Electrical workshop module4

Institute Of Applied TechnologyATE 1012Grade 10

Eng. Rose Hasan

Be familiar with the usage of Multi-meters, Oscilloscopes and Function Generators

Perform Measurements of electrical quantities using measuring instruments

Test diodes and connectivity

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Introduction Multimeter Voltage Measurement

Current Measurement

Resistance Measurement Diode Testing Continuity Test Function Generator Oscilloscope Practical Tasks

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Measuring and Test Equipment are used to:

measure electrical quantities

test electrical components

generate different types of signals to test the response of the circuit to that signal.

Measuring and test equipment can be used to:

troubleshoot electrical problems in many industrial and household devices such as batteries, lamps, motor controls and wiring systems

Eng. Rose Hasan

Eng. Rose Hasan

Purpose: A multi-meter is an electronic measuring instrument that combines several functions in one unit. It is used to:

measure voltage, current and resistance and to test diodes and connectivity

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Eng. Rose Hasan

Types: There are two types of multimeters:

analog & digital

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Eng. Rose Hasan

Voltage Measurement (Voltmeter): To measure the DC voltage across electrical components in a circuit, follow these steps:

Select on the digital multi-meter's setting switch on the largest voltage range.

Connect the positive (RED) (+) lead to the part of the circuit that is connected to the positive (+) side of the supply (battery).

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Connect the negative (BLACK) (-) lead to the part of the circuit that is connected to the negative (-) side of the supply (battery).

Switch on the multi-meter by pressing "POWER" button. Then select the best range that will give you the most accurate results.

Record the reading and the unit that are displayed in the multimeter's display.

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http://serc.carleton.edu/sp/compadre/interactive/examples/19095.html

Items Required:

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Measure the voltage across the batteries using a multi-meter:

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Record your readings on the following table. The true value is the value written on the battery

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3. Compare the measured value with the true value of the voltage written in the battery. Is the measured value close to the real value? If no, state why?

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4. You can test a battery using Multi-meter by:

(a) Voltage measurement

(b) Connectivity test

(c) Diode Test

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Current Measurements : To measure the DC current flowing in electrical circuit, follow these steps:

Plug the BLACK (-) probe into the COM input jack and the RED (+) probe into the mA or A input jack.

Adjust the digital multi-meter for current measurements .

Switch off the power in the circuit.

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Break the circuit between elements where the current to be measured.

Insert the probes of the multi-meter in the place where do you break the circuit.

Switch on the multi-meter.

Select the best range that will give you the most accurate results.

Record the reading and the unit that are displayed in the multi-meter's display

Eng. Rose Hasan

Eng. Rose Hasan

Resistance Measurements (Ohmmeter): To measure the resistance of a resistor, follow these steps:

Turn Off the power to the circuit and remove the components to be tested.

Select on the digital multi-meter's setting switch on the lowest resistance range.

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Plug the BLACK (-) probe into the COM input jack and the RED (+) probe into the Ώ input jack.

Connect the probe tips across the component you want to measure its resistance

Switch on the multi-meter and select the best range that will give you the most accurate results.

Record the reading and the unit that are displayed in the multimeter's display.

Eng. Rose Hasan

Eng. Rose Hasan

Items Required:

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Measure the resistance across different resistors using a multimeter and color code

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2. Record your readings on the following table

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3. Compare the value of resistance measured by the multi-meter and color code. Are the values close to each other?

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Items Required:

Resistors (200Ώ), multi-meters

Electricity & Electronics Constructor, EEC470

Basic Electricity and Electronics Kit EEC471-2

Power supply unit

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Construct the simple circuit shown below. Use 200 Ώ resistor values.

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Connect the multi-meter to the power supply. Make sure that the variable dc control knob is

fully counter clockwise, and then switch on the power supply.

Increase the applied voltage in 2 V steps from 0 V up to 5 V.

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At each step measure the current flowing in the resistor. Record your reading in the following table:

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To measure the resistance of a resistor, follow these steps: Turn Off the power to the circuit and remove the

components to be tested.

Select on the digital multi-meter's setting switch on the lowest resistance range.

Plug the BLACK (-) probe into the COM input jack and the RED (+) probe into the Ώ input jack.

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Connect the probe tips across the component you want to measure its resistance

Switch on the multi-meter and select the best range that will give you the most accurate results.

Record the reading and the unit that are displayed in the multimeter's display.

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To test if the diode is functioning or not, follow these steps:

Adjust the digital Multi-meter for diode-testing .

Connect the positive lead (Red) (+) to the anode (A(+)) and connect the negative lead (BLACK) (-) to the cathode (K(-))

Switch on the multi-meter. For a diode in a good condition the reading will be ≤ 300 mV for Gediode and ≤ 700 mV for Si diode.

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Eng. Rose Hasan

Now connect the (RED) (+) lead to the (K(-)) and (BLACK) (-) lead to the (A(+))

For a diode in a good condition the reading will be for both types.

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To test if two points are electrically connected, follow these steps:

Turn Off the power to the circuit

Adjust the digital Multi-meter for continuity-testing and Switch on the multi-meter.

When the probes aren't touching, the display shows "1“.

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Eng. Rose Hasan

When you touch the tips of the probes together, the display changes to a three digit mode. The multi-meter will also emit a beep.

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Purpose: Function generator is used to produce different waveform such as:

Sine

Square

Triangular

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It is used to test and examine the response of an electrical circuit to that signal.

(i.e. the motor response to a square or triangular signal).

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Main Control Keys: The function generator has many control keys to control the:

waveform shape

amplitude

frequency

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The following table shows function generator main keys and their usage.

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Purpose: Oscilloscope is a device that is used to display different waveforms simultaneously

(i.e the input and output of an amplifier).

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Main Control Keys: Oscilloscope has many control keys to scale the:

amplitude periods of the displayed waveform.

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The following table shows some oscilloscope main keys and their usage.

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Items Required:

Function Generator

Oscilloscope

speaker

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Oscilloscope

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Oscilloscope Lab Worksheet

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1. Connect the function generator and oscilloscope as shown below.

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2. Set the function generator to give 5v pk and 1 kHz.3. Select channel A on the oscilloscope. Set the volt/division

scale to 5v and time/division to 250 us (μs).4. Amplitude Measurement: measure the pk-pk voltage

of the waveform as seen in the following:

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Volt/division scale = ----------------------------- No. of divisions = ----------------------------- Pk-Pk voltage = -----------------------------5. Period Measurements: measure the period

of the waveforms seen in figure

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Time/division scale = ----------------------------- No. of divisions = ----------------------------- T (Period) = -----------------------------

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Be prepared for a Quiz next Class in module #4.

Do Homeworks 1 & 2 (From my Wiki). Next Class: Start with Module #5

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