texts:
I'm having CADENCE simulation problems in the section called ASSURA, when I do the simulation on ‘’ LVS ’’ it shows the following error:

  Starting Nvn PreExtraction...

  Starting /tools/cadence/ASSURA41/tools.lnx86/assura/bin/nvn
  /home/mvictor/pdktsmc180/IRUWB_TRANSMITTER/inverter/inverter.rsf
  -preExtract -exec1 -cdslib /home/mvictor/pdktsmc180/cds.lib Checking out license for Assura_LVS Checking out license for
  Phys_Ver_Sys_LVS_XL @(#)$CDS: nvn_64 version
  av4.1:production:dfII6.1.8-64b:IC6.1.8-64b.500.9 02/24/2020 20:04
  (vmip-172-18-23-226) $ sub-version 4.1_USR6_HF7, integ signature
  2020-02-24-1834 run on mvictor at Fri Jun 5 21:25:37 2020 WARNING
  (AVLVSNN-10029) : 'filter' command has been converted into
  'filterOptions' with the same function. 'filter' command is not
  supported. Use 'filterOptions' instead. Reading schematic network
  inputting netlist /home/mvictor/pdk/PDK/Assura/lvs_rcx/source.added
  Reading layout network inputting network
  ./IRUWB_TRANSMITTER/inverter/inverter.ldb Error: rootCell(or
  ?cellName) - cell 'inverter layout IRUWB_TRANSMITTER' from the layout
  does not bind to anything in the schematic.

  Finished /tools/cadence/ASSURA41/tools.lnx86/assura/bin/nvn

  WARNING /tools/cadence/ASSURA41/tools.lnx86/assura/bin/nvn exit with
  bad status WARNING Status 256 WARNING Assura execution terminated
  WARNING An error occurred during Nvn PreExtraction. LVS preprocessing
  requires a successful run of Nvn. Assura will now terminate.

  WARNING Bad exit from child process .. 0x100

  ** aveng terminated abnormally **

  ** aveng fork terminated abnormally **

  WARNING aveng exit with bad status WARNING Status 256 WARNING Assura
  execution terminated

I can't solve this, I need help please.


texts: PV voltage on solar charge controller always 13V

texts:
I just wired a solar panel with solar charge controller (SCC) and battery.

The  photovoltaic (PV) voltage displayed on the SCC is 13V, even though the PV voltage without load that I measured with a voltmeter is 19V.

After that I tried to put two PV panels in series and I measured again and got 39V.

But after I installed SCC with battery and connected the PV panels, the SCC still shows the PV voltage at 13V. I measured with a voltmeter and got the same 13V.

Is there a problem with my SCC or my PV panels?


texts:
I'm designing a general purpose interface board and want to make available as many of the peripherals available and usable on an expansion header without the need for permanent (soldering) changes.

One issue is making the I2C pullup resistors switchable, such that they can be disabled when not needed. My initial idea simply uses a free GPIO output to pull the resistors high or is disabled (high impedance) when not needed, as depicted below. This apparently saves me a switch transistor. Is there anything I need to be aware of, or is this feasible?

I know that the pullup resistor values depends on the bus length and speed, but we found that for our applications 4k7 Ohm are generally OK.

simulate this circuit – Schematic created using CircuitLab


texts: Boost 12v battery cranking amps with supercaps

texts:
I have a setup where a 12V AGM battery is powering an inverter. This inverter, for brief periods (1 or 2 seconds - compressor starting) needs more amps than the battery can provide.

Is there a circuit that i can connect to the system that can briefly provide a quick boost in amps when they are needed? I was thinking along the lines of supercaps or a small high-amp battery?

I can't connect a similar battery in parallel just because there is not enough room for another big battery... I could do with a smaller one, but then we have the problem of charging/discharging batteries with different AH's in parallel.

So to elaborate on the specifics:
Big battery of 100AH , inverter modified sine wave of 400watt, 800watt peak power, compressor of 70watt but no idea about the surge power.

