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Questions tagged [digital-logic]

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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simple six-position voting machine into a 7 position voting machine

I'm new to learning about full and half adders and what not. but I am struggling to understand this question out of my study manual. The pictures shows a simple six-position voting machine module ...
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0answers
28 views

What’s the disadvantage for solving 5 variable Kmap using overlay and reflection method? [on hold]

As far as I know solving kmap using Gray code is widely used but is there any disadvantage in it?
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1answer
55 views

Circuit Diagram with only NAND Gates

I need confirmation that the following circuit diagrams are correct for their Boolean expressions. I've been told that each logic circuit must have a MAXIMUM of 4 NAND gates, however, I cannot manage ...
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1answer
52 views

How to select 8 bits?

I am working on a simple counter that takes start, stop and increment values as decimal inputs. Here's the circuitry of the start value input of my counter: What the whole counter does is count from ...
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1answer
98 views

CPU Utilization Methods

To fulfill customer expentations and fill out customer reports about the device, is there also one section about CPU Utilization. Because I have never done such task before I have overview some "...
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1answer
85 views

What chips can be used to design an Anti-Counterfeit /Authentication circuit? [on hold]

I am an intern within the R&D branch of a company that designs tools that must operate with low noise at extremely high external temperatures (upwards of 175C). My boss asked that I look into ...
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4answers
140 views

what is the triangle component in electronics?

From the following image we can see 3 triangle symbols: looking to the triangle to the right i suppose it is a voltage buffer, but the ones at the left have 2 inputs. What are they? This image is ...
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0answers
12 views

Deriving state table /equation confused

A sequential circuit has two JK flip-flops A and B, two inputs x and y, and one output z. The flip- flop input equations and circuit output equation are JA = BX+B'Y' KA = B'xy' JB = A'x KB = A +...
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1answer
31 views

Down counter using 4510 IC

So i wanted to create a counter that counts from 59 down to 0 using 4510 IC component, so i created simulation in Proteus software. This is what i came up with: This circuit works perfectly fine ...
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1answer
34 views

How to know when the resault of subtraction is incorrect in a 4 bit binary subtraction circuit? [closed]

This is an image of a binary subtractor for unsigned numbers. Some times the output of binary subtraction is not correct and needs to be complemented to give the correct answer, how can I find out ...
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8answers
3k views

Ribbon Cable Cross Talk - Is there a fix after the fact?

I'm involved in a project where the customer defined pins in a ribbon cable, without considering possible cross-talk issues. The signals are 1 MHz data signals with no ground wire separating them. I'...
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1answer
24 views

3 Input XNOR gate made with XOR and not gates [duplicate]

hi i have implemented this equation with XOR and Not gate but i'm not getting the correct answers (A.B.C)+(A'.B'.C') What is the Problem ? thank you
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1answer
88 views

Logic gate on negative signals

I need a logic gate to check if A or B or C is negative voltage (referenced to the ground). It does not matter if the output is positive or negative logic (as long as it is in positive voltages) Does ...
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3answers
61 views

On-the-fly routing of digital and analog signals using unbuffered analog crosspoint arrays?

The issue I have is strongly related to a question which was asked over here. Unfortunately I did not find the answer I was looking for. Digging a bit more I've came across a class of IC's named ...
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1answer
37 views

Finding functions for JK / D / T flip flops

I am trying to understand this concept of flip flops. Given some Karnaugh Map, all I need to know is how to find the functions of various flip-flop types: sr flip-flop (\$s = \text{ ??} \quad r = \...
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1answer
51 views

4x 2:1 Multiplexer with multiple select lines. Does that exist?

I have been checking different supplier websites, and can't seem to find what I am looking for so I am wondering if it even exists or not. I am looking for a 4x 2:1 MUX IC with 4 select lines. I am ...
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3answers
60 views

Implementing digital control on analog potentiometer

I have an analog sound processor unit, which uses either ICs or spare components. There are four controls, which are simple potentiometers. I would like to control their levels digitally, storing the ...
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1answer
21 views

Implementing function with NAND only quickest way

I'm trying to remind myself how to implement given function or karnaugh map with NAND or NOR gates. I remember how DeMorgan's laws work. Let's say I have some Karnaugh Map and I want to implement the ...
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3answers
65 views

How does a digital logic NOT (inverter) gate work?

