texts: How to store/use energy that could be generated from a solar cell duing the off stage of a buck converter?

texts:
I am trying to design and build a MPPT charger to charge a battery from a solar cell. From what I understand, an MPPT controller is basically a buck converter where the output voltage is optimized such that the current being drawn from a solar cell is Imp, which will cause the voltage to be at Vmp.

Ideally, the current should be drawn constantly at Imp to maximize the power, but during the off stage of a buck converter, no current is being drawn from the solar cell when it could have been producing power. Is this really the case, and is there a way to store/use that power during the on stage?
Would adding an inductor and capacitor (L2 and C2 as shown below) to the input of the buck converter effectively store the energy from the off stage of the buck converter such that it will be used during the on stage?


texts: can I wire a ceiling fan to a 4 DP toggle switch?

texts:
I want to re-purpose a ceiling fan motor and would like to have each of the three speeds available on their own switch (or position on a toggle). Is this possible? and if so how should I go about this?

Thanks All!!


texts: What will be the bandwidth required for streaming 640x480@30fps Video as UVC (USB Video Class)?


texts:
I have a 230Vrms 1 phase output and i need to switch this with another circuit with a relay.
The relays are all given in ...VAC.

Is VAC= VRMS or do i need to take a relay with 330VAC(Vrms*sqrt(2))?


texts: How can I tell whether a DC device will accept a greater voltage than stated?

texts:
Over the time, as an amateur, I've developed a sense that DC powered devices with internal circuitry should be fed with the voltage stated on the case. Having seen certain devices (e.g a portable USB hard disk with a separate power supply) suffer damage when fed with a +50% voltage (accidentally connected a 19v laptop brick to the 12v port, blowing out the TVS diodes on the HDD PCB) I thought correct voltage was relatively critical to DC components

I was somewhat surprised then, to acquire a 3com wireless access point that stated (10-30v) next to its DC connector. Latterly I successfully powered a cheapo ethernet switch, whose case said 9v, with a 12v adapter to seemingly no ill effects; it's been running well for months now

It thus seems to me that some DC devices are more sensitive than others to the feed voltage and I'd like to know if it's possible to work out whether they are or not

I'm asking specifically in this case because I'd like to know if the manufacturer provided mobility scooter motor controller I have here can be fed with 36v instead of 24v to increase the speed of the scooter. I've no idea how to inspect a PCB in a DC application and determine whether 50% over voltage will destroy it or whether it has a natural range of input voltages and (in the case of a motor controller) will vary the output as a percentage of the input

I'm keen to know in a general sense whether one can (and if so how to) identify whether a DC circuit is voltage specific or more tolerant of varied input voltages?


texts:
simulate this circuit – Schematic created using CircuitLab

A battery pumps electrons by creating an electric field and converting electric potential energy to kinetic. Near the positive terminal the electrons have more kinetic energy so shouldn't the current be higher?

An analogy might clarify my question: If you drop a ball from a building, the ball will speed up as it reaches the ground because more potential energy has been converted to kinetic energy. Similarly, shouldn't the electrons move faster as they approach the positive terminal, since they have more kinetic energy? And consequently shouldn't the current be higher?


texts: Voltage Divider not functioning as expected

texts:
I've set up a voltage divider to take a 5V signal down to 3.3V. I'm using resistors with values of 6.8 kΩ and 3.78 kΩ. When I use a 5V source straight from a wall wart, the voltage divider works exactly like I would expect: I get 3.3V out of the divider.

However, when I use 5V from a different device, things get a little wonky. I'm getting the signal from Sparkfun's coin acceptor. This device is powered by 12V, but the signal it puts out to tell you about which coin it has received is 5V (There is a NC/NO option). When I hook the 5V coin signal up to the voltage divider, suddenly I don't read the signal as being 5V anymore. It drops to 2.6V at the input to the divider, and 1.6V at the divider's output.

When using the 5V wall wart, I connect the voltage divider's ground to the wall wart's ground, and when I'm using the 12V coin acceptor, I connect the voltage divider's ground to the same ground as the coin acceptor. Is this a mistake? The 5V coin signal that I read when not connected to the voltage divider is measured using the same ground that I connect the voltage divider to.

The reason I'm trying to get a 3.3V signal is so that I can safely connect it to a raspberry pi's GPIO pin.


texts: How to choose the right clamp diodes for CT overvoltage protection

texts: I have seen back to back diodes and TVS diode (no both at the same time) used for protection in current transformers. In my case, I have a CT signal with a DC offset of 2.5V. The max voltage I will see across the burden resistor is 320 mV (under normal current range). So I would like to protect the rest of the circuit in case of overvoltage. I think that as my signal has a DC offset, then back to back diodes may no be needed, but just one diode. Am I right? Or would a bidirectional TVS  fit better? My confusion is because back to back diodes are usually used when the signal swings around zero, but in this case it swings around 2.5V.


texts:
I am trying to understand the curves of a MOSFET. Sorry if the question is very basic.
Where the red point is is the saturation zone of the MOSFET, therefore the source drain voltage must be 0V because at this point the MOSFET is saturated conduction at maximum current, because on the X axis of the graph called Vds marks 10V for the red point.


texts: Altium - Is it possible to move the symbols added to pins when creating components?

texts:
I'm drawing a simple inverter and would like to have the Schmidt trigger symbol inside of it.
Altium places it outside the boundaries. Can't find how to move & scale it. Suggestions are welcomed!


texts: Two different silkscreen colours on the same PCB

texts:
Has someone seen or used two different silkscreen colours in the same PCB? If so, can you describe the use of them or how the manufacturing process was?

Just thinking about improving the aesthetic of the PCBs.


texts: How much electricity does a 1 GW plant actually produce if the plant's efficiency is 20%?

texts:
I'm trying to see what percentage of total electricity demand will be met by solar power in some year x. Let's say I have data saying that the total electricity demand in country A is 1000 billion units (BU) in 2025. Let's also say that the installed solar power capacity in that country in 2025 is 200 GW.

How much electricity will these power plants with a cumulative capacity of 200 GW produce? I also have information that solar power plants in these countries run with an efficiency of 20%, but I'm just confused. What does a 200 GW power plant actually mean (how much electricity will it produce, say, in an hour?) and if the efficiency is 20%, how does it change my analysis?


texts: Resistors in series and parallel conundrum

texts:
Three resistors of some resistance (ohms) are put in series and the measured total resistance is 24 ohm. Now, if the same three resistors are connected in parallel to each other and the total resistance measured for this combination is Rp, would the value of Rp ever reach 1.8 ohm or 4.4 ohm?
Also how would you set-up the equations to solve such a question?

I have tried to use the general resistor formulas to solve such an question:

r1 + r2 + r3 = 24 ohm

1/r1 + 1/r2 + 1/r3 = 1/Rp

But I cannot come up with a logical reason for this question. Would you be able to help me solve this conundrum?


texts: I need help designing a band pass filter that passes frequencies only between 500 and 1000Hz Attached is my filter that i made in multi-sim but for some reason nothing comes up on the oscilloscope. Can anyone help me?


texts: How to configure DMA to receive variable length USART messages?

texts:
I am trying to receive USART messages on a microcontroller originating from PC which will command it to execute certain tests.
I am using STM32F4, I chose to use DMA as messages on the same USART originating from the microcontroller would need to be at 2000000bps as I couldn't make it work with lower bitrate or without DMA. I am using binary rather than ASCII for both directions.

What I have designed so far "works" (updates real time almost) provided the rate of messages being sent is constant as each new message forces previous one to be flushed from the DMA register. If initiating though and having only a single instruction/USART frame being sent which happens to be less than the amount of data to be received for the HAL_UART_Receive_DMA(), message is stuck until pushed out by the next message.

An even worse case scenario would be if USART_take_size is 100 and there is a single 10 byte frame in the DMA buffer. In this case I would need to wait for another 9 (10 byte) frames before receiveing them all at once.

This is what my callback currently looks like.

void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart) {

    //              uart handle, global array, numb of bytes to trigger interrupt
    HAL_UART_Receive_DMA (huart, raw_serial, USART_take_size);

    // function that adds received bytes to the circular buffer
    AppendSerial(raw_serial,USART_take_size);

}

A thread pops bytes from the circular buffer, loops over them and based on SOF and EOF bytes extracts the message inside the frame.

My problem is that the frames that arrive are of varied length, if USART_take_size is set to be x and frame arrives and the length of it is less than x, it will have to sit in the buffer array in the extracting thread until another frame arrives which makes necessary bytes appear for the parser to obtain the embedded message.

I see three ways of solving this and each doesn't seem right:

Set USART_take_size to 1, which kind of defeats the whole point
of DMA
Have a fixed frame size and pad content with zeros before EOF if content is lesser than the USART_take_size. This just seems sloppy and wasteful. It would also need to trigger on every frame even though the overall rate at that instance could be much higher.
Configure the DMA to trigger ISR on variable number of bytes received, provided there has been a certain amount of inactivity preceding it.

I do not know much about DMA, and while it seems to be a trade off between how many ISR get triggered and what minnimum message you can read I think think there should be a way receive message after a period of inactivity. Any other approach of how to solve this would be great. Thank you!


texts:
In the circuit below, I'm trying to count the number of clock pulses that happen while the decode signal is high. In order to do this, I create a composite wire that takes the AND of clk and decode, and increment a counter at the positive edges of this signal.
module countPulses(clk, decode);
  input clk;
  input decode;

  wire composite = clk & decode;

  reg  [15:0] composite_counter = 16'h0000;  // Increments too often
  reg  [15:0] delayed_counter   = 16'h0000;  // Lags 1 cycle behind desired
  reg  [15:0] desired           = 16'h0001;  // Intended counter behavior

  always @(posedge composite)
  begin
    composite_counter <= composite_counter + 1;
    desired <= desired + 1;
  end

  // Manually fix up the desired results on the falling edge of `decode`
  always @(negedge decode)
    desired <= desired - 1;

  always @(posedge clk)
    if (decode) delayed_counter <= delayed_counter + 1;

endmodule

Unfortunately, composite_counter doesn't work as I expected. I'm looking for the values shown in desired, but instead, composite_counter increments again at the falling edge of the decode signal. I don't understand why this happens, as you can see in the trace that when this occurs, composite and decode are both zero. There should be no overlap between the rising edge of clk and the falling edge of decode, but for some reason, it's being treated as a posedge anyways. I'm new to Verilog and hardware design, so perhaps I'm misunderstanding how @ posedge works.
I also tried incrementing a counter (delayed_counter) at posedge clk instead of posedge composite and checking if decode is high. This doesn't exhibit the double-counting behavior that composite_counter does, but the values are delayed one cycle from those in desired. I understand why this is happening, but wanted to point it out as a potential solution that won't work.

