Question

PAD - 234 ANALOG / DIGITAL TRAINER
OPERATOR’S MANUAL
Rev. 7/94
1
GENERAL OPERATING PROCEDURES
1. This manual should be read thoroughly before engaging in any experimentation. 2. As a general rule, NEVER construct a circuit or insert any wiring with the PAD unit ON. 3. Construct the circuit. Double check your wiring. Then apply power to the circuit. 4. Should a problem occur. Turn the unit off immediately. Unplug the PAD and notify your instructor. 5. In the event this unit needs repairs, notify your instructor.
DO NOT ATTEMPT TO REPAIR THIS UNIT YOURSELF​!!

MAINTENANCE OF THE PAD 234 ANALOG DIGITAL TRAINER
* * * CAUTION * * *
FUSE REPLACEMENT 1. Before replacing the fuse be sure that the power switch is in the off position and unplug the pad !! 2. Use only MDL 0.5 amp fuses. 3. Unscrew the black cap on the right side panel of the PAD unit and remove bad fuse. Replace with the correct fuse in the same manner.
******* WARNING *******
Do not use all sources simultaneously !! keep liquids away from the PAD unit !! Do not use near flammable materials !!!

PAD 234 ANALOG DIGITAL TRAINER
POWER SUPPLY – (+) and (–) 12 volt regulated power supply, with 500 ma short circuit protection. – (+) 5 volt regulated power supply, with 1 amp short circuit protection. – (+) and (–) 15 volt variable supply (from 1.5 V to 15V) with 1.5 amp short circuit protection. – (+)12.6 Volt AC center tap power supply.
FUNCTION GENERATOR – Sine, square, and triangle output wave shape. 1 Hz to 100 Khz in 5 ranges, uncalibrated, buffered, adjustable output 0 to 15 volts peak to peak.
CLOCK OUTPUT (TTL) – Frequency determined by COARSE FREQUENCY FINE FREQUENCY adjustment knob. Rise and fall time is 400 ns.
INDICATORS – 8 BUFFERED TTL compatible LED'S.
SWITCHES – 8 binary toggle switches (0 or 5 Volts) 2 momentary pulse switches, debounced with complimentary outputs
BREADBOARDS – 2 breadboards with 840 plug-in tie points each.
POWER CONSUMPTION – 117 Volts at .5 Amps
ADDITIONAL FEATURES – High impact plastic case with a 3-wire grounded line cord. Fuse protected AC line.

OPERATION
DC POWER SUPPLY – +5, +12, –12, located in the vertical row of binding posts, positioned along the left side of the breadboards.
Use of 5V Supply – Connect the load between the binding post and the GND (ground).
Use of + 12V – Connector the load between the Binding Post marked + 12V and the Binding Post marked GND (ground).
Use of –12V – Connect the load between the Binding Post marked – 12V and the Binding Post marked GND (ground) .
VARIABLE DC SUPPLY – Located above left to the main breadboards and identified as + 15V, controlled by the appropriate knobs. (Lower left hand corner of the top plate.)
Using the + 15V – Connect the load between the tie blocks identified as + 15 V and OV (ground). Use the knob marked + 15V to control the output voltage of this tie block.
Using the –15V – Connect the load between the tie block identified as – 15V and OV (ground). Use the knob marked – 15V to control the output voltage of this tie block.
AC POWER SUPPLY – Located above right to the main breadboards and identified as AC Volts.
Using the 6.3 VAC – Connect the load between the tie block identified as 6.3 and 0 (ground).
Using the 12.6 VAC – Connect the load between the tie blocks marked 6.3 and 6.3.
FUNCTION GENERATOR – The output for the GENERATOR and CLOCK are Iocated in the top two Binding posts in the vertical row, on the left hand side of the breadboards marked GEN and CLOCK. – The generator and clock outputs are controlled by the five knobs located on the far left hand side of the PAD unit and marked accordingly

