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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JK Flip Flop Counter

I am designing a counter circuit that will perform the following function: A sequential circuit with three flip-flips A, B and C and two inputs X and Y. If X=0 and Y=0, the counter remains in the ...
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1answer
42 views

Driving 50-pin e-ink display with one chip?

I'm trying to connect this 50-pin e-ink display to an Atmel ATmega328p for a hobby project. The biggest design challenge I'm facing is connecting all the pins from the display to the MCU in an ...
0
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1answer
29 views

Level shifting 8 output IO Expander from 0V-5V to -2.3V to +2.3V

I have a circuit problem that I'm trying to find a solution for. I have an 8 output IO expander which outputs 0V-5V. It is running analog switches which have a Vdd and Vss of +-2.3V. Using the 5V ...
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0answers
28 views

What are some different metrics that can be measured in a circuit for implementation in FPGAs

First of all, I'm a CS grad, meaning that my knowledge in electronic topics is limited. I'm sorry if I'm confusing things. I've been asked by a professor to measure some metrics in a VHDL-programmed ...
3
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1answer
53 views

Half Adder and Two Function, A Contest Questions?

I ran into a 2013 contest question on computer-science filed. What is the following True about F and G function. (The output ...
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1answer
39 views

Necessary tools/environment for writing VHDL RTL? [on hold]

I decided to implement my own MIPS computer using Digital Design and Computer Architecture book. I decided to use VHDL since Peter Ashenden's "The VHDL Cookbook" I think is a great starting point. If ...
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0answers
15 views

Finding the State Table for a Synchronous Sequential Circuit

I'm learning about circuits in my ECE class and want to make sure that I have the correct table. I am working with D flip-flops and T flip-flops in this circuit. I want to make sure that I have the ...
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2answers
36 views

Working of 2 input AND diode register?

According to the description that I am reading in book it says that you need to connect +Vcc to both the A and B in order to get the output 1 at Q. I don't really understand this. What does the ...
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1answer
34 views

Rising edge pulse detector from logic gates

The circuits I describe are entirely made of 7400 series logic gates (7402, 7404 and 7408 ic). I'm trying to build a rising (positive) edge pulse detector using logic gates. The following circuit ...
2
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1answer
38 views

is the drawn diagram right for detecting a sequence of three or more 1's?

i saw this diagram in my textbook for the problem : Suppose we wish to design a circuit that detects a sequence of three or more consecutive 1’s in a string of bits coming through an input line ...
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0answers
60 views

Generating very low noise control voltage from an MCU?

I want to control the THAT Corp. 2180 VCA using an MCU. I'm using the positive VC input (it has one positive and one negative and they are symmetrical). The range that I want to generate is +/-540mV. ...
2
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1answer
50 views

Question about logic gate optimization and CMOS implementations

I am struggling with a conceptual question surrounding logic gates and how they're efficiently implemented in CMOS circuits. For example, let's say I want to implement a NAND gate. If I didn't know ...
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0answers
35 views

How to implement the bit count using logic circuit?

I am very interesting in these bit counting problems, since there are many programming implementations such as: http://gurmeet.net/puzzles/fast-bit-counting-routines/ Also someone discussed the ...
0
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2answers
41 views

K - Map essential and non-essential prime implicants

Here is the min terms for K - map simplification: F = summetion m(0,2,3,5,7,8,10,11,14,15) May i know, if i draw the graph means, what will i get Essential and ...
0
votes
3answers
98 views

Behavior of logic gates when one input is undefined?

I tried to understand to behavior of this circuit when it has no voltage supply at first which means the current state is neither 0 or 1. You can say that there is a 'nothing' input. Then when the ...
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0answers
24 views

SR Flip-flop builded from 2 SR-Latch

I just study about flip-flop in my class and this is the picture from the slide my teacher used that explain the construction of SR Flip-flop However, I find something was wrong with this figure. ...
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1answer
19 views

How to properly check/evaluate Multiplexer design implementation?