Any help would be greatly appreciated, since i'm not an expert in these things!


texts: Some help with 9V Longlife VARTA batteries?

texts:
I recently tried to make my own LED circuit to give some light to my room at night.I ended up with a circuit that goes like this:

A 9V battery with clips goes to a SWITCH and from the switch to a POTENTIOMETER (so that i can operate the voltage-light of the LEDs). Now from the potentiometer it goes to a 220 Ohm RESISTOR that's connected to a LED. From this LED it goes in serie to another RESISTOR that is connecter to a LED. At last another RESISTOR comes from the 2nd LED (in serie) and goes back to the SWITCH and my 9V battery(in order to protect her?).

simulate this circuit – Schematic created using CircuitLab

Well i'm not good at schematics but it looks like this i think.
Anyway..my circuit worked well at first with the 9V battery but it made the battery really hot even when the switch was on the OFF mode. So i thought that could be a problem and i unplugged the battery from its clips. An hour later i put the battery back turned the switch to ON and tried again and it also worked as well.But at night my battery was dead.I thought i had a problem with my circuit,but i didnt. So then i unplugged the battery and plugged in a new one also 9V similar to the previous one.This one had the same problem with the previous except that this one was used for 3 hours instead of 30 minutes.

So my main problem is that these "Longlife" batteries were both dead in so little time!!!
Why is this happening? I cant keep on spending money to batteries.
Do i have to change the last Resistor to a bigger one to "protect" the battery?

Thank you for your help and time.


texts: Angle between North and East from magnetometer values

texts:
I have a magnetometer from where I get X, Y and Z which point to the direction of the detectable magnetic fields.
I'm using these values to get the angle between X and Y using atan2. I am a bit suprised of the result because North is not "aligned" with South. In fact there is not an angle of 90° between any "axes" (N, S, E or W).
I can reproduce it with my phone. Can someone explain me why ? Am I Wrong ? Am I missing something ?
In fact my real problem is that my angle is not "linear". For example, in the image below, between North and East, with atan2 I get 270° which is obviously wrong regarding to the direction.
Here below, what it looks like :
Edit : diagram starts with East : angle = 0°. South is draw when angle = 90°.
magnetic cardinal points

My magnetometer is a IIS2MDC mems from STMicroelectronic. I am getting values from registers with a nordic MCU (but it would be the same with a ST MCU)
Edit :
My algorithm is copied from this post : https://arduino.stackexchange.com/questions/18625/converting-three-axis-magnetometer-to-degrees
Here is my function which converts from X, Y and Z raw values to angles in degrees :
static double main_calculate_angle_degree(int16_t x, int16_t y){
    double angle;
    angle = atan2((double)y, (double)x);

    if (angle >= 0) {
      angle = angle * (180 / M_PI);
    }
    else {
      angle = (angle + 2 * M_PI) * (180 / M_PI);
    }

    if(angle > 350){ // angle 360 = 0 because it is a circle, of course !
      angle = 360 - angle;
    }

    return angle;
}

Edit 2 : my algorithm
I have an offset which makes x = 0 in default position. This offset is applied to all axes. I tried without this offset and it makes no difference !
When angle = 0° : X² + Y² = 2² + 35² = 1229 (X is the average of 5 X values and the same for Y)
Then I rotate my mems of 90°, the angle displayed by my device is around 70° :
X² + Y² = 300² + 103² = 100609
Edit 3 : a photo of my setup
I'm using the dev board of an nrf MCU and the eval board of the mems. Both are attached together. I tried to move around the big dev board alone aroung the mems and it seems to have no impact.


texts:
I have a questions on my mind, and I hope that can be answered.
The line to ground voltage is 54Volt, and I would like to know if it is possible to have two bi-direction TVS diode in series.

