Radio interference from Edison bulbs – Good Article Alert

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If there’d been VHF in the 19-teens, there would have been a big radio interference problem – from light bulbs.

We know this because we’re getting RF noise from some of the new vintage-style bulbs that are in production these days. There’s evidence that Rustika brand ones, for example, are accidental Barkhausen-Kurz oscillators.

So says Dr David Lauder, in an absolutely fascinating article in this month’s RadCom,1 the publication of the Radio Society of Great Britain.

Modern bulbs – the ordinary kind – don’t do this. But the Edison ones, the only ones in use before 1913, did. Their tungsten filaments emitted electrons thermionically, as from a cathode; some of the supporting wires inside the bulb could function as anodes. Presto! You had a houseful of vacuum tube diodes! ‘If the bulb was powered by DC mains,’ explains Dr Lauder, ‘the oscillation would be a coherent carrier’.

Sure enough, this is what some of the modern retro bulbs do, and they generate what amounts to wideband FM with sidebands smack in the middle of aviation radio, right next to the 2-meter amateur band.

Apparently, Edison bulb interference did become a problem eventually, that endured into the 1950s, when the last of the bulbs burned out. Typically, it was television interference between 41 and 68 mHz.




1 August 2020, Volume 96, Number 8, pp. 74-5.

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Better detection than the coherer


You can impose waves, and waveforms, onto current in lines. I’d never thought about the frequency of an electrical signal changing, but that’s what makes voices audible in telephones. Pretty obvious.

‘Detection’ of radio signals means changing their frequency down to a range to which a pair of headphones (and your ears) can respond. You can do it with a transformer, such as the one I’ve found here, in one of those Ladybird ‘achievements’ books for children. Listening for a signal transformed to audio is a more sensitive way of detecting signals than trying to line up metal filings in a coherer, such that their collective resistance drops, and getting a bell to ring. 

Marconi is credited for devising this first, and doing it, as near as I can tell, in 1902. It became standard shipboard equipment for a decade or so, gradually being overtaken by systems that did the trick instead with galena crystals or with the vacuum tube diode, which Ambrose Fleming rolled out in 1903.

The received wisdom goes that nobody, not even Marconi, was able to say why this funny transformer setup worked. It begs the question, of why he devised it.

The system consists of a primary coil, through which RF signals run, a secondary coil into which current gets induced, some strong magnets perfusing their flux lines through the whole system, and a slowly moving (by hand or by clockwork) core of iron wire.

The reason it worked was, more or less, that the iron atoms in the moving core would line up in conformity with the magnetic field, in the absence of incoming current into the primary. (Why the core had to be moving for this, I don’t know.) When a pulse arrived, the atoms would change orientation, behaving in the manner of the core of an electromagnet. That change was detected by the secondary coil. We’re taught to say that ‘the magnetic field collapsed’ at that moment, though it’s not clear to me what this means. As soon as this collapse happened — and here my reading varies — the listener heard a tone or a click. I don’t know which. Either way, Morse code was audibly detected. 

This system was known to contemporaries as the ‘magnetic detector’, or the ‘Maggie’.  You can see a picture of one of these at John Jenkins’ SparkMuseum, here.


Photo credit:  F.G. Goodall, Robert Ayton, illustr., The Story of Radio (Wills & Hepworth, 1968), p. 31. 

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Cablecasting to the Victorians: in the prehistory of radio, part 2

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What’s the physical reality of pre-radio cable broadcasting?  Here is a timeline.

1877:  The idea of worldwide telephone broadcasting exists, shown by the harried cartoon performer in ‘Terrors of the Telephone,’ in the New York magazine Daily Graphic.  A popular song out of St. Louis, ‘The Wondrous Telephone,’ alludes to the idea of broadcasting lectures and music into the home.3

1880:  Clément Ader creates the Compagnie générale des téléphones de Paris for the purpose of broadcasting by wire.

1881:  The International Electrical Exposition in Paris demonstrates Ader’s telephone system at the Palais d’Industrie, with live performances from the Opéra, the Opéra-Comique, and, with some technical difficulty, the Théàtre-Français.It is in stereo,and is sensitive enough for listeners to hear the prompter.French President Jules Grévy is so pleased with this system that he has the Théàtre-Français piped into the Elysée Palace, along with the Opéra and Odéon Theater. Victor Hugo is so delighted with the demonstration that he takes his children to see the system up close at the Ministry of Posts and Telegraphs.He recalls it this way in his diary:

“Nous sommes allés avec Alice et les deux enfants à l’hôtel du Ministre des Postes. A la porte, nous avons rencontré [the chemist, Marcelin] Berthelot qui venait. Nous sommes entrés. C’est très curieux. On se met aux oreilles deux couvre-oreilles qui correspondent avec le mur, et l’on entend la representation de l’Opéra, on change de couvre-oreilles et l’on entend le Théàtre-Français, Coquelin, etc. On change encore et l’on entend l’Opéra-Comique.

