it looks good now and is in sync with a revision (Chetvorno's) coming down the pike that I just noticed. Fountains of Bryn Mawr (talk) 16:22, 14 September 2015 (UTC)

Trim down summary

Wasn't sure what this edit was about since the summary was a WP:IUC comment. Cleaned up what seems wrong: a laundry-list of people who noticed sparks cobbled together out of 5 sources, none of which make the statement "these were all significant predecessors" (WP:SYNTH). Parred down to main points in reliable sources and followed summary style/see also (we don't need to mention everybody, that's why we have other articles). Fountains of Bryn Mawr (talk) 16:00, 13 October 2015 (UTC)

Concur. This is Spark-gap transmitter, not History of electricity. What Luigi Galvani and his frog legs have to do with Hertzian wave transmitters beats me. --Chetvorno^TALK 06:57, 14 October 2015 (UTC)

Chetvorno, if you looked at the timeline of radio page, you would understand by Galvani deserves to be mentioned in a history of radio. — Preceding unsigned comment added by SQMeaner (talk • contribs) 19:00, 13 November 2015 (UTC)

If we put in everyone in history who noticed some effects from a spark we are never going to get to important people like Oliver Lodge, Ferdinand Braun, Jagadish Chandra Bose, John Ambrose Fleming, or Max Wien who actually had something to do with spark transmitters and -- bless my soul! -- are not even mentioned in this lousy article. See WP:laundry list, WP:undue weight and WP:synthesis. --Chetvorno^TALK 21:50, 13 November 2015 (UTC)

I did, I don't. Andy Dingley (talk) 00:12, 14 November 2015 (UTC)

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I have checked the archived link, so I changed the bot parameter to 'true'. However I think it might be better to find a more non-volatile source, such as in a text book on welding. LaurentianShield (talk) 15:32, 9 January 2016 (UTC)

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Rewrite

Completely rewrote and expanded article, adding more citations. Removed "inadequate citations" hatnote. --Chetvorno^TALK 09:19, 6 January 2019 (UTC)

Use of spark gap oscillators in TIG welding

@Chetvorno: From your recent edit summary: "User:ArnoldReinhold, there is nothing in the commercial website you gave as source about how a welding spark starter works; is it really a spark gap oscillator, or is it an ordinary CW oscillator feeding a spark gap? Also the source is a commercial promotional website and could be considered WP:Spam. Could you give a better source?"

Here is another source: www.manualslib.com/manual/1332609/Miller-Hf-15-1.html Miller Electric Co. HF-15/20 Owners Manual. Page 12 has a photo of the spark gaps with instructions on setting them. Page 13 has a schematic which is very similar to the 1917 diagram in the article. The big difference is that the output transformer couples to the wire carrying the welding current instead of to an antenna. Some newer high-end welding machines use a solid-state RF source, but spark gap sources are still widely used in industry.[4] Also there is nothing wrong with using a manufacture's documentation on how their products work as a reliable source.--agr (talk) 13:03, 6 January 2019 (UTC)

Okay, awesome, I didn't know about that application. Yeah, the circuit looks just like a spark transmitter (hard to believe in 120 years they haven't come up with new technology. Wonder what the advantages of the spark welder circuit are?) You want to go ahead and remove the tags from the sentence and put in the new source or should I? --Chetvorno^TALK 18:07, 6 January 2019 (UTC)

It's to initially strike the arc with a TIG welder. It's only low current - once the arc is struck, the main supply sustains it. Andy Dingley (talk) 18:28, 6 January 2019 (UTC)

Ah, right, that makes more sense. --Chetvorno^TALK 11:26, 7 January 2019 (UTC)

It's a little more complicated than that. RF start is one mode, but in TIG welding aluminum with an AC supply, continuous RF is traditionally needed. There are newer TIG welding supplies with solid state starters, but they are expensive. Spark gap is cheap and rugged. AC works better with aluminum and the continuous RF helps maintain the arc during the current zero crossings. https://www.thefabricator.com/article/aluminumwelding/aluminum-workshop-tig-welding-and-radio-frequency-interface In the picture I referenced above, note the heat sinks on spark gaps. I've seen rotary gaps on large welding power supplies, stuff you would see in an early radio museum. I worked for a company, Automatix, in the 1980s that made welding robots. It took a lot of work to shield the computers well enough to be used with TIG. Also, it was common in the early days of amateur radio for hams to build spark gap transmitters using automobile ignition transformers (Ford model T in particular). You can find lots of instructions on the Internet on how to build TIG RF generators using automotive ignition coils. I found a couple of photos of this in Flickr with CC licenses that I will try to upload.--agr (talk) 16:20, 7 January 2019 (UTC)

They are File:Bill's HF Start for a TIG welder (2986184869).jpg and File:Bill's HF Start for a TIG welder (2986184847).jpg. One might be appropriate for the article.--agr (talk) 16:37, 7 January 2019 (UTC)

What does it sound like?

I would be curious to know what the transmission sounded like on the receiving end. The dots and dashes would not be an electronic tone I shouldn't think. More likely the time intervals between a series of clicks or perhaps a lower frequency buzz at less than 60 Hz produced by the buzzer on the high voltage coil? Depending on the equipment. It would be helpful to understand the sound quality of what operators had to work with.

It sounds like a buzzing tone. Although the spark gap has a broadband output (broad in terms of audio range), the receiving equipment was very limited in frequency, based on the simple telephones of the time. So what you hear is mostly the frequency response of the headphones and the receiver. Andy Dingley (talk) 17:09, 20 May 2019 (UTC)

There are audio clips of a signal from a spark-gap transmitter and a lot of detailed information on this page by John Belrose, an engineer and historian who has published research papers on the technology of Marconi and Fessenden's early transmitters. --Chetvorno^TALK 18:40, 20 May 2019 (UTC)