Instructables

The most modern of modern gadgets, the wireless telephone,is actually not so modern after all. Within 6 years of the first American patent for a telephonic device (Alexander Graham Bell, 1876), another researcher discovered a method for sending voice through the air without connecting wires. His name was Amos Emerson Dolbear (1837-1910). From 1874 on Dolbear was chairman of the Physics Department at Tufts University. He worked throughout the 1870s on designing a working telephone (as did many other scientists in Europe and America), but was beaten to the patent office by Bell. Undaunted, Dolbear continued to develop his own ideas about electrical communication. One day in 1881 he was working in his lab when he made a startling, accidental discovery:

While at work at the single terminal receiver . . . the cord became detached from the line while I was unaware of it, and I still heard the speech from the transmitter plainly. Upon noticing this I began backing away from the end of the wire from the transmitter, letting the single cord hang free in the air. I could hear the talking in the most remote part of the room.

Wireless telephony was the next big step forward in communication. Telegraph and telephone systems required vast amounts of wire strung overhead on unsightly utility poles. The benefit, in time, money, and esthetics promised by wireless communication would be enormous. Dolbear applied for a patent on his discovery in 1882. Patent 350299 was granted to Dolbear in 1886, but nothing came of it. Wireless telephony did not become widespread till a century later, and not truly ubiquitous until after the turn of the 21st century. Why? Was there a conspiracy by the hard-wired phone company to suppress competing technology? Or was there a weakness, a fatal flaw in the Dolbear system? I decided to try to replicate his 1882 design, with features from later wireless phone designs by Nathan Stubblefield, Archie Collins, and Hugo Gernsback to uncover how well it worked--and how well it didn't.


 
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this is awesome! You should enter it in the Vintage Contest http://www.instructables.com/contest/vintage2014/

Thanks, but I don't think it's eligible (due to age?)

profort2 months ago
Wonderfully systematic and WELL DONE.
Mr. Apol (author)  profort2 months ago

Thank you. I hope everything's clear!

PBT

hzxasdf2 months ago

制作过程最好更详细一些。 More detail some of the best.

Mr. Apol (author)  hzxasdf2 months ago

Thanks for your comment.

osutton2 months ago
This is excellent! I loved all the history and explanations! Great work!
Mr. Apol (author)  osutton2 months ago

Thanks, this was a fun project. I plan to keep working on it to improve reception at longer distances.