Block Diagram of CRO or CRO Block Diagram – Explanation | New Topic [2024]

In this note, we are going to know about the Block Diagram of CRO or CRO Block Diagram. Welcome to Poly Notes Hub, a leading destination for engineering notes for diploma and degree engineering students.

Author Name: Arun Paul.

Block Diagram of CRO

Below we have discuss about the Block Diagram of CRO or CRO Block Diagram. In this section we will get an idea about the all fundamental sections of the block diagram of CRO.

The major block circuit shown in the above figure of a general purpose CRO, is as follows:

1. CRT
2. Vertical amplifier
3. Delay line
4. Time base
5. Horizontal amplifier
6. Trigger circuit
7. Power supply

The function of the various blocks are as follows –

1. CRT: This is the cathode ray tube which emits electrons that strikes the phosphor screen internally to provide a visual display of signal.
2. Vertical Amplifier: This is a wide band amplifier used to amplify signals in the vertical section.
3. Delay Line: It is used to delay the signal for some time in the vertical sections.
4. Time Base: It is used to generate the sawtooth voltage required to deflect the beam in the horizontal section.
5. Horizontal Amplifier: This is used to amplify the sawtooth voltage before it is applied to horizontal deflection plates.
6. Trigger Circuit: This is used to convert the incoming signal into trigger pulses so that the input signal and the sweep frequency can be synchronized.
7. Power Supply: There are two power supplies, a -ve High Voltage (HV) supply and a +ve Low Voltage (LV) supply. Two voltages are generated in the CRO. The +ve volt supply is from +300 to 400 V. The -ve high voltage supply is from -1000 to -1500 V. This voltage is passed through a bleeder resistor at a few mA. The intermediate voltages are obtained from the bleeder resistor for intensity, focus, and positioning controls.

Advantages of using -ve HV Supply

1. The accelerating anodes and the deflection plates are close to ground potential. The ground potential protects the operator from HV shocks when making connections to the plates.
2. The deflection voltages are measured with respect to ground; therefore, HV blocking or coupling capacitors are not needed, but low voltage rating capacitors can be used for connecting the HV supply to the vertical and horizontal amplifiers.
3. Less insulation is needed between positioning controls and chassis.