Tips for Buying Analog Oscilloscopes


Although almost all new scopes are digital, the analog oscilloscope, also called cathode beam oscilloscope, can still be found and perform well in many laboratories and other areas. Let's examine analog oscilloscopes in detail.

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What Is An Analog Oscilloscope

Although digital technology covers the entire industry, many analog oscilloscopes are still in daily use and provide excellent performance. Analog scopes are often referred to as cathode ray oscilloscopes. These analog or cathode ray oscilloscopes may not have the full functionality of digitals, but still provide the capabilities required for most laboratory and general testing applications. Generally, analog scopes can be put aside in the stock of laboratory test equipment. However, these testers can still be used to good effect in many cases, some prefer to use them in more advanced digital scopes. In some cases, analog scopes can still be purchased, although the number and selection of these testers is rapidly declining. If you were searching for analog oscilloscope for sale, we got you.


The key to the operation of an analog oscilloscope is its display. A cathode ray tube is used. This display format was the only valid display format that could be used to display images for many years. Accordingly, it has been used in televisions for many years, although nowadays other forms of display are used, including LCDs, LEDs, and many other formats, all of which require digital signal inputs to the display. The shape of the cathode ray tube used in oscilloscopes used electrostatics rather than magnetic deflection of the electron current. This enables much faster control of the electron flow, allowing analog oscilloscopes to achieve very high frequency operation. The magnetic beam deflection scheme used in televisions did not provide enough high-frequency operation. Looking in more detail at the operation of the analog scope, it uses the cathode ray tube to display signals on both the X (horizontal) and Y (vertical) axes. Typically the Y axis is the instantaneous value of the incoming voltage and the X axis is the ramp waveform. As the ramp waveform increases in voltage, the trace moves in a horizontal direction across the screen. When it reaches the end of the screen, the waveform returns to zero and the trace returns to the beginning. Using this approach, it can be seen that the X axis corresponds to time and the Y axis to the amplitude. In this way, known graphs of waveforms can be displayed on the cathode ray tube. The analog oscilloscope has a large number of circuit blocks and can provide stable images of the incoming waveforms. Analog scope has been around for many years and its circuits are well tried and tested. Looking in more detail inside the analog oscilloscope, there are several different circuit blocks that allow the process to take place.


  • AC / DC Selection: In most cases the signals will be superimposed on a DC bias voltage. Generally only AC elements will be interesting when looking at the signal. In these cases it is possible to place a capacitor in series with the input to make sure the DC is blocked. This allows the signal amplifier to see more detail without being overloaded by the DC content. When using a capacitor, choosing the AC option will mean that low frequency signals may be limited. Check scope specification for low end performance.
  • Y Attenuator: To ensure that the signals are presented to the Y amplifier at the desired level, the signals pass to the Y attenuator.
  • Y Amplifier: The basic Y amplifier provides amplification to the drivers to foam the cathode ray tube. It is especially important that this amplifier be linear, as it will determine the accuracy of the oscilloscope.
  • Y Deviation Circuit: Once boosted, the signal is transmitted to the Y deflection circuit. This uses the amplified signal and delivers it to the plates of the cathode ray tube at the required levels.
  • Trigger Circuit: The trigger system consists of a series of blocks on the circuit diagram of the analog scope. To ensure that a fixed waveform is displayed on the screen, it is necessary to adjust the ramp waveform to start at the same point in each cycle of the incoming signal to be monitored. This way, the same point on the waveform will be displayed in the same location on the screen.

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