Les enfants étaient charmés et moi aussi. Nous étions seuls avec Berthelot, le minister, son fils et sa fille qui est fort jolie.”

In Budapest there are experimental opera broadcasts, to 12 subscribers at a time, over a six-month-old system in trials.

1884:  Special transmission to the Ajuda Palace for the king and queen of Portugal, who wished to attend the premiere of ‘Laureana’ at the San Carlo Opera House, Lisbon, but were unable, being in mourning for the princess of Saxony. Edison director Gower Bell, who managed the feat, is awarded the Military Order of Christ. A Munich theater manager runs a telephone line to his villa on the Starnberger See to monitor the success of his shows. The Berlin Philharmonic is connected by phone to its own opera house. The opera in Antwerp is heard by ministers 30 miles away in Brussels.

1885:  The San Carlo Opera, Lisbon, offers subscriptions by wire to its 90 seasonal performances; the putative audience extends as far as Palhavã, Olivais, and Braça de Prata.

1889:  Ader’s system is first called the Théâtrophone.

1890:  First successful commercial telephone-based entertainment service, the Compagnie du Théâtrophone, set up by M.M. Marinovitch and Szaravady. It is a system of coin-operated boxes in waiting rooms and restaurants around Paris,and the listener can choose from 5 different city venues. Individual subscriptions are available too, but the cost is steep, at 180 francs a year, and 15 more each time the system was used. Across the Atlantic, at the electrical exhibition in the Lenox Lyceum, Americans hear bits of comic opera from New York theaters, and also instrumental music, speeches, and recitations from Boston and Philadelphia.No commercial service like the Théâtrophone exists in the United States, however.10

1891:  In London the Universal Telephone Company puts 50 microphones into the Royal Italian Opera House in Covent Garden, and 50 more into the Theatre Royal, Drury Lane, all for the sole use of Sir Augustus Harris, at St John’s Wood, who even has a special extension to his stables.

1892:  Demonstration telephone performance of The Mountebanks, a comic opera, from London’s Lyric Theatre. The evening’s revenues pay for the launch of The London Electrophone Company.11 The Electrophone exchange is private, housed in a building adjoining the General Post Office Exchange in Gerrard Street; there is a listening salon there.12

1893:  The Telefon Hirmondò, or ‘Telephone Herald’ (the expression is Magyar), is launched in Budapest, as an audio newspaper, direct to several thousand ready subscribers.13 Home subscribers can listen through their municipal telephones if they have them,14 or special earphones can be strung into their houses.15

1896:  Private connections extend to a variety of London venues, but still only for the affluent: it costs £5 to install the equipment in one’s house, and £10 to keep the wire live for the year.

1897:  The wired entertainment service grows in popularity in England. The Electrophone Company works in concert with the National Telephone Company, so that home subscribers must be connected with the telephone system in order to communicate with the Electrophone Company’s switch room. The electrophone receiver is fitted as an extension to the household telephone apparatus. There are also now sixpence-operated listening boxes in public venues like the Café Royal and the Piccadilly Restaurant: you put your coin in and wind up a clockwork timer that keeps the connection open for several minutes. It is popular music, for the most part, running during theatre hours; a remote-control pointer on the box indicates which venue is playing at the moment. Service is so popular that it originates even in popular churches, where the microphones are disguised as Bibles and hassocks. The Company invites public inspection at the Soho headquarters and at the Victorian Era Exhibition, Earl’s Court.16

1899:  The Queen at Windsor Castle hears the Electrophone for the first time, when cadets and schoolboys sing to her from Her Majesty’s Theatre in London. She and guests then listen to a concert at St. James’ hall.17

1901:  Hirmondòexperiments with coin-operated public listening posts.18 World’s Work observes in passing that there is still nothing like this system in the United States. The popularity of the Electrophone in England is still increasing, and rates are dropping, by more than 75%. Gone are installation charges, too. And the equipment is better. The Company offers a loudspeaker, able to fill an entire room with sound. They are proposing service to moving railway cars.19

1913:  In celebration of the Entente Cordiale between Britain and France, the Electrophone and Théâtrophone systems exchange attractions.

