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One of these obscure phones was recently sold on eBay for $1522.00(U.S.). Apart from the occasional mention in reference books, it is almost unknown. What little is known is presented here. The Pantelephone was another attempt to get around the Bell patents, and to make a transmitter that was a little more sensitive than Bell's Blake-Berliner model. Unfortunately the patents held by the Bell company effectively blocked most alternative ways of building a telephone transmitter. The biggest problem of Bell's transmitters is that they were not very sensitive. In a single-contact transmitter, the best way to increase the volume was to use a bigger diaphragm.

Leon de Locht-Labye, a Professor at Liege University in Belgium, published details of one such transmitter in 1880 in his work entitled La Téléphonie - Sa Théorie, Ses Applications - Le Pantéléphone (very roughly, 'The Telephone Its Theory and Applications The Pantelephone')

He described a loose-contact transmitter that used a suspended sheet of cork, mica or metal for a diaphragm, about 15cm on each side, and an adjustable weighted or sprung arm with a platinum or silver bead cemented to it pressing on the diaphragm. A corresponding bead or carbon strip was riveted to the diaphragm. An induction coil completed the circuit and stopped the "make and break" effect when the diaphragm was moved too violently by people shouting into it. An Ader-type receiver completed the phone. Although the telephone probably ran foul of Edison's carbon contact transmitter patents and Berliner's metallic contact patents, it went into limited production for a brief period.

The excellent photos show (see colour photos) the internal construction clearly. The arm appears to be brass, with a German Silver disc soldered to it. The adjuster screw is clearly seen at the base of the arm, just above the pivot. The diaphragm is the large solid-looking slab of cork suspended from the top of the case. The switchhook has an improvised but solid look to it, as does the bell ringer magnet assembly. The whole assembly was usually mounted on a heavy timber or metal backboard so that only the diaphragm would move. A cloth cover concealed the works and let the sound waves through to the diaphragm. The fabric is impressed with the Locht Labye name, and Brevete, which equates to "patented".

Even the peripheral parts, the bell, earpiece and wall mount brackets, show careful design for strength and durability. This probably explains why the phone is still in good condition after more than a century.

From the few comments available it was a fairly good, sensitive transmitter. It could apparently carry a call for several miles on a single-wire circuit, and pick up a conversation up to twenty metres from the transmitter, which would have made it better than the early Bell transmitters their transmission range was measured in hundreds of yards. Its sensitivity was due to the large diaphragm area, but this was also a drawback. As can be seen from the photos, the simple fabric screen would not have provided much protection to the internals. The transmitter was also sensitive to bumps and knocks, and it would have been impractical to build it into a desk phone.

The example on eBay is from South America, where many were sold into Argentina in the 1880’s. Some were apparently also used in a number of European cities. Does anyone have any more information? The eBay seller did a great job with the high resolution photos of this extremely rare telephone.

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