2.8. Osciloscopio analógico EN

Analog oscilloscope


Oscilloscopes are used to represent graphically in a scale the electric potential over time.


The device is divided in three parts: the cathode ray tube (CRT), vertical controls and horizontal controls.

However, externally, we can only see the screen, in which the cathode ray tube ends, and some other controls, which allow us to modify the intensity and position of the image, to control the amplitude of the displayed signal and to adjust the time base.


The device is connected between two points of an electric or electronic device. The difference of the potential between them is conveniently increased or reduced to get adapted to the oscilloscope characteristics. This produces a vertical deviation of the electron beam which goes through the cathode ray tube. The magnitude of this deviation is proportional to the difference of the potential applied. At the same time, we apply a voltage in saw-teeth shape, which causes a periodic horizontal deviation of the electronic beam.

The combination of both movements makes the electrons influence different parts of the screen, drawing on it a curve which will make as aware of the potential variation over time.


The first oscilloscope of cathode ray tube was developed in 1897, as a laboratory curiosity without any useful application, by the German physicist Karl Ferdinand Braun.

Its commercialisation as a measurement instrument started in 1946, with the Tektronix model, patented by Howard  Vollum and Melvin “Jack” Murdock.