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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24 views
Which minimization for the KMAP is correct
In the KMAP shown below, I can think of three different ways to minimize it. How can we determine which is correct? I have listed the minimized equations and why I think each one is acceptable below.
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2answers
27 views
Pulse Train Sampling Rate
Assume I have a pulse train with frequency of F Hertz. A normal square wave has all odd harmonics. From Nyquist, if I want to "Reconstruct" the waveform, sampling frequency Fs should be at least 2*(...
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1answer
33 views
MCP2551 to monitor CAN activity without processor
If I was to connect an MCP2551 to a CAN network and link the TX and RX processor connections would this allow monitoring of any activity on the network as just a 5v pulse train without disturbing the ...
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1answer
47 views
Integrator circuit time interval
I am designing an Alpha particle time of flight detector which consists of two scintillators separated by 5cm of vacuum (few Torrs).
The two scintillators are connected to two separate avalanche ...
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1answer
78 views
Question about AND gate using diodes
Consider the circuit below:
I'm assuming ideal diode model(\$V_{ON} = 0V\$). If \$V\$, \$A\$ and \$B\$ are all 5V, the diodes will be reversed biased and no current will flow through the circuit. ...
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2answers
56 views
How to implement a boolean function using just NAND or NOR logic Gates [on hold]
How to implement function mentioned below using Nand or Nor gate
Y=x1+ x2 x3+ x4'x5'
Where y is output
and x1,x2,x3,x4,x5 are inputs
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1answer
96 views
USB shield for analog and digital ground?
I'm new to Mixed-signal design and I'm having trouble deciding how to connect my digital and analog ground. I'm doing a 4 layer design, so I have a split ground plane.
As I understand, since I'm ...
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3answers
51 views
Is it possible to use DC-restoration as a half-wave rectifier?
A simple DC-retoration circuit:
seems to do the about the same job as a half-wave rectifier, is it standard to use these two circuit instead of each other ?
I tried to increase the capacitance of ...
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1answer
38 views
What matters, the rms or peak value of the Analog signal to choose appropriate ADC for digitization?
i have an 23 bit ADC with voltage reference of 1.4 V.
If my input Analog signal is AC with frequency 50 HZ and its rms ranges from 0.2 Vrms to 1.3 Vrms. Then its peak voltages will vary from 0.28 V to ...
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1answer
45 views
Voltage of pin set to high impedance? [duplicate]
Suppose a pin can be set to three modes, high (5V), low (0V), and high impedance (?V). What is the voltage associated with high impedance? I.e. if I stuck a probe on a pin set to high impedance, what ...
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3answers
79 views
Two TVs use the same antenna, but one affects the other
I’m having a problem with my TVs. I will call them TV1 and TV2. TV1 is Asanzo brand, and TV2 is LG 4K, which is much more expensive.
After replacing the antenna wall socket of TV2 (The TV is near to ...
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2answers
103 views
Prevent NPN Transistor Base-Emitter Current
I'm making a simple AND gate array out of 2n2222 transistors. Here is one cell:
simulate this circuit – Schematic created using CircuitLab
When Input "A", is disabled, and "B" is still on:
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0answers
43 views
Jellybean Radio Button logic Chip
Below is an LTSpice simulation of a 'radio button' circuilt.
Ignore the bottom button, I am working on a 'reset' mechanism to unlatch any of the other buttons.
The idea is that the button you push, ...
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0answers
17 views
4 Input /Output4x1 Mux Issue with bit amount
Good evening.
I am working to create a 4-bit Input/Output Mux. I started with a 1-bit input/output 4x1 Mux which I believe I built successfully. Then I attempted to use modularity to utilize the 1 ...
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1answer
41 views
Pipelined vs Low Latency implementation of cube of a number in Verilog
I was studying about FPGA design and then came across this terms Throughput and Latency. So the author provided an example of a ...
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2answers
75 views
Compare two numbers of four bits
I have two numbers both with four bits (a3 to a0 and b3 to b0 reading from left to right) and I would like to find out if a is bigger than b.
I have drawn a solution of mine and a short mathematical ...
