# Questions tagged [matrix]

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### How to find the matrix layout of an old EEPC keyboard

The title asks my question; how can I find the matrix layout of an old EEPC keyboard. I found an instructables about making a USB keyboard controller but it uses a Teensy microcontroller, and I think ...
1 vote
22 views

### RKJXT1F42001 Logic diagram

I'm looking into integrating an RKJXT1F42001 4-directional stick switch with encoder and center push function into a keyboard I am designing, but a little confused about the diagram. I want to make ...
24 views

### Reduction for a multi-port resistive network

I have an NxN admittance Matrix, G for a purely resistive network. There are total N^2 ports in the network such that each port is connected to every other port through some admittance. As expected, G ...
• 61
147 views

### Why are these diodes on the row inputs of this matrix keyboard with column pull-ups?

The following is the keypad circuit of a NEC TK-85 8085 trainer board. Port C-upper of the 8255 programmable peripheral interface is set to output, and you bring low the row you want to scan, leaving ...
• 990
66 views

### The matrix of 8 Term Error model in Vector Network Analyzer Calibration

My teacher gave me a matrix , I do not understand it, not to mention to use it. What is the relationship between b0, T1,T2,T3,T4 and b1. The meaning of the "cross" the center matrix of T1/...
1 vote
164 views

### Li-Ion BMS which protects parallel cells in addition to series cells

Background If li-ion cells are arrayed (series x parallel — S x P or P x S) to form a battery, it is generally recommended to manage parallel stacks of series cells (P x S) independently, such that ...
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23 views

I wanted to build a matrix capacitive trackpad. Ideally, its PCB would have 4 layers: 1--> The plate array 2--> The circuit that links the rows (horizontally) 3--> The circuit that links the ...
1 vote
89 views

### Electric-lock control via NMOS matrix

Currently I am working on the design that allows to control 8x8 electric lock matrix via PIC16F877A. As in comments for somebody it was not obvious (btw it was mentioned) I am using 64 electric locks ...
• 13
58 views

### Optimise matrix inversion in python for impedance calculation

To get the impedance profile for a circuit, I am using its admittance (G) and capacitance (C) matrices. I am using python to compute impedance profile at different frequencies but the issue is that I ...
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1 vote
47 views

### Compact Matrix representation for duplicate eigen values

For a diagonal matrix with diagonal elements equal to eigen values, I am interested to further use this matrix to carry out transient analysis using a numerical method (trapezoidal rule). There are ...
• 61
1 vote
135 views

### Hall effect sensor PWM matrix

Is it possible to set up a PWM output hall effect sensor in a matrix to reduce the number of GPIO pins required? I'm guessing not because there would always be a signal from the others in the row/...
• 13
82 views

### Controlling a 20x20 single-color LED matrix

I want to control a white 20x20 LED Matrix with an Arduino or an ESP32, but I can't find a proper way to solve the problem that there are not enough pins on either of the two boards. I want to be able ...
105 views

### I want to drive individual LEDs (not a ready made matrix) with a MAX7219 IC [closed]

I want to control 24 single LEDs with a MAX7219. I understand the concept of the matrix and I know how to control the MAX7219. What I don't understand is how to read the datasheet correctly and work ...
65 views

### Why color filter mosaic is still fixed for each camera model?

Color filter mosaic (color filter array) is fixed pieces of material that change input ray into another one and built over each pixel of camera matrix. Why it is still fixed? Is it possible to build ...
637 views

### How to calculate unknown resistance from known current in the vector-matrix form of Ohm's law

I was trying to answer this question (pic 1) using the following method (pic 2): Step 1. Apply junction law to find the current vector. Step 2. Apply loop law to find the voltage vector and resistance ...
348 views

### Scanning a keyboard matrix

I recently watched a video on YouTube by Branch Education. In this video, they describe two methods for scanning the matrix: Sequentially apply a voltage across each column so that at any instant ...
1 vote
109 views

