cro mulitimeter

CRO

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Introduction A graph-displaying device of electrical signal

X axis: Time Y axis: Voltage Z axis: Intensity or brightness

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Basic setting Vertical system

attenuation or amplification of signal (volts/div) Horizontal system

The Time base (sec/div) Trigger system

To stabilize a repeating signal and to trigger on a single event

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Introduction Information given by oscilloscopes

Time and voltage Frequency and phase DC and AC components Spectral analysis Rise and fall time Mathematical analysis

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Architecture of Oscilloscope

Cathode-Ray Tube (CRT)

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Cathode-Ray Tube (CRT)

• Found in oscilloscopes, and similar devices are used in TV picture tubes and computer displays

• Use an electron beam

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Cathode-Ray Tube (CRT)

Main parts of CRT

Control Grid Focusing anode

Electron gun

Deflecting plates

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Cathode-Ray Tube (CRT)

Control Gridregulates the number of electrons that reach the anode and hence

control the brightness of the spot on the screen.

Focusing anode

ensures that electrons leaving the cathode in slightly different directions are focused down to a narrow beam and all arrive at the same spot on the screen.

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Electron gun consist of cathode, control grid, focusing anode, and accelerating anode

Deflecting plates

An electric field between the first pair of plates deflects the electrons horizontally, and an electric field between the second pair deflects them vertically. If no deflecting fields are present, the electrons travel in a straight line from the hole in the accelerating anode to the center of the screen, where they produce a bright spot.

Cathode-Ray Tube (CRT)

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Introduction to the Function Generator

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Example of Function Generator

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What is a function generator? A function generator is a device that can produce

various patterns of voltage at a variety of frequencies and amplitudes.

It is used to test the response of circuits to common input signals. The electrical leads from the device are attached to the ground and signal input terminals of the device under test.

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Features and controls The amplitude control on a function generator

varies the voltage difference between the high and low voltage of the output signal.

The direct current (DC) offset control on a function generator varies the average voltage of a signal relative to the ground.

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Features and controls The frequency control of a function generator

controls the rate at which output signal oscillates. On some function generators, the frequency control is a combination of different controls.

One set of controls chooses the broad frequency range (order of magnitude) and the other selects the precise frequency. This allows the function generator to handle the enormous variation in frequency scale needed for signals.

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How to use a function generator? After powering on the function generator, the output signal

needs to be configured to the desired shape. Typically, this means connecting the signal and ground leads to an oscilloscope to check the controls.

Adjust the function generator until the output signal is correct, then attach the signal and ground leads from the function generator to the input and ground of the device under test.

For some applications, the negative lead of the function generator should attach to a negative input of the device, but usually attaching to ground is sufficient.

MULTIMETER

INTRODUCTION

• Also known as multi tester/ volt-ohm meter• An electronics device instrument that

combines several measurement functions in one unit.

• Used to measure voltage / current/ resistance

Why we use multimeter

• Accuracy • Resolution

Types of multimeter

DigitalAnalog