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DeVry ECT 246 Week 7 iLab Assignment

Question # 00051508
Subject: Engineering
Due on: 03/21/2015
Posted On: 03/01/2015 12:59 PM

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Lab 7 – Switching Transistors and Optical Devices


Student’s Name

ECT246 Electronic Systems III with Lab

Professor’s Name

DeVry University Online


Part A-Switching Devices

Week seven activities introduce the concept of electronic switching. Transistors can be used to turn on and off devices such as LEDs. The Silicon Controlled Rectifies (SCR) is another semiconductor that can be used as a switch. Controlling small dc motors is a common requirements and a special IC called an H-bridge is used.

TCO #8:

Given a DC switching application such as driving a motor in one and two directions use a SCR and a transistor and an H-bridge driver to successfully perform the operation, calculate and measure the operating voltages and currents.

A. Briefly describe how a transistor is used as an electronic switch including conditions of cutoff and saturation.

a. Write one to two paragraphs describing how a BJT is used as a switch.

b. Write one to two paragraphs describing how a JFET is used as a switch.

B. Given a transistor switch, calculate the saturation voltages and currents and simulate the circuit to verify proper operations.

a. Using the specification sheet, determine the maximum collector current for a 2N3904. .gif">= ________

b. Given the circuit, calculate .gif"> if.gif">.

.gif" alt="BJT_sw1">

.gif">= __________

c. Calculate .gif"> = __________

d. Determine the value of .gif"> required to drive the transistor into saturation if.gif">. .gif">= _________.

e. Download the file from Doc Sharing, week 7. If you have a different version of Multisim, use your version to create the circuit below. Verify the simulated results against the calculated values.

.gif">= _________

.gif">= _________

.gif"> = _________ (diode current)

Notice the series LED and a .gif"> resistor in parallel with.gif">. Determine why the LED is not on. Use the Multisim specifications for the LED (Left double click). Explain why the LED will not turn on. Correct the problem and verify the circuit’s operation.

f. Prototype the simulated circuit. Verify the operation of the LED. Measure the following values

.gif">= _________

.gif">= _________

.gif">= _________

Compare them to the calculated and simulated values.

C. Describe an SCR’s structure and operation.

a. Draw the pn structure of a SCR.

b. Draw the schematic symbol and label each terminal.

c. Briefly describe the SCR’s operation.

D. Given the data sheet of a typical SCR such as a 2N5060, determine the electrical characteristics and ratings and determine its on-off conditions.

a. Use the specification sheet to determine the Gate, Cathode and Anode terminals. Draw the diagram.

b. Record the following values:

.gif">= _________

.gif">= _________

.gif">= _________

.gif">= _________

.gif">= _________

.gif">= _________

E. Simulate a circuit using an SCR to control a motor or LED.

a. The Multisim circuit below uses a 2N5060 SCR to control an LED with.gif">,.gif"> and.gif">. Use the specification sheet for additional information and determine the value of .gif"> needed to trigger the SCR. Calculate the expected anode current.

.gif">= __________

.gif">= _________

b. Download the Multisim file from Doc Sharing, week 7. If you have a different version of Multisim, create the circuit below. Start the simulation. Closing SW1 should activate the SCR and the LED. The circuit does not work properly. Beginning with the SCR circuit, use the DMMs to troubleshoot the SCR and determine why it will not trigger. Explain why the circuit is not working and what changes are needed.


c. Make the changes. Use the DMMs to verify that the problem has been corrected.

d. Now troubleshoot the LED circuit. Use Multisim to determine the properties of the LED, double click on the diode.

.gif">= _________ LED Current

.gif">= __________

e. Use the DMMs to troubleshoot the LED circuit and determine why it will not illuminate. Explain why the circuit is not working and what changes are needed.

F. Calculate the gate and anode current, prototype and test the circuit and measure the operating values of a SCR used to control a motor or LED. Compare the results with the simulated values.

a. Prototype the working circuit used in the simulation.

b. Verify that the circuit will turn the LED on and off.

c. Measure the following values:

.gif">= __________

.gif">= __________

.gif">= __________ LED Current

.gif">= _________

How do these values compare to the calculated and simulated results.

G. Given a data sheet of an H driver integrated circuit such as a L293D determine the operating parameters and use drawing software such as Visio to create a schematic of a reversible motor control circuit.

a. Use the specification sheet for an H-Bridge IC driver such as the L293D or L293D and draw the package layout. Label the pins and their functions. For each pin, specify its function.

b. Record the maximum ratings for

.gif">= _________

.gif">= _________

.gif">= __________

c. Draw a schematic of a bi-directional dc motor circuit controlled by mechanical switches and explain how the circuit allows bi-directional operations.

H. Prototype a reversible motor control circuit then measure and record the operating parameters and troubleshoot any faults.

a. Given a dc motor determine the following.

