Cathode Ray Oscilloscope (Cro)
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Oscilloscopes (CROs)
Setting up | Connecting | Measuring | Timebase | Y amplifier | AC/GND/DC
Next Page: Power Supplies
Also See: AC, DC and Electrical Signals
| Circuit symbol for an oscilloscope | | Cathode Ray Oscilloscope (CRO)
Photograph © Rapid Electronics |
An oscilloscope is a test instrument which allows you to look at the 'shape ' of electrical signals by displaying a graph of voltage against time on its screen. It is like a voltmeter with the valuable extra function of showing how the voltage varies with time. A graticule with a 1cm grid enables you to take measurements of voltage and time from the screen.
The graph, usually called the trace, is drawn by a beam of electrons striking the phosphor coating of the screen making it emit light, usually green or blue. This is similar to the way a television picture is produced.
Oscilloscopes contain a vacuum tube with a cathode (negative electrode) at one end to emit electrons and an anode (positive electrode) to accelerate them so they move rapidly down the tube to the screen. This arrangement is called an electron gun. The tube also contains electrodes to deflect the electron beam up/down and left/right.
The electrons are called cathode rays because they are emitted by the cathode and this gives the oscilloscope its full name of cathode ray oscilloscope or CRO.
A dual trace oscilloscope can display two traces on the screen, allowing you to easily compare the input and output of an amplifier for example. It is well worth paying the modest extra cost to have this facility.
Precautions
* An oscilloscope should be handled gently to protect its fragile (and expensive) vacuum tube. * Oscilloscopes use high voltages to create the electron beam and these remain for some time after switching off - for your own safety do not attempt to examine the inside of an oscilloscope!
Oscilloscopes (CROs)
Setting up | Connecting | Measuring | Timebase | Y amplifier | AC/GND/DC
Next Page: Power Supplies
Also See: AC, DC and Electrical Signals
| Circuit symbol for an oscilloscope | | Cathode Ray Oscilloscope (CRO)
Photograph © Rapid Electronics |
An oscilloscope is a test instrument which allows you to look at the 'shape ' of electrical signals by displaying a graph of voltage against time on its screen. It is like a voltmeter with the valuable extra function of showing how the voltage varies with time. A graticule with a 1cm grid enables you to take measurements of voltage and time from the screen.
The graph, usually called the trace, is drawn by a beam of electrons striking the phosphor coating of the screen making it emit light, usually green or blue. This is similar to the way a television picture is produced.
Oscilloscopes contain a vacuum tube with a cathode (negative electrode) at one end to emit electrons and an anode (positive electrode) to accelerate them so they move rapidly down the tube to the screen. This arrangement is called an electron gun. The tube also contains electrodes to deflect the electron beam up/down and left/right.
The electrons are called cathode rays because they are emitted by the cathode and this gives the oscilloscope its full name of cathode ray oscilloscope or CRO.
A dual trace oscilloscope can display two traces on the screen, allowing you to easily compare the input and output of an amplifier for example. It is well worth paying the modest extra cost to have this facility.
Precautions
* An oscilloscope should be handled gently to protect its fragile (and expensive) vacuum tube. * Oscilloscopes use high voltages to create the electron beam and these remain for some time after switching off - for your own safety do not attempt to examine the inside of an oscilloscope!
Links: to other Electronics sites © John Hewes 2011, The Electronics Club, www.kpsec.freeuk.com