GENERATOR (CONTINUED) Before using the Generator or Clock output in an actual circuit, familiarize yourself with the functions of the five control knobs and the effects they have on the output waveforms. Connect an oscilloscope to the GEN Binding post and GND Binding post as described above. Adjust the O-scope as necessary to observe a clearly visible waveform. By using the five control knobs observe how you are able to adjust the output waveforms, by using these controls. (See the section below labeled "Using the Generator".
Using the CLOCK – Connect the load between the Binding posts . marked CLOCK and GND (ground). – Select the appropriate frequency using the knob marked COARSE FREQUENCY. – Adjust to the exact frequency using the knob marked FINE FREQUENCY.
Using the GENERATOR – Connect the load between the Binding Posts marked GEN (Function Generator) and GND (ground) .
1. Select the type of waveform required by using the top left knob. 2. Set the COARSE FREQUENCY knob to the correct range. 3. Fine tune the frequency (using the knob marked FINE FREQUENCY) to the exact frequency required. 4. Adjust the amplitude (using the AMPLITUDES) knob to adjust the output voltage maintaining a clear waveform. 5. Adjust the offset as needed with the bottom control knob marked OFFSET.

DIGITAL SECTION – Located across the top of the PAD – This section includes eight manual toggle switches, eight LED tie blocks and two pulse switches.
Using the Toggles – Connect the device between the tie block to be used (numbered 0 to 7) and GND (ground) . – When the toggle switch is in the up position, +5 volts is supplied to the device. When the switch is in the down position 0 volts is applied.
Using the LED Tie – Connect the device to the tie block directly under the LED to be used. When + 5V is applied the LED will light, when 0 is applied it will be off.
Using the Momentary – For + 5V pulse connect the device to the tie block marked O. When the switch is pulsed the output at the tie block will be +5V. For O V pulse, connect the device to the tie block marked 1. +5 V will be applied to the point block till the switch is pulsed, then the output will be O V.
To become more familiar with the toggle switches and LED tie points, take a piece of wire and connect between one of the Toggle tie point blocks and one of the LED tie point blocks. Flip the switch and observe that voltage is being applied, lighting the LED. Repeat this procedure using the momentary pulse switches.

PAD 234 EXTENDER DESCRIPTION

A 16-pin Insulation Displacement Connector (IDC), labeled EXTENDER on the top plate of the PAD 234, allows ribbon-cable connection to personal computers and other electronic equipment. The user can supply power, analog, and digital signals to add-on boards via a ribbon cable. The EXTENDER has eight uncommitted bidirectional lines which can be easily connected via tieblocks to the LEDs and switches of the PAD 234. Also, add-ons or external equipment can be interfaced to circuits already breadboarded on the trainer. In addition, the function generator built into the PAD 234 can be either AM or FM modulated by applying signals to either pins 15 and 16 of the IDC or tie-blocks X and Y. Since pin 15 (FM) is capacitively coupled to the function generator, it may be used as an additional DC-level signal in certain applications.

CET/EET235 DIGITAL ELECTRONICS DESIGN Logic Gate Summary

NOTE: An Inversion Circle “ ” on a gate indicates that the Logic Signal is INVERTED when it passes through the inversion circle. (Hardware inside the gate at that point inverts the signal.)


LOGIC GATE

LOGIC SYMBOL

BOOLEAN EQUATION

TRUTH TABLE

   A B F (OUT)

Buffer



f = A

0 1

0 1

Inverter (NOT)



f = A _


0 1

1 0


AND




f = A • B

0 0 1 1

0 1 0 1

0 0 0 1



NAND



f = A • B _____


0 0 1 1

0 1 0 1

1 1 1 0



OR




f = A + B

0 0 1 1

0 1 0 1

0 1 1 1



NOR



f = A + B _____


0 0 1 1

0 1 0 1

1 0 0 0



Exclusive OR (XOR)




f = A ⊕ B

0 0 1 1

0 1 0 1

0 1 1 0



Exclusive NOR (XNOR)



f = A ⊕ B _____


0 0 1 1

0 1 0 1

1 0 0 1

CET/EET235 DIGITAL ELECTRONICS DESIGN Boolean Algebra Summary


Boolean Algebra: is a logical algebra based on the binary system developed in the 1850s by George Boole, a mathemetician.