I am not electrical engineer at all. I am just participating in this course. I have been struggling for 2 days to implement Mux8Way16 - a multiplexer which has 8 different 16-bit inputs. How can I ...
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1answer
39 views

how to minimize the product of sum from canonical pos?

I have a canonical pos form which is derived from SOP by using demargon law. POS: (A+B+C) (A+B+C') (A+B'+C') So i need to reduce this to min pos. May i know, how to get like this form (A+B) ...
3
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3answers
94 views

Logical Design Operation, A Simple Questions?

I'm so sorry if I ask my first question that so simple. My filed is Math and Computer science. I self-study Digital Design. My challenge is how we can find the operation of the two following ...
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2answers
49 views

Finding number of don't care conditions

I'm new to these forums and have very little background in electrical engineering. I'm trying to figure out the number of "don't care conditions" based on an input of two numbers, each 0-9, for ...
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1answer
31 views

Code Converter Circuit

Make a BCD to Excess-3 Code Converter by using a binary to decimal encoder and 4 OR gates. I know how to make a binary to decimal encoder, but how do I proceed from there?
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1answer
56 views

Calculate a function with logic gates

I have to build a circuit, with logic gates, that calculates a function \$f(n) = 2^{2^n}\$ where n is a 4 bit number. I can't figure a way how to do this. I tried to use 2-to-4 decoders but I failed. ...
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0answers
27 views

arduino detech signal from bike pickup coil

I want use the arduino detech signal from bike pickup coil for calculate rpm and delay ignition. Should I use a good circuit? I just started the electronic Thank you
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2answers
45 views

Detecting HI-Z state of charge controller

I have been building a Li-Ion charge controller with MCP73831. The STAT pin has 3 states as shown below: The circuit I come up so far is this: Is there a way to detect the HI-Z state with ...
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1answer
29 views

Design a Decoder using Logic Gates to display letters on a 7-Segment Display

The task I got is to design a similar circuit to a standard BCD to 7-Segment decoder, except only using Logic Gates and to display a eight letter character word, for example: SHELFLES As I have ...
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0answers
29 views

How to construct a 4x1 MUX using FIVE 4x1 MUX(s) [closed]

I've been given this question and I cannot figure out a way to use 5 MUX 4x1 MUX to construct one single 4x1 MUX. Any help would be appreciated.
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7answers
1k views

Why are 11, 111, 1111, … equivalent to -1 in two's complement? [duplicate]

According to two's complement, the binary numbers 111 and 11111111 are equivalent to -1. Why or how are the binary numbers 11, 111, 1111, 1111 1111, etc. equivalent to -1 in two's complement? Can ...
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0answers
25 views

4-to-10 Decoder truth table

I was given in a lab a 4-to-10 decoder truth table. I was wondering why it stops at 10 inputs. However, my circuit could hold up to 15 instructions. So for instance, I built my circuit and it went ...
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1answer
34 views

designing a sequential circuit by having it's value table?

when learning about combinational circuits we could draw the truth table and construct a circuit by the help of min/MAX terms . and we could further simplify it with Karnaugh maps . BUT how we do ...
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2answers
40 views

How Verilog decides upon simultaneous events

Say we have a function, simple as f(x) = x. Say we have a clock that ticks every 20 nanoseconds, and say we change x as we wish. ...
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5answers
118 views

Is sequential logic really required to solve some types of problems? [on hold]

Can all digital design problems theoretically be solved using only combinational logic, or are there specific examples that have to be solved sequentially? I read that sequential logic is only ...
0
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0answers
27 views

Analog to digital converter for PIC18F2420

I am trying to get digital value in PIC18F2420 from analog input. The analog input is connected to RA0 port. Following is the code. I am getting 0 value for my interger "myvariable" when i look in ...
0
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1answer
47 views

Insight on analog and digital Lock-in amplifiers operation principle?

As far as my knowledge goes, in the analog case, the discrimination of the, low S/N ratio, signal is done by (demodulation) comparing it to local oscillator with almost identical frequency and then ...
3
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3answers
167 views

Why All 1's used as a second input in decrement operation of ALU?