With that, my two questions are:

Why does always @(posedge composite) fire when composite is (and remains) zero?
How can I achieve the behavior shown by desired without resorting to such haphazard techniques as decrementing the counter on the falling edge of the decode signal?


texts: Sequential Logic - Primarily For Signal Storage?

texts:
New here :D

I've been reading David M. & Sarah Harris's book "Digital Design and Computer Architecture" and came to wonder about the role of sequential logic. To me, it seems that the significance of sequential logic is primarily in its ability to store signals (HIGH/LOW, ON/OFF, 0/1, etc.). However, I've also noticed that the characteristic property of sequential logic is its dependence on past inputs in generating outputs.

Now as a rookie EE student, this confuses me. As I understand it, memory (in the electronics sense) is just the ability to store and retrieve past signals. With this in mind, signal storage doesn't seem like a hard task at all; ROM, for example, is (from what I've heard) purely combinational and stores signals - ie. memory. If we can make memory with combinational circuits, why are sequential elements so highly regarded as fundamental to memory? There must be a reason for this that I haven't read about yet (probably something with computer organization I'm assuming?).

I'm sorry if this post seems extremely naive and/or presumptuous :[ I haven't been taught formally on sequential logic :/


texts: How would one determine the maximum current output you could achieve from an improved Howland source given a specific op amp? In other words, what do I need to look at in the op amp's datasheet? (I am using a TL074)


texts: Finding free electron concentration to check authors' calculations for electron drift velocity

texts:
I am currently studying Practical Electronics for Inventors, Fourth Edition, by Scherz and Monk. Chapter 2.5.1 How the Shape of a Conductor Affects Resistance presents the following image:

I wanted to check the authors' calculations for drift velocity, since there has been some issues[2][3] related to their electron drift velocity calculations in prior sections of the textbook.

My understanding is that the drift velocity of electrons is calculated as

$$\dfrac{\text{current density}}{\text{free electron concentration} \times \text{electron charge}}$$

But, as far as I can tell, we are not provided with the free electron concentration in this case, so how does one calculate the drift velocity (to verify that the authors' calculations are correct)?

I would greatly appreciate it if people would please take the time to clarify this.


texts:
For my smart home, I am trying to develop a system that allows me to identify which person is located in which room.
I am a software engineer but I don't really have experience with hardware development etc.

The system should work with as little action required by the user as possible.

I ruled out RFID because of its short range. I ruled out facial recognition because of the creepy feeling it leaves with everyone if your house can see you.

I am now thinking of using Bluetooth:
Each person that needs to be identified wears a Bluetooth sender and each room contains a Bluetooth scanner.

Questions:

Can this actually work?
Is this the best option I have?


texts:
Yes, it is me again with a PCB Design. I am learning a lot thanks to you. This time, the specs are;

10-32 V input
35V 4A output
Boost converter
The controller IC is LM3478.

Schematic & PCB:

Q1 has a breakout board footprint. R1 and L1 are on the solder side. The ground line of 100 th under Q1's footprint is going to be covered with a lot of solder. Q1 and D1 are connected to a heat-sink. This is going to be a home-made single sided PCB.

LM3478 Datasheet

IXTH24N50 Datasheet

CTB-34 Datasheet


texts: Problems with Memory Initialization in Quartus

texts:
I have the following code snippet in my VHDL code to initialize a ROM block:

type graphics is array(0 to 307199) of std_logic;
signal disp : graphics;
attribute ram_init_file : string;
attribute ram_init_file of disp : signal is "vga_init.mif";

When I compile the code (Quartus 16.0) I get the following warning:

Warning (10541): VHDL Signal Declaration warning at shotbot.vhd(23): used implicit default value for signal "disp" because signal was never assigned a value or an explicit default value. Use of implicit default value may introduce unintended design optimizations.

Like the warning implies, this causes the signal to revert to its default when I access it later, using disp(index).

Any ideas as to why this is happening or possible fixes?


texts: PCB Critique: Soft-start power distribution from 24V battery

texts:
Design

I'm designing a power supply to break out power from a 24V cordless battery that contains a 6s2p configuration of Samsung INR18650-20R cells (datasheet, pdf), each capable of 40A pulse and  22A continuous discharge. The power is broken out into three rails:

Isolated 5V - 30W max, typically <2A
Isolated 12V - 30W max, typically <<1A
24V - 10-30A continuous, 40A peak @ <10ms

Isolated circuits are provided by CUI's PDQ30 series. The reason for the soft-start is that the 24V rail will have significant bulk and downstream capacitance and requires a soft-start. The soft-start is based on TI's LM5069 which uses a high-side FET (nexperia PSMN1R0-40YSH) to current-limit during startup. Plugs in lower left are for external SPST switches to allow separate power-up for isolated vs 24V (both have soft-start).

Schematic

Nothing surprising here; mainly followed TI's Typical Application for the LM5069, with values approved by TI's LM5069 calculator tool. Happy to provide specific part numbers if desired.

Layout

My main concern is layout, and whether the board will actually be able to supply these types of currents. 2-layer board, 92mm on a side. I've tried to make all the main power traces as large as possible to distribute current, as well as provide thermal sinking. All components aside from the spade terminals that connect it to the battery are on the top.

Top layer:

Bottom layer:

Main concerns:

Am I being too optimistic? Would this require something like a solid copper bus bar for the 24V rail?
Considering I have three separate power rails on the top side, it's pretty hard to lay out the board in a way that allows there to be a ground plane on top.
The current-sense resistor for the 24V is 1mOhm. It seems scary having 30A go through that small choke point, but at 30A that's only 0.9W and the datasheet suggests it's rated at 1W@70C, so that seems acceptable...? PMR25HZPFV1L00 datasheet
The ground plane is on the bottom layer, but I needed to get the bulk capacitance for the isolated DCDC converters connected to ground, so I put a 7x8 grid of vias in the upper left to try and spread the heat from both sides of the caps along the top copper traces. Is this useful?
As above, I used 24 vias to bring the ground plane up to the circuits in the lower left.
I'm also not using thermals for most of the connections, as I'm concerned that they'll heat up too much trying to dump that much current.

Any/all thoughts are much appreciated!

Edit: Added link to current sense resistor datasheet.


texts: What kind of sensor can sense Infrared radiation from any direction?

texts:
I am designing a device that uses a remote control with an infrared emitter and receiver. Originally I designed the device with a Tsop38238 but this sensor seems like it's better suited for a DVD player. You have to aim the remote directly at the sensor to get it to work and it only works in one direction, the front of the sensor. This doesn't really work with my design which is actually a bike alarm.
Are there inexpensive IR sensors that receive signals from any direction around it? What keywords should I search and what specs should I look for? By the way, I would like my center band frequency to be 38 kHz.


texts: 24Vdc to 5Vdc 3A Buck Regulator over-heating

texts:
The last time I asked a question on this forum you were all incredibly helpful thank you for that: First PCB (raspberry pi hat)... can't find short circuit, I have an extension on this previous question.
Problem: The LM3489 chip (supposedly rated for max current of 4A) used previously became very hot to the touch (drawing around 500mA... chip does not get hot at all under no load) and while all of the components worked for > 30 min I am worried about the continuous use of this overheating chip. I understand that the tracing on the previous board was horrible and I did not follow the recommended layout at the bottom of the data sheet, but the only example circuits that I found demonstrating the LM3489 show between 100-500mA outputs, nowhere near the 3A that I need. https://www.ti.com/lit/ds/symlink/lm3489.pdf?ts=1612195295134&ref_url=https%253A%252F%252Fwww.google.com%252F
Working (but hot) Schematic for LM3489:

Current Bad Layout:

Question: Why was the LM3489 getting so hot (tracing just that bad / chip can't actually run pulling 3A)? Will fixing the layout to match the recommended on the data sheet fix the heat?
I would really like to avoid another costly round of boards not working, so any help at all that you can provide would be immensely appreciated.
What I have now tried: Switched out C2 with a lower capacitor 100nF to 1nF with no success (board did not produce 5V out and became really hot under no load).
If any parts of this post are confusing or if I should provide any other helpful information, please let me know and I will update the information as soon as I can.


texts:
I'm generating an AC square wave output waveform with the 555 timer circuit below. However, I'm getting these obvious overshoots. Can anyone help me?

R1 is 8.2K ohm
R2 is 68k ohm
C1 is 0.1uF


texts: Why is the output current not equal to the input current in this current mirroring circuit?

texts: Why is the output current not equal to the reference current in this current mirroring circuit? (I have been explicitly told that they are not equal). Both of the transistors are equal and in the saturation region. I thought that the voltage applied to the drain of the second MOSFET (Q4) did not alter the output current as long as it remained in saturation?


texts: Why do new phones and tablets with a USB Type-C connector use a USB Type-A charger?

texts:
I have noticed that many relatively new phones and tablets with USB Type-C connectors (e.g., Nokia 6.1 or Samsung Galaxy Tab A T-590) are bundled with USB Type-A fast chargers (e.g., 12V, 1.5A) and a USB Type-C-to-Type-A cable.

What are the advantages of this practice?

It would seem much more natural to me to ship USB Type-C devices with USB Type-C chargers. Charging could probably be faster (or at least more standards-compliant) through a pure USB Type-C cable that supports USB Power Delivery specification revision 2.0.


texts:
Are clamp meters as accurate as multimeters?

Could I replace a multimeter with a clamp meter?

What can clamp meters do that multimeters can't?

What can multimeters do that clamp meters cant?


texts: Fault current indicator - what should I do?

texts:
Part of the power plugs in my flat stopped working this morning. I checked the breakers box and one of the breakers was in OFF position, with a yellow indicator.
After checking the producer's website, I've come to the conclusion that this means fault current. Here is the exact model:

I've disconnected all appliances from the power plugs and tried to reset the breaker, but it returns to the OFF position with the same yellow indicator.
My electrical engineering skills basically resume to those needed to change a light bulb, but I would like to understand if there is something I could check or do in this situation before calling a qualified electrician.
I'm also interested in a (layman's terms) explanation why the breaker is indicating fault current when there are no appliances connected.


texts:
So im Building a project these leds will be arranged in a circle there will also be about 15 more of these. with inputs to activate them the 3.3 volts will be from a raspberry pi gpio pin. The 12v sorce is a power supply to light all the leds that ill be using. Just want someone to look over this before i buy everything. to double check me and also help me find the value of the Resistor on the 3.3v for the transistor. Each Led in this will be blue.