3 basic functions: AND (•), OR (+), NOT (_); variables; equations; hierarchy of operators

LAWS of Boolean Algebra:

1. Commutative - “order doesn't matter” AND: A • B = B • A OR: A + B = B + A

2. Associative - “grouping doesn't matter” (only applies to ≥2 variables and/or constants) AND: ( A • B ) • C = A • ( B • C ) OR: ( A + B ) + C = A + ( B + C )

3. Redundancy (Tautology) - simple reduction A _ _ = A A • 0 = 0 A + 0 = A   A • 1 = A A + 1 = 1   A • A = A A + A = A   A • A _ = 0 A + A _ = 1

4. Distributive / Factoring A • B + A • C = A • ( B + C ) A + ( B • C ) = ( A + B ) • ( A + C )

5. Absorbtion a. A • ( A + B ) = A • A + A • B = A + A • B = A • 1 + A • B = A • ( 1 + B ) = A • 1 = A b. A + ( A • B ) = ( A + A ) • ( A + B ) = A • ( A + B ) = … = A c. A + A _ • B = ( A +A _ ) • ( A + B ) = 1 • ( A + B ) = A + B d. A _ + A • B = ( A _ + A ) • ( A _ + B ) = 1 • ( A _ + B ) = A _ + B


DeMorgan's Theorems:

A • B _____ = A _ + B _ ⇒ “the complement of a product = the sum of the complements”



A + B _____ = A _ • B _ ⇒ “the complement of a sum = the product of the complements”

CET/EET235 DIGITAL ELECTRONICS DESIGN Units Reference


Factor Number Prefix Symbol Example 1018 quintillion Exa E Eb - exabyte 1015 quadrillion Peta P Pb - petabyte 1012 trillion Tera T Tb - terabyte 109 billion Giga G Gb - gigabyte 106 million Mega M Mhz - megahertz 103 thousand Kilo k kΩ - kilo ohm 100 -   10 -3 thousandth Milli m mH - millihenry 10 -6 millionth Micro µ µF - microfarad 10 -9 billionth Nano n ns - nanosecond 10 -12 trillionth Pico p pF - picofarad 10 -15 quadrillionth Femto f fs - femtosecond 10 -18 quintillionth Atto a ab - attoboy!?!

Table 1: Engineering powers of 10



Color Digit Value Multiplier Value
Toleranc e Value Black 0 10 0 - Brown 1 10 1 - Red 2 10 2 - Orange 3 10 3 - Yellow 4 10 4 - Green 5 10 5 - Blue 6 10 6 - Violet 7 10 7 - Gray 8 10 8 - White 9 10 9 - Gold - 10 -1 ±5% Silver - 10 -2 ±10% (none) - - ±20%



Table 2: Resistor Color Code

CET/EET235 DIGITAL ELECTRONICS DESIGN Parts Kit Inventory List


Qty. Description                                              Labs Used

I.C.s:   1 4001 CMOS Hex Inverter 11   1 4009 CMOS Quad NOR Gate 11   1 7404 TTL Hex Inverter 10   2 74LS00 Quad NAND Gate 4,15,16,18   1 74LS02 Quad NOR Gate 4,15   1 74LS04 Hex Inverter 2,3,5,7,9,16,20   1 74LS08 Quad AND Gate 3,5,7,8,9,19   1 74LS14 Hex Schmitt Inverter 22   1 74LS32 Quad OR Gate 3,7,8   1 74LS42 BCD-to-Decimal Decoder 12   1 74LS47 BCD-to-7-Segment Decoder 14   1 74LS74 Dual D Flip-Flop 16,17   1 74LS75 4-bit Latch 16   2 74LS76 Dual J-K Flip-Flop 17,18,19,20   1 74LS83 4-bit Adder 9   1 74LS86 Quad XOR Gate 4,5,8,9   2 74LS90 BCD Counter 19   2 74LS93 4-bit Binary Counter 19   1 74LS95 4-bit Shift Register 21   1 74LS150 Multiplexer 13

