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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Do I need a decoupling cap for a line buffer gate?

The data sheet does not say anything about the decoupling capacitors for this buffer gate. Would it be correct to assume that no caps needed? Please, explain.
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1answer
35 views

Logic Level Conversion. Different Voltages on High Side

I've used this circuit before to do logic level conversion. The diagram is labeled to reflect I2C however I am using it for UART. Usually my scenarios have been where the low side is 3.3v and the ...
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1answer
55 views

How can we use D flip flop and a combinational circuit to retain a bit?

I am trying to solve a problem, which involves designing a gate level circuit, and I'm stuck on the last part of the problem. The last part wants me to retain the carry flag generated from the adder ...
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3answers
84 views

What happen when input changes the same time clock pulse changes in edge triggered flip flop?

For example take positive edge triggered D flip flop.If input (D) changes from 1 to 0 at the same time when clock pulse goes from 0 to 1(positive edge of clock pulse), what will be the output (Q).Will ...
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2answers
58 views

Circuit for switching LED with minimal impact on digital signal

I am looking for a ciruit which allows switching an LED according to a digital (bus) signal. The actual signal should only be minimal affected (rise time etc.). An example: Light up an LED when a SPI ...
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2answers
41 views

CMOS Logic system

When I was practicing logic circuit design using PMOS and NMOS , It's said that we have to use all PMOS for Pull Up Network (PUN ) and NMOS for Pull Down Network (PDN). But we know that for input ...
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1answer
68 views

ADC conversion using a Datasheet

Is it possible to find a corresponding digital value for an analog current value(Amps) using the ADC component datasheet? If yes, what are the parameters I should consider? Thank you!
2
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2answers
51 views

FSM with Counter

I have a state diagram that is consisted of 3 states and in reset it comes to state s0 then if an event happen on start signal goes to state 2 and statye there for 15 clock sycle and then after that ...
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1answer
50 views

Why do we use one hot coding for the FSM Machine? why not binary coding to be used?

I would like to know why it is best to use grey coding or one hot rather than just binary coding.althiugh we would require more number of flip flops for its implementation.
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39 views

multi stage digital design

while design a NOR3A ie a 3 input nor with A input inverted. we have two ways build a two stage nor3A OR build a 3 stage and3BC(apply demorgans to NOR3A ) so while computing the delays i found that 3 ...
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0answers
32 views

Mealy Machine and registered outputs and delay increase

I am implementing an absolute value block containing a bit-serial Subtractor, the output connected to an 8-bit shift register which in turn connects to a two's complement block at the output there is ...
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1answer
52 views

How can you design a frequency divider circuit?

I have been trying to design a frequency multiplier circuit which can translate frequencies from Mhz range to a few Ghz range using PLL. But I am not able to figure out how to create the frequency ...
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0answers
28 views

555 to debounce comparator output for PIR circuit

I'm trying to create a circuit that takes an input from a PIR and outputs a high signal when movement is detected. My circuit currently looks like the schematic below (VCC is 5V). The circuit works ...
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1answer
34 views

Modern 3.3V CMOS Logic gates

I wonder what series of 3.3V CMOS logic gates are the standard in the year 2015. Decades ago, when I learned about digital logic the 7400 TTL series was just going out of favor for the CD4000 series. ...
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2answers
107 views

Analog NOT gate

I am pretty new to electronics and was wondering how you could get a NOT gate for a 9v battery. I understand that it can not make power at the output when there is no power input, so it would probably ...
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2answers
39 views

Measuring Switch State using PIC

What is the best way to measure the state of a latching switch using a micro controller? Keeping in mind the voltage level of the input to the switch is higher then the maximum voltage input to a MCU ...
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0answers
25 views

Wave Digital Filter (Basic)

DOWN wave is the reflection, am I right? And is D considered as reflection-free (rf) in dtyeh's illustration? Because the root of the tree is D, there should not be rf on D and since there is no rf ...
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3answers
62 views

Digital signals have two states or interger values

Some people have the concept that digital signals are in the form of 0's and 1's. But in a book i got the concept that digital signals can have integer values. Which concept is correct?
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1answer
49 views

Tristate logic equivalent in NMOS logic

Suppose I have 3 signals generated by NMOS logic. Each of those signals has an associated enable pin that when driven high will result in the value of the signal appearing on the output (I should note ...
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1answer
69 views

Nonlinear increase in logic utilization for FPGA design

I am creating a design using the Altera Stratix V GX-series FPGA. For host device communication we are using the PCIe x8 interface. The interface itself takes up 3,058 ALMs (out of available ...
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0answers
50 views

IC chip: reverse current

First lets talk generally, if there's reverse current, how do I track it down to find the source of it? If I look at the component datasheet, what parameter do I look at and how do I determine it? Is ...
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4answers
93 views

74HC00N getting really hot with 5V and GND attached

I'm doing a project with an SN74HC00N NAND gate and when I wired it up the chip got really hot really quickly. I immediately unplugged everything and tested just with 5V and GND plugged in and none ...
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2answers
40 views

How to create counter with unique sequence

I have a sequence: 001, 110, 010, 001, 110, etc. Although there are 3 bits that I want to represent, only 2 are needed for states (3 states). What I get confused with, is utilizing only 2 state bits ...
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1answer
47 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
31 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
48 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
113 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
89 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
352 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
101 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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1answer
59 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 ...
2
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2answers
91 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
37 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 ...
2
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1answer
72 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
58 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
57 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
294 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
50 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
25 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
78 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
63 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 ...
0
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1answer
57 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
104 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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0answers
40 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 ...
2
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2answers
100 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 ...
0
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1answer
59 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
31 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
70 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
66 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 ...