Led forward voltage is 3.8v and they are all 20ma

Transistor is a TIP120

Thanks for you help


texts:
I have a circuit that includes an arduino and an electromagnet thats periodically turned on.
I can easily measure the current consumed when its turned on and when its off by wiring in my multimeter in series and observing the drain. However I want to know how I can measure the total current consumed (for example overnight). The frequency in which the electromagnet will be turned on will be somewhat random.

This is the multimeter I have https://www.amazon.co.uk/gp/product/B01N3RVVJ4/ref=od_aui_detailpages00?ie=UTF8&psc=1

I've seen some multimeters that have the capability to measure total current passed in, by the looks of it mine doesn't have that. I did consider buying one of those USB multimeters which can do this and splicing the wires to connect it in series with my circuit but I figured surely there's a better way to measure this?


texts:
This question was asked in GATE 2021. Here I am finding it difficult to "manage" propagation delay of XOR gate. Solving it using timing diagram takes a lot of time and rough space.
Is there any other easier method to solve this question ? The answer is 5. Thank you


texts: Incorrect results from DSP48: possibly using 1's complement instead of 2's

texts:
I'm using Vivado to write code for an Ultrascale+ FPGA in Verilog and I'm facing an issue with a DSP48. The DSP seems to be outputting the wrong result.
I have manually added a DSP through the IP catalog and the DSP is configured to compute P := A*B + C, where A, B and C are all wires and A is 27 bit long, B is 18 and C is 48. Now, when I simulate the block containing the DSP in Vivado 2020.1, I don't always get the result I expect from the DSP. In particular, I noticed that I get unexpected results whenever the most significant bit of B is 1 (in my current tests, the MSB of A is always 0). Moreover, the results I get appear similar to the negation of the expected product, so I'm assuming it might somewhat related to signed multiplication.
Thus, my questions are:

Is that a correct assessment of the situation?
If so, how do I make the DSP compute the unsigned product?

Here's a minimum example of my problem:
`timescale 1ns / 1ps

module small_alu1 (clk, s0, s1, a0, a1, a0s0, a0s1_a1s0, a1s1);
input clk;
input [12:0] a0, a1;
input  [3:0] s0, s1;
output [12:0] a0s0, a0s1_a1s0, a1s1;

wire [26:0] A = {a1[10:0],  3'b0, a0};
wire [17:0] S = {s1[1:0], 13'b0, s0[2:0]};

wire [47:0] result;
wire [47:0] C = 47'b0;

dsp_1827 DSP(.clk(clk), .A(A), .B(S), .C(C), .P(result));

wire [12:0] a0s0 =      result[12:0];
wire [12:0] a0s1_a1s0 = result[28:16];
wire [12:0] a1s1 =      result[44:32];

endmodule

When A = 2_0001 (in hex) and S = 3_0004 (also in hex), after the delay due to pipelining, result is equal to fffe_0007_0004, rather than the expected 6_000B_0004.
The DSP is a DSP48 Macro (3.0), it has only one instruction set to A*B+C, which means there are three incoming ports (CLK, A{26:0], B[17:0], C[47:0}) and one outcoming (P[47:0]), pipelining is set to automatic and the implementation options list the port sizes as above, full precision output and no additional ports used, while Use DSP slice is set to on.
EDIT: after more research, I suspect that signs have nothing to do with this, but instead the DSP expects the input and outputs the result in 1's complement. Is that normal behaviour? And if so, is it possible to have it use two's complement?


texts: DC motor smoother speed control with PWM

texts:
I'm using an L298N motor driver to control a DC motor. I'm using only a single input pin since I need only a single direction control. I'm using a PWM pin on my Particle Photon (uses Arduino libraries) to control the speed of said DC motor. I have a 12V motor so I supply 14V to the L298N (due to 2V drop by it to get 12V actual on the motor).
analogWrite(PWM_PIN, 0 - 255)

This line will set the speed motor. However, it's not smooth speed control.
Values:
0 - 70: Noise, no movement.
70 - 130: Slow movement not really usable for my case.
130 - 255: Seems to be max speed.
The speed does not increase as I would expect. Additionally the changes in speed are sudden instead of smooth.
Is there a way to make the speed changes smoother and reflective of the value, instead of just having what appears to be Nothing, Slow, Max.? Could this also be an issue with my motors? I'm using a generic DC motor.
I was thinking of maybe upgrading to something of more quality like a A2212 2200KV Brushless DC motor.


texts:
So I'm  trying to build an 8x8x8 LED cube according to this Instructables. But I'm using slightly different parts:

74HC595 shift registers instead of 74HC164
2N2222 transistors instead of 2N3904

I'm still using the same 100 ohm resistors as him for each output on the shift registers.

My question is, what base resistor value should I take for the transistors so that I don't pass too much current through the shift registers?

LED Datasheet


texts: Is it possible to protect smart card from being copied?

texts:
I'm currently working on SLE4442 smart card. I'm trying to make a payment system. but the card has to be "copy-protected" what I mean here is that if that data on the card is copied as it's, this data is no more valid and it's only valid for this card.

my knowledge of cryptography is basic, I read about digital signature but it seems it doesn't prevent copying.

also for using 'PIN', my design allows users to have their cards PINs.

also if any book I can read about this, I'm open to suggestions.


texts:
New to RFID world.

I am working on a Healthcare product. One of the feature includes authentication of patients which will be done through RFID reader MFRC522. Application schematic in the datasheet explains about the matching and tuning circuits. But I couldn't find anything related to interfacing an external 13.56MHz antenna.

Can I use an external antenna 1462360001 from Molex in place of Lant (Antenna in datasheet pg.81)?

Datasheet of External antenna - https://www.molex.com/pdm_docs/sd/1462360001_sd.pdf

Edited:

I do not have much filter experience. Those application notes are really helpful. I am using AN1491 to design EMC filter & matching circuit for the chosen external antenna 1462360001.

Antenna datasheet doesn't specify all the parameters needed in the calculation tool to design like Ca & Ra values are not mentioned.

Here is the snapshot of the calculation.

La = 2.11uH (from antenna datasheet), Ca = Ra = 0 (missing in datasheet) Which gives L0, C0, C1 & C2 values.

Please let me know if I am doing anything wrong.


texts: How to reduce 24V to 0- 2.5V through a pot?

texts:
I have a 24V DC supply and I need to give a heater a 0-2.5V variable input. I have a very limited understanding on electronics but I've read here about voltage dividers. I used a 10k pot (and the 2 relevant resistors shown in a typical voltage divider diagram). I used the wiper output feeding the voltage divider and put on a voltmeter.

All was looking really good as I turned the pot: slowly increasing voltage. But right at the end, in the last few degrees of the pot,the voltage shot back up to 24V! (as though 24V had "leaked" through the divider). Could someone please tell me what I have done wrong? I even tried with other pots but all with the same effect.

The heater is mains powered, but the heater temperature is either controlled via a built in pot on the unit, or via a remote pot pluged into the side using either a 0-10V or 4-20mA input. We require this option but because the unit outputs 650 degrees Celsius, we want to limit this to around 150. So we need to restrict the input voltage to 0 - 2.5V.


texts:
If we will take the voltage output from the dc source in both circuits will we get same voltage output ? Will the voltage drop across the capacitor will be same ?

Note: Upper end of AC source is positive and lower is negative initially.


texts:
I have this very simple circuit - actually there are 6 of them on a board.

simulate this circuit – Schematic created using CircuitLab

The MCU is connected to an MCU, and it is used to drive RGB led strips with PWM singals. My problem is that the MOSFET is not fully turned off. Or so it seems. When the MCU line is high and the Q1 transistor is fully turned on, then the gate of the M1 MOSFET is at 0.6V (one junction). Even though the threshold voltage of M1 should be about 2V, it is not 100% turned off at 0.6V. The result is that the LED strip glimmers a bit. It is almost nothing, but the LED strip is 20 meters long, and all of that small glimmering adds up. Basically, I cannot use this circuit as it is, because of that small glimmering. It becomes very distrubing in room that is used to watch movies in the dark.

Would it be possible to turn the FET fully off? My only idea is to use a dual power supply, and put the emitter of the Q1 transistor at -0.7V instead of 0V. However, creating a -0.7V supply just for this seems to be an overkill.


texts: Why doesn't aliasing of broad band noise 'pile up' in the sample band?

texts:
I recently built a simulation to study sampling, the effects of aliasing and the effects of anti-aliasing filters on the sampled signal.

For fundamental frequencies above the sample band it's obvious one sees 'imposters' in the sampled signal. Using an antialiasing filter I can eliminate imposters.

But if I rather impose a broadband noise (actually white noise) signal into the sampler then it doesn't make much difference whether the anti-aliasing filter is present or not. The peak to peak noise is the same in either case. Of course the bandwidth of the noise has changed.

But furthermore I would expect the (imposter) aliased broadband noise outside the sample band to be superimposed on the broadband noise that is genuinely passed in the sample band thus 'piling up' with a larger peak to peak level.

Why doesn't this happen?

I should mention that my simulation time step is in the MHz and my system under study in the 1 kHz range. So the system is virtually in a continuous world.


texts: Reprogramming MCU Flash Memory I/O placed on a PCB of a mechanical keyboard

texts:
I've decided to modify some things about my mechanical keyboard (Hermes M1), so I tough starting with installing the software driver it's a good idea. Thus I've changed some things about lighting of it and stuff, until I've come to MACRO submenu of the software, and the software crashed.
The problem that the keyboard has in its memory now is that the layout is all messed up, for example if i press: ASDF on a normal keyboard, on this broken one it leads to : AFJ: , and so on, all of it, only few key match, I cannot start the software of the device, because it crashes.
So.. I've decided to fix it, the "complicated" way, my toughs are that somehow i can hard reset all the memory that is stored in its MCU, I've tried something with DFU-Util, but no succes (i don't know if it's the best soft to do this), i've looked up at Renesas Flash Programmer, but aswell no succes.
Here's some photos with the back of it:

The model of the MCU is HT68FB560, and from their website it is an I/O Flash USB MCU with SPI (their website), so is it a way to reset all their software settings from that MCU? All the opinions are well received. I have to mention that before this the keyboard didn't have any problem, and all the circuits from PCB are well connected.


texts:
I am trying to use this:

To work with these:

When I hook up transformer, I hook up hot(black)from source to one red wire and neutral(white) to other red wire on primary. Which makes 24vac on secondary side.

