The major block circuit is shown in the fig below for a general purpose CRO, is as follows:

• CRT
• Vertical Amplifier
• Delay line
• Time Base
• Horizontal amplifier
• Trigger Circuit
• Power Supply

The function of various blocks is as follows

CRT:

This is cathode ray tube which emits electrons that strikes the phosphor screen internally to provide a visual display of signal.

Vertical Amplifier:

This is wide band amplifier used to amplify signals in the vertical section.

Delay Line:

It is used to delay the signal for some time in the vertical sections.

Time Base:

It is required to generate the sawtooth voltage required to deflect the beam in the horizontal section.

Horizontal Amplifier:

This is used to amplify the sawtooth voltage before it is applied to horizontal deflection plates.

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.

Power Supply:

There are two power supplies a negative high voltage and a positive low voltage. The two voltages are generated in the CRO.The positive low volt supply is from +300 to 400V.The negative high voltage supply is from -1000 to -1500 volts. This voltage passed through a bleeder resistor at a few mA. The intermediate voltages are obtained from the bleeder resistor for intensity focus and position control.