Massachusetts Institute of Technology
Sign in Create Account

MIT Physics Demo -- Telegraph Transmitter

A solenoid enclosed in another solenoid is connected to a 12 volt battery. Also contained in the circuit is an iron contact switch connected to a spring arm, with a gap on one side of it. When the circuit is closed, the inner solenoid attracts the iron switch across the small gap. This breaks the circuit, making the switch move back to its original position, which closes the circuit again. Thus, the switch moves back and forth quickly, causing oscillations of high voltage in the outer solenoid. This high voltage causes sparks to jump the large gap between the ends of the outer solenoid.

These sparks cause electromagnetic radiation, which is how telegraphs were originally transmitted wirelessly. Morse code can be transmitted by opening and closing the power source.

This specific transmitter was made by the Marconi company, and is very much like the telegraph machine that would have been used on the Titanic. Read more about spark gap transmitters here.

Comments (2)

cool, very cool.

Posted almost 7 years by Anonymous User

spark gaps are also used as a means for modulating how much power can get through a circuit at a certain point.

Posted over 6 years by Anonymous

You need to log in, in order to post comments. If you don’t have an account yet, sign up now!

MIT Department of Physics Technical Services Group

MIT Department of Physics Technical Services Group

Category: Science | Updated 2 years ago

Created
April 10, 2008 13:56
Category
Tags
License
Creative Commons Attribution-NonCommercial (What is this?)
Additional Files


Viewed
51192 times

More from MIT Department of Physics Technical Services Group

Pulling a Cloth From Under a Beaker

Pulling a Cloth From Under a Beaker

Added over 4 years ago | 00:00:50 | 17107 views

Faraday's Cage

Faraday's Cage

Added over 6 years ago | 00:01:23 | 63831 views

MIT Physics Demo -- Low Friction Atwood Machine

MIT Physics Demo -- Low Friction At...

Added 7 years ago | 00:00:46 | 48103 views

Curie Point of Iron

Curie Point of Iron

Added over 3 years ago | 00:01:23 | 5309 views

Laser Diffraction and Interference

Laser Diffraction and Interference

Added over 6 years ago | 00:02:25 | 38438 views

Barkhausen Effect

Barkhausen Effect

Added over 3 years ago | 00:01:02 | 4999 views