Image of lights, says 24vac on one line and GND on other, I assume GND is ground? The only way I could get the 24vac on one of the black secondary wires was to hook up the other secondary wire to the ground(green wire) from source. Is this the correct and safe method or is there another?


texts:
Background of my question:
I was checking the signal strength of wifi access points on my laptop in parallel with the internal Wi-Fi card and a nano usb wifi adapter connected to the same laptop. I saw that the signal strength measured on the nano usb wifi adapter was lower by 15 to 20 dBm as compared to the internal WiFi card, although measured almost at the exact same location.

My explanation for the behavior:
I assume that this is mostly due to confined space on the nano USB wifi  adaptor compared to the internal Wi-Fi card, mainly limiting the antenna size, etc.

My actual question:
Unfortunately the drivers for both cards did not provide any noise measurements. However, now I would be interested what to expect for the measured noise in that situation. Specifically, how the measured noise on the WiFi radio is related to things like the antenna size/layout.
Naively, I would put the received signals on the WiFi radio into three groups:

The signal itself, which is received via radio waves
Outside noise that is also received via radio waves (for the 2.4GHz band e.g. microwaves, baby monitors, Bluetooth, etc.)
Internal noise produced by the electronics inside the WiFi radio (operation amplifiers, thermal resistor noise, etc. as outlined here)

I assume that noise from group (3) will be independent for both WiFi adapters, as they will use different components and different layouts. From what I have seen in my experience, I expect them to be typically below -90dBm.
Am I right to assume that group (2) noise will also show up with different levels on my two Wifi radios, since also the actual WiFi signal strength is different.

Finally my theoretical hypothesis:
Assuming there is a babymonitor (from group 2) producing heavy noise on a 2.4GHz WiFi channel which shows up as noise around -60dBm on my internal adapter, could I then expect that this will cause a noise level of around -75dBm to -80dBm on my nano USB WiFi adapter, if also all WiFi signals (group 1) measured on the two WiFi radios typically differ by about 15 to 20 dBm.
Thereby I assume that the internal noise (Group 3) for both WiFi radios is below -90dBm and not a factor for the measured noise value, which would be dominated by noise from group (2).
Is my hypothesis right?
In other words, can I assume that the signal to noise ratio for both adapters will be the comparable, if only dominating noise from group (2) is considered?


texts: SSR LED light on even when ESP8266 pin is off

texts:
I'm powering a heater with an SSR and esp8266 nodemcu module. I've found out that I need a higher voltage to effectively trigger it than what the nodemcu can put out on a digital pin (from previous post SSR ticking when controlling heater).

I have added a transister and diode combo into my network (based on https://electronics.stackexchange.com/a/220504/137437) which allows the 3.3v from the esp8266 to trigger 5v:

This works but when the digital output from the nodemcu is off, an LED on the the SSR still maintains a very slight glow.

If I power the nodemcu from a different wall wart that is plugged into an external wall socket (see diagram below) the led on the SSR is off when the digital output is off.

Is there some feedback or something that is making the SSR Led be on when there is no power to the P1 pin? I have tried testing the voltage across the SSR low voltage input but only have a rudimentary voltage tester and when I try it doesn't read anything and the led goes off.. Or is my wall wart used in the first diagram just dodgy?


texts:
I was looking for space grade rad-hard microcontroller. It is widely mentioned that microcontrollers are limited in their usage in space domain. The reason being that due to high cosmic radiation there could be adverse effects on the flash, thereby corrupting the code stored.
So, I decided to look at FPGAs as they are much more stable (vis-a-vis radiation effects). Is it possible that I select an FPGA and program a softcore that can fulfill my microcontroller needs ?

My present board has the LPC4337 dual cortex MCU. Is there any similar chips that are rad-hard ? Most of the rad-grad MCUs are from Atmel,ST and a couple of vendors (intersil,surprisingly). But not many are ARM compatible.

Atmel has a SPARC core, which again causes software migration issues. Are ARM cortexes used in space ? I would appreciate any pointers in this direction please.


texts: Current Determination - 12V to 5V (USB Output)

texts:
I am attempting to determine the current in an automotive installation of a 12V to 5V converter that will supply a USB output. Max output on the 5V side will be 3 Amps.

Power = Volts * Current = 5V * 3 Amp = 15 Watts

Therefore, does the 12V side have to conform to:

15 Watts = 12V * I, solving for I giving, 1.25 Amps.

Thus a 2 Amp fuse is sufficient?


texts: How to generate constant 38 kHz square wave for IR light source?

texts:
Application: IR light barrier over a distance of 1m

Receiver: e.g. Vishay TSSP4038 IR sensor (tuned to 38 kHz)

Ambient temperature range: -10 to 40° C

Here I’ve found a circuit with a Schmidt trigger that should do the
trick, if there was a crystal oscillating at 38 kHz. But I can’t find
any. Digikey lists 38 kHz crystals, but – looking at the spec
sheets – it turns out that they are actually 32,768 Hz crystals.
How do I get 38 kHz?
I’ve also considered an NE555 based circuit, but that’s not temperature
stable, and it requires trimming. Another option, I’ve been told, would
be using an Arduino to generate the 38 kHz, but that looks like
overkill.
Update
Following the recommendation in the application note mentioned in Ali Chen's answer, I finally decided to use an Arduino Nano. For generating the 38 kHz, I used the timer as described in an Arduino forum post by Nick Gammon to the Arduino forum. His code example:
const byte LED = 11;  // Timer 2 "A" output: OC2A

void setup() {
 pinMode (LED, OUTPUT);

 // set up Timer 2
 TCCR2A = _BV (COM2A0) | _BV(WGM21);  // CTC, toggle OC2A on Compare Match
 TCCR2B = _BV (CS20);   // No prescaler
 OCR2A =  209;          // compare A register value (210 * clock speed)
                        //  = 13.125 uS, so frequency is 1/(2 * 13.125) = 38095 Hz

}  // end of setup

void loop() { }

Via an interrupt pin, I hooked the Nano up to a Yún, which runs the main logic and which tells the Nano to turn the signal on or off. Keep in mind that the Vishay application note is about measuring the distance to an object, whereas my application is simply about measuring whether a beam is interrupted or not.
Next steps: Get rid of the Nano; Upgrade from 38 to 56 kHz for slightly faster sensing.


texts:
The question is Find the Q-points for the diodes in the circuit using the ideal diode model:

The book solution is:

However, per my analysis both diodes are conducting because if as assumed that D1 is cut off the voltage at D1 cathode side would be -3.92 V which is less than the voltage for the same diode anode side! Thus, since
VD1 (anode side) = 0 - VD1 (cathode side) = -3.92
0-(-3.92) = 3.92
D1 will conduct.
Am I right?
The Book is:
Microelectronic circuit design / Richard C. Jaeger, Travis N. Blalock. — 4th ed.
ISBN 978-0-07-338045-2


texts: Resistor network in half bridge rectifier

texts:
I have come across the following half bridge rectifier circuit connected across phase R and T.

I'm wondering about the large resistor network in parallel with the source. What is the point of this and is there any benefits to it?

Thanks.


texts:
How do you wire up Ethernet electrically without a switch? An approximately equivalent phrasing of this question would be what is going on electrically inside an Ethernet Hub?

To clarify, I'm not trying to connect two computers here. I'm thinking specifically of creating a small network of microcontrollers on a single board. Can it be done without a switch or a hub through just electrical connections. This would be for 10BaseT or at most 100BaseT.


texts: How much longer should we expect DIP (or DIL) Packaging to be around?

texts:
More or less in response to this question:
Reliability of anti-static packaging

A few comments were made (which made sense) on manufacturers not really shipping many DIP packages in comparison with SMD devices. So my question is, should we expect this type of package to end eventually at some point, and is it just a matter of "whats left" in production.

It makes sense for a manufacturer of chips not to really care about hobbyists which only make up a small portion of their sales. But do you think the package itself will be phased out completely? (especially with Popular Boards like Arduino becoming even more popular?)


texts: 24v output from two 12v batteries in series, charge them with 12 volts in parallel

texts:
I have a solar charge controller which can charge 12volts batteries. I have two 12 volt batteries which are connected in parallel. I need to have 24volts output without using dc-dc step up converters. Can I connect two 12 volt batteries in both parallel and series? like first having a parallel then having a series connection with some Diodes to control the current/voltage flow. Is it possible? are there some best practices?

EDIT: goal is do charge/discharge the batteries simultaneously.


texts: Need comments on low noise band-pass filter design

texts: I am a beginner in filter design. This is the bandpass filter and its central frequency is 2kHz. Would you please give me some comments on this design?


texts: Do you think I should add Pi matching circuit behind the dipole wire antenna input to achieve the highest LNA gain and low SWR and fine tune it by SimSmith program and NanoVNA ? The route is CPWG 50 Ohm.


texts: How to bake MSL components for DIY reflow?

texts:
I'm intending to reflow solder some components from Analog Devices. Since they are an LFCSP package, hand-soldering is not possible. They arrived with a warning that they are moisture sensitive (MSL3) and require baking at 125 degrees for 24 hours before reflow soldering.

My question is, as a hobbyist with limited equipment, how can I safely remove the moisture? I don't have access to a reflow oven, only a kitchen oven (and it's not feasible to cook components in that for 24 hours, I am not even sure if that would be safe).

Alternatively, is the risk of popcorning that great? I only intend to make one or two prototype boards, and I have 6 ICs so could afford to sacrifice one or two.


texts: Connect motor in 220 VAC single phase (Line - Neutral) or in 110VAC two phases (110VAC - 110VAC "180 degree out of phase")?

texts:
I need to connect A motor of 220VAC to single phase connection :Line - Neutral(220VAC - Neutral).
In my country that doesn't exist so in my country we have this : L1-L2-neutral (110VAC - 110VAC "180 degre out of phase" - Neutral).
I would like prove that doesn't matter the way I connect the motor , either Line - Neutral  (220VAC - Neutral) or Line1 -Line2 (110VAC - 110VAC "180 degree out of phase" ) .
The following image explain what I try to prove :

So I begin :
Single Phase Connection :
$$ Line1 =  220sen(w+\theta)\\
w = 2\pi f; \theta=0\\
w = 2\pi 60H ;\theta=0\\
w= 377rad/s
$$
So potential difference in original single phase instalation would be :
$$V=220sen(377rad/s)VAC - 0VAC\\
V=220sen(377rad/s)VAC
$$
Now in two phases connection:
$$Line1 =  110sen(w+\theta)\\
w = 2\pi f; \theta=0\\
w = 2\pi 60H ;\theta=0\\
w= 377rad/s\\
Line1=110sen(377rad/s)VAC
$$
Line two has 180 degree out of phase:
$$Line2=110sen(377-180)\\$$
By trigonometric Identity:
$$L2=110[sen(377)cos(180)-cos(377)sen(180)]\\
L2 = 110[sen(377)*(-1)-0]\\
L2 = -110sen(377rad/s)$$
Finally we do the difference potential of the two Lines in the two phase conection:
$$V =L1 - L2\\$$
$$V=110sen(377rad/seg) -(-110sen(377rad/seg)\\
= 110[sen(377)+sen(377)\\$$
By trigonometric identity:
$$110[2*sen(\frac{377+377}{2}*cos\frac{377-377}{2})]\\
$$
Solving we get the two phase difference potential:
$$V=220sen(377rad/s)
$$
Voltage in motor in single phase connection is the same that voltage in two phase connection.
So, We say it doesn't matter If I connect the motor in this way (220VAC - Neutral) or this way (110VAC -110VAC) and this mathematical demostration prove that.
Am I wrong ? Or Am I perfect in that demostration ?


texts: Why we want to convert a voltmeter to an ammeter or vice versa?

texts:
Why in laboratory experiments do we want to convert a voltmeter to an ammeter and vice versa? What is our main aim here that is for what we are doing it?

