1920-1940

This time was marked by a lot of invents, very important for the history. These inventions are used even in the present time. The technology doesn’t have been only an instrument of these times; it has been the all times since humanity birth.

POLYGRAPH
Polygraph was invented in 1921 by John Larson. This device had electric sensors, and it could, measure heart and respiratory rate and blood pressure. This was written in a paper where they had many lines. The lines showed if the subject was saying truth.


SOUND TELEVISION
This wonderful invent, was seen first by Warner Brothers in 1926. The first name of this invent was Vitaphone. The system was a sound recording of the spiking text, and the sound band, this was synchronized with the images.
Sound Cinema was a success too.

PEN
This invent was tested by Lazlo Biro in 1938. He used a pellet with oil ink. He saw that the ink dried faster. This was a solution for the pilots writing. The Pen replaced to fountain pen.

RICHTER SCALE
This is the best invent of that time. Richter scale was invented by Charles Richter and Beno Gutenberg in 1935. They were trying to invent a way for measure and grade the earthquakes, to determinate the main and minor scale of the earthquakes.
This scale is used even in the present

FM
Frequency modulated, was invented by Edwin Armstrong, in 1936. This frequency is better than the AM, because the FM doesn’t have interference. This system works with waves that take any sound signal transmitted near.