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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Digital multimeter repairing [on hold]

i have a sign of battery on display of MY digital multimeter and it was giving no reading except "-1" all the times with that battery sign .. i changed the battery but it doesn't worked ,,, i have ...
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1answer
33 views

Problems reading the RC1 pin on PIC16F887

I have this kind of problem, that pin RC1 always reads as 0, even when it has high voltage connected. All other pins of PORTC ...
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2answers
39 views

What is the function of multiplexer boolean expression?

Here is the image of multiplexer: May I know, what is the output form of Boolean expression, how it is working function? Can anyone help me to guide me? Any help would be highly appreciated,
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2answers
42 views

Using a single inverter to turn a light off

I'm planning on adding two strips of LED lights to the edge of my headlight enclosure. This is obviously an aesthetic "mod" however I'd like it to be semi useful as well. I'd like to be able to wire ...
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1answer
54 views

Can I use an AND gate before a clock input?

Can I use an AND gate with a clock input? For example, in the picture below, I have a positive-edge D flip-flop. I'm using an AND gate with the Select_chip input and the Clock input but I'm not sure ...
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1answer
26 views

Constructing a Sequential Circuit with two D Flip Flops

A sequential circuit with two D flip flops (A and B), two inputs (x and y), and one output (z) is specified by the following next-state and output equations: A(t+1) = xy' + xB B(t+1) = xA + xB' z = ...
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5answers
61 views

Generating a PWM ramp signal using logic gates

I have a microcontroller outputting a ramp signal on an I/O pin in PWM form. i.e. the duty cycle steadily increases from 0% to 100%, then drops to zero and repeats. After smoothing I end up with a ...
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1answer
124 views

Can logic analyser show high impedance state?

Quick question: are there logic analysers that can show us high impedance state in circuit? I could only find information about different voltage levels for TTL and CMOS, but couldn't find clean ...
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0answers
22 views

Using two 4-bit registers, AND and OR gates and inverters, what would be a one bit slice of the logic diagram that implements all of the following?

C0: R2 <- 0 (clear R2 synchronously with the clock) C1: R2 <- R2' (complement R2) C2: R2 <- R1 (transfer R1 to R2) The control variables C0, C1, C2, ...
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1answer
44 views

Logic Gate Cookbook [closed]

Is there a concise book that brings together all of the different Logic devices that can be implemented with basic logic gates? I have several digital/computer architecture books that have the ...
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0answers
13 views

Multisim 11: any way to display logic signals without use of probes?

So I have a large (pure logic, no electric components) circuit I need to debug. Is there any way (an addon or something) to make the wires display signal that is being transferred on them? (like, 1 - ...
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1answer
45 views

NOT gate with an NPN (2N3904) transistor not working?

I have the book Getting Started In Electronics, by Forrest M. Mims III, and it has an RTL NOT gate schematic that looks pretty much the same as this: About a month or two ago, I was starting to get ...
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1answer
27 views

Can diodes be used as an OR gate when I use RTL for other gates?

I have been using RTL (Resistor-Transistor Logic) to build things like NOT gates, or any other types of logic. If diodes control the flow by letting electricity only flow one way, then could I use two ...
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1answer
41 views

Allowable rise rates for logic families

The 74HC595 and the 4094B shift registers are quite comparable in their functionality. However, under the hood there are many differences in their specifications, e.g. the supply voltage range. I can ...
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2answers
55 views

74LS163 Counter Exhibits Constant Voltage on an Input Pin

I built a circuit that uses the 74LS163 synchronous counter. I am using in such a way that I reset the counter, using the /clear input pin, externally via and LPF connected to a tactile switch. The ...
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1answer
50 views

PIC 18F PORTA pins as input

I am working on PIC18F4550. I have configured PORTA Pin0-Pin3 as inputs using following code PORTA=0X00; LATA=0X00; ADCON1=0x0F; CMCON = 0x07; TRISA =0XCF; and ...
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2answers
55 views

Real time digital audio frequency changing device

I want to make a device, which takes an AC audio signal like a guitar pickup signal, or piano or what have you as input, and changes the pitch using this function: ...
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2answers
65 views

Numerically Controlled Oscillator (NCO) Sample quantity

Ive been doing some research on NCOs and some initial information (or lack of information) is bugging me. Ive read a few articles on this topic: FPGA based NCO Blog on NCOs But i still don't ...
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7answers
310 views

circuit to simulate pressing a button twice

I need a circuit that when reading a push button input will activate a relay for 0.5 seconds ON - 0.5 seconds OFF - 0.5 seconds ON then stay OFF until the push button it's pushed again. Thank You. ...
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3answers
132 views

How Can A Coded Firmware Control Hardware [on hold]

I really want to know how could a virtual coded program really affect and imitate and animate a piece of hardware. I Have Always Seen The Diagram Of Processors In the Book Showing ALU and CPU as The ...
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2answers
74 views

Bus value if some pins are floating

I'm working on plugin for simulation software (digital IC only). For example there is 8 bit bus. User wants to read it's value. On plugin side I check each pin's state. It can be 1, 0 or undefined. At ...
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1answer
37 views

How to design 4 input Xnor gate

Ok I want make this 3 input device 4 input legged.Any suggestion?
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3answers
70 views

Solder joint used between copper wires and a button switch is behaving strangely. I don't think it's a cold joint

The circuit I'm attempting to construct: I'm constructing the circuit shown in the above image, but I'm experiencing strange behavior when I solder on the switches and test the circuit. The ...
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1answer
36 views

Analog to digital converter question

What is the maximum input frequency that can be applied to a dual slope integrating type analog to digital converter? Is it \$f_{clk}/2^{n+1}\$? or \$f_{clk}/2^n\$? And does the time required to ...
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3answers
171 views

Logic gate using transistor

I think it should be OR gate, my reasoning explained below: If A is F/0V and B is F/0V then BaseEmitter of both are reverse biased and thus no current flows, (BaseCollector is at zero potential ...
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2answers
55 views

Is inverting the output of a CMOS network a bad practice?