I've read several so-called explanations on the web of how a NOT gate works, but they all explain WHAT it does, not HOW it actually works. I know what it does. Consider this schematic of a NOT gate: ...
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2answers
59 views

Correctly using MOSFETs

I'm using a P-Channel (DMP1045UQ) and an N-Channel (BSS138K) FET to pull a 12v Logic line (12v @ 5mA) high (from GND) from a Logic Level(3.3v) MCU I/O pin. Here is the schematic, where ...
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2answers
33 views

1-wire differentiate read from write

I've been reading documentation on 1-wire and I think I'm having a brainfart. How does the slave differentiate a read slot from a write slot? reference: https://www.maximintegrated.com/en/app-notes/...
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3answers
982 views

Detect the first rising edge of 3 input signals

I have 3 input signals which are pulse waveforms The output is switch to high once once all 3 first rising edges of 3 inputs are detected. Is there a digital circuit from logic gates, flip flop that ...
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1answer
26 views

“Cross simulation” between analog and digital

I was interviewing for an analog/digital design engineering team and the guy said that my first task on the job will be to run cross (or crossing) simulation between analog and digital section, what ...
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1answer
90 views

Simple counter circuit resets at the wrong value

I wanted to create a circuit that would count from 2 to 12. In order to do so, I created a simple synchronous counter that resets itself when I have logic Highs at the third, second, and zero flip-...
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2answers
51 views

Basic questions about output impedance of a logic inverter using an NMOS

I have drawn below an NMOS logic inverter and its equivalent circuit for HIGH state: 1- Why is this gate said to have high output impedance at HIGH state? Is that because of the open switch or ...
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1answer
39 views

expressing a boolean function in another way

The following boolean expression is given: g(p,q,r) = ((p->q') -> r) Depict this boolean function only by using the operations ∧ (AND), v (OR), ¬ (NEGATION). How can I do this? I thought I could ...
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1answer
46 views

Disjunctive Normal Form

The boolean expression: y= (a'+b) * (b(c'+d')) = (a'+b) * (bc' + bd') is given. Find out the disjunctive normal form to this boolean expression. My suggestion: y= a'bc'd' + a'bc'd + a'bcd' + abc'...
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1answer
56 views

The boolean expression from a circuit

Would the final boolean expression to the circuit be right? Or do I have to multiply the brackets b(c*d)' out to bc' + bd' simulate this circuit – Schematic created using CircuitLab Edit: My ...
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1answer
98 views

Design simulates perfectly but won't work on FPGA

First, thanks for the help yesterday. This time I will document my code correctly. So, we were tasked with creating a parking meter that would take 4 inputs, one adding 50 seconds, one adding 150 ...
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2answers
60 views

n-bit majority digital logic

Question: Is there an algorithmic way to produce a digital logic circuit for an n-bit majority function? (hopefully reasonably efficient as well). Motivation: Half adders can be put together to make ...
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1answer
68 views

logic gates, implementation [duplicate]

Task: Draw an AND circuit with 8 inputs, a circuit which implements the expression a∧b∧c∧d∧e∧f∧g∧h. Condition: Use only NOR-Gates with two inputs to solve this task. Could anyone give me a hint, ...
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2answers
76 views

Reducing the range of a D flip-flop frequency detector

I'm designing a frequency tracking circuit and I came up with a circuit that tracks frequencies from Fclk to Fclk/2: However, it would be very nice if the bandwidth was a bit narrower, from Fclk to ...
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1answer
32 views

What happens when there is a simultaneous Read and Write launched to the same address in AXI3/4?

I have a doubt regarding the AXI3/4 protocol. Assume a hypothetical scenario where a single master issues a valid Read and Write transaction to the same address simultaneously. From the AXI ...
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3answers
64 views

How to interpret this timing diagram?