Resistors:   1 47Ω ¼W Resistor (yel-vio-blk) 14   1 56Ω ¼W Resistor (grn-blu-blk) 10   1 330Ωx8 16 pin DIP Resistor Array 14   1 1kΩ Potentiometer 10,22   2 4.7kΩ ¼W Resistor (yel-vio-red) 15   1 5kΩ Potentiometer 14

Capacitors:   1 0.01µF Ceramic Disc Capacitor 22   1 0.68µF Mylar Capacitor 22

Miscellaneous:   1 Red T-1¾ LED 14   1 7-segment C.A. Display 14   1 SPDT Toggle Switch 15



Custom Prepackaged Parts Kit Available From:

R.S.R. Electronics, Inc. 1560 Hart St. Rahway, NJ 07065 Ph: 908-381-8777 FAX: 908-381-1572

CET/EET235 DIGITAL ELECTRONICS DESIGN Experiment Troubleshooting Guide


The following is a list of some common problems encountered during lab experiments. For each problem listed, a suggested solution is given.

• Wrong chip used.  Make sure correct chip number is read from I.C., i.e.: not the date code.

• Chip inserted upside-down.  Correctly identify pin 1 and orient chip so pin 1 is to the lower left.

• Chip plugged in incorrectly.  Make sure chip straddles one of the open channels in the breadboard. Also make sure all pins are present, straight and fully seated in a breadboard hole. Bent or broken off legs can quickly cripple an I.C.

• Wrong pinout used.  Double check your I.C. pinout charts to be sure correct chip is being used.

• No power to I.C.  Ensure both Vcc and Ground are connected to the trainer power supply, including connections through breadboard horizontal busses. Some CMOS I.C.s additionally require a Vdd connection.

• Short between Vcc and Ground.  This problem is easily identified by observing the logic probe while not connected to any part of the circuit. The light should be dim, indicating a floating input. If the logic probe doesn't light at all, a short between Vcc and Ground exists. Immediately remove power and thoroughly check all power busses on the breadboard to correct the error.

• Wrong pin count.  Make sure you are counting pin numbers counter-clockwise around the chip starting from pin 1, which should be towards the lower left. It is also common to incorrectly count pins 1 to 7 across the bottom and 8 to 14 across the top when a 16 pin chip is being used.

• Bad or broken wire.  It is possible for a wire to become broken inside the insulation somewhere along its length, causing a broken connection. A quick check for this problem is to connect this wire between a switch and an LED and verify proper LED operation. Also, use only solid conductor wire, stranded wire does not work well with breadboards and should be removed from your kit and discarded. Use wires of appropriate length. Excessively long wires only makes troubleshooting more difficult. Make sure the ends of the wire are stripped to about 1/4" and are straight. Obtain wire cutters/strippers from the instructor to correct these problems.

• Bad I.C.  It is possible for an I.C. to become damaged and non-functional by abusive handling, improper wiring, etc. although actual occurrence of this problem is rare. The chip in question should be isolated in a test circuit configuration for diagnosis.

Laboratory Hints:  Wire power pins to all I.C.s first. This eliminates the possibility of forgetting these connections.  Use a highlighter to mark connections on the circuit diagram as they are being made.  Use the logic probe -- it is your friend. This tool can be used to diagnose specific points in the circuit and nearly always finds wiring errors.

