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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Is a debounce switch necessary when creating a Moore and/or Mealy state machine?

I understand that a debounce switch is important for negating voltage spikes triggering clock edges. A Moore machine's outputs are dependent on only the present states. A Mealy machine's outputs are ...
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1answer
45 views

I need a quad NOR gate that is pinned out like a quad AND gate? Is there a good way to search for this?

So I have the footprint for a 2-input Quad AND gate (SN74LV08A) on a PCB. It is a 14-TSSOP and is pinned out like this: However, I want to change the logic to four NOR gates. The problem is, all of ...
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1answer
28 views

Using an analog demultiplexer as a digital demultiplexer

If I want to use an analog de/multiplexer as a digital demultiplexer, do I have to use pull-up / pull-down resistors? For example when driving a CMOS IC like the 4015 with the CMOS analog 4051, do I ...
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2answers
39 views

Is my circuit hitting a limitation of the AND gate on IC 74HC08N?— How does PWM frequency affect performance?

How does PWM frequency affect the AND gate performance? And, is this a limitation of this chip or technology? Using a PWM signal set to 20 KHz on the input, along with +5V on the AND gate the output ...
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1answer
104 views

How can I easily convert an analog signal to a digital signal?

I've tried searching for an answer on this topic but I must be phrasing it wrong because I can't find anything. I have a voltage range of about a 1 volt. I want to pass it through an Op Amp (or ...
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3answers
71 views

Optoisolator with Logic Output - How To Use IC Circuit Example?

I'm looking at an Optoisolator with a Logic Output..It's an optoisolator with a Schmitt Trigger on the output. I think the datasheet is a little bare for my comfort level, so I'm looking for some ...
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7answers
333 views

What makes a circuit digital?

I've been trying to understand how a circuit becomes digital. I understand the different between an analog signal and a digital signal, but I don't see where digital circuits come from if all the ...
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0answers
93 views

digital dice counting from 1 to 6

check it out guys ]3]3 the circuits above are both for an electronic dice that is suppose to count from 1 to 6 but none of the LEDS are turning on for the one that is far below can anyone tell me ...
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0answers
34 views

Digital filter fault detecting code [closed]

I'm trying to design a code for detecting single fault error on a linear digital filter, I have the state matrices, A & B, which could use for a MATLAB simulation but don't know how to simulate ...
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0answers
74 views

Digital Potentiometer and Motor Speed Controller [migrated]

I'm trying to get a Chinese 20A DC Motor Speed Controller working with a MCP42100 Digital Potentiometer. The analogue potentiometer supplied was 100kOhm. I have programmed my arduino with the ...
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1answer
45 views

Customized Digital Clock(two power sources)

I am quite newbie in electronics. Recently I bought a Digital Alarm clock and tried to customize it by adding DC motor wheels . Idea is to set an alarm , when its alarm time apart from sound it should ...
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2answers
81 views

Unused select line combination in 3x1 MUX?

While designing a 3:1 mux we require 2 select lines, but one combination is not useful, say 2'b11. If this combination occurs the output becomes 0 irrespective of the value of input lines. Is not the ...
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0answers
34 views

Conditioning negative ADC voltage with separate AGND and DGND

I was looking to condition a negative voltage analog input for an ADC and I saw these two posts describing a voltage divider circuit to do so. How do I sample a -2 V to +2 V analog signal with a PIC ...
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1answer
61 views

shift registers/d flip-flop memory states

I know D flip-flops retain a certain logic level(memory) but when they output(i.e. shift) this retain memory do they loose it? for example: lets say I have 3 d flip-flops connected as a serial shift ...
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1answer
56 views

Is there a shared lead AND Gate IC? [closed]

Hi I'm an electronics hobbyist still learning some basics of digital logic. I'm looking into building an arduino shield, but I want the arduino pinouts I'm using to be accessible when the shield is ...
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1answer
53 views

Malfunctioning H-Bridge

A PCB that I designed just came in (schematic pictured below). After soldering the components in, some things are happening that I don't understand. Most importantly, one part of the circuitry, an ...
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1answer
287 views

See my prototype electronic board w/connectors. Is it acceptable as a commercial product by Western standards?

