Digital electronics treats discrete signals, unlike analog electronics that treat continuous signals. Digital logic is used to perform arithmetic operations with electric signals, and constitutes the base for building CPUs.
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2answers
61 views
Filter for a digital input
her everyone, i need to read an input of 220V and convert it in TTL logic 0-5V for my arduino. if there's a presence of 220V at the input of my circuit, i read 0V in my arduino, else i read 5V.
in ...
1
vote
0answers
35 views
What would be state diagram of robot controller?
Robot Controller Problem
A computer needs to control a robot, where the computer sends the following commands:
Do nothing 00
Turn right 01
Turn left 10
Move forward 11
You have to design a circuit ...
3
votes
5answers
512 views
Removing digital noise on quadrature encoder signals
I am using a quadrature encoder with 3 lines to track the rotary position of a shaft attached to a BLDC motor(through a planetary gearbox).
When I rotate the shaft, the A, B and Z lines always have ...
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0answers
36 views
How to implement this timing diagram
I'm really confused on this question, usually j and k are given and this doesn't even have an input for k.
How should I go about beginning this question?
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1answer
27 views
What is the boolean expression?
I'm not sure how to tackle this problem. I think it might involve creating a logic table first. Please help!
An elevator has the following sensors:
G - The gate is closed
L - The elevator is loaded.
...
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votes
1answer
97 views
AND Logic Gate Error!
Hi everyone,
as you can see from the picture, i have an AND logic gate. The LED has to be off when the Va is 0V and the Vb is 5V, but it turned on?????? Can you guys explain why?
Thank you.
0
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1answer
71 views
How am I supposed to connect two logic circuits which are not of the same family
Say I have to couple a NOR \$I^2L\$ and an ECL logic circuit, in such a way that the output voltages of the \$I^2L\$ are suitable for ECL use. Let me show you what I mean:
I thought adding a voltage ...
0
votes
1answer
21 views
What does it mean to establish the state of the internal node in CMOS circuit?
This is the NAND circuit and the 'int' is the internal node of the circuit.
It is seen that A = B= 0→ 1 gives the worst delay in the below table. What does it mean to establish the state of the ...
0
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1answer
31 views
4 To 1 MUX - Figuring out the inputs
If i have a 2to1 mux together with logic gates like this:
I can simply create a karnaugh map and test the different values of XYZ and get a function.
From this i get the function f = x'z + yz + x'y
...
-6
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0answers
30 views
Design a vending machine [on hold]
Design a vending machine that give you a bottle of rs 15 and expect only 5,10,20 rupees note and provide the change also.
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3answers
68 views
Trouble using the 7555 timer IC
I'm trying to build a circuit that uses T-flip-flops to generate the sequence "CSE231-1-6" on a 7-segment display. It works fine on logisim, so there are no design-related errors here.
So ...
0
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0answers
19 views
Possible number of combinations for 16 implicants in 6 variable truth table with 64 rows
You have a function with 6 input variables, which corresponds to 64 rows on the truth table and there are 16 minterms(where the function is 1). How many possible combinations of implicants are there?
...
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2answers
37 views
“Shorting” clock inputs of multiple flip-flops
I have 2 7473 (JK-FF) ICs. So there are a total of 4 flip-flops with 4 clock inputs. They will all have the same clock pulse (check attached simulation screenshot).
I'm using a 555 timer IC to send ...
2
votes
0answers
55 views
Question on BJT operation mode
I know this might sound a little bit easy for some of you but i do really need a clarification on this.
I have a question about the operation modes of the Bi-Polar Junction Transistor.
In the graph ...
0
votes
1answer
32 views
Wiring or resistors for using a JK (7473) IC as a T flip flop?
I know that the J and K inputs need to be the same signal, but do I do it using a wire or resistors? For driving multiple of these T flip-flops with the same clock source (pin 3 from a 555 timer), ...
0
votes
1answer
44 views
What does low-impedance mean in the CMOS inverter circuit?
For the CMOS inverter the text states "once the transients have settled, a path always exists between VDD and the output realizing a high output (“one”), or, alternatively, between VSS and output for ...
0
votes
1answer
59 views
Will does this circuit require any resistors for its 7-segment display?
