Re: coherers (SSTC As a transmitter)

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

Original poster: "davep by way of Terry Fritz <twftesla-at-qwest-dot-net>" <davep-at-quik-dot-com>

Tesla list wrote:

> 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>

>>For filings I tried pure nickel, coin silver from a
>>pre-LBJ quarter, and filings from a current nickel.  They need to be
>>made as fine as possible, and Marconi recommended using a worn out
>>file!  I washed everything with soap and water and then proceeded to
>>file and file and file, but finally got enough of each to experiment
>>with.  The silver seemed to work best, but all of them worked. 

> I made some coherers with iron from nail and with stainless steel.
> Filed with a grinding wheel and sorted from dust with a magnet.
> The stainless steel filings work quite well, and don't oxidize.
> A typical coherer requires a few volts for excitation. An interesting
> fact that I could verify is that they switch to conduction in a few 
> nanoseconds only.


> The coherer action is too fast for something mechanical or thermal.

	Coherer action was, at the time, much debated, and
	remained unresolved, as crystal diodes, etc, took
	over.  About 10 years back, more research was done,
	which was published, I THINK in the UK.  IIR (and i
	may be wrong) the coherer is a sort of crude
	scr/thyristor.  (While it is common to picture Solid
	State as high tech, ultra pure materials, much CAN be
	done with more 'hands on' approach, and patience, and
	luck.  To some extent the formal birth of Solid State
	(Shockley, Bardeen, et al) was a result of various (mostly
	military) realizing:
		crystal detectors are key to our New RADARs
	and
		We have No Clue how crystal detectors Really
		Work...)

	best
	dwp

...the net of a million lies...
	Vernor Vinge
There are Many Web Sites which Say Many Things.
	-me