Does this prototype meet a commercial standard for acceptability--knowing that it is a prototype? In other words, will my Western (USA) customer be upset when he sees it, or will it go by unnoticed ...
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0answers
24 views

How can I implement this circuit using an 8-to-1 multiplexer and S[2:0] = abc control signals?

I understand that on the top MUX I1 is always 1 and I2,I3 are always 0. I know how to construct a MUX if given the boolean function but I can't do the opposite. Any pointers?
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48 views

Why Boolean Satisfiability is measured with POS form, rather than SOP form?

Boolean Satisfiability means to provide an input pattern, which can make a boolean function 1, and if there is not such pattern, than that should be proved. So in SOP form of a boolean function. this ...
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0answers
23 views

find cache hit rate for direct mapped cache memory

I have this practice exam problem which I am having trouble with. I have gone over many slides but haven't been able to really get it. The question is I currently have an 8 block main memory with ...
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1answer
67 views

Circuit to Decrement by One

How to decrement a bit by one? I have A and 1 . I want the result to be 'A-1' . How to draw the circuit?
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2answers
60 views

Mixing multiple “boolean” audio signals

I want to mix up to 4 rectangle audio signals which come directly from a microcontroller's timer output pin and contain only one frequncy each. For example, if the microcontroller outputs 400Hz and ...
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1answer
44 views

How can I build a 2 input AND gate 24VDC PNP inputs and 24VDC output?

I'm trying to build an AND gate that takes two inputs from standard 3 wire 24VDC PNP sensors and provides a 24VDC output. I was thinking using some sort of diode resistor logic (link to circuit: ...
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2answers
103 views

How to switch between two analog outputs with a digital output?

I have a circuit with a 74ls93 counter and I want to use one of its outputs to switch between two analog output, i.e., when the output of the counter is HIGH, the output of the circuit must be V1 and ...
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38 views

movement decision taken upon the light seen by a line follower robot

I'm working on a line follower robot and it has to check traffic lights every estimated distance and a decision of whether to move or wait is to be taken upon the current state's light of an external ...
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2answers
92 views

Why mosfet is preffered over voltage divider for voltage level shifting

Before writing this question I read several similar threads, but didn't found the answer I am looking for. When we need a voltage level shifter the first thing that come to the mind is a voltage ...
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1answer
55 views

how does RS flip flop works? [duplicate]

I am confused by this question for a long time. Let's say the initial states are R=1,S=0,Q=1,Q'=0, and both NOR gates are ideal (no propagation delay). Then both gates should change their states ...
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0answers
28 views

Using Optoisolator to Control a Toy

I'm trying to control Tweet Monkey (http://codefoster.com/tweetmonkey) using a optoisolator. It's a 816S, but it looks like the specs are identical to the more popular PC817. I have an Intel Edison on ...
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0answers
67 views

A general purpose 16-bit shift register

I cannot seem to locate a general purpose 16-bit serial-in parallel-out shift register that is still being made. Although there are plenty of LED drivers that can adapted for the purpose. All I need ...
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2answers
61 views

What is the wiring for a pull-down resistor on the Or gate?

Is this wiring and resistor the best choice as a pull-down resistor? Is it necessary to put the pull-down resistor(s) on all inputs and outputs? I put a 10K Ohm resistor connected to the chip ground. ...
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1answer
51 views

When untied inputs are necessary, what is the technology to use for an OR gate?

