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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 ...
ImTheBeemoPlush's user avatar
1 vote
0 answers
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 ...
printsmith3d's user avatar
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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 ...
Dev's user avatar
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2 votes
1 answer
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 ...
cjs's user avatar
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2 answers
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/...
Lv Yaojia's user avatar
1 vote
2 answers
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 ...
kando's user avatar
  • 437
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0 answers
23 views

Matrix Trackpad

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 ...
Andrea Scarpellini's user avatar
1 vote
0 answers
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 ...
Alioth's user avatar
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0 answers
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 ...
Dev's user avatar
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1 vote
0 answers
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 ...
Dev's user avatar
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1 vote
1 answer
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/...
Arkyris's user avatar
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1 answer
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 ...
zDylant's user avatar
0 votes
1 answer
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 ...
prepzel's user avatar
0 votes
2 answers
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 ...
Moorhuhn's user avatar
4 votes
3 answers
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 ...
ARNOB Chatterjee's user avatar
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0 answers
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 ...
vector X's user avatar
1 vote
0 answers
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 ...
user16266657's user avatar
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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 ...
Jean Labuschagne's user avatar
0 votes
2 answers
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 ...
asking's user avatar
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0 answers
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 ...
Jelani Thompson's user avatar
3 votes
2 answers
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 ...
Alessandro Mini's user avatar
2 votes
1 answer
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 ...
NoobxCamper's user avatar
3 votes
1 answer
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 ...
Abundance's user avatar
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1 answer
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, ...
Leyonad's user avatar
  • 11
4 votes
3 answers
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 ...
Lutz's user avatar
  • 61
4 votes
1 answer
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). ...
Roy Meijer's user avatar
0 votes
1 answer
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 ...
germanynewbie's user avatar
0 votes
1 answer
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 ...
imperf's user avatar
  • 15
3 votes
1 answer
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 ...
mikabytes's user avatar
  • 181
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0 answers
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 ...
Kid A's user avatar
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0 answers
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 ...
Humphrey Appleby's user avatar
1 vote
2 answers
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 ...
Wallflower's user avatar
0 votes
0 answers
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....
meanthatmuchtoyou's user avatar
0 votes
0 answers
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 ...
DODO's user avatar
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0 votes
1 answer
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 ...
WilsonMCS's user avatar
0 votes
1 answer
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. ...
Sebas Tian's user avatar
0 votes
1 answer
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). ...
Mihai Cristian Ursa's user avatar
0 votes
2 answers
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 ...
Luke Pitman's user avatar
2 votes
4 answers
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}\...
Wassim Jaoui's user avatar
3 votes
1 answer
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). ...
Cros Dude's user avatar
0 votes
1 answer
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 ...
MagicMan's user avatar
0 votes
1 answer
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 ...
Souvik Saha's user avatar
2 votes
0 answers
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 ...
Pekkle Juice's user avatar
0 votes
0 answers
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 ...
ssabassaba's user avatar
0 votes
4 answers
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 ...
Mike's user avatar
  • 3
1 vote
1 answer
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, ...
BobIsNotMyName's user avatar
0 votes
1 answer
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 ...
ghazaleh moghadam's user avatar
0 votes
0 answers
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 ...
user11015833's user avatar
1 vote
5 answers
542 views

Huge analog switching matrix

My application is a PCB that has 2 different 100 pins connectors and has to be capable of arbitrarily connect each pin on the first connector to each pin of the second. The signal going through the ...
Oznerol's user avatar
  • 13
3 votes
1 answer
425 views

How to implement an interconnection matrix in VHDL?

I was reading through the documentation of the AXI standard when I came across the interconnection matrix shown below. In short, the interconnection matrix provides a path for several masters to ...
Leonhard Euler's user avatar