Experiment Number 2

Oscilloscope

Dr. Amr A. Abd-Elghany

Medical Equipment Technology Department

Objects of the experiment• Connection of the generator with the

oscilloscope.• Differentiate between sine, square, and

triangle waves.• Determining the periodic time, frequency, and

amplitude of unknown waves.

Principles

• Cathode ray oscilloscope consists of:• High evacuated tube: containing a gas at 0.01mmHg

to accelerate the beam of electrons.• Electron gun: a filament when heated emits a beam

of electrons.• Deflecting system: consists of: a. 2 horizontal plates

y1, y2 producing vertical electric field. b. 2 vertical plates x1, x2 producing vertical electric field.

• Fluorescent screen: coated with zinc sulphide which produce light spot when the electron hit it where a part of the K.E. of the electron beam is converted to light energy.

• Emulsion of carbon: to remove the electron contamination.

• For the oscilloscope to draw the signals:

• Vertical plates x1, x2 are connected to the sweep circuit which produce saw tooth potential increases gradually then vanishes suddenly.

• Horizontal plates y1, y2 are connected to the unknown wave.

• To get stationary wave the frequency of the sweep circuit matches with the frequency of the unknown wave.

• Frequency F: is the number of complete cycles per second.• Periodic time: is the time taken to complete one cycle of the

wave.

Procedure

1. Prepare the oscilloscope and connect it with the generator producing sine wave.

2. Measure the number of division in the X- direction.

3. Determine the time/div with sec then get the periodic time T= no. of div. in X-direction x T/D (sec).

4. The reciprocal of the periodic time in sec is the frequency in Hz.

5. Measure the number of division in the Y- direction.

6. Determine Vpp= no. of div. in Y direction x V/D (volt).

7. The amplitude A= Vpp/2 volt.

8. Repeat the above steps for the square and triangle waves.

9. Tabulate your results and draw the three types of waves.

A=Vpp/2 Vpp V/D No. of div. Y-dir.

Freq.(Hz).

T (sec) T/D No. of div. X-

dir.

Type of wave

Sine

Triangle

Square