Re: coherers

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz <twftesla-at-qwest-dot-net>" <acmq-at-compuland-dot-com.br>

Tesla list wrote:
> 
> Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<evp-at-pacbell-dot-net>

>         Your university seems to have a lot of really neat antiques!  That
> sounds like the classic Marconi detector, particularly if it is in a
> large flat box with the detector mounted on the top panel. 

Yes, it has a label from the Marconi company. It is actually double,
with a coil and two magnets at each side.

> IF the wire
> is still there it would be really interesting if you could borrow it and
> attempt to measure its properties, an in particular see what the "click"
> really sounded like.  

Unfortunately, the wire is missing... But it has no reason for being
insulated. No current travels on it, and it doesn't touch anything
conductive. The two pulleys are made of ebonite, and the wire
passes inside glass tubes at the centers of the coils.

> One claimed advantage of the device was that it
> could produce quite a lot of signal current and operate several
> low-impedance headsets in series, permitting multiple operators to try
> to transcribe the same message under "difficult" conditions.

In that receiver, the same wire is used in two independent detectors.

Along with it is a box with a kind of tuning circuit with three
cylinders
at the top and several nice switches.

Antonio Carlos M. de Queiroz