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 over 5 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 5 years by Anonymous

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

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


Viewed
48693 times

More from MIT Department of Physics Technical Services Group

Refraction & Total Internal Reflection

Refraction & Total Internal Reflection

Added over 1 year ago | 00:01:53 | 3813 views

Fire Extinguisher on a Tricycle

Fire Extinguisher on a Tricycle

Added over 5 years ago | 00:00:53 | 36028 views

Lenz's Law with Copper Pipe

Lenz's Law with Copper Pipe

Added 2 years ago | 00:01:38 | 5261 views

Spring Paradox

Spring Paradox

Added over 3 years ago | 00:01:01 | 16796 views

Strobe of a Falling Ball

Strobe of a Falling Ball

Added over 5 years ago | 00:00:41 | 36825 views

Ring Falling in a Magnetic Field

Ring Falling in a Magnetic Field

Added over 2 years ago | 00:03:27 | 9464 views