I will be using TSPMF4L30A, and the reverse standoff voltage is 30V. If I were to put two of this TVS diode in series, would I then have reverse standoff voltage of 60V, and would it clamp at 96.8V (48.4V + 48.4V)


texts: Ferric Chloride or Muriatic Acid + Hydrogen Peroxide for etching?

texts:
Currently purchasing the required kit to start etching my own boards and have gotten to the etching solution stage.  Ferric Chloride seems to be the standard for etching but I have also read about Muriatic Acid + Hydrogen Peroxide ecthing, which apparently is better all round (both for the environment and my pocket).

Has anyone had any experience with this method of etching?


texts: How can I make a power supply with Arduino Due?

texts:
I got a question:
I need to make a power supply to heat a heater, for that I need to use an Arduino Due, and use one of the analog pins (it´s like a built-in DAC) of this microcontroller, and draw voltage from that pin, with an external current source or something similar, I need power control the current that passes through the circuit controlled from Arduino, controlling the voltage that I give it through the software, that is, I choose the voltage that I pass to the circuit with the Arduino's analog pin and with this choice, I have to have a certain current that allows me to heat the heater resistance as much as I want. I need to give the resistor a power of 10 W, and the resistance of the heater is 50 Ω. so I need a current of approximately 400 mA to pass through that resistance.
How can I do this circuit?
The main problem I've had so far is that the output current is always very small.
Any suggestions? Thanks.


texts:
I am trying to use the backlight from a Samsung laptop for a light box but have NO idea what the input connections are. I've found some Datasheets for other models but not the right one. LTN141XB-L01

Most other inverters seem to have 6 wires but this connector has 12 and is rather complicated. I understand there are several 12v Inputs, grounds and an on/off 5v input but which wires they are is a complete mystery.


texts: How to measure Johnson Noise precisely experimentally?

texts: I want measure Johnson Noise across a resistor having certain over the certain range of frequency or bandwidth practically. I am starting from scratch, how can I build circuitry and instrumentation so that I will get more precise output values. Like theoretically we can calculate (for example, \$V_n^2 = 4RkT\Delta f\$ ; \$V_n = 1.6\mathrm{mV}\$ for \$R=16\mathrm{k}\Omega\$, \$T=300K\$, \$\Delta f=10\mathrm{kHz}\$, \$k=\$ Boltzmann constant ) but practically I am facing some problems with circuitry.


texts: Designing a combinational circuit that converts a 5 bit binary into its 2's complement

texts:
I have a small homework the teacher gave us to assess our previous Digital Logic course. The question is to design a combinational circuit whose input is a 5-bit binary number and whose output is the 2's complement of the input number. I am also told to use the Quine-McCluskey method to simplify the circuit.

I have started by constructing a truth table of 5 variables with possible 32 combinations.

--------------------------------
 v  w  x  y  z    A  B  C  D  E
--------------------------------
 0  0  0  0  0    0  0  0  0  0
 0  0  0  0  1    1  1  1  1  1
 .
 .
 1  0  0  0  1    0  1  1  1  1
 .
 .
 1  1  1  1  1    0  0  0  0  1
--------------------------------

I have 5 outputs. I'm confused on how to procced with this.

Output A can be expressed as:

A = v'w'x'y'z + v'w'x'yz' + v'w'x'yz + v'w'xy'z' + v'w'xy'z + v'w'xyz' +
    v'w'xyz + v'wx'y'z' + v'wx'y'z + v'wx'yz' + v'wx'yz + v'wxy'z' +
    v'wxy'z + v'wxyz' + v'wxyz + vw'x'y'z'

The same can be done for B, C, D and E. How do I proceed? Do I process (simplify) each output individually? If so, how can I combine them at the end?

Thanks,

Tamrat


texts: MCUs which can trigger an interrupt on a port mask

texts:
(Hobby and learning, not a professional question.)

I'm designing a circuit which uses a CPLD to turn a half-dozen inputs into a single output which triggers an interrupt in a microcontroller.