I am very confused on how to interpret this timing diagram?
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1answer
24 views

Pairing vs Master-slave between BT Module to BT Module

If I take two identical BT modules, for example HC05 or HC06 then is it possible to pair the two modules with each other or is it like you need 1 master and 1 slave module for pairing? Edit: Now I ...
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1answer
21 views

Common output from two proximity sensors

I need help wherein I'm using proximity sensors to trigger an event in a device. The device looks for 12V from the sensors and registers it as an event trigger. There's no problem when I'm using one ...
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1answer
34 views

Coaxial S/PDIF input circuit

Can someone shed some light on the rationale for the SPDIF coaxial input circuits in: (1) the DIR9001 evaluation board (see schematics, page 7), and (2) in this Application Note from ST (see Figure 10 ...
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0answers
85 views

Car winker light mechanism - Someone's Hammer?

A few years ago a professor in my college drew some circuit and explained how it manages itself to be connected and disconnected each second or so, using inductor and some other parts. He said that ...
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0answers
37 views

Interfacing with a Nest Hello 'chime connector' module

I currently own a Nest doorbell that uses a "chime connector" between the doorbell wires and doorbell chime as shown below. I have tried to create a digital doorbell chime that will wirelessly ...
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2answers
152 views

NPN: Not fully sinking to GND

I'm using an NPN to pull a 12v (5mA) signal low from an MCU (logic level). My problem is that when I pull the 12v line low, 7.4v are still present at the 12v side of the line using the circuit below: ...
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1answer
84 views

SRAM-Logic Block Diagram

I am a beginner and I am trying to understand the block diagram of a Static RAM. I want to draw a "256x4 bit SRAM" block diagram. According to some information I collected from the internet I managed ...
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0answers
49 views

Can a classical Toffoli gate be built from irreversible gates?

The Toffoli gate is a reversible gate with three inputs (A, B, C) and three outputs (S1, S2, S3) generated as S1 = A S2 = B S3 = AB ^ C It can be implemented in a classic way using the following ...
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2answers
56 views

How to create a switch that when pressed opens, but after a time delay returns to the original state?

I am creating a buzzer driver that turns on when the output of an AND gate goes HIGH. What I would like to create is some way to shut off the signal to the buzzer by opening an SPST switch, but the ...
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1answer
63 views

boolean algebra question regarding how to simplify a 5 input circuit

Background: I'm teaching myself computer architecture because I do not have a technical degree and want to learn this even though my finances won't ever allow me to have a formal education. I am doing ...
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1answer
40 views

Eliminating power-on state changes caused by input signal fluctuations

I have a circuit that uses several comparators to read an analog input signal and control some downstream digital logic. When the device powers up, the logic states fluctuate because the input signal ...
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2answers
78 views

Is it possible to toggle a pin between “ground” and “not connected”?

I am trying to control a pump (ismatec ecoline V380) from a microcontroller (xmc4300, infineon) using an analog interface. The pump takes several inputs, most importantly: the speed (from a current ...
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1answer
40 views

Address decoding different bank sizes in 64K memory

I'm doing a small Motorola 6809-based computer project, and since I'm a bit rusty when it comes to boolean algebra I'm wondering if I'm doing my address decoding a bit too complicated for my simple ...
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2answers
63 views

Is the ultimate purpose of electronic circuits always to supply power to other devices? [closed]

I studied physics and computer science, so sadly im not too familiar with electronics. My question is kind of weird but hear me out: After reading a bit about (simple) electronic circuits, I got the ...
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3answers
71 views

Arduino Uno reading a logic 0 signal as 1

I have a program on my Arduino Uno that needs to execute quickly, so I'm trying to carry it out by dealing directly with registers. I made a few recent changes to my code, which was originally working ...
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3answers
75 views

Why is my Gated Latch not a Gated Latch?

After watching the excellent Carrie Anne's Crash Course Computer Science #6 (https://www.youtube.com/watch?v=fpnE6UAfbtU), I tried to design a Gated Latch in Logicly. I played with it a little, and ...