CRO Block Diagram | Cathode Ray Oscilloscope

Hey, let's see and understand the CRO Block Diagram. You can easily understand the working principle of CRO from the Block Diagram of CRO. CRO stands for Cathode Ray Oscilloscope. As the electrons are emitted from the cathode which is also called an electron gun that is why it is called Cathode Ray Oscilloscope. CRO is the most useful electronic instrument.

Block Diagram of CRO

Here the typical block diagram of CRO is given below. Remember that it shows the analog Cathode Ray Oscilloscope. Nowadays, digital CRO is also available in the market.

Actually, the CRT or Cathode Ray Tube with some additional circuits is called CRO which you can see in the above figure. 

First of all, let's discuss what is inside the CRT.

1. Inside the CRT, you can see it has an electron gun which is used to produce the electron beam.

2. The electron beam goes through the Horizontal Deflection plates and vertical deflection plates and falls upon the phosphor-coated screen.

3. When the electron beam falls upon the screen a bright visible spot is created.

4. The additional circuits in CRO are used to control the position and strength of the electron beam using the vertical and horizontal plates.

Now, let's discuss each block of the circuits inside the CRO.

Power Supply: First, you can see there are two power supply is taken, one is a High Voltage(HV) supply and another is the Low Voltage(LV) supply. Here the low voltage is given to the heater of the electron gun to generate electrons. 

The high voltage is given to the accelerating anode plate to increase the speed and strength of the electron beam. The low voltage supply also is given to the other control circuits of the CRO such as amplifier circuits, trigger circuits, etc.

Amplifier Circuits: The amplifier circuits, horizontal amplifier, and vertical amplifier are used to create a high voltage DC supply which is required for the proper deflection. The horizontal deflection plates are connected to the horizontal amplifier and the vertical deflection plates are connected to the vertical amplifier.

Delay Circuit: The Delay circuit is used to create delays when the waveform is displayed on the screen. Basically, it introduces a specific time delay between two signals or events. It allows us to observe and analyze signals that occur at different times but need to be displayed simultaneously on the CRO screen. The delay circuit in a CRO typically consists of a delay line and a time base generator. The delay line is responsible for introducing the desired delay, while the time base generator controls the sweep speed of the CRO.

Time Base Generator: The Time Base Generator or Sweep generator circuit is used to control the speed of the electron beam when it just tends to fall upon the screen. 

If a high-speed electron beam falls upon the screen it will be not visible that is why the generator circuit is used to control the speed of the electron beam.

Trigger Circuit: The Trigger circuit is used to switching of the power supply and to synchronize the horizontal and vertical deflections.

 Read Also:

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• Actual Difference Between Oscillator and Amplifier
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