Operating voltage .gif">= _________

Operating current .gif">= _________

Static dc winding resistance .gif">= _________

b. Prototype a motor control circuit using an H-bridge IC. The schematic below contains the LS7404 and the L293D motor driver. Will the L293D support the motor’s current requirements? Yes/No.

.gif" alt="L293D">

c. Confirm the motors bi-directional operations

I. Discuss the need for back EMF protection when switching motor circuits.

a. Draw the schematic of a transistor switch used to control a small dc motor. Include a protection circuit for reverse voltage spikes.

b. Explain the need for the protection circuit and how it works.

Part B-Optical Devices


Given an application that requires electrical isolation choose an appropriate optical isolation device to provide the necessary isolation for that particular application.

A. Explain the operation of a 4N25 optical coupler.

a. Draw the internal layout for an optical coupler such as a 4N25. Label the pin numbers and functions.

b. Describe briefly the operation of an optical coupler.

B. Use the specification sheet for typical optical couplers such as the 4N25 and determine suitable operating parameters.

a. Use the specification sheet to determine the following values

Diode forward voltage .gif">= __________

Diode forward current .gif">= __________ Max Value

Collector output current .gif">= __________

Isolation voltage .gif">= __________

Collector to emitter voltage .gif">= __________

C. Simulate a circuit that will provide the isolation between two different supply voltages, such as a 5V TTL control circuit and a 12V motor circuit.

a. Using the circuit below, calculate the value of .gif"> that allows the switch (Sw) to operate the motor. .gif">, .gif">, .gif">, .gif">, .gif">, .gif">. Use I(LED) of 2mA

.gif" alt="optockt">

.gif">= __________

b. Download the Multisim files from Doc Sharing, week 7. Simulate the circuit. If you have a different version of Multisim, use your version to create the circuit.


c. Record the following values from the simulation.

.gif">= __________

.gif">= __________

.gif">= __________ LED Current

D. Prototype a circuit that will provide the isolation between two different supply voltages, such as a 5V TTL control circuit and a 6V motor circuit and compare the simulated values with the measured ones.

a. Prototype the circuit above.

b. Record the following values.

.gif">= __________

.gif">= __________

.gif">= __________ LED Current

c. Compare the measured values to the simulated and calculated results.

Part C-Internet Device Searches

1. Use the Internet to locate information on the SN754410 Quadruple Half-H Driver. Download the specification sheet. Specify its package layout. Write a brief description of the device. Is it compatible with the L293D? Why or why not.

2. Use the Internet to locate information on the 4N33 optically coupled isolator. Download the data sheet. Give a brief description of the device. What is its package configuration? How does it differ from a 4N25? Can it directly substitute for a 4N25? Why or why not.

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DeVry ECT 246 Week 7 iLab Assignment

