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.

learn more… | top users | synonyms (3)

1
vote
1answer
22 views

Help me implement the crossroad traffic lights using multiplexers 4/1?

I came across this problem and it has a solution and everything, but I don't understand it. Here's the illustration: So, the picture shows a crossroad which has sensors along the higher-priority DC ...
0
votes
0answers
35 views

How to determine IC function

I have a lab assignment coming up in which my instructor is tasking us to determine the function - essentially construct a truth table - of several unknown integrated circuits of varying difficulty. ...
1
vote
1answer
27 views

Number of possible IOIO pulse inputs

Looking at this page it mentions that double precision digital pulse input (32-bit timer) can be divided into 2 single precision 16-bit timers. https://github.com/ytai/ioio/wiki/Pulse-Input It says ...
0
votes
0answers
44 views

What careers do the workers at a computer part manufactring (or design) company have? [on hold]

What's the profession/career of people who design and are in charge of manufacturing CPUs, DRAM memory modules, hard disks, motherboards and other digital computer parts and what's their role in the ...
0
votes
1answer
45 views

Termination of digital lines

So when exactly is termination of a digital signal required? In my case, I'm dealing with a 1.8V signal that comes from an FPGA. This signal connects to a high impedance input of an OpAmp. The trace ...
0
votes
1answer
55 views

Understanding operation of decoders and multiplexers

I just started to study decoders and multiplexers and I saw this task which I'm not sure how it's done. Can you please explain me (solution attached): Using the decoder DEK 3/8, construct the decoder ...
0
votes
2answers
39 views

Feedback loops and Logic Gates

Setup: a simple 3 bit incrementer that is both connected to a digital display and to itself simulate this circuit – Schematic created using CircuitLab Assuming that there is no clock to ...
1
vote
1answer
38 views

Why can't I get the expression for this karnaugh map using minterms?

I am getting ab + bc'd' + ab'c', But I keep failing, it doesn't work for my table. Can someone explain to me what am I doing wrong? This is using minterms.
0
votes
1answer
48 views

Need help understanding LCD Power Enable circuit

Here you will see a schematic for an LCD panel. Header on the right, panel on the left, backlight power circuit on the bottom left and enable circuits in the middle. I am having difficult ...
0
votes
0answers
38 views

Choosing a DAC for Amateur Radio applications

I'm looking to make a software defined radio, and I'm currently looking at what DAC to choose. I'm fairly new to this area of RF design, so I don't know what specs to look for. Most of my signals ...
0
votes
0answers
46 views

How can I use 3-input NAND gates to create a 1-bit full adder?

I have already implemented a 1-bit full adder with 9 2-input NAND gates. Out of curiosity, if the number of inputs on a NAND gate changed, say from 2 to 3, would the truth table and full adder ...
1
vote
3answers
139 views

Digital Frequency tripler design

How can I implement a digital circuit using boolean logic gates? As you see, on each rising edge, an oscillation happens and signal returns back to HIGH logic level after oscillation. This is also ...
0
votes
2answers
56 views

Oscilator with Limited oscillation count

I did implement below oscillator using cascaded not gates. I want to know how can I change such circuit to oscillate only for limited number of oscillations? e.g. I want designed circuit oscillate ...
0
votes
1answer
23 views

Digital Logic current flow IFF current in different circuit

Using only digital logic gates, how do you make it so a path is only open for current to go through if there is current flowing through a different part of a circuit. Specifically, block current from ...
1
vote
1answer
41 views

What am I doing wrong? Logisim problem

I'm doing my homework for digital logic in logisim. I need to make function solver for this function: f(x,y) = 6*y-8+x in 4bit arithmetic. Here is my solution but it is not working for some inputs. I ...
0
votes
4answers
169 views

How to implement 8-bit 2:1 multiplexers on a PCB?

