NTNUJAVA Virtual Physics Laboratory
Enjoy the fun of physics with simulations!
Backup site http://enjoy.phy.ntnu.edu.tw/ntnujava/
July 06, 2020, 10:21:34 am *
Welcome, Guest. Please login or register.
Did you miss your activation email?

Login with username, password and session length
   Home   Help Search Login Register  
An interaction between two opposites produces a unique outcome. ..."Jules Henri Poincare(1854-1912, One of France's greatest mathematicians)"
Google Bookmarks Yahoo My Web MSN Live Netscape Del.icio.us FURL Stumble Upon Delirious Ask FaceBook

Pages: [1]   Go Down
Author Topic: EJS version of oscilloscope  (Read 13481 times)
0 Members and 1 Guest are viewing this topic. Click to toggle author information(expand message area).
Fu-Kwun Hwang
Hero Member
Offline Offline

Posts: 3085

Embed this message
on: March 27, 2011, 03:32:29 pm » posted from:Taipei,T'ai-pei,Taiwan

Like a televison screen, the screen of an oscilloscope consists of a cathode ray tube. Although the size and shape are different, the operating principle is the same. Inside the tube is a vacuum. The electron beam emitted by the heated cathode at the rear end of the tube is accelerated and focused by one or more anodes, and strikes the front of the tube, producing a bright spot on the phosphorescent screen.

The electron beam is bent, or deflected, by voltages applied to two sets of plates fixed in the tube. The horizontal deflection plates, or X-plates produce side to side movement. As you can see, they are linked to a system block called the time base. This produces a sawtooth waveform. During the rising phase of the sawtooth, the spot is driven at a uniform rate from left to right across the front of the screen. During the falling phase, the electron beam returns rapidly from right ot left, but the spot is 'blanked out' so that nothing appears on the screen.

In this way, the time base generates the X-axis of the V/t graph.

The slope of the rising phase varies with the frequency of the sawtooth and can be adjusted, using the TIME/DIV control, to change the scale of the X-axis. Dividing the oscilloscope screen into squares allows the horizontal scale to be expressed in seconds, milliseconds or microseconds per division (s/DIV, ms/DIV, µs/DIV). Alternatively, if the squares are 1 cm apart, the scale may be given as s/cm, ms/cm or µs/cm.

The signal to be displayed is connected to the input. The AC/DC switch is usually kept in the DC position (switch closed) so that there is a direct connection to the Y-amplifier. In the AC position (switch open) a capacitor is placed in the signal path. As will be explained in Chapter 5, the capacitor blocks DC signals but allows AC signals to pass.

The Y-amplifier is linked in turn to a pair of Y-plates so that it provides the Y-axis of the the V/t graph. The overall gain of the Y-amplifier can be adjusted, using the VOLTS/DIV control, so that the resulting display is neither too small or too large, but fits the screen and can be seen clearly. The vertical scale is usually given in V/DIV or mV/DIV.

The trigger circuit is used to delay the time base waveform so that the same section of the input signal is displayed on the screen each time the spot moves across. The effect of this is to give a stable picture on the oscilloscope screen, making it easier to measure and interpret the signal.

Changing the scales of the X-axis and Y-axis allows many different signals to be displayed. Sometimes, it is also useful to be able to change the positions of the axes. This is possible using the X-POS and Y-POS controls. For example, with no signal applied, the normal trace is a straight line across the centre of the screen. Adjusting Y-POS allows the zero level on the Y-axis to be changed, moving the whole trace up or down on the screen to give an effective display of signals like pulse waveforms which do not alternate between positive and negative values.
The above information are quoted from http://www.doctronics.co.uk/scope.htm

This applet simulate how the socilloscope works (This is an EJS version of the oscilloscope applet).

The oscilloscope is an electronic instrument widely used in making electrical measurements.
The main component of the oscilloscope is the cathode ray tube (CRT).
The CRT is a vacuum tube in which electrons are accelerated and deflected under the influence of electric field. The electrons are deflected in various directions by two sets of plate placed at right angle to each other in the neck of the tube.
Signal for the horizontal deflection plate (X-axis) is generated by the scope
It mathematic form is Fx(t)= C t + D (default)
C : time scale
D : horizontal offset
The external signal (need to be measured) is applied to the vertical deflection plate (Y axis).
The default form for this java applet is Fy(t)=A sin(w t + B)

   You can change X or Y axis signal to either kind of signal.

Embed a running copy of this simulation

Embed a running copy link(show simulation in a popuped window)
Full screen applet or Problem viewing java?Add http://www.phy.ntnu.edu.tw/ to exception site list
Press the Alt key and the left mouse button to drag the applet off the browser and onto the desktop. This work is licensed under a Creative Commons Attribution 2.5 Taiwan License
  • Please feel free to post your ideas about how to use the simulation for better teaching and learning.
  • Post questions to be asked to help students to think, to explore.
  • Upload worksheets as attached files to share with more users.
Let's work together. We can help more users understand physics conceptually and enjoy the fun of learning physics!

* oscilloscope.gif (21.62 KB, 786x415 - viewed 1197 times.)
Hero Member
Online Online

Posts: 1796


Embed this message
Reply #1 on: May 13, 2020, 05:08:08 pm » posted from:SINGAPORE,SINGAPORE,SINGAPORE

Dear professor,
Is it possible the simulation has a bug?
My colleague was unable to find the period of the wave from the oscilloscope jar.
Hero Member
Online Online

Posts: 1796


Embed this message
Reply #2 on: May 14, 2020, 02:59:24 pm » posted from:SINGAPORE,SINGAPORE,SINGAPORE

the HTML5 version is available and bug fixed too!
Pages: [1]   Go Up
An interaction between two opposites produces a unique outcome. ..."Jules Henri Poincare(1854-1912, One of France's greatest mathematicians)"
Jump to:  

Related Topics
Subject Started by Replies Views Last post
Basic Function of an Oscilloscope « 1 2 »
Fu-Kwun Hwang 44 378726 Last post August 21, 2015, 02:40:05 pm
by aliciad234
torsional wave
Request for physics Simulations
Fu-Kwun Hwang 1 10500 Last post April 16, 2010, 11:03:07 am
by Fu-Kwun Hwang
Physics of rainbow (EJS version)
ahmedelshfie 5 12077 Last post February 16, 2020, 10:33:11 pm
by visasoulii9
Physics of rainbow (EJS version)
Questions related to EJS
ahmedelshfie 4 9407 Last post May 12, 2010, 11:30:28 pm
by ahmedelshfie
Ejs Open Source Cathode Ray Oscilloscope CRO Java Applet
Collaborative Community of EJS
lookang 4 25834 Last post June 05, 2018, 04:56:51 pm
by mayankroy
Powered by MySQL Powered by PHP Powered by SMF 1.1.13 | SMF © 2006-2011, Simple Machines LLC Valid XHTML 1.0! Valid CSS!
Page created in 0.054 seconds with 22 queries.since 2011/06/15