Digital electronics use a finite number of states, 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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Displaying a 4-bit ALU result as 3 digits

I have managed to design (using Logisim) a 4-bit ALU that adds, subtracts, multiplies and compares. Everything seems to be working fine. However, I am having trouble figuring out how to display the ...
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1answer
64 views

Pull high in software

I was porting Arduino library ps/2 mouse to pic and I wondered why pull high works when declaring the pin as an input and then making it high and that worked for pic and Arduino alike, but when I ...
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1answer
47 views

Why does my counter count strange values?

I was designing a people counter that uses two infrared leds and two phototransistors. The logic was derived using a finite state machine where by I derived a circuit that detects an entrance ...
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2answers
64 views

why should we have small number of registers? [on hold]

I read in my book that we should have a small number of registers (such as 32 registers) What are some reasons?
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0answers
27 views

One's complement circuit to calculate a 4-digit binary numbers

For those who are not quite familiar with one's complement: It basically reverses all the digits, for example 4 = 0100, -4 = 1011 At first I started to plan the circuit by planting NOTs after each ...
3
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3answers
166 views

need logic gate output higher than vcc

I am currently studying an intro course in digital logic and had a small project I needed to create. I had to use a NOT gate(74HC04) to set off a buzzer when a simulated front door of a house opens(so ...
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3answers
216 views

Why would you want to write to a file when writing VHDL? [on hold]

I have never so far been in the need to write to a file when making a testbench in vhdl. Seeing the signals being plotted has always been enough so far. Could someone please give me a case or the ...
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1answer
45 views

Sum of products or product of sums?

What does P indicate in this expression? F(A,B,C,D) = P(4,5,6,7,8,12,13)+d(1,15) And does d(1,15) represent don't care condition?
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2answers
65 views

Delay time for traffic light

I am doing a traffic light design control circuit, so the light will change from red to yellow (for 3s) to green(for 12s) then to yellow(3s) , my question is how do when the light is green, how do I ...
3
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1answer
64 views

Reasons to use an analog temperature sensor instead of a digital one

I'm designing a microcontroller-based system that includes a thermostat. When choosing which temperature sensor to use, I noticed that analog ones have more or less the same power consumption, the ...
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1answer
21 views

Not gate dividing voltage

simulate this circuit – Schematic created using CircuitLab I am working on a binary calculator using 2n3904 NPN transistors. I noticed when using a NOT gate the voltage gets divided when ...
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0answers
19 views

Digital Circuits complete courses/books/resources [on hold]

I am currently working as a programmer and studying electrical engineering. I have not had much of a brush with digital circuits before a few months ago but now (after a very mediocre and short ...
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1answer
40 views

Correct 2 to 1 Multiplexer Truth Table

What is the correct way to write a 2 to 1 multiplexer truth table? In a couple of tutorials I've come across (1,2), the table is presented as follows: However, the same tutorials show the 4 to 1 ...
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1answer
86 views

Solving a Lock and Key Logic Gates Problem [on hold]

Edit: "Duplicate Question" Answer does not solve this. Must use a comparator and counter in logisim and D Flip Flops (which that answer uses) are not allowed. Building D Flip Flops using basic gates ...
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1answer
33 views

Adder tree with 4:2 compressors. What to do with Cout?

I'm trying to build an adder tree using 4:2 compressors. I want to add together 16 bytes at total, so I figured that a possible architecture for that tree is the following: Each 4-Byte adder has 3 ...
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2answers
35 views

How to decode a two bit signal into one-hot encoding, with 7400 series ICs?

Is there a single 7400 series IC which does this directly? (I know can do this with 4*NOT + 4*AND gates, but that will be 2 ICs.) Truth table: ...
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1answer
40 views

Electric Bell Quiz with IC

I have a quiz bell circuit electrically. When one bell is pressed, the LED will light and bell other will not work. The problem is when bell is pressed simultaneously, then the other LED will also ...
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1answer
70 views

digital logic gates

I'm still trying to wrap my head around the functionality of a counter. The program I am using is Logisim and I'm trying to implement a counter into my design. I currently have this: EDITED OUT ...
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1answer
67 views

Logic gates - Creating a Digital counter [closed]

I'm wanting to create the following digital counter using only basic logic gates (AND, OR, NOT, NAND, NOR, etc): I've done some searching and the answers provided are much more complex than what ...
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0answers
55 views

XOR gate eval board at > 1.2 GHz [closed]

I need a wide bandwidth (>1.2 GHz) zero-crossing detection circuit. I have a signal at ~600 MHz that I connect to a power splitter with 90 deg lag in one output. Outputs of the power splitter are fed ...
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2answers
68 views

simple counter in VHDL

I am trying to write a little counter in VHDL using the two process methodology. However it is not working. Could someone explain me why? ...
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1answer
42 views

Create 3 input AND from 2 input NANDs

Is this the correct result? a and b and c = not((a nand b) or not c) simulate this circuit – Schematic created using CircuitLab Is there any better decomposition?
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0answers
35 views

scr8645 help with digital output [closed]

I got this bluetooth module csr8645 and i like to stream audio to i2s line. Is it possible? If yes, how to configure this module (i have spi programmer and possibility to change pskeys).. I got ...
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0answers
17 views

How to implement bit shifts in logisim [closed]

I'd like to implement shifting in logisim so that I can effectively shift right and shift left both arithmetically and logically. The use of barrel shifters is quite interesting, however I'm more ...
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1answer
50 views

will there be any difference between the output of a 555 oneshot and one made with a 74123?