If our goal was to change the range of the meters, then we could do the same by converting an ammeter to another ammeter or a  voltmeter  to another voltmeter. Then why are we doing this type of conversion, for what?


texts:
I live in a reasonable warm place, which requires me to run an AC all day, but I also need to use hot water for shower and other purposes. In this regard, I had the following idea, though I am unable to calculate the efficiency to know if it is practical.

I want to connect a few (maybe 20) Peltier devices with heat sinks on both sides such that the hot side circulates water into a thermally insulated storage tank and the cold side is connected to a circulator that is filled with a refrigerant and connects to a AC unit. This way, I am trying to use the full potential of the Peltier devices. Is this going to be efficient for the following purpose:

The water heating tank is 50 litres and needs to go upto 50C.
The room to be cooled is 48m^3.
I plan to keep the water storage unit right outside the room to be cooled so that there is less thermal wastage due to long pipes.

The ambient temperate is between 25C to 30C and I want to cool the room as much as possible. In particular, my goal is to try to utilize as much of the Peltier output as possible in the most efficient way.

My question, is this is a viable strategy in terms of efficiency? Where can I learn about how to calculate the efficiency of this setup vs a standard setup?


texts: Problems with small signals through BNC connectors?

texts:
I have a 120kHz signal from a transducer with peak to peak values of typically 40mV being carried over coax cable and connected at both ends via BNC connectors. Most of the time this seems to work, however there do appear to be occasional signal quality problems. Is there likely to be a problem with such small signals though this arrangement?
By "signal quality" I mean distortion of the sine wave and/or added noise related to the twisting of the cable. I am guessing that this may be related to the connector pin rotating and causing changing conductivity at the contact points


texts: How to get the unknown variables through voltage division?

texts:
Given this circuit, how do I find E, Vz, and Vy when Vx is 3V?
When I tried solving it, through simplification of circuits, (correct me if I'm wrong) I got a total resistance of 12k while resistance of Vy is 10k. Upon getting the total resistance, I used the voltage division formula to get E, since the formula is Vx = E(Rx/Rt) where E is the voltage source, Rx is the resistance of x and Rt is the total resistance, I manipulated it to get E, which, in my calculations, is 2.4V. Now this is where I'm confused, since E, which is the source, is less than the voltage of a resistor, did I make a mistake in my calculations? Since, from my understanding, a voltage source's voltage is always greater than the voltage of its elements? Also, can I solve it in the manner of finding Vy first, then Vz, then E? If so, how?


texts: Freerouter doesn't want to route to inside an FPGA

texts:
Prefacing this by saying I'm entirely new to designing electronics for a PCB and I've only worked with breadboards before, so if there's more that I'm doing wrong in my project besides just the PCB design I would be very appreciative if you let me know.

I'm trying to use an iCE40HX8k-CT256:

For example, there are multiple I/O bank power pins connected to the same source (I haven't finished drawing the symbol):

VCCIO_1_1 and VCCIO_1_3 are connected in the schematic, and as such are connected by a rats nest line in Pcbnew:

Freerouter absolutely hates trying to route connections inside the FPGA, including the example above:

What am I doing wrong? How can I make it so that Freerouter wants to and is able to route outside connections to inside of the FPGA?

If it helps, the current KiCad source is up at https://github.com/bgec/bgec-hw.


texts: At which negative Vce voltage will an NPN transistor be damaged?

texts:
Assuming an open base, how low can Vce go (negative) before the transistor is damaged? Can I protect a transistor by connecting a diode's cathode to the collector and and anode to the Emitter?

If this is different depending on the transistor please use this one as an example http://www.nxp.com/documents/data_sheet/PBSS4350SPN.pdf


texts: How does the CAN bus avoid damage when multiple nodes command the bus?

texts:
For example, although they are not the same, I²C uses pull-up resistors and open drain drivers. Resistors, not the nodes, set the bus idle state. Many nodes can be added to the bus without loading the bus. Because all the drivers use open drain, many drivers can pull the bus low without any problems.

In CAN the nodes command the bus idle state. If many nodes are added to the bus how is loading avoided?

If all but one node command the bus to a dominant state, how does the one node that is still commanding the bus to a recessive state not get damaged?


texts: Will 3.3v to 5v level converter work with USB data lines?

texts:
I'm trying to design a low-speed USB device based on ATmega16a. That chip doesn't have any USB interface, but it is possible to use bit-banging and there are even ready-made libraries to do so, like V-USB. So the programming part is quite clear.

What is unclear, it is how to physically interface AVR to USB. The problem is, USB gives +5V, but uses 3.3V levels on data lines D+ and D- (which aren't always differential). The V-USB suggests two solutions: running a whole AVR at 3.3v (with two clamp diodes on 3V line) or making a lousy level converter by attaching two 3.6V zener diodes, to clamp voltage from AVR.

Low speed USB runs at 1.5MHz, so ATmega16A should run at 12 MHz. According to datasheet, it is not rated to work reliably at that frequency when powering from 3.3V, so I required to run it directly from 5V and the first option (with clamp diodes) is not available for me.

I've implemented this on a breadboard with zeners, so test circuit works. But I think this is not very robust solution, because data from USB to AVR could be on AVR 1-level margin. I think about using a bi-directional level converter, like txb0104.

This is my question: will level converter work for USB data lines? I want to figure out the way how to analyze timing parameters in the datasheet to ensure it will not screw USB signal timing too much.


texts: Eagle Board Editor: Garbage or stray marks of a particular component stays back even after moving it

texts:
I am designing a primitive PCB design in Eagle. I used many tools like move, route, delete, smash, etc. I dont know why I bumped into this problem. When i move a component ,there is a part of the component(like wire frame) staying back , but the full component is movable.
I assumed it may be a bug(where eagle is not refreshing the screen) but when i checked for errors, these stray marks we mentioned in the error's list. Please help me with this.


texts:
I want to connect this microphone amp to my audio interface:

  Please note the stereo output Jack socket (J1) connections: only the two inner connections are used, leaving open the external one. In this way the two earpieces are wired in series, allowing mono operation and optimum load impedance to Q4 (64 Ohm). Source

Is this possible? J1 has no GND connection (differential audio?). Can I just connect pin3 form J1 to GND to make this work?


texts:
Newbie here.

We have a 3 phase installation for our dimming control system for our lighting system. During inspection while our 3 phase is safe with lock out tag out. Normally, we will get a low voltage reading from phase to phase less than 3 V.

This time, we encountered a phase to phase low voltage reading more than 3 V with a fluctuation up to 6 V.

What can cause this higher voltage?
What is this called, Unbalance load?
How can we correct this?


texts:
Since the neutral wire is grounded at the circuit breaker panel, I am confused as to whether current actually flows along the neutral back to the service head?

If not, then what actually absorbs the current? (I realize that it is AC, but the current must be going somewhere during a single cycle).


texts:
I'm building an electronic musical instrument which I would like it to have a 3.5mm audio output socket, so it would work with any "regular" headphones, like a cellphone does.

For a long time, I've tried to googling the electrical standard for such a socket (having TRRS + CTIA connection) and couldn't find one.

How should I design my signals for the connection?
What are the voltage ranges?
What is the output impedance my circuit should show?
Is the analog signal being the signal being played? or the socket output signal contains some sort of modulation?

If you could please clarify how should I accessing the socket subject,

Thank you.


texts:
I'm trying to find the name of the connectors I need to use in PCB to connect with the three cables below:

I suspect the second one is a DIN5 connector and the third one is an IDC connector, but I don't have a guess about the first one.

Could someone help me?

Additional Info: The three cables are used in Quanser's 2DSFJ robot and these pictures are from the robot manual.

Update: The first cable connector is the "Output" connector of the picture below:

Thank you


texts: What exactly is meant by beta dependence in this fixed bias BJT scheme?

texts:
What I understand that, in a fixed bias BJT scheme the problem is beta dependence.

Below is an example from a text:

Now I read that this is not a good design. But I will still solve this by assuming we have a constant unchanging beta:

So the aim is to obtain around 7.5V(half-rail) at output when there is no small signal input.

I will use beta and write KVL as follows:

I neglect Vbe since it is small relative to the 7.5V; I also take Ie=Ic=100*Ib.

KVL:

Ib * Rb + Ie * Re = 15V or

Ib * Rb + 100 * Ib * Re = 15V

Since we want 7.5V output it means:

Ib * Rb = Ie * Re = 7.5V this yields:

Rb = 100 * Re

Using the KVL equation with this becomes:

Ib * 100 * Re + Ib * 100 * Re = 15V

Re = (15/200) * (1/Ib)

Re = 7.5/Ie

So if we set Ie = 1mA

Re = 7.5k Ohm

Rb = 750k Ohm

Now above assumes beta is known equal to 100 and is fixed and never changes. And I read it is bad design. Now the reason is given as because it is dependent on beta.

But here what is meant by beta dependence? Does that mean two same models have different beta or does that mean beta is changing by time for the same unit?


texts:
In this article, the author talks about 3 phase and the magic of a missing neutral wire. And there's the following paragraph:

  In a 3-phase system the voltage between any two phases is 3 times higher than the voltage of an individual phase by a factor of 1.73 (square root of 3 to be exact). If your X-N (and Y-N and Z-N) voltage is 120V (common in the US), the X-Y (and Y-Z and Z-X) voltages (a.k.a. “cross-phase” voltages) will be 120V * 1.73 = 208V.

When he says the X-N voltage is 120V, with N being the reference voltage, is the reference voltage 0V or does it have some value?

