A multiplexer selects one of two (or more) inputs based on a control input. It then outputs the selected input.

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30 views

Discrete logic multiplexer

I posted a more in-depth outline of what I'm doing here, but basically I'm building this circuit (for n=3): The circuit displays an output based on the combination of three three-input DIP ...
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88 views

Operation of Logical Gate and Big Challenge

i get confusing on Digital Design Course. Anyone Could Describe why the (1) is different from (2) to (4)?
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1answer
39 views

I'm getting a noisey/square wave output for my mux/demux?

I am using a "CD74HC4051 High-speed cmos logic analog multiplexer/demultiplexer" I put 5V to VCC, put my oscilloscope probe to the common out/in, put 3.3V to A1 (channel in/out), and have a wire ...
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1answer
66 views

How could I go about building a 2-bit comparator that compares two 2-bit numbers and determines whether one is greater than or equal to the other?

Using an 8:1 multiplexer, I understand there are three inputs, so I'm not sure how I'd go about getting two 2-bit numbers, which would be four variables, not three. Any pointers on how to get started ...
6
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4answers
480 views

Multiplexing a Circuit

Frankly, I'm overwhelmed with this circuit that I have to start building in lab tomorrow. Last week we built an octal decoder that takes a 3-bit binary input from 000 to 111 and displays a unique ...
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0answers
30 views

switching 1:8, 8:1 at 24v, max 1A [closed]

I am trying to make a testing device for some I/O boxes. The problem is that I want one cable in to my box and one cable out, and internally there will be 8 different circuits that needs to be ...
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1answer
28 views

Design a full adder of two 1-bit numbers using multiplexers 4/1

How can i implement the full adder of two 1-bit numbers using only multiplexers 4/1? I created a truth table for a one-bit full adder, which looks like this: A = first bit B = second bit Pu = bit ...
3
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2answers
239 views

Using Arduino Mega With lots of strain gauges

I was looking for a strain gauge shield for an Arduino Mega. I found this link which I found really useful: http://www.osengr.org/Projects/Load-Cell-Shield/Load-Cell-Shield.html At the bottom of the ...
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2answers
71 views

do demultiplexers remember

I'm working on a high school project were i need to make a score board using 420 LEDs controlled by an Arduino. I can see that the 74HC4105 demultiplexer will let us turn three pins into 8, but if we ...
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5answers
107 views

Easiest way to read a large bank of LED's

I have a pretty straight forward question but every answer I come up with seems over complicated or just plain wrong. I'm designing a data logger/fault detection system to be used for a large piece ...
0
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3answers
48 views

Is a multiplexed signal same as a composite signal?

Used to StackOverflow, this is my first question here. So please bear with me if the question is too simple and obvious to you as I am not good in Electrical Engineering stuff. I really need to ...
2
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2answers
74 views

Laser Multiplexing

I'm new to ECE stuff, but I was wondering what kind of equipment I'd need to have an 8x8 or more grid of lasers being controlled with specific on/off patterns. I'd want 5mW lasers in an 8x8 grid. It ...
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2answers
85 views

How to measure trace impedance?

I have seen that trace impedances in PCB's are maintained 50 ohm & so on. How to measure this impedance using a simple multimeter?
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1answer
92 views

Looking for a way to output 100-144 Analog Channels from Arduino

I've been searching for days and found 2 ways that could work, but not sure about implementation: Using shift registers like in: ...
0
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4answers
193 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 ...
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1answer
67 views

Mutually exclusive headphone and speaker

I have a device that has only one set of analog audio out signals that are amplified for headphone usage. I want to be able to use these signals to output to a set of speakers OR a headphone jack, but ...
2
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1answer
178 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 ...
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3answers
171 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
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3answers
49 views

SN74HC138 demultiplexer. How do I implement a switch?