I think there won't be any difference because the professor wants us to build both with 10 us pulse and with a duty cycle of 25%. I didn't have enough time to build both MMV, so that's why I am ...
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1answer
100 views

Digital Logic Reset [closed]

Question Too broad apparently.
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0answers
28 views

Stick Diagram for D Flip Flop

I am new to Cadence and I am trying to design a D Flip Flop with asynchronous reset. However, I am having trouble with drawing the Stick Diagram from Euler's trail. My flip flop is designed this ...
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1answer
39 views
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0answers
44 views

What is the necessity of clock signals? [duplicate]

In many articles on the web clock signals are introduced to be "synchronizer signals" in digital sequential electronic circuits, which can cause various parts of the circuit to operate and do their ...
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1answer
67 views

load cell continuously monitor load

I want use 50 kg of load cell of weighing machine to measure 30 kg of load for an one or two months,and load continuously decreases because of consumption on daily basis. my question is that the ...
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1answer
80 views

Digital Logic Basics - Creating simply lock mechanism

I'm not sure where else I can ask a question like this, I've been searching around and can't seem to find a proper place to ask about basic digital logic. I'm doing a computer science course and have ...
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0answers
19 views

cmos and gate design

When I was learning the computer organization course, I learnt multiplier can use carry look-ahead to speed up computing time. The carry look-ahead design uses 'and gates' with more than two inputs. ...
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1answer
35 views

Monostable multivibrator with NAND gates

I would understand the behavior of the V_C potential in this circuit. The IN-M voltage is a pulse wave with 5% duty cycle. I think that it works in this way: When the IN-M is HIGH the NAND 1's ...
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0answers
27 views

For the same complexity and frequency how does the cost and the power scale with manufacturing process node?

This is a follow-up on some answers to this question: some of the answers implied that manufacturing a microcontroller with 350 nm and even 3000 nm technology: 1) would be cheaper than with, say, 32 ...
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2answers
38 views

What are the differences between line tree decoder and matrix decoder?

Here's the reference material which has me confused. After reviewing these 2 images I am confused about the differences between the 2 as the 6 to 64 decoder looks remarkably like a matrix decoder ...
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0answers
27 views

8 bit magnitude comparator using IC 7485

When making an 8 bit magnitude comparator by cascading two 7485 ICs, why do we connect the A=B pin to "HIGH" while A>B and A to "LOW" ? A comparator will first compare the MSBs before the LSBs. ...
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1answer
48 views

Large range input single level shifter

I have an application where I will be taking serial signals will need to level shift the signal to 3.3V. The input signal will be from 15 to 5V for a high input and I need them all shifted down to ...
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2answers
40 views

Minimizing AND gates in ANF

If I have a boolean expression made up of ANDs and XORs in algebraic normal form, are there any algorithms which can minimize the circuit further? I'm looking to minimize AND gates specifically. I'm ...
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1answer
38 views

How can I build a monostable multivibrator (one shot) using 74LS123?

how can I build a monostable multivibrator using 74LS123? with 10 microseconds of pulse. please help
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4answers
94 views

How important is gate delay when designing a Circuit?

First year EE student here, we've been learning about CMOS Inverters in class and about the of logic gates, but it hasn't really been mentioned how much this effects the design of a Circuit in ...
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1answer
42 views

Do I need to connect a resistor to either one of the 2 input pins of this “and” logic component? If so, what would be the value for it?

The said component is sn74lvc1g08 from TI, datasheet. I was planning on connecting 3 1.5 volt AA batteries (in other words, 4.7 or 4.8 volts max in total) to one of the input pins (either A or B) and ...
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2answers
71 views

Is it possible to connect a NOT gate (74hc04) to connect two separate circuits in parallel?

Say I am low on the number of IC, can I use the same not gate for two different connections in parallel in a breadboard? Will there be any interference like short circuits or unexpected behavior if I ...
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2answers
82 views

First Time Using Integrated Circuits

I am building a circuit for a custom application. I have an old Toyota truck, and I keep leaving the headlights on, because there is no warning buzzer! I have designed a circuit that takes 3 inputs: ...
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3answers
59 views

Circuit to test ICs at home? (74hc04, 74hc08, 74hc32)

I have the above IC and I want to check them before using them. I don't have access to a lab currently and I only have access to the usual stuff (LED, resistors) and a simple ammeter/voltmeter. What ...
-6
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1answer
42 views

design 8-bit adder with 74LS83 [closed]

How can I design a 8-bit adder with chip 74LS83?
0
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1answer
46 views

Creating logic gate for minimum comparison

Is there any way to create a (simple) logic gate to compare two integers which are stored in a temporary register? Edit: It's okay for just one-digit long integers.
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1answer
34 views

4 bits logic unit

I understand how 1 bit logic work . For example A =0 and B=1 => A and B = 0 // A or B = 1 . But how do you work out if A and B are 4 bits . For example A[0,0,1,1] and B[0,0,0,1] What are A and B , ...
1
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0answers
35 views

How to control chip select and Load DAC signals for a DAC chip?

I have a DAC7643 (Texas Instruments) - 16-Bit, Dual Voltage Output DIGITAL-TO-ANALOG CONVERTER I have been mostly unsuccessful with controlling the CS and LDAC signals. I have simulated a circuit ...
0
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1answer
38 views

genarating +/- 5V with a common ground [duplicate]

I am working on a digital voltmeter circuit using ICL7107 IC. Having trouble powering it up. There is a -5 V supply to pin 26. I used a 7805 regulator for +5V supply but wondering how to supply the ...
0
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0answers
21 views

0's and 1's catching in JK master-slave flip-flop

I'm learning about flip-flops from Givone's Digital Principles and Design and I've encountered a section on 0's and 1's catching in JK master-slave flip-flops which is described as: "If the slave ...