1922:  Théâtrophone-style feed from Stockholm Opoera House used for experimental radio broadcast.

1925:  Hirmondò begins radio simulcasting.


Says who:

  1. Reproduced in A Tower in Babel: A History of Broadcasting in the United States to 1933(New York: Oxford University Press, 1966).
  2. Marvin, 209-10. The hot updraft from the footlights at the Théàtre-Français interfered badly with the microphones. See “The Telephone at the Paris Opera,” Scientific American, December 31, 1881, 422-3.
  3. Illustrated in detail in “Souvenirs de l’exposition d’électricité,” Le Magasin pittoresque (1882): 91-4, and more broadly later in Théodose du Moncel, “Le telephone,” Bibliothèque des merveilles, 5thedition (Paris: Librarie Hachette, 1887), 117-27.
  4. Marvin, op. cit., for much of this overview.
  5. Victor Hugo, Choses vues. Souvenirs, journaux, cahiers, 1849-1885, ed. Hubert Juin (Paris: Gallimard, 1974), entry for November 11, 1881.
  6. “The Theatrephone,” [sic] Electrical Review, June 21, 1890, 1.
  7. “Wanted, a Théatrophone,” Elecrical Review, July 5, 1890.
  8. Unlike “the weighing machines and pull-testers that so overcrowd our waiting-rooms everywhere.” “The Theatrophone in Paris,” Electrical Review, August 29, 1891.
  9. Link expired.
  10. “Digital Futures MSc course from the University of Plymouth,” September 2004, at, 12. Link expired.
  11. “Telephonic News Distribution,” The Electrical World, March 18, 1893, 212.
  12. “Telephone newspaper,” The Electrical World, November 4, 1893, 362. There were technical tricks to keeping sound quality high along what amounted to a party line and for preventing subscribers from talking back into the system.
  13. “The Telephone Newspaper,” The Electrical Engineer (London), September 6, 1895, 257.
  14. J. Wright, “The Electrophone,” The Electrician (London), September 10, 1897, 343-44, discusses the technical points in detail.
  15. “The Queen and the Electrophone,” The Electrician (London), May 26, 1899, 144.
  16. Thomas S. Denison, “The Telephone Newspaper,” World’s Work, April, 1901, 640-3.
  17. “Electrophone in England,” Electrical Review, October 5, 1901, 414.

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Cablecasting to the Victorians: in the prehistory of radio, part 1


Before there was radio, there were phones. Before there was broadcast radio, there was broadcasting by wire. Both of these things originated in a certain amount of nerdy improvisation, and a certain amount of business opportunism, and the success of both these things was impeded by a surprising level of resistance from their potential audiences. Astonishingly to us, contemporaries were not widely receptive to piped-in news and entertainment. How these two things germinated, and how they interrelated, is complex, and not really understood.  But it’s worth pointing out to the historian of early wireless, at the very least, that by the coming of radio the public did have about a generation’s-worth of experience with the idea of mass communication by electricity. People knew it could be done, and many of them had clear expectations about what it ought to be like. The systems were actually quite good, too. Why they worked, and spread the way they did (or didn’t), is a matter of cultural history as much as technical history. That’s kind of my thing. So here I offer some work I did ten years ago for the Antenna (vol. 20, no. 2), the newsletter of the Mercurians, who are the communications interest group within the Society for the History of Technology.  I’ll serialize it and update it a bit.  And I’ll try to make the writing better.

Think of cable broadcasting as a French invention from the 1880’s, that in its first few decades existed in varying forms in France, Portugal, Britain, the United States, and Hungary. The reasonable observer would expect such a thing in these places, there being an affluent and consuming public in all of them and also a maturing telephone system, through whose wires these enterprises could transmit. Telephones were good enough technically that Londoners, for example, could hear the French system if they chose to. And interest in entertainment by wire was well in place in all these places too. Late-night line operators improvised concerts for each other on quiet phone and telegraph networks routinely, as the Boston Herald reported in 1891, for example. So, there were numerous commercial trials, some big and some small. The Home Telephone Company of Painesville, Ohio, broadcast a live recital to a thousand customers in 1905, for example, and the New York Magnaphone and Music Company broadcast a recorded one in 1912.1

Scholarship that describes and explains all this is spotty, focusing generally on the regional technical variations, and concluding that the whole undertaking was doomed by the arrival of broadcast radio,2 though exactly what happened at the end of the wired service is not actually clear. The scholarship ignores, in any case, the very basic and very interesting question of why some systems did well and others did not. For they were not all the same, and the populations that used them weren’t either. The Portuguese system died early; the American experiments never reached commercial sustainability; and though the French and British Théâtrophone and Electrophone appear to have lasted through the Great War, their coverage was never as close to universal as their designers had hoped. The mighty Telefon Hirmondó in Budapest, by contrast, was instantly and enduringly successful, eventually simulcasting with radio, and staying popular with listeners until its destruction in the Second World War.