Lab 1: DIGITAL TRAINER FAMILIARIZATION Exercises
Read and perform the following exercises. If you are unsure about any step, please ask for assistance. It is better to ask than damage the equipment (and possibly yourself!).
Using the Digital Trainer – Overview From this point forward in this lab, you will make use of the Digital Trainer or National Instruments MultiSim to build and test Digital Logic circuits. The Digital Trainer, shown in Figure 1, provides a simple-to-use hands–on digital interface which will allow you to more easily and rapidly construct experimental circuits from real Integrated Circuit components.
For this lab, we will use the following features of the Digital Trainer : +5.0V regulated power supply, attached breadboard, LED indicators, digital logic switches, and the Clock Function Generator. The Digital Trainer power supply is current and voltage regulated to prevent damage in the event of a short circuit, with no additional steps required. Also, the LED indicators do not need a ground or current-limiting resistor. These are integrated into the Trainer. Finally, the digital logic switches output either HIGH or LOW logic voltages which you can use DIRECTLY as logic inputs to your gates or to the LEDs.

Figure 1—Digital Trainer
Exercise 1: Equipment and Component Inventory 1. Get a Digital Trainer unit from the equipment Cabinet. If you need additional connection wires, see the instructor.
2. Download the “PAD-234 Digital Trainer - Operators Manual” from Contents > Handouts. This describes all of the controls on the Digital Trainer.
CLK Frequency Generator Terminal
CLK Freq Gen Controls
+5V Circuit Power (VCC)
0V Ground (GND)
Indicator LED Inputs
Logic Switches Logic Switch Outputs
Lab 1: Digital Trainer Familiarization      2 / 8

3. Also download “CET235 - Quick Reference - Gates, Boolean Logic, Etc.pdf” from the Handouts area. This file contains Gate functions and other helpful information you will need during this and subsequent labs. Save this file with your other course files and BRING it with you to labs.
4. Open the Quick Reference document and just briefly look at what is on each page.
5. Obtain one 74LS04 Integrated Circuit (IC) (both work same for this lab) from your Electronics Parts Kit, or from the instructor if you did not purchase a kit. If you purchased the Electronic Parts Kit from the Campus Bookstore for this course, verify that the kit contains all of the components listed on the “parts kit inventory list” included in the box.. Be careful not to confuse integrated circuit ID numbers with date codes. See the instructor if any questions.
6. Open the black Digital Trainer Case. The trainer consists of power supplies, digital switches, LED digital indicators, and a breadboard area where you can construct IC circuits.
7. With the Trainer in front of you, read the following paragraphs carefully, at least two times. Look at the PAD-234 Digital Trainer - Operators Manual as needed for additional information or more photos of the controls.
The breadboard is constructed with disconnected power busses ( RED + and BLUE – ) running left to right across the whole breadboard at the top and bottom, and IC Chip / component insertion areas between the power busses.
The horizontal pins in each power buss are all connected together all the way across the breadboard. The Blue busses should be used for ground, and the Red busses should be used for +5V (VCC) power.

The IC Chip / Component insertion areas are between the busses and also extend all the way across the breadboard. Each insertion area has an upper set of pins (A – E), and a lower set (F – J), with a small valley between the two groups. Each column of 5 pins above the valley is connected together. Each column below the valley is connected together.   Insert ICs horizontally so the pins on one side of the IC are above the valley and the pins on the other side are below it.   Since the column of 5 pins are all connected, you can put a connection wire into any of the pins in the column to connect that IC pin to another gate or to a device.
8. Verify that the Trainer breadboard is empty (nothing plugged in it). NOTE: If you ever notice any wires broken off in your breadboard, bring it to the instructor's attention -- do not attempt to remove them. Instead mention it to your instructor.
9. Using connecting wire, connect the Trainer’s BLACK Ground Terminal (0V, GND) to one of the Breadboard’s BLUE GND busses.
10. Connect the Trainer’s RED +5V Terminal (VCC) to one of the Breadboard’s RED +5V busses.
11. Plug in the digital lab trainer and turn the POWER switch ON. For each of the following trainer components, identify it and perform the related procedure.
GND 0V
VCC +5V
Lab 1: Digital Trainer Familiarization      3 / 8