The circuit I'm trying to build is attached as a logisim simulation screenshot. The source is a 5V battery. The display is a 5161AS common-cathode display.
I've seen people use resistors whenever ...
1
vote
1answer
42 views
Arduino: Did I damage analog joystick clicker by using analog instead of digital input?
I am using a thumb joystick for Arduino UNO, trying to work with it.
There are x and y values that I get with analog input <...
0
votes
0answers
38 views
Can you use the 7555 timer IC with JK flip-flops (7473) without any resistors?
The circuit I'm trying to implement is attached as a logisim simulation screenshot. I am using a 5V battery. The 7-seg will show "CSE231-1-6" in a Moore-model sequence.
I'm using 7473 IC (JK-FF) ...
1
vote
0answers
25 views
Sequential Logic D flip flop excitation equation
I'm a computer science student having trouble solving a problem in my digital design textbook, I just can't seem to figure out how to make an excitation equation for the following circuit.
As far as ...
1
vote
3answers
147 views
Can you short two output pins of a decoder (74LS154N)
Let's say for two inputs, the output values will be the same. So instead of using an AND gate, I was wondering if i can just short them. Please check the attached logisim screenshot to get a better ...
-5
votes
1answer
49 views
Logisim, what gives with the red signals? [closed]
I'm a beginner with Logisim.
I am stuck on the following circuit and have been unable to find help on web.
What causes the red signals and how can I try and correct the situation?
6
votes
2answers
155 views
What is this trapezoidal logic gate?
What is this thing called? how does it work?
I've tried googling so much, even pasted the image in the google search box haha
Its used here on the MSP430:
-3
votes
0answers
39 views
How to create a simple digital system using VHDL and QuartusII and implements a software (Java) in it? [closed]
Heeeelp!
Hi! I'm beginner student of Computer Science in Brazil and I have to create a (very simple) digital system using VHDL and the software QuartusII.
Also, it would be very good to make a ...
0
votes
2answers
57 views
Understand H-Bridge
I try to understand H-bridge, I have edit the circuit and followed the advices in this tread. Is this a good H-bridge design?
simulate this circuit – Schematic created using CircuitLab
I have ...
3
votes
3answers
68 views
Decoupling capacitors values in mixed-signal circuit
I know theory about decoupling capacitors (ESR, ESl, parallel capcitors etc.)
I have read Electromagnetic Compatibility Engineering, H.W. Ott.
My question is about practical design. How shall i ...
1
vote
2answers
34 views
How to add reset functionality to a master-slave D-type flip-flop?
I'm trying to implement a shift register and therefore need values to be stored on the downwards edge of the clock signal (otherwise the whole register just sets to the input), so I am using a master-...
0
votes
3answers
77 views
Is it possible to add resistance using a push button?
Does anyone know if this is possible to add resistance using a momentary switch/push button?
Meaning that I just want to push down on a button and go from 2 Volts down to 1 Volt. Any help is greatly ...
0
votes
1answer
42 views
How to manually create switches to light up a 7 segment display connected to ICs?
The circuit has been shown above. I have connected the ICs. Gave power to ICs using a 9V battery. I have got two questions:
How to simulate the inputs x, y, z using 'household' electrical circuit ...
0
votes
1answer
24 views
S/PDIF to TTL converter
This is how S/PDIF to TTL converter usually looks like. I simulated poor quality smoothed out signal with a sine wave.
Can comeone explain how it really works? Inverter with feedback resistor ...
1
vote
1answer
25 views
Difference between select lines and control lines in Digital circuits? [closed]
I want to know about the conceptual difference, not a specific case.
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1answer
57 views
Is it good to code combinational and sequential logic separated into two always blocks?
Modeling both sequential and combinational logic within the same always block a good practice or is it recommended to code them in separate blocks.
...
1
vote
1answer
85 views
Simple accessible microcontroller for learning low level digital logic [closed]
Sorry if this isn't the right place for this question- if so, please correct/redirect.
I have a technical background, but as for electrical engineering and programming, I'm really just a hobbyist.
I'...
3
votes
1answer
53 views
Line Decoder Logic Race
I have a problem with this logic circuit I have designed:
The intended behaviour is: when the clock comes high, the counter's state is latched and decoded
What happens is: when the clock is high, ...
