Thursday, May 14, 2020
  Poulsen's Telegraphone

Starting a new set of 'patient tech', with a theme of Ancestral Recorders. First I've animated Valdemar Poulsen's 1902 patent for the Telegraphone or wire recorder. Next will be the Dictaphone.

Wire recorders occupy an uncomfortable spot in the history of sound-handling tech, never adopted by business or entertainment, but useful for dishonest activity.

Poulsen invented the device at a time when wax cylinder phonographs were highly popular for entertainment (play only) and for office use (record and play). Wire never dominated office use, and never made it into the home entertainment market.

I've seen and played with wax Dictaphones in storage rooms of old offices; they were still used in some offices in the '60s. I've used and owned disc recorders, which were especially popular around WW2. I've never seen a wire recorder at all, so I don't have a good feel for them.

= = = = =

The Telegraphone was meant to be used with a regular phone set to provide the microphone and earphone. Some versions placed the controls on the phone, and others connected to the phone line for remote dictation.



The dial on the front showed current location in the overall length. You could turn the two end needles inward to record only in one segment and leave other segments untouched. (A feature that never appeared on tape recorders!) The switch on right was for forward / off / backward, and the pushbutton on left was for instant stop or pause.

Poulsen's first version, which I'm using here, took special care to keep the wire strictly lined up in one layer on each reel. The reels were driven forward and backward by worm gears, so the wire always traveled straight through the fixed heads.



There was no easy way to remove the reels. This one wire was permanent. You couldn't take it off and store it or mail it. You could only dictate and listen. Adequate for ordinary dictation and transcription, but useless for archiving or distributing the audio itself.

Later on, Poulsen and other inventors found ways to keep the wire from tangling without this complexity, and found ways to remove and store pairs of reels. Still, wire never approached cylinders and discs for convenience.

Poulsen was brute-forcish with mechanisms but brilliant with magnets. A closeup of the three heads:



Each head is actually a pair of electromagnets, with the top and bottom halves wired in series. This meant that the top and bottom sections were opposite poles as seen by the wire.

When the wire was running rightward for recording, the left head erased by forcing a constant one-way polarity, then the middle head recorded the changing waves of the incoming audio. On the return trip, the right pair erased and the middle recorded. Later versions of wire and tape recorders got rid of this unnecessary symmetry, and just recorded and played in the same direction with one erase head in front of the record/play head.

If we can believe movies and TV, wire recorders were mainly used for bugging, by police and by blackmailers. The only advantage of wire was LENGTH. A wire recorder could sit there and record for many hours without attention, while dictaphones typically ran 15 minutes and disc recorders were 5 minutes. When tape was perfected around 1950, it instantly replaced wire and disc but not Dictaphones.

= = = = =

Because I don't have hands-on experience with wire recorders, my first attempt at animating the reels failed. Looks OK until you realize that the wire is coming off both reels at once. This is why the Patent Office required physical models of inventions for many years. It's too easy to miss problems like this in a sketch. A digital animation is no better. In patents as in education, a text or drawing or software can easily misrepresent reality, but reality can't misrepresent reality.

= = = = =

Linking back to the previous set, which was interesting and meaningful from several angles. I don't think this new set will be especially interesting, but I like to keep things moving.

Summary of Ancestral Clocks.

Labels: ,

 


<< Home

blogger hit counter
My Photo
Name:
Location: Spokane

The current icon shows Polistra using a Personal Equation Machine.

My graphics products:

Free stuff at ShareCG

And some leftovers here.

ARCHIVES
March 2005 / April 2005 / May 2005 / June 2005 / July 2005 / August 2005 / September 2005 / October 2005 / November 2005 / December 2005 / January 2006 / February 2006 / March 2006 / April 2006 / May 2006 / June 2006 / July 2006 / August 2006 / September 2006 / October 2006 / November 2006 / December 2006 / January 2007 / February 2007 / March 2007 / April 2007 / May 2007 / June 2007 / July 2007 / August 2007 / September 2007 / October 2007 / November 2007 / December 2007 / January 2008 / February 2008 / March 2008 / April 2008 / May 2008 / June 2008 / July 2008 / August 2008 / September 2008 / October 2008 / November 2008 / December 2008 / January 2009 / February 2009 / March 2009 / April 2009 / May 2009 / June 2009 / July 2009 / August 2009 / September 2009 / October 2009 / November 2009 / December 2009 / January 2010 / February 2010 / March 2010 / April 2010 / May 2010 / June 2010 / July 2010 / August 2010 / September 2010 / October 2010 / November 2010 / December 2010 / January 2011 / February 2011 / March 2011 / April 2011 / May 2011 / June 2011 / July 2011 / August 2011 / September 2011 / October 2011 / November 2011 / December 2011 / January 2012 / February 2012 / March 2012 / April 2012 / May 2012 / June 2012 / July 2012 / August 2012 / September 2012 / October 2012 / November 2012 / December 2012 / January 2013 / February 2013 / March 2013 / April 2013 / May 2013 / June 2013 / July 2013 / August 2013 / September 2013 / October 2013 / November 2013 / December 2013 / January 2014 / February 2014 / March 2014 / April 2014 / May 2014 / June 2014 / July 2014 / August 2014 / September 2014 / October 2014 / November 2014 / December 2014 / January 2015 / February 2015 / March 2015 / April 2015 / May 2015 / June 2015 / July 2015 / August 2015 / September 2015 / October 2015 / November 2015 / December 2015 / January 2016 / February 2016 / March 2016 / April 2016 / May 2016 / June 2016 / July 2016 / August 2016 / September 2016 / October 2016 / November 2016 / December 2016 / January 2017 / February 2017 / March 2017 / April 2017 / May 2017 / June 2017 / July 2017 / August 2017 / September 2017 / October 2017 / November 2017 / December 2017 / January 2018 / February 2018 / March 2018 / April 2018 / May 2018 / June 2018 / July 2018 / August 2018 / September 2018 / October 2018 / November 2018 / December 2018 / January 2019 / February 2019 / March 2019 / April 2019 / May 2019 / June 2019 / July 2019 / August 2019 / September 2019 / October 2019 / November 2019 / December 2019 / January 2020 / February 2020 / March 2020 / April 2020 / May 2020 / June 2020 / July 2020 / August 2020 / September 2020 / October 2020 / November 2020 / December 2020 / January 2021 / February 2021 / March 2021 / April 2021 / May 2021 / June 2021 / July 2021 / August 2021 / September 2021 /


Major tags or subjects:

2000 = 1000
Carbon Cult
Carver
Constants and variables
Defensible Cases
Defensible Times
Defensible Spaces
Equipoise
Experiential education
From rights to duties
Grand Blueprint
Metrology
Natural law = Sharia law
Natural law = Soviet law
Shared Lie
Skill-estate
Trinity House
#Whole-of-society

Powered by Blogger