Power Supply
12. The trainer contains internal DC regulated power supply outputs located at the left of the breadboard fixed at +5V, +12V, and –12V. Additional adjustable voltages (1.5 V to 15 V) +V and –V outputs are also available. You will only use the +5V and GND power terminals today.
13. Verify that the POWER LEDS for +5V, +12V, –12V are ON. Inform your instructor if not all ON!
NOTE: NEVER allow any of the power supply outputs to come into contact with each other or with ground (GND), as this may blow a circuit breaker.
LED Indicators
14. Above the breadboard on the right, are eight LEDs (LED7–LED0) which indicate the logic level of whatever they are wired to (ON = logic high, OFF = logic low). Note their numbering (MSB on LEFT, LSB on the right) and that with nothing connected, these LEDs are internally biased to be OFF.
15. Connect a single wire from one of the LEDs first to +5V then move it to GND and note the results on the LED.
16. Check ALL of the LEDs in the same way to verify they are working. If not, inform the instructor.
Logic Switches
17. To provide Logic Inputs to your circuits, the trainer has a number of logic switch outputs across the top of the trainer. This includes eight logic switches (7 thru 0). The switches produce a logic HIGH or LOW output depending on their position.
18. Reconnect the previous wire from the LED to one of the logic switches and note the effect on the LED of each of the switch's two positions. Switch is ON when switched UP and OFF when DOWN.
19. Two pulse switches also provide either a HIGH or LOW by default, then give the opposite value while pulled forward.
20. Reconnect the previous wire from LED 7 to a pulse switch “1” pin (positive logic) and note the effect on the LED as you pulse the switch. Connect another wire from the “0” pin (negative logic) of the same pulse switch to LED 6, and observe the different output pattern the “1” and “0” pins between the two LEDs. One is a pulse high, and the other is a pulse low.
21. Disconnect the LED wires.
Function Generator
22. A Function Generator on the left of the Trainer supplies timed voltage wave outputs on the Trainer’s GEN Terminal in the form of Sine wave, Square wave, and Triangle wave at variable voltages. You will NOT use the GEN Terminal during this lab.
23. The Generator also supplies a timed Digital Logic output on the Red CLK (Clock) Terminal. Later in this lab we will use the Red CLK (Clock) Terminal to provide a 1 Hz logic signal to our circuit.

Lab 1: Digital Trainer Familiarization      4 / 8

Exercise 2: INVERTER Gates Investigation 24. Power OFF the trainer.
25. Place the TTL level HEX Inverter 74LS04 horizontally (sideways as shown) on the RIGHT side of the breadboard (closer to the LEDs and Switches). Position it with the case indent on the LEFT as shown. 26. Straddle the IC over one of the valleys on the breadboard so the pins on top are above the valley, and bottom pins are below the valley, similar to the following.
                         
The 74LS04 IC has six individual Inverter logic gates combined in one IC. The IC requires a separate +5V power supply connection and a connection to Ground. This power connection provides power to the transistors in the IC which make up the logic gates. 27. Connect the Trainer’s Red +5V terminal to one of the RED power busses on the breadboard. Connect the Trainer’s Black Ground Terminal to one of the BLUE power busses on the breadboard.
28. Using the 74LS04 pinout diagram below, connect the IC power pin 14 (VCC) to the RED breadboard Buss from previous step (+5V). Connect the IC ground pin 7 (GND) to the breadboard Ground BLUE buss from previous step.

On the Inverter gate symbols:         ,      the straight (LEFT) side of the triangle is the INPUT, and the small circle (RIGHT) side is the OUTPUT. Each inverter gate functions like the Transistor Inverter Circuit we looked at in lecture copied below right:   A HIGH input results in a LOW output. A LOW input results in a HIGH output. The small “Inversion Circle” on the inverter output indicates that the signal is INVERTED (also known as “Complemented”) as it leaves the gate.