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0answers
43 views
How do I get the FSM table from the given diagram?
Given one is question and another solution. I cant come to this solution. can anyone help here
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1answer
21 views
How do I get the sum and carry expression for ripple carry adder?
please check the photo and kindly let me know how to find the expression.
I know sum expression only with xor gate. Cannot come to this conclusion.
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1answer
67 views
Problems with input leakage current in a microcontroller
I'm trying to build a system in which a microcontroller receives (through one of its input pins) a logic 1 if a switch is pressed and a logic 0 if it's not. For that purpose, I want to implement a ...
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1answer
34 views
Sequence Detector with multiple inputs
The question:
Design an automaton that receives inputs X0, X1 and produces outputs Z0, Z1.
Z0 is 1 If the last two bits of X0 are the complement of the last two received on X1.
Z1 is 1 If in the ...
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1answer
29 views
Logic Level Converter (3.3v <-> 5.0v) returning HIGH for Low Volt. & High Volt. sides when nothing is plugged in. [Raspberry Pi]
The Goal
I have a Raspberry Pi that I'd like to control my treadmill with. The Pi's GPIO ports output 3.3v and the treadmill's motor control board only takes 5v signals. Because of that, I bought a ...
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1answer
44 views
Problem with my 8-to-3 line priority encoder using verilog gate level description
I am attempting to build a working 8-to-3 line encoder using gate level description in verilog. Although, I have working models, in terms of successful compilation and simulation, the recurring issue ...
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3answers
46 views
Converting an AC switch signal into a reliable Digital ON/OFF signal
I am working on a project to add some digital processing, using Arduino, to an old Electro-Mechanical Pinball Machine. Specifically, I want to detect the score reel triggering on the pinball machine ...
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0answers
14 views
On k-map, the problems on what to do when we have to compute two kmap
F(A,B,C) = min sum(0,2,4,6,7)
G(A,B,C) = min sum(1,2,3,6)
X= F +G
What would be the sum of minterms expression of X?
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3answers
1k views
What equipment do I need to test an eye diagram for USB?
I'd like to test USB full speed with a goal of testing high speed (480 Mbit/s), I have a tek scope that does 300 MHz (which I could upgrade to 500 MHz) and I'm looking at a 500 MHz differential probe. ...
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3answers
88 views
Measuring a binary number with maximum electrical certainty [closed]
I want to be sure, with arbitrary precision (let say, for example, with 10^-100 certainty), that I can check the following statement (in binary):
x = 49
That is, I want to check that a number that ...
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1answer
39 views
How to use multiplexor 74HC4067
I am using 74hc4067 IC(Multiplexer 4:16) for the extend the gpio pins can i use that gpio pins same time or not? and any one suggest about the ic how it is used?
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1answer
81 views
LOGIC GATES and logic circuits in a calculator
i am tasked to do a circuit using logic gates regarding the work of a calculator. it is said that how can we make number 3 shown in a calculator represented by logic gates. can someone help me?
i ...
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1answer
25 views
TL866 programmer schematic question
See the full TL866 programmer schematic
Below is the pin driver schematic for the MiniPro TL866 universal device programmer (page 2 of the PDF schematic). The L2, L3 and L4 are powered from VDD, ...
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1answer
26 views
Sense Connector Presence On BMS
I have a bit of a challenge and was hoping to get some ideas.
I have a BMS board that is connected to some batteries, and part of that BMS has an MCU. There are two connectors in the design, a data ...
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1answer
72 views
How to build a relay switch that resets when power goes out?
I'm trying to build a kill switch in my car so that when I turn the ignition, a button also has to be held down. When the power goes through, the button can be let go and the system stays closed until ...
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5answers
368 views
I don't understand why do I need to put a resistor between the gate and the source of a N-type transistor in this circuit
I have a diagram that represents a circuit whose purpose is enabling/disabling two leds basing on a logic programmed in a micro-controller.
In the circuit below, as far as I understand, there are two ...
