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Picture of The Model 1882 Wireless Telephone
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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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McGee 20212 days ago

After much testing, I have found a way to use a vacuum tube instead of a transformer. I recently purchased 200 vacuum tubes and have found a way to make everyone of them work with the phone.

Mr. Apol (author)  McGee 2021yesterday

That sounds great. Are you getting radio propagation using tubes, or still trying for induction/conduction transmission?

Paul

PS. This guy is doing earth conduction using modern amps, etc.:

McGee 20211 month ago

I can't seem to get it to work. See any problems? I think it might be the antenna.

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Mr. Apol (author)  McGee 20211 month ago

I've thought more about your problem. I don't think a tight helical antenna is appropriate to transmit. All the old books I consulted (and my own exeriments) use a wide diameter hoop of wire rather than a closely wound spiral. This may be your problem.

Paul

Mr. Apol (author)  McGee 20211 month ago

Hmm, it's hard to tell what's going on from the photo, but some thoughts:


How much battery power are you using? Prof. Dolbear used 100 volts DC on his initial experiment.

Over what distance are you trying to transmit? Start close and work your way apart.

Induction antennas usually use many yards of wire. Your copper pipe may not be sufficient to transmit (plus, what are you using to receive?)

Keep at it,

Paul

McGee 20211 month ago

BTW, the 'pipe' is actually a wooden dowel wrapped with copper wire

McGee 20211 month ago

I'm using induction, I have tried 10 6v batteries, any distance I can,and have used over 1000 yards of wire. My receiver is simple an antenna that is about 1/5 the size of the transmitters antenna connected to a capacitor connected to a speaker connect to the othe wire from the antenna.

McGee 20212 months ago

Yes and yes. I am using this as a wireless phone and I have put it in a back pack. I used the idea for a portable phone from one of stublefield's patents and have strung up about 4 miles of copper wire around my long driveway. I hope it works!

Mr. Apol (author)  McGee 20212 months ago

Ambitious! Let us know how it turns out.

PBT

McGee 20212 months ago

this is a link to the patent:http://www.google.com/patents/US887357

McGee 20212 months ago

I also used this as a science project And got first place over all.

Mr. Apol (author)  McGee 20212 months ago

Great! Was this at a Science Fair?

PBT

McGee 20212 months ago

I made another wireless phone based on the original model with a K.W. Ignition coil. This is what it looks like

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Mr. Apol (author)  McGee 20212 months ago
Interesting. Did you use the KW coil to amplify the phone's output?

PBT
McGee 20214 months ago

could I use a 12 volt car battery to add amperagee?

Mr. Apol (author)  McGee 20214 months ago
Yes, but it's better to add batteries of equal voltage and power. I used up to 8 6 volt lantern batteries at a time in my experiments. Watch out for overheating your microphone, too.
McGee 20214 months ago

Amperage.

Mr. Apol (author)  McGee 20214 months ago
Amperage?
McGee 2021 made it!4 months ago

this was a very nice project for me and it worked perfectly.

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Mr. Apol (author)  McGee 20214 months ago

Glad to hear it! Tell me more about it.

Paul

McGee 20216 months ago

A circuit diagram would help a lot.

Mr. Apol (author)  McGee 20216 months ago
I don't have the specialized graphics needed for a good diagram. That's why I took photos and labelled all the parts.

PBT
McGee 20216 months ago

would a 120v-16v transformer work?

Mr. Apol (author)  McGee 20216 months ago
Sure--wire it backwards, of course, to boost the output of the transmitter.

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?)

profort9 months ago
Wonderfully systematic and WELL DONE.
Mr. Apol (author)  profort9 months ago

Thank you. I hope everything's clear!

PBT

hzxasdf9 months ago

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

Mr. Apol (author)  hzxasdf9 months ago

Thanks for your comment.

osutton9 months ago
This is excellent! I loved all the history and explanations! Great work!
Mr. Apol (author)  osutton9 months ago

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