I have this demultiplexer and I need to configure it in such a way that I can control 8 transistors using its outputs. They NEED to be NPN transistors, so when I select an output using the addresses, ...
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2answers
236 views

Determine the Number of Transistors Needed to Build CMOS circuit

I would like to determine the number of transistors that will be used in the CMOS circuit below. Is there a specific formula for it?
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2answers
39 views

Multiplexing buttons using shift register - high impedance output

I have experience with 74HC4094, and I believe the 74HC595 is essentially the same - the datasheet says they have "tristate output", but that is only when OE is low - then all pins are tristate. What ...
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1answer
113 views

How do I find the Truth Table for Mealy State Machine?

This is a followup to my previous question: I have this assignment in college: You are to design a Mealy state diagram for a safety device. Assume that two debounced push-buttons, A and B, are ...
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1answer
87 views

Mealy Safety Device with 2 inputs

I have an assignment in college and I would like to ask some questions: You are to design a Mealy state diagram for a safety device. Assume that two debounced push-buttons, A and B, are available ...
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3answers
90 views

How to adjust red brightness on MAX7219 with RGB LED

I want to use MAX7219 (datasheet) to control bunch of RGB LEDs. With common anode LEDs I should be able to use up to 16 3-color bulbs in following configuration: simulate this circuit – ...
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1answer
94 views

Mealy machine to detect sequence of 2 inputs

I have the following assignment for a project at college and I have a few questions regarding it. You are to design a Mealy state diagram for a digital lock. Assume that two debounced push-buttons, A ...
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0answers
56 views

pin connection added

I am trying to communicate 24 hall sensor via arduino & 8:1 Mux . I am using CD74HCt4051E 8:1 multiplexer. Instead of hall sensor i have used potentiometer 24 nos and connected to MUX IC devide ...
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3answers
269 views

Audio Signal Switching - “DPDT switch vs. 4066”

I've got a signal coming from an electric guitar and I need to switch it. Basically it's a distortion circuit. I need to switch between the distortion and clean (directly connected to the output) My ...
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1answer
61 views

PIN selecting problem over arduino

My schematic as below. I have connected 8 hall sensor as shown in picture. Problem i am facing here is SO, s1, s2 The Led light are not glowing .Even the forard voltage across is 3.9v. i have tested ...
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1answer
64 views

Implementing F using a demultiplexer and an extra AND gate

Use a 1-to-8 Demultiplexer and an extra AND gate to create the function: F(x,y,z) = ∑m(1,3,5) If I were using an OR gate I think this would be trivial, simply put the 1 3 and 5 ...
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1answer
88 views

Multiplexer CD4067 bug:signal appears in unselected channels

I connected a multiplexer CD4067 with arduino. I will select ch0-ch15 in turn and pass the selected channel to A0 on arduino to do AD Convert. Then I only connected ch0 to 5V on arduino and selected ...
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0answers
86 views

High-voltage seven segment LED display driver problem

I've a circuit similar to THIS project, with a 74LS04 as inverters instead of 74HC54 (tested 74HC04 and CD40106 too) and ULN2003 instead of ULN2803. The circuit seems to work perfectly but when I turn ...
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2answers
159 views

Multiplexing problem with Arduino, MAX7219 e BJT

I tested the circuit below with an Arduino UNO, a MAX7219 and BC338. The sketch in Arduino is a chaser, so the leds should turn on in sequence. It consist of 7 segment (A-G) and two Digit (0-1). The ...
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1answer
65 views

A circuit that outputs one input voltage by default, or another if it is present

I'm trying to come up with a simple design that will take two analog inputs voltages (~0.2-1.6 V each). One is an "internal" voltage and should always be present. The second "external" input can be ...
0
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1answer
157 views

i2C multiplexer to use multiple sensor of the same type

I would like to hook up multiple sensor of the same type (temperature, pressure and so on). The problem is that each sensor can only have 2 different unique values for the register, so can't put more ...
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2answers
93 views

How does one implement the following function with these tools provided?

Suppose I have a function defined as follows, such that it is expressed in POS form, with the product of the following max terms of 4 variables (A,B,C,D): 0,3,4,7,9,10,12,15 and I only have a 4 to 1 ...
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1answer
62 views

Can avrdude address individual usbtiny programmers?