Figure 2—7404 / 74LS04 Pinout Diagram
29. Connect the output of one of the logic switches DIRECTLY to the input (pin 1) of the 1st Inverter (Don’t use resistors.) AND, connect pin 1 DIRECTLY to LED7 (NO resistors.) This lets you easily see the ACTUAL input value of the gate (not through any inverters) for debugging your circuit.
30. Connect the OUTPUT (pin 2) of 1st Inverter to LED6 so you can view the inverter output.
Case Indent
BreadboardValley
Input Output
Gate 1 Gate 2 Gate 3
Gate 4 Gate 5 Gate 6
=
Inverter circuit from lecture

Case Indent
Pin 1
Pin Numbers
Lab 1: Digital Trainer Familiarization      5 / 8

31. Turn ON the power and toggle the logic switch to change the input to the gate back and forth between ON “1” & OFF “0” states, and fill in both rows of the Worksheet Truth Table “1 Inverter Output” column based on your observations. Verify that your 1 Inverter Outputs are correct using the Inverter gate Truth Table in the CET235 – Quick Reference document.
32. Next, Connect the output of the first inverter to the input of the 2nd inverter shown below. Connect the output of the 2nd inverter to LED5. The Inverter gate input/output pin numbers are shown:

33. Toggle the switch as necessary to observe the output of the second inverter on LED5 based on the switch input to the 1st inverter, and fill in both rows of the 2 Inverters Output column of the Truth Table. This column indicates how a logic signal 0 or 1 is affected after traveling through 2 inverter gates.
34. Connect the output of the 2nd inverter to the input of the 3rd inverter. ALSO connect the output of the 3rd inverter to LED4. The gate pin connections are shown:

35. Toggle the switch as necessary to observe the output of the third inverter on LED4 based on the switch input to the 1st inverter, and fill in both rows of the 3 Inverters Output column of the Truth Table. This column indicates how a logic signal 0 or 1 is affected after traveling through 3 inverter gates.
36. Connect the 4th inverter in line as shown. Connect the output of the 4th inverter to LED3 as shown:

37. Toggle the switch as necessary to observe the output of the fourth inverter on LED3 based on the switch input to the 1st inverter, and fill in both rows of the 4 Inverters Output column of the Truth Table. This output indicates how a signal is affected after traveling through 4 inverter gates.
Lab 1: Digital Trainer Familiarization      6 / 8

38. Use the pin numbers shown below to connect the 5th inverter in series and connect it’s output to LED2. Toggle the switch as needed to complete the 5 Inverters Column. Finally connect the 6th inverter and also connect it’s output to LED1 then complete the 6 Inverters Column of the Truth Table appropriately. KEEP YOUR WIRES NEAT so you’ll have to do LLEESSSS troubleshooting!

Figure 3—Final Six INVERTER Chain Schematic
39. LED7 displays the input switch value, and LED6 through LED1 allow you to see how the input signal is inverted by each inverter, one after another, as it travels through your circuit from left to right.
40. Toggle the logic switch back and forth between High and Low. Observe how the switch signal propagates through the series of inverters. If you set the Input Switch ON, what is the output of the 1st inverter?   What does the 2nd inverter do to the signal? What does the 3rd inverter do to the signal? What does every odd number inverter do the signal?    Every even numbered inverter?
41. Complete the questions on the Worksheet after Inverters Connected in Series Truth Table.
Replace Switch with Digital Clock Signal. 42. Turn the Trainer OFF.
43. IMPORTANT !!: DISCONNECT the wire from the logic switch to the 1st inverter input pin, but leave all other pins connected.
44. Set the Frequency Generator Mode dial (top left) to Square Wave ( ), and the COARSE FREQ dial to 1 Hz (NOT 1K Hz !) 45. Connect the Trainer’s Red CLK (Clock) Terminal to the 1st Inverter gate’s input pin to connect the CLK’s 1 Hz oscillating clock output to the Inverter gate’s input.
46. Turn the Trainer back ON. 47. You should now see the 1 Hz CLK signal traveling all the way through the six connected inverters in the 74LS04 as displayed on the LEDs. The CLK signal is successively complemented by each inverter as it travels through each of the six inverters.
Exercise 3: Control Gate Investigation For this exercise you will hook up an “AND” gate between the output of the CLK signal and the 1st inverter input and investigate one common way for a gate to control a signal. The AND gate has two inputs. The CLK signal will be connected to one of the AND Gate’s input pins, and a SWITCH will be connected to the other. 48. Turn the Trainer OFF.
49. Leave all of the inverter and LED pins connected. Obtain a 74LS08 Quad 2–Input AND Gate IC from your parts kit or from the Lab parts bins.
Inverter.