Are there any microcontrollers where a combination of inputs (on one port) can trigger an interrupt?  (Mostly interested in Cortex M0/3/4, but will consider others.)

e.g. Have an interrupt triggered only when port A matches ?1110?01.  11110001 would cause an interrupt, but 11110000 wouldn't.


texts: Connect one of 16 loads to power (12 V, ~300 mA), decoder IC?

texts:
I am wondering if there is an IC that performs the following task.

If I didn't know any better, then I would probably build the following circuit from discrete components.

simulate this circuit – Schematic created using CircuitLab

However, this seems like such a common necessity! I'm sure that there's an IC for that.

I've managed to come across analog switches and multiplexers, but these seem to be used for low power analog signals, not power.

Is there a circuit that can do this?


texts: A2212-15t 930kv brushless motor voltage limit

texts:
So here's the thing,
I am planing on buying those brushless motors (a2212-15t 930kv motor) and I was planning to use it with 5 li-ion battery. I was gonna do this until I saw the line saying: No of cells: 2-3 Li-Po. I'm not able to find any reference to those. I do see someone using a2212 brushless motor at 5s but not the 15T.

This is what I have currently
Battery: 5s battery pack (18.5 v)
ESC: 30A (Model doesn't matter)
Controller: Arduino (Just for testing. Gonna move it to a FC later)

The circuit diagram? I don't have but it's pretty simple. A motor wired to an ESC which is connected to a Arduino and a battery pack.

Will the motor power on with 5s? If so, will there be a side effects to this?

EDIT: this is the motor
https://www.amazon.com/WST-Brushless-Outrunner-Multicopter-Quadcopter/dp/B01DC8SAOO


texts: What is a popular cheap and robust substitute for 2n7000 MOSFET for use with 3.3 Volt designs?

texts:
What are the popular equivalents to the 2n7000, for 3.3 Volt MCU circuits to switch higher voltage devices?

Background:
For 5 Volt microcontroller based prototypes and experiments, my go-to solution for low frequency, low side switching of 50-200 mA currents or 10-40 Volt devices driven by a digital / PWM pin, has been the dirt cheap ($0.05 retail here in India) and ubiquitously available 2n7000 MOSFET.

The best aspect of using this MOSFET is, I have made a bunch of little building block PCBs with a 100 Ohm gate resistor and 10 k gate pull-down, and simply plug them in to almost anything that isn't high frequency or high load. It just works, and is almost bulletproof. If I could find any 4 x 2n7000 array parts locally, I'm sure I would make 4-channel building blocks too.

When working with 3.3 Volt MCUs and boards (e.g. TI MSP430 Launchpad) what is the equivalent easily available, robust switching solution, if any, that one turns to for non-critical quick prototyping?

I currently end up using either 2n7002, whch does not turn on hard enough, or various IRL/IRLZ parts, though they cost as much as 10-20 times as much. IRL/LZ are often unavailable off-the-shelf at the "electronic components market street" where I pick up random parts for my personal component shelves when I am not working to a BOM or a plan.

The AO3422 suggested in comments to this question simply is not available locally in retail.

I want to avoid BJTs for this purpose as they tend to run hotter than MOSFETs, and I create enough magic-smoke gizmos anyway.

I know there isn't necessarily one correct answer to this, but good advice would, I am sure, benefit many people jumping into 3.3 Volt devices.


texts: Problem related to the compliance voltage

texts:
I have a question that I am using a stimulator to generate biphasic current source for stimulation. At the output of the stimulator, a 1K resistor is in series with 0.1uF capacitor. The I use two scope probes to measure current and voltage respectively from the oscilloscope. One probe is across the resistor. Another one is across the resistor and capacitor. The power supply of stimulator is 12V. If I lower the external  power less than 12V, it will reach the compliance voltage limit. Then the voltage wave across resistor and capacitor become flat( compliance limit, constant charging). But the current is linearly decreasing which means the impedance is increasing.

V+ is connected to the adjustable external power supply. Link 2 is the result observed from the oscilloscope and the shady parts are missing when voltage reached the compliance limit.