I'm envisioning a panel programming jig. In my mind, it consists of a Raspberry Pi, a powered USB hub, and a collection of usbtiny clones each connected to a pogo jig and a target on a panel. The ...
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1answer
255 views

Custom built 16x32 (40) LED Matrix controlled by Arduino

I am planning to build a clock / thermometer / info display. I have ordered 10 pieces of 8x8 LED matrixes from ebay (http://www.ebay.co.uk/itm/331064583297). As this is not a pre-built one I have got ...
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0answers
37 views

MAR /MBR / MUX Device

How can I modify this circuit to permit loading of the MBR from either the hex keyboard or from memory. As it is, the circuit can only load the MBR from user input.
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1answer
91 views

3 State Shift Register with 2-to-1 multiplexers

For a homework assignment I need to Redesign the right-shift register circuit of Figure 12-10 using four D flip-flops with clock enable, four 2-to-1 MUXes, and a single OR gate. The figure ...
0
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1answer
88 views

Strategy for up to 40 ADC inputs using alert feature

I'm working on a project where I want to monitor 40 phototransistors (IR breaker beams), but without having to constantly poll the ADCs. Ideally I'd want a digital pin pulled when one of the beams is ...
2
votes
2answers
187 views

Is it possible to drive a 4x4 RGB common-cathode LED matrix with a MAX7219?

The MAX7219 (datasheet) is a LED matrix driver that's designed to drive an 8X8 single-colour LED array. tronixstuff has an intro on how to use it with an arduino that has some relevant diagrams. I'm ...
0
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1answer
67 views

Transistor Isn't Forming the Connection

I have wired the following diagram. simulate this circuit – Schematic created using CircuitLab My understanding of transistors is relatively poor, and thus I am assuming it has to do ...
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1answer
106 views

How to increase current output of a multiplexer for activating a relay

I want to make a multiplexer for my project which needs 24v dc to operate. I am using an OR Gate IC for generating an output. My 4 gate inputs are connected to 6V battery power and I am getting a 6V ...
0
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2answers
115 views

Shift registers(?) failing after being left on a while

Resolved: SLCLR on SN74HC595 was not tied to VCC, so behavior was inconsistent. I have a custom built board that is running seven 7-segment displays, multiplexed using SPI from an 5v Arduino Pro ...
0
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2answers
51 views

How are the Intersymbol Interference and Symbol Time (duration) related to each other?

In a lecture slide I noticed that OFDM(Orthogonal frequency-division multiplexing) mitigates the problem of Intersymbol Intereference over wireless systems because the symbol time is increased, in ...
0
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1answer
85 views

Circuit design for short-circuting outputs when needed

I am working with two sensors with 4 pin as output. My question is simple: I want to make circuit that allows me to short circuit the output of either one of the sensors individually when needed. ...
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3answers
174 views

Driving 60 signals one at a time, in constant sequence

I have an application where I need to turn on/off one of 60 signals one after another in a constant order, ever repeating. (1, 2, 3, ... 59, 60, 1, 2, ...) Only one signal is on at any given time. The ...
6
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6answers
855 views

What's the maximum number of outputs you can control from a microcontroller with n outputs?

Been pondering this for a while, and I think it's \$2^{(n-1)}\$ outputs. If I have 5 outputs, I'll use 1 as the signal, and the other 4 as control lines to cascaded decoders, which gets me 16 ...
3
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2answers
321 views

Using the raspberry pi to measure multiple electrical circuits

I am looking to use the raspberry pi to measure the power consumption of multiple household electronics and record the information to analyze later on. However, I'm not sure if it's possible to ...
2
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0answers
212 views

What's up with my 74HC4052?

I am using a TI 74HC4052E to multiplex a TTL UART on a Microchip PIC32MX695F512 microcontroller. The expected behavior is for the TX and RX signals to pass through the switches unaffected; sadly ...