Why? What made Hungarian broadcasting so hearty, and its analogues in the west so sickly? The answer has nothing to do with broadcasting technicalities. It is a story of legal and cultural differences instead.


Tune in next … for an Overview of the Systems


Says who:

  1. Carolyn Marvin, When Old Technologies Were New: Thinking about Electric Communications in the Late Nineteenth Century (New York: Oxford University Press, 1988), 212. There was also Thaddeus Cahill’s strange and gigantic Telharmonium project that offered an early form of Muzak to restaurants along Broadway. See Thomas Martin, “The Telharmonium: Electricity’s Alliance with Music,” Review of Reviews, April 1906, 420-3.
  2. Robert Hawes, Radio Art (London: The Green Wood Publishing Co., 1991), 24.

Picture:  Théâtrophone, Jules Chéret (1890) © 2018 Jules Chéret / Artists Rights Society (ARS), New York

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Victorian online conferencing

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There was a Morse code teleconference in mid-century, of 33 American Telegraph offices between Boston and Calais, Maine, a circuit of 700 miles.  The idea was to act on the resignation of one of the company officers.  Speeches were made, remarks received, and the meeting adjourned with kindly feelings after an hour very efficiently spent.   

Punch magazine, delighted by this, perseverated on the need for a streamlined electric Parliament.   


Says who:

George B. Prescott, History, Theory and Practice of the Electric Telegraph, 1860, p. 350.

Picture:  World telegraph map, 1855.  Computer History Museum:   

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What telephone service was like in 1890

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It’s no bad thing for radio scholars to consider what the public expected of communications generally at various stages. At the end of the 1880s, in America, telephone calls several states away were practical; some of the lines were now buried (said to be impossible 10 years before) or under water (submarine telephony had been made to work to about 10 miles). Loudspeakers brought sermons to the living room, and plans were underway to bring music on tap into homes by subscription, pending improvements to acoustic fidelity. The Europeans were already doing this quite a bit. I’ll post separately on that.  Exactly 11 years from now, Marconi will say he heard his famous letter S from Poldhu.  Small wonder that many Americans were ready to hear about it by then.  

Says who:

Remark by E.J. Hall, Jr., vice-president of the American Telegraph and Telephone Company at a telephone convention in Detroit, in “Extension and Improvement of Telephone Service,” The Electrical World, September 20, 1890, p. 197.   

Picture credit: Chicago Public Library:

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Good Victorian science

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Signalling beyond a third of a mile or so was a daring idea in 1892. The demonstrated range so far was only a few hundred yards. But contemporaries suspected that much could be done yet with wireless electricity. Their inferential models of current in the air were growing in sophistication. William Crookes, the physicist, aware of the work of Heinrich Hertz and Oliver Lodge, and having himself worked a bit with David Hughes, imagined electrical intelligence vibrating in the ether in all directions, or refracted in directional ‘sheafs of rays’ through pitch lenses, in wavelengths of thousands of miles down to a few feet. Received signals ought to be made louder by reflection, he thought. Signals fade, he observed, ‘according to the law of inverse squares.’ He was aware that receivers could be made to ‘respond to wavelengths between certain defined limits and be silent to all others,’ by ‘turning a screw or altering the length of a wire.’ In this he was ahead of where Marconi was ten years later. Signals restricted to as little band space as possible, added, would be difficult to find, and therefore tantamount to private.   

Says who:   

William Crookes, “Some Possibilities of Electricity,” Fortnightly Review, February 1, 1892, pp. 174-6.

Picture:  Assembling cathode-ray ‘Crookes Tubes’, in H. Snowden Ward, “Marvels of the New Light: Notes on the Röntgen Rays. The Windsor Magazine, vol. 3 (Jan 1896):372-84.