Lab 1: Digital Trainer Familiarization      7 / 8

50. Plug the 74LS08 AND IC into the breadboard in the same manner at the 74LS04 Inverter IC. The 74LS08 AND IC has four (Quad) individual AND logic gates combined in one IC. Each gate has two inputs and one output. The IC also requires a separate +5V power supply connection and a connection to Ground. The AND gate ONLY gives a logic HIGH output when BOTH inputs are set to logic HIGH, otherwise the output is LOW.
51. Using the 74LS08 pinout diagram below, connect the IC power pin 14 (VCC) to the RED breadboard Buss from previous step (+5V). Connect the IC ground pin 7 (GND) to the breadboard Ground BLUE buss from previous step.

Figure 4—74LS08 Quad 2–Input AND Gate Pinout Diagram
52. See the diagram below, and Connect the output of the Trainer’s Red CLK Terminal to Pin 1 of the 74LS08 IC (1st input of 1st AND gate). 53. Connect the output of the SWITCH to Pin 2 of the AND IC (2nd input of 1st AND gate). 54. Connect Pin 3 of the AND IC (Output of 1st AND Gate) to Pin1 of the Inverter IC (1st Inverter input pin).   This places the AND gate between the CLK output and the 1st Inverter gate.


Figure 5—AND Gate Control of CLK Signal to Inverters
55. Turn the Trainer back ON. 56. Turn the SWITCH ON, and VERIFY that LED7 blinks at the frequency set on the Clock control. IF NOT, check and verify the connections from the CLK terminal. Also check the SWITCH to the AND gate inputs, and the AND gate output to the 1st Inverter. ALSO CHECK the AND IC POWER +5 and GND connections from the busses to the AND IC.   See instructor for help. 57. Toggle the SWITCH ON and OFF and observe what happens in each case to the signal propagating from the gate output to the series of inverters.   Answer Exercise 3 questions in the Worksheet.
Obtain Credit for the Lab. 58. Leave your circuit connected with the oscillator running, until you Demonstrate your circuit operation to the Instructor or Lab Assistant for Credit. Have your instructor SIGN–OFF your Worksheet for CREDIT.
59. WRITE the NAME of the team members who were present for the lab ON THE WORKSHEET.
Gate 1 Gate 2
Gate 3 Gate 4
Inverter 1 Inverter 2 Inverter 3
SWITCH
… rest of circuit intact…
AND 1
1
2
3
CLK
LED7
Lab 1: Digital Trainer Familiarization      8 / 8

60. Turn in your filled in Worksheet for Credit.
61. Turn OFF the Trainer.
62. CAREFULLY Remove all wires so as not to bend or break the pins. Remove the IC (or use the chip remover tool) and return all components to where they belong.

Answer 1

In your experiment if, the input signal is high that is if it has an constant or variable voltage or amplitude greater than 2.5 then it will be considered as logic 1, and if there is no signal or the amplitue of the signal is below 2.5 then it considered as logic 0.

If the input signal is high then the first inverter inverts the input signal. So, the output of the first inverter will be logic 0. Then the second inverter inverts the output of the first inverter so the output will be logic 1. After that the third inverter inverts the output of the second inverter so that the output will be low. Likewise, the output of all odd numbered inverters is high or logic 1. All even numbered inverters output is low or logic 0.

If the input signal is low then the output of the first inverter will high that logic 1.Then the second inverter inverts the output of the first inverter so the output will be logic 0. After that the third inverter inverts the output of the second inverter so that the output will be high. Likewise, the output of all odd numbered inverters is low or logic 0. All even numbered inverters output is high or logic 1.