I need to implement a 2:1 multiplexer for 8-bit data. That is: as inputs it should take two 8-bit numbers and a Select line; and as output an 8-bit number. I could use two 74HC(T)157s (this is a quad ...
0
votes
1answer
55 views

Why is there a guard band in ADSL

I recently learned about ADSL and its modulation method DMT. I know the frequency spectrum is split up into a number of orthoganally spaced bins: Voice(PSTN) - Guard Band - Upstream - Downstream ...
0
votes
2answers
44 views

Saleae logic analyzer, exporting data to .csv file

I have bought Saleae Logic Analyzer, everything is good except the fact that when I try to export data to .csv file and then open it using MS Excel I get all data in one column. I would like to get ...
0
votes
1answer
102 views

How can I switch power between two hard drives using transistors?

Application I have two hard drives that draw approximately 1.1A / 1.5A on their 12V and 5V power pins. I have several 2SA1020 PNP transistors which are rated 50V 2A and was hoping to use them to ...
0
votes
1answer
70 views

Simple digital circuit schematic question

Below you'll find the schematic for a circuit I have to build and analyze tomorrow for a lab. simulate this circuit – Schematic created using CircuitLab (Note that the blocks I've shown ...
0
votes
3answers
39 views

Powering on specific pieces of circuitry in sequence

I'm trying to power on specific pieces of circuitry in sequence, and have one piece active at a time. I thought a decade counter would be the way to go but most people seem to think a decade counter ...
0
votes
1answer
55 views

VHDL process causes errors

I'm new to VHDL so I just have a question to ask about why this produces an error. I have an ALU defined in VHDL: ...
0
votes
2answers
56 views

How to get a simplified circuit out of three smaller circuits?

I completed the three basic tasks in three independent circuits; however, the optional part is a bit confusing for me; how could I simplify them in one single circuit? Should I find inspiration in the ...
0
votes
2answers
72 views

Creating a basic ab + a'c circuit on a breadboard, how are the inputs placed?

I am supposed to design my first circuit on a breadboard and the output will be defined by the logical formula: ab + a'c The problem is I don't understand how are the inputs placed, a b c as inputs ...
3
votes
5answers
336 views

Implementation and usage of gray code?

Generally and briefly, are there any direct application of gray code in electronics? If so, what are they?
1
vote
1answer
28 views

how to compare each and every element with other element of two multi dimensional arrays in verilog?

I want to compare two multi dimensional arrays with each element of one array with the other array. What is the procedure to make it possible? ...
2
votes
2answers
71 views

How to draw a timing diagram

How can I draw the timing diagram for the circuit below? What are the steps? I can't understand even how to read it. What do I do with the numbers below each logical port, eg: 5ns , 10ns etc)?
4
votes
1answer
55 views

Best way to OR two LED signals

I am recreating the Adafruit Powerboost 500c Circuit, but I want to reduce the LED's I need down to one. It has four LED's to represent the following signals, next to which I put the desired behavior ...
0
votes
3answers
68 views

Can I use 1 resistor for both inputs of an RTL NOR gate?

I am working out the ideal RTL NOR circuit to use as universal gates for a large project. Based on what I've found on Wikipedia, to implement a NOR gate using BJTs and resistors, we have the ...
0
votes
3answers
77 views

Finite-State-Machine-based digital design

How do I implement a specific digital design using mealy model and then implement the same design again using Moore model ? Can anyone provide detailed steps ? Thanks. Update: In the digital logic ...
0
votes
2answers
44 views

Best way to use multiple decoders for an LED matrix

I'm designing a 16 x 32 RGB LED Matrix and its controller / driver board. So I've designed a couple of solution approaches and I'm wondering if there is a better way to drive multiple 4 to 16 line ...
2
votes
1answer
165 views

A circuit having 2 inputs and 2 outputs

I am going to design a circuit that should have 2 inputs and 2 outputs. when both inputs are low both outputs should be low when input 1 is high and input 2 is low, output 1 should be a square wave ...
2
votes
2answers
76 views

Only Allow One LED To Light Up

I'm trying to design a simple circuit for a 4 LED indicator. Its basically like a game show device that has four buttons. The first one to press their button would have their LED light up and "lock" ...
0
votes
1answer
92 views

open collector digital output

I have a digital output board design which has 32 open collector (sinking) outputs which can be connected in parallel to drive a resistive load. The collector of each output transistor is connected to ...
1
vote
1answer
22 views

ALU once compiled giving errors of missing source signal?