From the diagram (in the link,) I realise that the neutral wire is grounded, but is this the same as earth grounding? Doesn't the neutral wire go back to the transformer so as to provide a closed circuit?


texts: Is it possible to Speed control this AC Motor?

texts:
This is a 230V AC Motor. One Phase.

Is there a way to lower its speed?

I have tested using fan capacitors which didn’t work.

I tried a triac phase cutting settup, but it seems dirty, noisy (humm) and it seems the fan doesn’t like it.

The cleanest way seems to be a frequency adjustment. But of course its expensive.

Right now i am thinking of converting ac to dc, and then using 2 tyristors to create ac with varying frequency.


texts: Parallel to less parallel without throttling

texts:
I'm modeling a camera-serial interface in Verilog. My design takes video frames in, packetizes them in a certain format, and then distributes them among 1 to 4 parallel lanes. Each lane is 8 bits wide. It is configurable how many lanes you want to use. The packetizer passes 32 bits to the lane distributor every clock cycle.

My question is what is the best way to pass data along without throttling if less than 4 lanes are used?

So if 32 bits are passed and only two lanes are open, the distributor can only pass 16 bits per clock. Is there a fast way to do this without control signals that stop the packtizer from send data every other clock. It seems like there isn't because the data would pile up.

Any help would be appreciated!

Another question: at the end of the data send, there needs to be and "End of Transmission" byte sent on every lane. How would you handle this if the number of bytes sent is not a multiple of the number of lanes? The EoT byte would be sent on different lanes at different clocks. Is there a nice way of modifying a state machine to handle these edge cases?


texts: Is it possible to rotate a fan by splitting the phases by 100 degrees?

texts: I have learnt, a motor can rotate only when the main and auxiliary windings are at 90 degrees phase shift.but is it possible to rotate it in between 90 and 120 degrees.


texts: Atmega328 doesn't respond after power loss while uploading program

texts:
While uploading program to atmega328 I accidentally disconnected it from power. After that I get "target doesn't answer" message while trying to upload.

I am using USBasp programmer, connections are correct. I would like to know what exactly happened. Its third chip that died because of power loss while uploading.

Can someone explain what it could possibly be?


texts: What factors are limiting form factor of e-ink displays?

texts:
Please help me understand what engineering problems are currently limiting e-ink displays from reaching sizes let's say comparable to sizes of standard LCD screens.

I originally thought there are business reasons only (that minimum of folks would buy a display with limited colors and slow response times), but after I found out that even e-ink manufacturer builds e-ink wall consisting of 7,4" e-ink displays, I started to believe there must be other limiting reasons, too.

In other words: Is there some problem constructing e-ink matrix let's say 25" with FullHD resolution? (although with limited colors, but still suitable for working with text etc.).


texts: Connector type suggestions required for 12V supply

texts:
I made a power supply enclosure with a mains switch and now I need external DC connectors to be mounted in the slot shown.

I want to mount two female connectors onto a 3D printed panel, that will sit where the slot is (see pictures below) and which will connect to the 12V DC output of the power supply. I will then put male connectors onto two wires, so I can easily unplug the power supply from the machine. What is the best connector for this?

Please note I am not an electronics guy and primarily do mechanical engineering/design work so my knowledge on electronics is very limited at this point.

Thanks in advance!


texts: Quartus II - SignalTap II Getting the Period of Sampled Data

texts:
I am working on a VHDL project where I am trying to make an LCD controller.

I have been trying to get the period of my scaled clocks using Signal Tap, however the time bar does not show the time accurately. The time bar just shows the sample units. When I set it to time units, it just adds a seconds to the sample numbers. I would like to figure out the period of my scaled clocks as a verification that it is the correct frequency as it is used for timings on the read and writes to the LCD.

I can't seem to figure out how I can get the frequency of a probed node in signal tap.

Does anyone know how I can do this?


texts: What is this SMD component, marked as D7 with an underline?

texts: I'm trying to identify the SMD component (marked as D7 with an underline) on a circuit board of an ARGB LED controller. I think it is a diode or resistor, but I'm not sure about it. Please can I get some help with identifying it?


texts: How exactly pullUp and pullDown Network in CMOS should be defined... I mean why "PullUP" or "PullDown"? And why PMOS in pullUp network and NMos in Pulldown network?Why not Pmos in pullDown and Nmos in PullUp?


texts: Multiple instances of same device on I2C bus

texts:
I am currently designing a board where I need to include a whole bunch of I2C devices. Since the number is quite high, address clashing is an issue, that of course we can solve implementing different bus segments, or with translators.

There is a particular situation though, where I had an idea.

I have two arrays of 8xADG2128, and I want them to be configured in the exact same way. The I2C-compliant solution is to use a bus isolator, or an address translator, and get over it, but I was wondering if it is advisable to just hook them all to the same bus, and hope for the best.

To abstract a bit:

I have two identical devices, with an I2C slave interface, with the same address. I want to send them the same packets, in the same order and so on. Can I just connect SDA and SCL in parallel, and get away with it?

I do not need to read from the devices, and I am aware that a NACK would be hidden. Also, the devices do not support clock stretching.

Edit, to clarify some comments:

Yes, I do not care if a device stops working and understand I have no way of knowing

The master we are using does not resend data on a NACK, but raises the error to the host.

The board we are designing is meant to be used in an electronics lab environment, as a support to evaluate a product that my company is making. We expect to make ~20 boards, no mass production, no board will be sent to a third party.


texts: What is causing this distortion of a pulse wave when recorded to a reel-to-reel tape?

texts:
I'm currently trying to record a pulse train used as a tempo clock for music instruments (e.g. output of Korg Volca 'sync out') onto my Fostex M-8 reel-to-reel recorder, with the aims to then reproduce the recorded pulses to act as a clock source for the instruments. A working demonstration of this using a different tape recorder can be seen here in this youtube video, so I know it's possible to get working.

My problem: When I use my recorder pulse signal as  input to a Volca Bass unit, I'm getting very erratic behavior where the playback is irregular and at a different tempo than when I recorded the signal.

I'm using a Roland tr-09 as my clock source, and the output of the trig jack gives a nice clean square wave:

The captured signal from the output of the reel-to-reel gives a slightly attenuated pulse, with a very long discharging tail from a negative polarity back to zero.

I'm getting this weird capacitance looking discharge. Is this just the nature of the tape that's causing this? Is there something about a DC component being filtered out? Why did the demonstration in the linked video work, which is also recording onto tape, but I'm getting this result?


texts: Driving Power MOSFET with Optocoupler Problems (Component FOD3182)

texts:
simulate this circuit – Schematic created using CircuitLab
So I am trying to build a BLDC motor controller using a Teensy4.0, FOD3182 Optocoupler, and some power mosfets. Currently I am working on just getting the FOD3182 to switch an LED on and off before I start working on the Mosfet portion of the circuit.
EDIT 1:
Hey all, thanks for the help both on this problem and using this site, first time on here obviously and I really appreciate it.
so, RED.LED.1 will be replaced with a Power MOSFET to drive the coils on the BLDC but I will exclude that until I can get this working properly.
Obviously R2 isnt doing anything, but I added that in to represent the voltage divider I'll be using to drive the MOSFETs eventually. The thing is, RED.LED1 is constantly on and doesnt seem to be affected by the PWM changes at all.
here is the Data sheet for the FOD3182
https://html.alldatasheet.com/html-pdf/505064/FAIRCHILD/FOD3182/978/2/FOD3182.html

original post below
Teensy4.0 (pin10) to FOD3182 LED Anode then a 220 ohm res (current limiter) to a RED Led then to ground. The RED Led is just so I can visually make sure there is power, and that the PWM signal is passing through, as I dont have access to test equipment. This side of the circuit seeeeeems to be working fine as I modulate the PWM.
The isolated side of the FOD3182 opto is the issue and wired as such
+12V to a 1k resistor and then to VDD. There is a 0.1uF cap between VDD and VSS. VSS is connected to 12Vground. V01 has an LED (for visual on/off testing) and then to ground.
as an amateur, I would think that the Arduino side LED and the +12V side LED should flash in unison and at proportional amplitudes, even though they are not electrically connected. Unfortunately the +12V side LED is permanently on.
Mayhaps I am wiring this wrong, or just didnt understand what type of optocouple to get, but considering the FOD3182 is purpose built to drive a Power MOSFET I cant see why this is not working as this should be a fairly simple on/off circuit.
Part of what I am wondering is if the Rail-to-rail aspect of this optocoupler needs something more than I am understanding. It should just basically be an electrically isolated on/off switch when the LED is powered but it doesnt seem to be blocking the voltage on the load side.
HELP lol.
I'll upload an illustration when I can, but this is just a bit frustrating.


texts: Why does a triac trigger with gate current in either direction?

texts:
I've been coming up to speed on thyristors, and triacs in particular. I've found detailed material on them a little hard to find, in particular on the device physics. Horowitz & Hill is silent on them, Sedra & Smith as well, not even a mention.

I suppose I get a vague idea that thyristors belong a bit to a past era, but they're still a key component in solid state relays (SSR) for example, so I thought I'd be able to dig up more.

Anyway, one of the questions that's still open for me is why a triac triggers with gate current in either direction (in/out). That seems a bit odd so definitely aroused my curiosity.

Does anyone understand how that bit works?


texts: Few questions on my project (Schematics) -> resistor, transistor

texts:
I have a school project where I have an electronic circuit connected to a microprocessor, with a thermometer controlling LEDs, and buttons changing the date, etc.
I made a quick schematics (orange arrows go to the microprocessor which takes 3.3V maximum)

So my questions are :

Is there something stupid I made ?
Do I need any resistor in that system ?
Can I control the 5V entry with a transistor from the 3.3V entry ?

References :

Thermometer (generates 10mV / degree Celcius)

Analogic to Digital Converter

Button Switch

Transistor (The one I need to use if I implement it)

Unfortunately I have no information about the power needed by my leds, but I guess it should be around 3V.

I hope this isn't too messy, thanks for help !


texts: Is it possible to drive a low voltage (7V) brushed DC motor with a low duty cycle, 220V DC source?

texts:
I am trying to drive brushed DC motor rated at 7 volts in only one direction. The motor can sink high currents under load (I expect up to 20A). My genius plan is to run it from rectified mains electricity in an attempt to use very few converters/parts and thick wires. I know that the coil inside the motor in conjunction with a PWM voltage source and a flyback diode acts like a buck converter.