### How to convert Thévenin equivalent to Norton equivalent in this schematic?

I am learning the bus admittance matrix from Power System Analysis by Hadi Saadat electrical engineering. I have a very big problem in chapter 6.2 - Bus Admittance Matrix. At the beginning of chapter ...
72 views

### Audio matrix using ESP32 and relays

I want to build a matrix for a pre-amplifier and a second ine for my amplifiers and speakers. The pre-amp one is not my main concern now. I have 6 amps and 3 pairs of speakers, and I want to be able ...
178 views

### I want to understand this circuit and these equations

I have a hard time understanding this circuit that I’ve been given because of the way it looks. I don’t know why, but electrical circuits seem very confusing to me even after reading the chapters to ...
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228 views

### Modifying code for 61-key to 49-key keybed matrix

I'm currently working on a DIY music keyboard project and I have a newbie question as I've gotten stuck in the process and my electronics knowledge doesn't extend past some basic Arduino blink ...
99 views

### Selectable digital communcation links between any two of eight devices [closed]

I'm building a small computer where I have 8 units that need to communicate with each other. Each unit also has eight serial 6 Mbps async lines, so 16 pins. The driver I'm looking for should be able ...
91 views

### Switch matrix activating more than 1 row at the same time

I'm new to electronics and I am working on a 3x3 switch matrix prototype using an Arduino UNO. I created a simple circuit using TinkerCAD but it seems that whenever I press a button, the susbequent ...
92 views

### What is meant by the shifting property of the companion form?

I am going through the book "Linear System Theory and Design" by Chi-Tsong Chen, where they talk about the controllable canonical form and how it is a realization of a transfer matrix. In ...
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96 views

### Nodal Analysis wrong result

I'm trying to solve this problem, where I have to find the voltages v1 and v2. This is the circuit: This is what I came up with: Then I calculated the inverse matrix using WolframAlpha. Finally, ...
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585 views

### LTspice singular matrix error by changing model parameters

I am trying to create a model of an IGBT with the Z-model from LTspice. Started with the default values it works. When I change parameters more and more I get the "singular matrix error" for ...
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90 views

### Incorrect results without printing message

I am trying to make a custom tv remote using an ATmeta328p microcontroller. It contains 28 buttons which are wired in a matrix configuration, resulting in 5 outputs (columns) and 6 inputs (rows). ...
72 views

### Why is the coefficient symbol changed?

I'm solving this very basic problem with 3 voltage sources and I have no problem getting to the equations to create the matrix [U=RI], These are: I1-I2-I3 = 0 U1-I1R1-I2R2-U2 = 0 U2+i2R2-I3R3-U3 = 0 ...
292 views

### Detecting magnets regardless of polarity

I'd like to build large matrix of sensors to detect objects placed on it. I can place magnet or metal inside detected pieces. I tried to use reed switch and hall sensors. Hall sensors seems like ...
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147 views

### Replacing a keypad on DYMO LetraTag

I'm rebuilding my label printer to become an Internet service using an ESP8266. It's a fun project, never mind the usefulness. The keypad will be removed and instead my MCU emulates keypresses. The ...
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466 views

### Nodal Analysis and Matrices for more complex circuits

I would like to know how I should write a matrix equation for a circuit containing dependent sources, diodes, capacitors, and voltage sources. I am familiar with the $\small G V = I$ matrix equation ...
45 views

### Combining S-parametric Blocks

I would like to ask you, please, how I can combine general S-parametric blocks together. Consider the situation in the following picture. Considering this example, I would like to connect these three ...
1 vote
482 views

### Mutual inductive coupling in a nodal admittance matrix

I have this question that has been haunting for quite a while now. To compute the nodal admittance matrix $Y_N$ of an electrical network, one can make use of the incidence matrix and the branch (or ...
• 459
213 views