0
votes
2answers
82 views
Why no resistor is connected in open collector TTL logic?
What will happen if we connect it internally in IC itself?
Why do we need to manually connect it outside?
Is there any advantage of doing so?
1
vote
1answer
55 views
What is the relation between noise margin and impedance in a CMOS circuit?
A well-designed CMOS inverter, therefore, has a low output impedance, which makes it less sensitive to noise and disturbances.
How can we say that a well designed inverter i.e with proper noise ...
0
votes
1answer
29 views
Is the Q2 in this diagram based on J2 and K2?
Down here is a basic diagram Im practicing on. Im not sure if I get the answers correctly. But should I find Q2 based on J2 and K2?
X = J1 = K1
Q1 = J2* = K2
Q2
Z = Q1* + Q2*
4
votes
3answers
514 views
Why does this 7-Segment Display not function properly?
I've provided details in image.
Although, I'll once again provide in text:
IC : 74LS47N (Binary to 7-Seg Display)
7 Segment : Common Anode
M.S.B : D
L.S.B : A
This ...
0
votes
2answers
46 views
Safe to power up the digital circuit for troubleshooting IC chips? [closed]
I have a complex digital circuit board used in Scanning Electron Machine.
In it, there are lot of IC chips, FPGA chips. diode SMD, capacitor SMD and others.
This problematic board produces no image. ...
0
votes
0answers
65 views
What's wrong with my timer in verilog?
The verilog code is all from another lab that I have that is fully working, all I need to do for this lab is add a 750 clock cycle timer/counter that returns the user to the locked combo 1 with the ...
0
votes
0answers
25 views
troubleshooting 62256 ram I/O speed
I can't figure out if I'm using the wrong value pull-up resistors or if the ram is too slow. The diagram shown is rough with only the most important connections shown. Basically I have one GPIO pin ...
0
votes
3answers
136 views
Creating a logic circuit with only NAND gates
I am supposed to make a logic circuit with only NAND gates.
I have created a truth table and i have extracted the boolean expression using a karnaugh map.
My function is: \$\overline XZ + XY\$
How ...
0
votes
0answers
30 views
Create excitation table for the circuit
For the above circuit, I got the following equations for the outputs :
End = A'(S0)B'
D1 = End + S3 + (S2)Stop
D0 = (S0)B' + S3 + (S2)Stop
Below is what I currently have for my excitation table....
0
votes
1answer
50 views
What is the difference between excitation table and truth table?
In flip-flops what is truth and excitation table iam getting confused between them ,earlier I learnt a truth table of flip-flops but now its called excitation table so I wanna know whole thing behind ...
0
votes
1answer
48 views
Building a circuit that starts the circuit
Sorry for the confusing title. Basically, I want to build a circuit that takes an input. When the input is 1, the circuit outputs a 1. However, on the next rising clock , it will output a 0 for the ...
-3
votes
0answers
24 views
5x5 bit unsigned multiplier on the Altera DE2-115 board [duplicate]
How to design & Implement of a 5x5 bit unsigned multiplier on the Altera DE2-115 board?
0
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1answer
52 views
7-SEGMENT DISPLAY : Why does this 7-Segment Display not light up? (IMAGES PROVIDED)
Why this (IC7447 and 7 -Seg combo) not light up?
I'm not sure as if what to do of the 3 lines of the IC7447 (Pin - 3,4,5) which I've depicted in GREEN below. Because at certain sites they have been ...
0
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0answers
58 views
fintite logic, truth table
I have a homework question that I just don't quite understand, (teacher and textbook has talked/wrote very little about).
"Construct a finite state machine that accepts a base 2 value entered one bit ...
0
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0answers
22 views
Simulink design of MC 14538BD
I am trying to design MC14538BD in Simulink. But the data sheet seems pretty vague.
I assumed somehow that the flip flop used here is a D flip-flop. But the flip flop in simulink seems to have ...
0
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0answers
74 views
Logical Circuit question
I have a homework question that I just don't quite understand, (teacher and textbook has talked/wrote very little about).
"Construct a finite state machine that accepts a base 2 value entered one bit ...