Why would the current waveform be linearly decreasing(a resistor is in series with a capacitor)?

Waveform observed from oscilloscope:

USB circuitry:

Biphasic current source:


texts: C code for DDR Access in Xilinx SoC devices

texts:
In my design, I want to write to DDR and then I want to fetch the data from DDR memory and then pass them to FPGA to be processed, after that, the data will be written back to DDR memory.I am using Xilinx Soc device(ZCU102),It has both fpga an in built processsor(PS).To do the same I need to write a C code for accessing DDR.
So how it is done? What is the keyword used to write values to DDR and to do Memory mapping??
Or if Possible can someone share the C Code for that??


texts:
I have three SN74HC161N connected such that an overflow on the first triggers the second etc. (the normal ripple carry setup, where RCO feeds into ENT). The clock inputs of these are connected to a 1 MHz oscillator. The voltage in the circuit is 5V.
From what I can see from the data sheets (https://www.ti.com/lit/ds/symlink/sn74hc161.pdf and https://www.ctscorp.com/wp-content/uploads/MXO45_MXO45HS.pdf) everything should work properly. It seems like the maximum frequency for these counters would be 1 / 500 ns =  2.00 MHz, well above the 1 MHz frequency of my oscillators. I have verified that the counters work using a much slower clock (a 555 timer), but for some reason it doesn’t count when using oscillators (I’ve tried several of them). Have I misunderstood the data sheets (English isn't my native language), or am I overlooking something here?

(Larger version of image)
Below are some pictures of the actual circuit. I've used yellow wires for ground connections (except the four going to LEDs). Red and orange (and one white) indicates power (5V). The green wires (and the longer oranges) are just used for connections between different counters. All capacitors are 0.1 µF, except for the one connected to the 555 timer (on the right) which is 3.3 µF. As the image shows, the long blue wire is connected to the clock inputs of the counters and is currently driven by the oscillator, meaning the 555 isn't really doing anything as for now.
Also a little note: In the schematic, the ENP, CLR* and LOAD* pins are directly connected to 5V, but in the actual hardware I've used green/orange wires to wire them together.
I apologise if my pick of colours doesn't seem natural, however my arsenal of wires is pretty limited at the moment (new ones arrive in a week or two).
The red and blue wires in the top left are connected to an Arduino Uno's 5V and GND pins.


texts: Colpitts Oscillator - Supply/Output Voltage

texts: I try to simulate Colpitts oscillator but i got stacked about one thing. When I simulate this circuit, the output Vpp is 24 V in other words, it oscillates between 0 V and 24 V. The question is, we give 12 V DC supply voltage to the circuit and we get 24 Vpp output voltage what is the reason of it? Why the output peak to peak voltage is more than 12 volt while supply voltage is equal to 12 volt? So much thanks.


texts: Stepper Motor Everything in Order, Not Moving

texts:
So I'm very confused. I have everything hooked up according to their various diagrams and am attempting to run the following recommended test code:

 void setup() {
     Serial.begin(9600);
     pinMode(2, OUTPUT);
     pinMode(3, OUTPUT);
     digitalWrite(2, LOW);
     digitalWrite(3, LOW);
 }

 void loop() {
    digitalWrite(3, HIGH);
    delay(1);
    Serial.println("I got here");
    digitalWrite(3, LOW);
    delay(1);
 }

Nothing is moving, and to be honest I'm a little terrified working with this power supply. Does anyone have a way of troubleshooting this that won't get me electrocuted? Also for anyone interested, it claims that it reaches "I got here" every time.


texts: Number Blocks toy that changes colors according to how many blocks are connected

texts:
Number Blocks is a British children's show that gets kids to enjoy learning numbers and simple arithmetic. I watch the show with my 4.5yo and it's really well done. One neat thing they do with the numbers is assign each a personality and a color scheme: 1-6 are ROYGBIV (-ish), 7 is a rainbow, 10 is white with a red outline, 20 is a lighter shade of orange than 2, etc. When they are teaching math, like 1+1=2, they show 2 red one-blocks combining to become 1 orange two-block.