### Autocorrelation function of discrete time sequence

Say you have 2 discrete information sources each one being represented by a Gaussian random variable. This is the idea. Say I want to find the correlation of the 2 to know whether they are stationary....
40 views

### Charaterization of waveguide to coaxial adapter

I'm trying a method to characterize a high frequency waveguide to coaxial adapter( 2-port network). For this, I use 3 adapters A1, A2, A3. After a TRM calibration, I measure A1 connected with A2 with ...
• 1
82 views

### Implement a voltage feedback method to reduce the crosstalkin resistive matrix

I'm new in electronics and i want to develop a resistive matrix that is pressure sensitive. Right now, I have a 7x7 matrix and I'm implementing this using multiplexers, a reference resistor and an ...
166 views

### Effective resistance from a random resistance network

I am trying to calculate the equivalent resistance from a random resistance network formed by carbon nanotubes (CNTs.) I have a MATLAB program where the CNTs are randomly distributed inside a volume. ...
422 views

### RGB LED matrix 64x32 + ESP32 powering

I'm trying to figure out what's the best way to power a 64x32 RGB LED matrix and an ESP32 WROOM 32D using both a power bank (some 18650 2000mAh 3.7V in parallel + voltage regulator) and USB C (5V 3A). ...
3k views

### Solving nodal analysis equations using matrices- gives a full rank matrix

I am trying to solve for node voltages in a circuit using nodal analysis. I am using the fact that the sum of the currents into each node must equal 0. I have a system of equations which can be ...
203 views

### Circuit analysis (Current intensity)

In my electrical engineering lecture we analyse such circuits with given Resistances $R_i$ and given $U_{q1}$ and $U_{q2}$ ( see example below ), and we try to find the current intensity \\$I_{i}\...
814 views

### Pressing one key in a button matrix reads all keys in that column

I'm using an MCP23017 IO Expander to make a button matrix (4x4). ...
100 views

### Scattering matrix in microwave amplifier

What exactly is the scattering matrix in a microwave amplifier. I tried to deduce from lectures what it is used for in a microwave amplifier, but all I found were the formulas corresponding to the ...
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303 views

### ARM CMSIS Matrix conversion to a uint16_t array

I'm working on the STM32L476RG and I'm looking to perform some matrix operations on the controller, using C and CMSIS-DSP for ARM. I have 2 uint16_t arrays which I will be converting to matrices and ...
101 views

### Using an MCP23008 IC with a 4X4 matrix keypad on a Raspberry Pi [closed]

I want to be able to free up the native GPIO pins on my Raspberry Pi Zero. I know the MCP23008 gives me 8 extra pins, but I can't seem to find any resources on using the additional pins with a 4X4 ...
63 views

### Axis of Euler rotation matrix

I'm searching the way to measure rotational displacement by using Euler rotational matrix. And I could find various information about it. Then I've found something wrong with reference axis. In the ...
283 views

### Is it possible to solve for the values of this grid of photoresistors in software?

In this question a circuit was set up as shown: The idea is to power the rows one at a time, and read off the voltages of each column. But there's a subtle problem. There are alternate paths to ...
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1 vote
145 views

### 5v analog switch for 3.3v logic ok?

I have a project where I want to interface with a keyboard matrix / scanner (this is a PCB from a consumer electronics device). There's already an implementation that uses some analog muxes for this, ...
66 views

### 4*4 reverse matrix code in matlab wich has variables

Here is the system of which I have found the state space equation. I need to get the transfer function. [SI-A] is a 4x4 matrix and it's so hard to get the reverse ...
29 views

### In the AT42QT1245 touch sensor controller, how do the buttons wire to the device?

Referring to the datasheet wiring diagram, page 4 here: https://www.mouser.com/datasheet/2/268/Atmel-9632-AT42-QT1245_Datasheet-1368898.pdf It simply says "Matrix X Drive" and "Matrix Y ...
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1 vote