[GreenKeys] FAX in an early movie

[Richard Knoppow]

I don't think this is exactly an acoustic coupler, more like a magnetic 
one. Its shown in both the live action and animation as being connected 
to the _receiver_ and in the animation it appears to be coupled 
magnetically to the diaphragm of the receiver.  That will certainly work 
and can be demonstrated by using a couple of pair of old style magnetic 
headphones.  Now, the receiver is normally connected to a transformer 
which couples it to incoming signals and also  to the signal from the 
microphone (transmitter in Telco parlance)through a sort of bridge to 
control the side tone level. Its been a while since I fooled with old 
style telephones but I am pretty sure one can couple a signal to the 
receiver and have it transmitted through the line. A way around the long 
standing reluctance of the Bell System to have any "foreign" equipment 
connected to its lines.
     BTW, it occurs to me to wonder what the utility of having an 
airplane mounted on a car was.  Perhaps to transport the plane somewhere 
but, since the car has to achieve take off speed and probably can't 
accelerate any faster than the plane, what point does it serve other 
than a good show for the news reels (remember them?).  Maybe the ground 
was too rough, that car was sure bouncing around a lot.
     The mobile darkroom in a truck appeals to me.
On 1/20/2016 1:12 PM, Jones, Douglas W wrote:
> On 01/20/2016 12:13 PM, Richard Knoppow wrote:
>> FAX among other things is shown in a 1937 industrial at:
> Not only an old fax machine, but they use an acoustic coupler to connect it to the phone line.
>
> The movie doesn't discuss the use of an audio carrier for the analog brightness signal, but aside from that it's pretty good.  I like their use of the string rolling machine to demonstrate scanning.
>
> 		Doug Jones
> 		jones at cs.uiowa.edu
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-- 
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL

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