My questions are:

Is this going to destroy the motor by applying a much, much higher voltage than the motor expects, even if it's in short and frequent pulses?
If 220V will destroy the motor, how high can I go voltage wise?


texts: power loss between 12v to 5v ac inverter vs. 12v to 5v dc only inverter

texts:
I have an inverter in my vehicle for my tablet. I that know it uses 5v and my vehicle is a 12v system. My inverter has a usb jack and also 2 3-pronged US sytle plugs. Its a fairly beefy one rated at 750 watts continious. Its good for power tools on a job site without a good outlet. I also use it to power my tablet on camping trips.

I bought a cheap Chinese volt/ammeter to moniter my draw. Turning on my inverter costs around .5 amps. Plugging in my tablet costs another .25 amps (on a 12v scale). So, most of my draw is from the inverter doing it converting.

I am wondering what the base draw would be to just have a dc to dc voltage drop?  I can seee on Ebay that they are fairly inexpensive but I wonder how they work (guessing they do the switch on and off thing really quick to immitate ac so you could use a transfomer? And of course you could just put a resister of the right size to drop it down, but  I would guess that would be the least inefficient.)  My main question is though, if is it would be less of a draw than than the inverter. And, if so how much?


texts: Flash/obtain ROM code for Sitara on BeagleBone Black

texts:
How is the ROM code loaded/provided on the BeagleBone Black?

I see a few possibilities:

It is loaded on in TI's factory and is immutable [unlikely]
It is flashed on during manufacture of BeagleBone [most likely]
Some other way

If it is open-source, where can it be obtained from?

If it is not open-source, and it is not flashed onto the Sitara by TI, can it be obtained as a binary blob, or can it be extracted from another Sitara?

How would it be flashed (via USB? JTAG?)

Does this ROM code take a similar function as a PC BIOS?  Resetting initial system state (including configuring boot devices), then loading a bootloader?

This question is the sequel to this one.

I have been playing with FreeRTOS on some Cortex M3 and F1 boards for a while and I decided to start learning how more complex embedded systems work.


texts:
I want to thank you for reading this question , keep in mind it might seem silly but it has been troubling me for a couple of hours.

I am using a PIC16F628. All i am trying to do for now is turn a simple LED on.
I have created the following code using MikroC:

void main()
{
  TRISA=0x00;
  PORTA=0xFF;
}

Have simulated the following circuit with Proteus:

I am aware that only 4 leds would light up.

An uploaded the code to the PIC and veryfied it using PICkit2 (Software and Programmer).

I have read that the Programming pin (RB4/PGM) should be set on low , which I have done.

The PIC is wired on testing board and it doesn't turn on any LED. None of the pins (RA0,RA1,RA2,RA3) give enough voltage (they give about 0.3V).

1)I am supplying the circuit with 5V.

2)I am using the correct pins.

3)I have reprogrammed it a couple of times , no success.

4)MCLR is connected through a resistor to Vdd.

5)PGM pin is connected to GND (Vss)

6)LED are the correct way connected (even tried to rotate them in case I had mistaken).

7)I have tested the wiring , it is not interrupted.

It doesn't work , and I don't know what to do. Could somebody ,please  explain what I have done wrong ?


texts:
I am buffering in data from an ADC.  The data comes in MSB-first.  Naturally, I have a 16-bit register to buffer in the data:

reg [0:15] sample_in;

The MSB index is 0, since it comes in first.  This makes the most sense when your indexer is a simple counter.  I am using a floating-point conversion module that looks like this:

module int16_to_float(input [15:0] a, output [31:0] b);

As you can see, the input has a different bit direction from my original register.

My question is this:  If I set the input a to my register sample_in, is the synthesizer smart enough to wire them together MSB-to-MSB, or does it simply stick them together?  In my case, sample_in LSB would be wired to a MSB, and vice-versa.

Also, I realize it's easy to change the sample_in bit direction, making everything match.  This is more of a theoretical question that a practical one.


texts:
I need to design a circuit that outputs a 5V PWM with a frequency of 50Hz and a duty cycle between (5% and 10%). If you are familiar with R/C servos this's the typical signal to drive servo position. This circuit should output the PWM with 5% duty cycle until an event (another 5V TTL signal) change state from low to high. Once the event have been caught the PWM signal should change to 10% duty cycle. The accuracy in duty cycle should be better than 0,1%.
It's not mandatory that the circuit reset to initials conditions after the input signal goes back to low (but it's welcome).
My first approach was to use a small micro but unluckly this's not the case since I cannot use programmable devices in this application.
I was thinking to use NE555 or NE556 IC but as far as I remember duty cycles below 50% and very low frequencies as those I need to manage are not very stable.


texts: How to Size Line Reactors and Understanding Reactor Specifications

texts:
I've got a 600 VAC, 75 HP VFD that I want to place line and load reactors in series with. Usually, I find charts like this that give me a horsepower table to follow as they are the easiest to use. However, today I googled sizing electrical reactors I've found sites have varying information and suggest different sizings.

I've never challenged suppliers on why these are sized the way they are. When I've purchased them it was simply by using the voltage and horsepower ratings of the VFD/motor but now I'm curious as to the rationale behind all these numbers.

With respect to the guidelines linked above and the following reactors: RL-08002, RL-08003.

Why is 3% on the line side and 5% on the load side recommended?
What does the 3% and 5% relate to?
How is this percentage used to calculate the equivalent mH rating (0.4 and 0.7 mH)?
If I wanted to calculate a required reactor size without the use of an equivalent horsepower table, what would be the proper starting point? How can I determine an unbiased value?


texts:
I have a system that has at most 10 20V batteries and each battery can push out 10A.  At each battery I have a SPST relay disconnecting each positive terminal in the ckt.  The SPST is driven by a 5V micro controller and a transistor.  I am trying to replace a N.O. Relay with a N-chan MOSFET.  This is what I currently have:

simulate this circuit – Schematic created using CircuitLab

This is what I thought I can do:

simulate this circuit

Can anyone confirm that I am approaching this correctly? What would be other's suggestion in replacing these relays?


texts: What type of wire should be used for 230 v ac while using this relay

texts:
I want to drive a 230v bulb with the help of a relay, so I soldered a 5v relay on a perforated board with a transistor driver circuit which is working perfectly fine. The relay I am using is HL JQC-3FC(T73) whose datasheet is here

But I would like to know what type of wire should I use for 230v ac appliances(Single strand or multistrand, the thickness etc).

Also I know that I cannot use two rails(for rails I mean the lead lines which I use to connect electronics components on my soldering board) which are side by side on the board which carry 230v ac voltages, so what should be the distances of such rails.

Thankyou for your time


texts: Can I use the ground wire of the grid with the power from my inverter?

texts:
In other terms : Can i connect ground wires 1 and 2 together ?
EDIT : I'm in France, Grid is connected to a ground rod. System is 230v AC.


texts: What is the correct way to measure voltage with an optocoupler?

texts:
I'm using an optocoupler to measure a voltage, I'm making a current loop to control the current through the LED, so I'm using three op-amps: one to measure the voltage, one to set up a current offset because at very  low  currents the CTR is far from linear and finally a third one to make the actual current loop.

I measure the voltage with a uC in the points marked and get this characteristic

The saturation starts at a quite low current for the LED, about 5mA. The results I get  playing with the operation point aren't bad - the right scale is for the error, both scales in volts.

But I wonder if its a better way to to this, for example I'm not using the base of the transistor externally, would be that a better option than the current offset? Would that increase the linear region?

Edit

Kevin White, do you mean  doing this:

That's definitely a simpler solution and it allows to avoid the math for calculating the voltage through the op-amp transfer function and the linear regression.


texts: Trouble Calculating Transistor Voltage Drops

texts:
simulate this circuit – Schematic created using CircuitLab

The transistor in this circuit is supposed to act as a switch, with the LED operating with 2V at 10mA. I do not know how to calculate the collector-emitter voltage and base-emitter voltage of the transistor in such a case where transistors arent used for amplification. I am interested in finding theses calculations when SW2 allows current to flow to the base of the transistor (Q1). This will be greatly appreciated since I cannot find anything on the internet that explains how to calculate for the voltages of the transistor in this scenario. Much thanks!


texts:
I was taking the the P.E. practice exam and there is a question that shows a CPU without pipeline stages.  There were options for both a 1 stage pipeline or that it was a non-pipelined architecture.  The correct answer was that it was non-pipelined.

What is the difference between a non-pipelined architecture and a 1 stage pipeline architecture?  I had assumed that they were the same thing.


texts: Implementing input capture correctly on a PIC

texts:
I'm using a PIC16LF1827 with the XC8 compiler in MPLAB X. I need to store the time between pulses that are coming from an external moisture sensor. The length of time correlates to the measure of moisture.

I'm utilizing input capture to capture the falling edge of the pulses. I believe I've set up the proper bits in the appropriate registers, but my debugging pin "SightPin_A3" (changes state of the pin every time function is called) doesn't change value. I can't figure out why that section of the interrupt vector isn't being entered.

One possibility is that I'm misunderstanding which port pin is connected to the capture mode, but according to the datasheet (pic below) this should be pin P1A (aka pin 0, port B) since bits 3 and 2 of CCPxM are 01 (necessary to configure CCP to capture mode).