I am an Electronics & Comm. Engg. 3rd yr. student and we are learning CMOS logic for the first time this semester under the subject VLSI design. While designing for the logic equation: \$Y= A + ...
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2answers
95 views

I know basic gates but not their structure

I know everything except the structure of logic gates. Recently a HighOrderThinkingSkill question asked the gate from structure where I was totally stumped please help me: simulate this circuit ...
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1answer
89 views

Help me fix my logic circuit

I'm trying to learn more about electronics. So to do that I decided to implement boolean logic gates in a circuit simulator. So far I have made NOT, AND, NOR and a S-R latch. I wanted to try connect ...
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2answers
77 views

High voltage to TTL conversion

I'm designing a circuit that is going to sense the existence of high voltage DC(400V+) via microcontroller. I've already designed it for AC voltage using an optocoupler; however, I will not able to ...
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2answers
45 views

How are stuck at faults in a combinational circuits considered

I came over this example given in literature explaining the stuck at faults (possible) to be considered in a combinational circuit. I don't understand why g, h, i nodes in the circuit are considered ...
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1answer
80 views

Logic Circuit Design

I am not Electrical engineer but I am taking digital logic classes. I have a homework but I didn't understand how to do it. This is the question : The temperature control logic accepts an 8-bit code ...
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1answer
46 views

Classification of logic hazards in combinatorial networks

I've got a doubt about the classification of logic hazards in combinatorial networks I could not dissipate searching the net. What I know is that: a static hazard happens when an input transition ...
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2answers
56 views

What is The Difference Between PAM And ASK

In Digital Communication can We use PAM in place of ASK The Diagram is Given as The Book Later Talks about Symbols. I Don't Understand, in PAM we don't have specific signal as input like in ASK ...
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1answer
23 views

Combining CMOS and TTL logic

I have a bunch of 74LS383 (TTL octal transparent latch with three-state outputs) and MM74C83N (CMOS 4-bit binary full adder) that I would like to connect together. I need to connect the output of the ...
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1answer
29 views

How is this method of addressing memory scalable?

I've been watching Computerphile videos about memory. I'm currently watching this one In it he goes over using some logic gates to address flip flops. He explains that is is cumbersome to add a wire ...
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26 views

Forming Larger Decoders / Encoders

I was asked if we could implement a 4x16 decoder with different sets of smaller circuits. two 3 x 8 decoders with one 1 x 2 decoder, five 2 x 4 decoders four 2x 4 decoders and three 1 x 2 decoders ...
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1answer
48 views

How to implement a xor gate with nand gates

I try to resolve a problem, how to implement a xor gate with nand's gate. A xor B = A'B + AB' So, this becomes : A xor B = A'B + AB' + AA' + BB' = A(A' + B') + B(A' + B') = (A + B)(A' + B') = ...
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2answers
58 views

Muxes, Adders, Comparators, and Gates

This question is actually from one of my previous discussions, which I still don't understand how to implement. The goal is to use abstraction to design a circuit, which converts two-digit ASCII ...
2
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3answers
319 views

what is quadruple in IC gates

What is quadruple in integrated circuit gates? Is it just about 4 gates inside the IC or anything else more special?
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1answer
47 views

S-R latch / flip- flop question

First I want to ask, why are S and R inverted when comparing an S-R latch with NAND and NOR gate. It just seems odd to me that they're being inverted. Secondly, why is a multi-transition behaviour a ...
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3answers
102 views

How to turn continuous signal into a short pulse using logic gates?

Basically, I want to turn a continuous "1" into a short "1" pulse then "0". I'm new to logic gates, apologies if it's too obvious.
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2answers
61 views

Logic gate with certain truth table needed

I'm making a thing in Multisim and for it to work I need a logic element which works like in this truth table: A B X 0 0 A 0 1 0 1 0 A 1 1 0 So, if B ...
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2answers
53 views

How did they get to the SR-latch with 2 NOR gates?

I understand SR latches and how they work, but I was trying to recreate the SR latch to see if I can get to the same well known circuit with 2 NOR gates. However if I write the following logic table ...
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1answer
35 views

How can I implement a K-Map with negative feedback?

How do you describe a boolean function using a K-Map in such a way that the boolean function depends on the previous value of this function?
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1answer
140 views

Building binary to two’s complement converter

This is a sample exam question, and no solutions were given I don't understand the concept of 'one bit slice', and I've tried to understand the meaning of the table, I stared at it for a long time, ...
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0answers
19 views

JK flip-flop and sequence network

State diagram of the sequence network S looks like the following for a jk flip-flop: Is this the right truth table for it? ...
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0answers
52 views

Karnaugh Map from this expression?

Here is the expression I am trying to represent in the Karnaugh Map: This is what I have done: Can somebody confirm if this is right? I have done the truth table right, however I am having doubts ...
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1answer
31 views

XOR in domino logic

I was reading about domino logic and I noticed that several resources mention that domino logic can't be used for inverting functions like (NAND, NOR) and also can't be used for XOR. I understand why ...
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2answers
286 views

What would be the output of A = 0100 and B = 0111 with S = 1 in a 4-bit binary adder-subtractor?

I understand S = 1 means subtraction and S = 0 means addition. So then, the output would be the result of 0100 - 0111. But since it's negative, I'm not sure how it would be represented. I know the ...
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68 views

Discrete logic multiplexer

I posted a more in-depth outline of what I'm doing here, but basically I'm building this circuit (for n=3): The circuit displays an output based on the combination of three three-input DIP ...