I think it would be great to have a set of blocks that match the color-changing behavior of the TV show. A translucent block that can attach on any side to other blocks, where each block has an RGB LED inside (which would be diffused by the translucency). When a block is by itself, it would be red. When 2 blocks are connected, both blocks would be orange. When 3 blocks are connected, all the blocks would be yellow. When 7 blocks are connected, there'd be a ROYGBIV array. And so on, at least up to 10. The color scheme goes non-monochromatic after 10:

When a set of blocks hasn't changed colors in a while, it would turn off to save battery (probably a watch battery in each block which I hope could be expected to last a long time).
I'm a software guy rather than an electrical engineer but I do some 3d printing as a hobby and I've been wondering how practical it would be for me to make a prototype. I've looked at Cubelets but they are rather expensive and target a different demographic. (Also they don't have a 3 color LED block, just a flashlight block.)
My question for EE is what the most cost-effective electronics would look like on the inside? Could the "how many blocks are connected to me" kind of logic be done with a breadboard? Or would a microcontroller be necessary, greatly increasing the cost? I suspect 1-6, 8, and 10 (solid colors) should be possible without a microcontroller, but 7, 9, and 11-19 would be far trickier.


texts: Is it a bad idea to connect two Li-ion batteries in parallel?

texts:
Suppose I have two Li-ion batteries for smartphones. One could say that if they are connected in parallel, then the voltage given to the device would be the same, but the capacity would be doubled, hence doubling the lifetime of the total battery (i.e. more time to use the smartphone without charging it).

However, this seems a bad idea to me. The first thing that crosses my mind is that doing this would lead to huge currents between the two batteries if the voltages are not exactly the same.

Would this approach work? If not, are there any other drawbacks on top of the one I described?


texts: Max Discharge Rate of typical Alkaline Button Cell Batteries

texts:
I have simple circuit that has some led diodes,  3 LR41 batteries and no resistor.

By looking at this website, it seems their capacity is about 30mAh. But I couldn't find anywhere the max discharge rate of these kinda of batteries.

Can we say that their max discharge rate is 1C or 30mA, or they can deliver even more?


texts: Measure the speed of a stationary bike with belt drive

texts:
I have a problem with the measurement of the speed of my stationary bike.

 (also here)

Parameters:

radius of flywheel is 13cm
second wheel is 12cm (0.12m)
the sensor is simply a reed switch

I'm trying to calculate the speed using this formula :

$$\text{angular velocity} = \text{rotation per second (Hz)}\cdot 2\cdot \pi$$

$$\text{speed} = \text{angular velocity}\cdot{0.12}m/s$$

$$\text{speed} =\text{speed} \cdot 3.6 km/h$$

Are my formulas correct? I'm not using a flywheel in this calculation. I'm using an Arduino Mega with Interrupts. The result isn't quite good (output: pastebin.com/V2mtGzmn).

How to do it more acurrately?

The code is here.


texts: Is there a widely used vocabulary for electronics and electrical systems, much like the UMLS for medicine?

texts: I am searching for an inclusive view and typology of electronic and electrical systems, and the design and engineering concepts etc. that underpin them. Is there a widely used vocabulary for electronics and electrical systems, much like the Unified Medical Language System (UMLS) for medicine?


texts: Can anyone teach me how to convert a light activated switch into  dark activated switch vice versa.