Here's the code below:

void InitTimers()
{
        T1CON = 0b00000011;             /********************************************
                                         bits <7:6>(TMR1CS) = 00; TMR1 clk source is instruction clk
                                         bits <5:4>(T1CKPS) = 00; divide by 1 prescale
                                         bit    3  (T1OSCEN)= 0;  TMR1 oscillator disabled
                                         bit    2  (T1SYNC) = 0; synchronize external clk with
                                                                 sys clock
                                         bit    1           = unimplemented
                                         bit    0   (TMR1ON)= 1; TMR1 on
                                         *******************************************/

        T1GCON = 0b10000100;            /********************************************
                                         bit 7(TMR1GE) = 1; TMR1 contolled by gate function
                                         bit 6(T1GPOL) = 0; TMR1 gate active low
                                         bit 5(T1GTM) = 0; gate toggle is disabled
                                         bit 4(T1GRPM) = 0; single pulse mode disabled
                                         bit 3(T1GGO) = 0; clear when bit 4 is clear
                                         bit 2(T1GVAL) = read only
                                         bit <1:0>(T1GSS) = 00; TMR1 gate pin
                                         *******************************************/

        CCP1CON = 0b0110100;            //capture mode: every falling edge

        T2CON = 0b01111110;     // Fosc / (4 instruct * 16 prescale * 16 postscale * 60 PR2) = 65 Hz
    PR2 = 1;
}

void InitInterrupts()
{

    PIE1 = 0b00000110;      // Enable TMR2IE, interrupt when Timer 2 matches PR2
                    // Enable CCP1 interrupt
        CCP1IF = 0;

    INTCON = 0b11000000;            // Enable GIE, Enable PEIE

}

This is the interrupt vector:

void interrupt ISR()
{
    counter++;
    if (TMR2IF)
    {
        if ((counter % 2) != 0)
        {
            PORTA |= BIT2HI;

        }
        else
        {
            PORTA &= BIT2LO;
            counter = 0;
        }

        TMR2IF = 0;     // clears the TIMR2IF (timer 2 interrupt flag)

    }

        if (CCP1IF)
        {
            static unsigned int uLastEdge;
            char highByte;
            char lowByte;
            int CCPR1_Snapshot;

            SightPin_A3();

            highByte = CCPR1H;
            lowByte = CCPR1L;
            CCPR1_Snapshot = (highByte<<8) | lowByte;

            uPeriod = CCPR1_Snapshot - uLastEdge;
            uLastEdge = CCPR1_Snapshot;

            CCP1IF = 0;

        }

}

RESOLUTION:
this is the takeaway after having been on the phone with microchip

(1) input capture pin is set to default RB3 not RB0

(2) in the T1CON register if bits 6 and 7, the TMR1CS bits, are clear (which sets the TMR1 clk to instruction clock (Fosc/4)), then T1OSCEN bit (bit 3)must be set

(3) T1OSCEN bit can be clear, if bits 7 and 6 are set to 0 and 1, respectively

the input capture is now working properly


texts: Which is the physical insight behind the widely approved 'space vector' notation used in the analysis of the dynamic model of electric machines?

texts:
When approaching the study of electric machines in transient condition, it is customary to discard the real physical vector quantities like magnetic field and magnetic induction and to define fake vectors like flux linkages, currents and voltages (among which there also induced electromotive forces) which are directed along the magnetic axis of a certain coil (for instance in a three phase winding system) and have the magnitude equal to the actual scalar value.

I have read that they are not intended exactly as physical vectors, rather as complex numbers, lying on a complex plane which is the shadow of the actual plane defined by a cross section of the machine: for instance the real axis is aligned with the phase 'A' magnetic axis and the other two phases 'B' and 'C' windings correspond to a couple of complex conjugate points; then, such quantities are used, without any particular derivation, as actual vector lying in the cartesian space (for instance the flux has component along two orthogonal axes, usually called \$\alpha, \beta\$ or \$d,q\$).

I perfecly understand, that, in order to simplify the analysis and improve the understanding of a complex system like an electromagnetic device, a certain abstraction, which requires to define also artificial entities, is needed, but I cannot see the reason why such 'abuse of notation' is physically legitimized, in fact I am not sure if it is still an abuse of notation or directly a misuse of notation.

The most confusing situation is the anisotropic (salient pole) rotor used inside synchronous machines, where, for instance, the flux produced by a sinusoidally distributed winding in the stator, linked with another distributed winding (which can be the same phase or another) is simply computed using direct flux and quadrature flux as fluxes produced when the rotor is aligned or in quadrature with that winding.

I think that, when dealing with physical phenomena, before using powerful mathematical tools like these, one should prove that they produce the same result of a strict physical approach (just like when Maxwell equations are replaced by other theoretical tools, like circuit theory or transmission lines, after showing that this is actually possible, not only sought). I hope someone can help me understand this formalism.

EDIT:
In order to better explain the problem, if a winding of a certain phase, no matter what, is distributed along the stator inner periphery, it is accustomed to consider the field it produces as sinusoidal (considering just the first angular harmonic) and the coil distribution can be approximated as sinusoidal as well, centred about the winding magnetic axis. Now to compute the mutual inductance between two stator phases, one should compute the flux linkage of a differential coil (in the angular span between \$\theta\$ and \$\theta +\mathrm{d} \theta\$) produced by the sinusoidal field produced by another winding, then integrate this infinitesimal contribution along all the flat angle, whereas often the problem is roughly solved drawing a flux vector (which is not a vector) and decomposing it along the axes of the other windings, like there were just single loop coil for each phase (non distributed windings).


texts: Bluetooth antenna problem with SIM800C on my board

texts:
I have designed a board with a SIM800C and I have followed all details with its given datasheet. Everything is working well except the Bluetooth that gives very low antenna strength (less than 10cm.)
https://simcom.ee/documents/SIM800C-DS/SIM800C-DS_Hardware_Design_V1.01.pdf
Things that I have tried:

Three different modules.
One SIM800C wired on the air to see if some signal collision is happening on my board
Connecting and trying 3 different WiFi 2.4Ghz, 50ohm antennas directly to the BT pin of the SIM800C.
Adding almost random capacitors and a few random resistors between/on antenna and BT pin.
Have tried other BT module's antenna by directly wiring it to the SIM800C BT pin and disconnecting its path from original module.

None of these even helped to increase to 50cm of BT antenna strength. I do not understand it at all. What I am missing? Do I need to add a specific resistor or capacitor to make it work? In the datasheet it says it is usually zero without any capacitors.
I am not an expert with antenna stuff and could somebody tell me step by step what do I need to do? I really need help, please! note that GND is connected to GSM by default in the module and works fine. I have 4.1v-3A on my module.
I attach some pictures, although if needed I can share more.


texts: 9v & 2 high power LEDs | LEDs dim after time, bright again after being off

texts:
I'm trying to learn some basics of electronics and electricity with a simple solution to a problem.

Problem: I have an African Violet in a terrarium that I want to help bloom, which means it needs more light.

Solution:  Create a simple circuit with 2 high power grow LEDs connected to a battery (so it's portable) that I can place over the plant to extend the time and intensity of light it receives.

I did some math, came up with the resistors I needed and wired it together and it works.  Great brightness, the resistors are handling the power and not burning up, etc.  After some time, 30 min or maybe an hour, you can tell the LEDs are dimmer.  I turn the battery off, wait a little, turn it back on and the lights are bright again.

What is happening?  Is the current draw to big on the 9v?


texts: Charging two 18650 batteries in series with a 5V USB wall charger?

texts:
I'm looking for a good and space-saving solution to charge two 18650 batteries in series.

The project is a small boombox, using an amplifier board that works with voltages between 4.5V to 25V. The battery will be fixed inside and might be rechargeable from a 5V wall charger. I already have a few projects working with one battery and the TP4056, but I've been reading that this will not work for series charging.

Does anyone have a solution?

Be lenient, this is my first post. Thanks in advance.


texts: I came upon this expression "Balanced demodulator" while reading about signal modulation, but didn't find anything that explain what is a balanced demodulator, can anyone explain this or give me any reference that helps me understand what is a balanced demodulator?


texts: Problem with the fall time of a NPN transistor

texts:
I have the below circuit to translate a slow digital MCU on/off (3.3V) signal to a higher voltage signal (range from 12 to 24V). I have a specific attention for the Vin=12Vdc case, the voltage drop from Vin to Vsignalout shouldn't be more than 2V (extra safety guard is always good). With the below circuit I have about 1.7V drop that is ok.

But I have a big problem with the signal fall time is about 200 us that is too much (acceptable level should be about <80 us for my purpose).

This is the signal monitor for the above circuit (R2 is 1k):

The green signal represents the base signal of U$2 (now I see, I could rename it as T2 anyway), and the yellow one represents the signal at the collector.

Below one is for R2 is 100 k:

(The green probe is on the collector this time) First, I thought lowering the current helped the fall time, but e.g., I tried with 1 M ohm that had the same signal.

I am not really sure why my fall time is terrible and how to fix the problem. Do I make a mistake by not using an extra base resistor for U$2?

Here are the datasheet of the transistors:
U$2: PZT2222AT1G
Q1: BCW66GLT1

One interesting thing is that I use MJD31C for the same circuit configuration that gets quite decent signal (but the voltage drop is too much that I am trying to replace it with PZT222A).

I got stuck on it and would highly appreciate for any suggestion

I was playing with R1 resistor by lowering the value to let it conduct more current, placed 47 ohm, but didn't help (MCU's GPIO has 2mA limitation).

If anyone asks U$1 is a LDO to limit the output voltage to 15V, and the end diode is a CLD to limit the output current, I tested with them by removing and short circuit their paths, but it didn't help the signal ( my circuit should work with those components anyway).


texts: Analysis of current flow at a component's edge

texts:
For one of my projects, I've designed the following component to deliver power to loads/circuits:

Fig.1

The component in (Fig.1) breaks into 3 parts(a,b,c), my initial analysis of the current flow is shown in the diagram as (I), however, my concern is with the current flow from component a to b.

Fig.2

How does the current flow in that region?

Fig.3

I tried to break down 3 possible current directions on that edge, which one would be most accurate to describe the current's flow?

The reason I am analyzing that segment, is because of the possible magnetic field associated from this component.

What makes sense to me is a magnetic field that literary wraps around the component, however, a field produced by the sub-current (1) in Fig.3 seems unlikely.

Update:

FEA simulation via ANSYS Maxwell:

Fig.4

Fig.5


texts:
I am trying to take readings from the Melexis Tri-axis Hall effect sensor MLX90393, but all I seem to get is garbage.

I am reading the sensor over SPI, with a 1MHz clock. Here is an example of a couple of SPI transactions with the device, just to show that the waveform is nice. I have shown the two transactions closer together than they really are, just to fit them on the image. In reality they are 3ms apart.

Here is a description of the full set of transactions:

Reset. Send F000 (then wait 3ms)
Write Mem adr 00 with 000C (wait 100us)
Write Mem adr 01 with C380 (wait 100us)
Write Mem adr 02 with 0068 (wait 100us)
Start single measurement read: Send 3E (wait 1ms)
Read Measurement: Send 4E, receive FF75 8FEF FFFB (wait 100ms)

Then I loop 5. and 6. over and over.

The values I get back seem to make no sense. They certainly don't look like a slightly noise analog signal, which is what I would expect. For example, multiple reads from channel 0 look like: FFFB 0707 0707 8FEF 0707 F3AF FF75

What am I doing wrong?


texts: I am new to advanced integrated circuits as it is my first course on the subject and there was a discussion about geometrical scaling in the seminar. The discussion proceeded with the fact that geometrical scaling has its limits because after a certain time leakage current(read tunnelling) through the MOS dielectric at the gate becomes high enough to override the reason we switched from BJTs to FETs in the first place(reduction of power consumption by switching from a current controlled source to a voltage controlled source). Hence, they inferred, the semiconductor industry started using High K materials. But High K simply means a higher dielectric co-efficient. What has High-K got to do with subjugating tunnelling infused leakage? When I last learnt about tunnelling, schrodinger's wave equation never featured any term for di-electric constants??