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DeVry_ECT_246_Week_7_iLab_Assignment._._._._.docx (722.6 KB)
Preview: value xx needed xx trigger the xxx Calculate the xxxxxxxx anode xxxxxxx x ____11k xxxxxxxxxxx _____36 641µA____Download xxx Multisim file xxxxxxxxxxxxxxxxxx ms xxxx xxx Sharing, xxxx 7 If xxx have a xxxxxxxxx version xx xxxxxxxxx create xxx circuit below xxxxx the simulation xxxxxxx SW1 xxxxxx xxxxxxxx the xxx and the xxx The circuit xxxx not xxxx xxxxxxxx Beginning xxxx the SCR xxxxxxxx use the xxxx to xxxxxxxxxxxx xxx SCR xxx determine why xx will not xxxxxxx Explain xxx xxx circuit xx not working xxx what changes xxx needed xxxxxxx xx not xxxxxxx because of xxx resistance connected xx the xxx xx high xx works only xxxx the resistance xx decreased xx xxx ohms xxx to higher xxxxxxx drop than xxx permitted xxxxx xxx will xxx trigger Make xxx changes Use xxx DMMs xx xxxxxx that xxx problem has xxxx corrected Now xxxxxxxxxxxx the xxx xxxxxxx Use xxxxxxxx to determine xxx properties of xxx LED, xxxxxx xxxxx on xxx diode = xxxxxxxxxxxxx LED Current= xxxxxxxxxxxxxxx the xxxx xx troubleshoot xxx LED circuit xxx determine why xx will xxx xxxxxxxxxx Explain xxx the circuit xx not working xxx what xxxxxxx xxx needed xx is not xxxxxxxxxxx because of xxx resistance xxxxxxxxx xx to xxx LED is xxxx hence Voltage xxxx is xxxxxx xxxx the xxxxxxxxx value so xx will not xxxxxxx the xxx xx glow xxxxxxxxx the gate xxx anode current, xxxxxxxxx and xxxx xxx circuit xxx measure the xxxxxxxxx values of x SCR xxxx xx control x motor or xxx Compare the xxxxxxx with xxx xxxxxxxxx values xxxxxxxxx the working xxxxxxx used in xxx simulation xxxxxx xxxx the xxxxxxx will turn xxx LED on xxx off xxxxxxx xxx following xxxxxxxx ______999 997mV____= xxxxxxxxxxxxxxx ____10mA______ LED xxxxxxxx ____3V_____How xx xxxxx values xxxxxxx to the xxxxxxxxxx and simulated xxxxxxx Given x xxxx sheet xx an H xxxxxx integrated circuit xxxx as x xxxxx determine xxx operating parameters xxx use drawing xxxxxxxx such xx xxxxx to xxxxxx a schematic xx a reversible xxxxx control xxxxxxx xxx the xxxxxxxxxxxxx sheet for xx H-Bridge IC xxxxxx such xx xxx L293D xx L293D and xxxx the package xxxxxx Label xxx xxxx and xxxxx functions For xxxx pin, specify xxx function xxxxxx xxx maximum xxxxxxx for = xxxxxxxxxxxxx ____3V_____= _____2A_____Draw x schematic.....
DeVry_ECT_246_Week_7_iLab_Assignment.docx (722.6 KB)
Preview: motor xxxxxxxx Draw xxx schematic of x transistor switch xxxx to xxxxxxx x small xx motor Include x protection circuit xxx reverse xxxxxxx xxxxxx Explain xxx need for xxx protection circuit xxx how xx xxxxx The xxxxxxx should be xxxxxxxxx from reverse xxxxxx to xxxxxxx xxxxxxxxx voltage xxxxxx to the x c motor xxxx B-Optical xxxxxxxxxxxxxxxxxx xx application xxxx requires electrical xxxxxxxxx choose an xxxxxxxxxxx optical xxxxxxxxx xxxxxx to xxxxxxx the necessary xxxxxxxxx for that xxxxxxxxxx application xxxxxxx xxx operation xx a 4N25 xxxxxxx coupler Draw xxx internal xxxxxx xxx an xxxxxxx coupler such xx a 4N25 xxxxx the xxx xxxxxxx and xxxxxxxxx Describe briefly xxx operation of xx optical xxxxxxx xx optical xxxxxxx helps in xxxxxxxxx and combining xxx data xxxxxxxx xxxx optical xxxxx cables Use xxx specification sheet xxx typical xxxxxxx xxxxxxxx such xx the 4N25 xxx determine suitable xxxxxxxxx parameters xxx xxx specification xxxxx to determine xxx following valuesDiode xxxxxxx voltage= xxxx xxxxxxxxxxxxxxx forward xxxxxxxx ___100mA_______ Max xxxxxxxxxxxxxx output current= xxxxxxxxxxxxxxxxxxxxxxx voltage= xxxxxxx xxxxx (rms)_______Collector xx emitter voltage= xxxxxxx Volts_____Simulate a xxxxxxx that xxxx xxxxxxx the xxxxxxxxx between two xxxxxxxxx supply voltages, xxxx as x xx TTL xxxxxxx circuit and x 12V motor xxxxxxx Using xxx xxxxxxx below, xxxxxxxxx the value xx that allows xxx switch xxxx xx operate xxx motor , x , , x Use xxxxxx xx 2mA= xxxx Ohms_________Download the xxxxxxxx files Opto1 xx from xxx xxxxxxxx week x Simulate the xxxxxxx If you xxxx a xxxxxxxxx xxxxxxx of xxxxxxxxx use your xxxxxxx to create xxx circuit xxxxxx xxx following xxxxxx from the xxxxxxxxxx = ____57 xxxxxxxxxxx ____177 xxxxxxxxxxxx xxxx 161mA_______ xxx CurrentPrototype a xxxxxxx that will xxxxxxx the xxxxxxxxx xxxxxxx two xxxxxxxxx supply voltages, xxxx as a xx TTL xxxxxxx xxxxxxx and x 6V motor xxxxxxx and compare xxx simulated xxxxxx xxxx the xxxxxxxx ones Prototype xxx circuit above xxxxxx the xxxxxxxxx xxxxxx = xxxxx 303mA______= __302 xxxxxxxxxxxxxx ___1 085mA_______ xxx CurrentCompare xxx xxxxxxxx values xx the simulated xxx calculated results xxxxxxxxx values xxx xxxxxxxxxx values xxx in agreement xxxx each other xxxx C-Internet xxxxxx xxxxxxxxxxx the xxxxxxxx to locate xxxxxxxxxxx on the xxxxxxxx Quadruple xxxxxx xxxxxx Download xxx specification sheet xxxxxxx its package xxxxxx Write x xxxxx description xx the device xx it compatible xxxx the xxxxxx xxx or xxx not Package xxxxxxx The.....
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