Suppose the first four data inputs are X (X0, X1, X2, X3) and the second four data inputs are Y (Y0, Y1, Y2, Y3) in a 4-bit ALU. Why "All 1's" are used as an input for Y in the decrement operation of ...
0
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3answers
113 views

**Solved** D Flip Flop Frequency Divider - Simulates but doesn't work on protoboard *Pics/Simulation Data Included*

I'm having a problem that is probably trivial, but I can't seem to make any progress. Just a disclaimer, I'm an analog EE and digital design isn't my strong suite. That being said, I'm trying to build ...
2
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2answers
195 views

How to protect a MAX232 from PIC programming high voltages?

This question is derived from this Board review thread, I thought it would be preferable to make it a standalone question. I want to be able to reset a PIC remotely using the only communication port ...
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1answer
49 views

Do shift registers refresh?

Say there are 2 Shift Registers chained together with the following values SR1 : 11111111 SR2 : 11001111 The data is written to SR1 and then to SR2 like: ...
0
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1answer
41 views

# of gates in a 32 bit ripple carry adder?

# of gates in a 32 bit ripple carry adder? I know the answer to this question is (4X32=128). But could someone please explain to me why this is the case? I don't understand how they got the 4? FYI: ...
0
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1answer
59 views

Exceeding voltage ratings on microcontroller pins using series resistor

I've been designing a circuit which requires a microcontroller to read a voltage above its current VDD or below its current VSS. I've done this once or twice before by putting a large-ish resistor in ...
0
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1answer
72 views

Board review: is this PIC16F877 RS232+ICSP board correct/robust?

I want to make my own development board based on a PIC, to make a RS232 bootloader from scratch. It's been a while I haven't used a PIC, and it was on a ready made development board. I've looked ...
0
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1answer
71 views

Why do I experience a voltage drop between logic gates when combining multiple gates (7408 and 7402)

I am trying to combine logic gates (using ICs instead of trying to piece them together using transistors or MOSFETs). Below is the simplest example of what I am trying to accomplish, though ...
0
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2answers
45 views

How to convert this NOT/AND/OR counter to an all NAND counter?

Sequence: 000,010,111,001,100... Have to build it using a JK Flip Flop for Q0 and 2 D flip flops for Q1 and Q2 and all NAND gates. Basically I have no problem building this counter with just the ...
0
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2answers
38 views

How does design compiler constrain combinational paths?

This is with reference to the question asked here: Finding Critical Path of Combinational Logic. When design compiler command report_timing is run, it appears the ...
0
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1answer
112 views

How to interface PWM output from a microcontroller with power MOSFET?

How to interface PWM output from a dsPIC30F6012 microcontroller with power MOSFET TrenchFET like SiE818DF? I want use PWM to control the brightness of the LEDs. Four PWM channels, one PWM per channel. ...
0
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0answers
28 views

how to solve mosfet size match error in tanner 14.1 for 0.18um process

I have refer your answer for spice simulation. but it is not going with 14.1 version. please help me with respect to 14.1 version.
2
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3answers
249 views

SR Flip Flop: NOR or NAND?

I started studying flip flips recently and I am stuck at this point: At some video tutorials, people explain the SR Flip Flop like this: So they use NAND gates, producing a transition table like ...
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1answer
22 views

Peak current requirement for switching logic

Is there a way of estimating peak current requirements for sets of logic gates? This is to qualify the regulator. I have a Gumstix Parlor board with a 1.8V regulator (MIC5247) at 150mA on it. This is ...
0
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1answer
51 views

need help identifing IC's and symbols from a diagram

I am tring to make a circuit and need to purchase the required components but there are some IC's that I can not identify. I tried to google them up but I haven't found anything helpful yet.I also ...
1
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2answers
72 views

Analog vs Digital attenuation for an ADC

I'm designing a digital parametric EQ that will go in front of a high gain guitar amplifier. I want to have the option to boost signals up to 12dB. I plan on implementing this either by attenuating ...
0
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1answer
31 views

Earle Latch Properties

I just read a textbook describing the Earle latch but no truth table was given for this device , does anyone know this truth table. Also the book states that by varying the complementary clocking ...