This is ALU, not sure whether if it is all properly connected but all blocks are the correct ones. This has 3 4 bit latch registers, 5 2:1 ultiplexers, 4 4 bit adders. Can anyone help me? The problems ...
0
votes
1answer
50 views

How to generate bar using decoder

Ic74154 decoder generate active low o/p i.e for example if input is binary 5 , 4 becomes low. I want a circuit which will give output when i/p is binary 5 then o/p is low for 0 to 4.It is possible by ...
3
votes
2answers
127 views

walking ring sine wave generator

simulate this circuit – Schematic created using CircuitLab Here is the low pass I have used. I used the 347 op amp just because it was cheap from a local surplus house. I will get ...
0
votes
1answer
119 views

Electronic schematic of 7408 and 7432 logic IC

How are these schematics different from the traditional BJT logic gates that we learn in high school? Schematics:AND GATE and OR GATE.
3
votes
4answers
211 views

What are the rules for combining transistors to form digital circuits?

I just read Harris/Harris - Digital Design and Computer Architecture and in it they described how AND/OR/etc gates are made out of transistors. I read the book for fun (I'm not an EE person, my ...
3
votes
2answers
208 views

Do I have to power-on reset CMOS counters?

I am designing a project that contains several CMOS counter ICs (CD4017 specifically). What is the state of the counter on power-on? Do I have to incorporate circuitry that pulls the reset pin high ...
0
votes
1answer
44 views

Making a clock cp for counter, using a photodiode

I need to make a device that counts light impulses, basicly a light detector counter, i need help with my counter cp, how to implement a photodiode(can't find phototransistors in the stores) to do ...
3
votes
1answer
49 views

D-domain vs Time-domain (Digital Linear sequential ciruits)

I wonder if anyone could give my a short explanation of the D-domain and T-domain in linear sequential digital ciruits. Got an exam in about 3 weeks. Last chapter is very theoretical. I got a hard ...
0
votes
2answers
75 views

EEPROM Reading/Writing without Use of Programmer

I am designing a small password based door lock project which is fully made from logic gates and ICs without the use of any sort of programmable devices(it is a simple university project for the Logic ...
0
votes
1answer
35 views

Digital Output Control over ECU discrete inputs

I am looking for a better solution or method for controlling the discrete inputs to an ECU using a simulator and signal conditioning. The discrete input signals from the ECU provide an output of 15V ...
0
votes
4answers
91 views

Circuit to Detect State of Output Pin

I am trying to implement a circuit using mosfets that will detect the state of a pin with 2 outputs. The input (I) to output (O) relationship I want is this:
0
votes
3answers
54 views

Simple switching between clocks using oscillator disable pins

I am working on a circuit where I need to use different clock sources. I am using two HCMOS oscillators. Both oscillators have an disable pin. When disabled, the clock output buffer is placed in ...
0
votes
1answer
62 views

Is there a way to use a depletion mode MOSFET “inverse”?

I aquired some surplus led strips and I want to make a certain control circuit for it. I took another goal of using only the components I have laying around. I found a nice reclaimed power MOSFET to ...
1
vote
3answers
146 views

How to switch between two input lines based on a digital pulse

How can I switch between two inputs based on a digital signal. I would like to have the Input 1 connected to the Output for the duration of the pulse and Input 2 connected to Output when the signal ...
0
votes
1answer
96 views

NAND gate in proteus

I am trying to make a JK flip flop circuit in proteus but 2 of the nand gates does not seem to be working. There are no errors provided. Two of the 2-input nand gates does not seem to show output ...
1
vote
1answer
89 views

H Bridge Control using Raspberry PI / Micro controller

I am looking for input on this circuit that I have designed. I am currently working on a project called the Net-EEL RC Car. It is an RC car that will be controllable using Network Socket Servers / ...