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0answers
32 views
Trick/insight to I implement given boolean function with minimum numbers of given gate
I solved bunch of questions which give some function and then ask to implement it with minimum number of gates of specific type, each having specific number inputs. I was making mistakes in all those ...
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1answer
50 views
Number of prime implicants
How many prime Implicants are there, 2 or 3?
F(w,x,y,z)=Σ(5,7,8,10)+d(9,11,13,15)
I am confused if red block will be counted as Prime Impicant or not?
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0answers
78 views
Help with Espresso optimization options
I need to minimize some boolean functions. I found in some posts here that Espresso is a great open source tool to do this. I found this link where the different optimizations options for Espresso ...
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3answers
161 views
IC that would pull output to the ground, perhaps NOT gate?
I have a board with four relays on it. It has a standard Vcc, Gnd, and In1-In4 pins. I want to control it with Arduino or in my case an ESP32. However, I noticed that when output pin on my controller ...
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1answer
80 views
Prime Implicant
In a K-map, I know block consists entirely of don't cares and is not part of a bigger block is considered as Prime implicant.
For ex-The one in red in the given figure-
But I am not able to figure ...
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1answer
65 views
Need help understanding an universal pin driver schematic
I was studying a schematic of an universal 48-pin device programmer, and while most of it seems pretty straightforward to me, I have trouble understanding the reasons behind some of the decisions made ...
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1answer
56 views
Essential Prime Implicant
While solving this question using Quine–McCluskey algorithm , I am getting total EPIs as 3 but by definition , it is giving 2 EPIs. I am attaching both solutions. Please correct me where I am wrong.
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3answers
90 views
Is it possible to create a working JK-flip flop using gate level description in Verilog
I am attempting to create a working JK flip flop using gate level description in verilog. Although, the design is successfully compiled and simulated, the outputs to the FF are always unknown.
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1answer
92 views
I don't understand why this open collector not gate needs diodes
I'm trying to understand why the following circuit, which corresponds to an open collector not gate, needs to use two diodes. The circuit I'm taking about is below:
I think I understand the one just ...
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1answer
85 views
Essential Prime Implicant with Don't Care
According to me, 3 is the number of Essential Prime Implicants.
If a don't care is used in getting minimal solution, then the group
with that don't care can also be considered as EPI(provided it ...
2
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2answers
65 views
Can digital clocks and other electronic devices “ride through” a momentary power interruption?
I recently attended an electric utility training course discussing relay protection practices. One topic that came up was a fuse saving scheme where a protective reclosing device would momentarily ...
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0answers
51 views
Why signals occupy small portion after being scaled and how to change it?
I am a newbie and try to understand why signals watched on logic analyzer shrink on screen when resolution is changed (as on the pics) so that they occupy a small region on the screen? It'a a ...
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6answers
2k views
Logic: Output a 1 when a = 1 and b = 0
I'm a hobbyist just discovering logic gates and would like to know, is there a logic gate that will only output a 1 when a is a 1 and ...
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1answer
83 views
How many flip flops are required to build a digital circuit?
Here is an example:
The periode of the this circuit is 9, and i want to build a digital circuit with only J-K flip flops.
Here is my argument, I can tell there is nine different states that leads ...
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2answers
127 views
Building a DIY Oscillocope
I have decided that I would like to design a DIY DSO Oscilloscope, the idea has been in my mind for a while, I just haven't had the time to look into it, I am surprised as there doesn't seem to be ...
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2answers
46 views
Use regulator when input voltage is above threshold other wise use direct input voltage
I don't have much practical knowledge of electronics. I am trying to operate esp12e with single Li-ion battery with charging circuit. I am planning to use a good LDO regulator because Li-ion battery ...
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1answer
81 views
How long can I run a portable washing machine which requires 220V and 300W from a 12V, 120AH, 800A auxiliary battery? [duplicate]
portable washing machine and the leisure battery (https://i.stack.imgur.com/MeQi6.png)
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1answer
57 views
Do I need an impedance controlled connector for RS422?
I've never implemented RS422 before (crazy right?). Since the impedance of the line is controlled to 120Ω do I need an impedance controlled connector for that? If anyone has implemented RS422 which ...