What is the best technology to implement for an OR gate when there will be an open input? I would prefer a common IC. I wired a quadruple 2 input positive OR gate, HD74LS32P. I have a PWM signal ...
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81 views

Digital Input Clamp Circuit Protection

To be able to connect some peripheral to digital input, I'm designing the circuit protection to avoid any possible failure due to over/under-voltage issue. So, I will add a clamp protection circuit. ...
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2answers
53 views

Design Priority Encoder using only NAND and NOR Gates

I'm trying to build an 8-to-3 priority encoder using only nand and nor gates. Below is a 4-2 priority encoder, however it is using only ands, ors, and nots. If I have specific activation levels (some ...
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1answer
59 views

Logic Level Shifter

I am trying to connect two devices on a PCB. One operates with 3.3V digital high and the other works with 5V digital high. I actually grouped the input and output pins (There is no bidirectional ...
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1answer
50 views

problem on logic 0 at 4027 ic

I have a circuit to generate simple sound with astable multivibrator and enable/disable it with j-k flip flop with reset pin, something like this pic: i have a problem with logic 0, when it occurs ...
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3answers
102 views

Analog power pins vs Digital power pins on chips

We usually have digital & analog power/voltage pins on our ICs. Analog power most probably for PLLs etc & Digital Power for Core. So, my questions are :- The different Analog & Digital ...
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1answer
41 views

IC to replace 4 FETs (switches)?

I have 4 data lines that I want to put to high-Z if a pin (let's call it EN_OUT) is high (or low, if necessary), otherwise connect through. I've successfully done that by putting an N-FET on each ...
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3answers
170 views

Divide-by-3 with square output?

I'm thinking of making an 8MHz about-square clock starting from a 24MHz about-square clock. All signals are CMOS with 3.3V(±10%) power. What are my options? I'd like it low-power, cheap and easy to ...
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2answers
84 views

TTL logic level , how NOT gate checks logic level ?

This is a TTL logic level checker circuit , highlighted blue area is a checker pin. Voltage at checker pin is 0.65V so this must be logic 0 , LOW LED will on. But in input of first 7404 NOT gate in ...
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1answer
59 views

3 - bit Counter (repeat after each 6 clocks)

I have tried to make a counter which counts until six clock cycles and then repeats. And would like to know whether I have done all right and the counter works correct. simulate this circuit ...
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1answer
43 views

Inclusion gate as universal gate

Assuming that logic 0 is available, show that the INCLUSION gate is a universal building block. I don't know what inclusion gate is.
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2answers
50 views

Shift registers in series

If we have for example 3x16bit shift registers connected in series, can we clock 48 bits of data through one shift register at once and then latch all of them to output data registers, LATCH CLK and ...
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2answers
52 views

Single input for consecutive state transitions in an FSM: preventing fall-through

Consider the following state diagram where the inputs are c and v. The system is also receiving a high frequency clock ...
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3answers
130 views

Computer peripherals to immediately (<5ms) detect digital input state change in C# programs

The C# application I'm working on needs to be able to be able to call a function within 5 milliseconds of a digital input signal's state change (0V = off, 5V = on). Rather than using software to ...
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2answers
57 views

how will i convert an if less than condition to hardware in digital?

i have a condition like if a number less than a constant ,then how can this be converted into hardware in digital design.Will this be converted into mux or something else?
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4answers
73 views

How to check if sync signal is inverted?

in input of a CPLD, I have a syncronization video signal that can be like this (positive polarity): or like this (negative polarity): I want to recognize the type of the sync signal and invert ...
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2answers
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State diagram for JK-flip-flop

I'm trying to create a simple state-diagram for a JK flip-flop, and this is what I've come up with. I've seen other variants of this diagram, but to me this seems like a correct one if you look at ...
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1answer
45 views

Circuit controlling 6 leds

I want to build a circuit with logic gates and flip-flops, in each clock which will turn 6 LEDs in the following sequence: 1 - 6, 2 - 5, 3 - 4, 4 - 5, 4 - 6, 5 - 6, (repeat). I have spent 2 days in ...
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3answers
112 views

Can you use diodes instead of OR gate?

I am building a computer and thought if I could simply use diodes instead of OR gates. Will this work with logic ICs such as the 74LS, 74HC and 75HCT series? Sorry if this is a stupid question, I am ...
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1answer
27 views

Question about SR latches

I was just watching this video: https://www.youtube.com/watch?v=ti5jD7Q7BSA At 25:10, he says that if you have an active high SR latch with initial conditions S=R=0, Q=1, and you set S to 1, Q will ...