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What amateur culture was in 1906

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The best teaching case in the very beginning of amateur culture, because it’s so well documented in QST, is that of Irving Vermilya, in Mount Vernon, New York. I’ve done some posts about this fascinating kid and his circle already. Between 1903 and 1910 he was part of a rowdy and growing cell of experimenters across town, several dozen teen scroungers who communicated illegally with each other by backyard telegraph (they purloined the power from the city tram) and made life hell for commercial and military interests on the air, where they attracted the attention of the Department of the Navy. (When they were bored, the kids liked to jam the fleet in Brooklyn.) The navy, for reasons I’ve never understood, was the arm of the government generally charged with management of wireless communications at the federal level. (This endured all the way to World War 2.) A number of these Mount Vernon kids grew up and got jobs in wireless, and Irving Vermilya was one of them.

Exactly the same scrabble between tinkerers, syndicates, and a generally befuddled Uncle Sam was happening in other cities at the very same time, and exactly the same slow move to eventual citizenly resolution. In 1906 Technical World Magazine reported on a dozen high schoolers in Newport, Rhode Island, who had come under inspection by one Commander Albert Gleaves, USN, for having caused some serious problems for a nearby torpedo installation. The nucleus of the kids’ organization was a homebrew transmitter in a converted henhouse. The Commander came away blinking, telling Washington that these kids were really very ingenious, and that their example proves that anyone can get on the air, cheaply, and that the army and navy should take note of this and do it too. In the free-for-all world of 1906 it wasn’t clear whether a reprimand or a commendation was actually in order.

Two of these Newport Irving Vermilyas were Charles Fielding, a telegraph messenger, and his pal Lloyd Manuel, he of the henhouse. They were not especially interested in matriculating into commercial wireless, at least for very long. They wanted to make fortunes as wireless inventors. Their families could ill afford to spend money for whims, as Technical World politely put it, which might explain the boys’ ambition.

It probably does explain their ingenuity. They made spark gaps out of old nails. They wound their coils on jars and curtain rollers. They made detectors out of arc-light carbons and sewing needles, or, emulating Fessenden, from incandescent lamps that they filled with nitric acid.

I do find Lloyd Manuel possessed of a 500-watt station in 1924, at 169 Thames Street, Newport, a modest address, under callsign 1BOG.  He stayed on course, by the look of it, and went legitimate, even if he didn’t make a fortune.  No mention of Charles Fielding.


Says who:

“Wireless Station in Henhouse,” Technical World Magazine, September 1906, pp. 62-3.  Available at

United States Department of Commerce, Amateur Radio Stations of the United States, Edition June 30th, 1924, p. 13.


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Who was in the amateur game in 1904

young pioneers

There’s a fascinating snapshot of radio culture in 1904 in the June issue of Amateur Work, about a couple of Boston eighth-graders who built a wireless station in shop class, that had an eventual range of a good 8 miles.

This Amateur Work is probably a descendant of the serial of the same name whose publication began in 1881, a do-it-yourself manual in lathes, clocks, and violins, greenhouses, book-binding and electro-plating, glass, microscopes and fishing tackle, sun-dials, fly-tying and photography – you get the idea. These early issues are being digitized by the Smithsonian [] right now, and they’re very good reading.

By 1904 this publication was carrying articles on wireless. The art was still young. The editors felt obliged to put quotes around “wireless,” and the young inventors, Samuel Breck and Newell Thompson, called their transmitter a “disperser,” and their receiver a “responder.” The project apparently surprised the Boston school system.

Nevertheless, it got off the ground swiftly. The boys had seen a wireless exhibit in a Mechanics’ Building fair only at the start of the school year. When they came asking for help, their shop teacher and their headmaster were both quick to get involved. Visitors came to the school to watch the prototype in action. The lads’ parents helped them arrange subsequent distance tests of growing lengths across the Charles River.

The lesson is that wireless culture was developed enough in mid-1904, in the popular press, in trade and educational institutions, and in the public imagination, that even schoolboys could be mentored onto the air, and fairly readily.

Says who:

“Wireless” telegraph plant by Amateur Work readers.  Amateur Work, June, 1904, p. 223.  Available at


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Good Book Alert: “The Radio Boys and Girls,” by Mike Adams

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Fans of Irving Vermilya’s backyard telegraph community (see my old posts about him), or the Hardy Boys and their shortwave mystery, will want to read this lovely book I’ve just found, The Radio Boys and Girls: Radio, Telegraph, Telephone and Wireless Adventures for Juvenile Readers, 1890-1945 (McFarland Publishing), compiling and discussing over 50 communications-related stories for young people from World War Two back to the 1890s.  It’s an obvious cultural history project, that no one has done until now — and I’m so glad Mike Adams has!  He’s got a website about it here, and Ed Sharpe, of the Southwest Museum of Engineering Communications and Computation, has a fine review of the book, here.

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