texts:
I ran into this old cockpit/pilot room for heavy mining machinery in which there was an LCD display that's not lit properly, that is, the image was there but the backlight clearly was gone.
Upon careful disassembling the display, I found out that the backlight was indeed not properly working. However I couldn't tell if it was the fault of the fluorescent tube, or the power supply.
So I measured the power supply voltage for the tube, the voltage naturally was in AC instead of DC, and the output was around 7 volts.
This led me to believe it probably was the fault of the converter board instead of the tube, because no way you could light up a fluorescent tube with a meager 7 or so volts, which sometimes requires as much as 10,000 volts! However I have no specialty in this and relied solely on my common sense, I could be wrong, as there could be for example circuitry that brings up the voltage in the LCD assembly?
But that is unlikely as I should probably point out that the display was, and I say it with great confidence, a run-of-the-mill 17 inch commerical lcd display, nothing special about it, other than it was embedded in the control panel of the pilot room for mining machinery.
So... was my judgement correct? What is the typical voltage for driving LCD fluorescent backlight tubes?


texts: V-USB with ATtiny2313 to communicate with Android

texts: How would one interface a ATtiny2313 with usb to communicate with a android device? I know it involves using V-USB, but how does the circuitry work? Am I supposed to connect certain pins on the ATtiny2313 to certains parts of a usb head? (How do I connect the ATtiny2313 to a micro USB connection) I would really like for the usb to end up connecting straight to the android device.


texts: What is an expression for the output voltage?

texts:
simulate this circuit – Schematic created using CircuitLab

Is this just a voltage divider principle and it boils down to sin(1000t)+sin(5000t) ?


texts: Solar Panel (5v/500mAh) charging USB Power bank (5v/1a)

texts:
I've been trying to find information on this but haven't found an accurate answer.

I have a USB Power Bank that has a max charging input of 5v/1a and a 5v/500mAh solar panel that can output up to 5-6v.  Since the USB Power Bank already has a regulator built in, is it possible to just directly connect the small panel directly into the power bank?

I'd imagine I don't need a regulator since one already exists, but maybe something to cut off if the power is too low?


texts: Current flow in a series circuit with two voltage sources

texts:
I specifically want to know how does the current flow in the schematic attached. There are two voltage sources (one dependent, the other independent) in the figure. Correct me if I'm wrong, but it appears to me that the current generated by 35 V and 2vx will collide each other though the magnitude of their currents are equal since all the elements are in a series connection.

This circuit I'm working on is one of the practice problems of Kirchhoff's Laws in Fundamentals of Electric Circuits by Alexander and Sadiku. The ones asked in this problem is vo and vx. I tried solving the problem but it does not match the given answer in the book (the solution is not shown though).

I would like to know how the current flows across 5 Ω resistor.

@Ignacio Vazquez-Abrams: That was precisely why I asked the question. Though many here are saying this is a simple circuit, I had been confused with this problem because I was imagining how the current will flow due to the two voltage sources.

@The Photon: No, this is not a homework question. I was reviewing for a quiz the other day by picking questions on our textbook.


texts: Effect of Reversed Phase Polarity on Active & Reactive Power of 3-Phase System?

texts:
I am trying to investigate the Power/Energy of 3-Phase System under Different Faults.

I have a Three Phase Source and Load, Load is balanced i.e same phase angle and current (Phase-Neutral V = 230 rms, Current = 10 rms) for a power factor of unity (Ideally, typically 0.9-0.95). There is a device (Energy Meter) in between them which is measuring Power/Energy transferred from Source to Load.

Everything below is related to calculations and measurements of that Measuring device. Phase reversal/polarity does not have an effect on source /Load, only the Meter measurements will be affected.

I know about the phase sequence and Power equations of a 3-Phase Balanced System.

(Kindly forgive me if it gives you a headache, I realized after writing this question, how large it became)

I am using +ve Phase Sequence in my calculations.

So the Power Equation is like this;

P_Total = 3 * V_phase * I_phase * cosθ

The Fault Condition is like this:
"The Phase_C and Neutral are swapped or Phase C polarity is reversed".
i.e. Black Wires goes in 5 and comes out of 6, while yellow wire goes in 7 and comes out of 8 of Meter.

  In this condition, Meter shows Active Power of 9.249KW, Reactive Power
  of 1.89 KVAr, while power factor is still 0.9.

Now I want to measure the voltages, their phasors and ultimately the Power.

This is what I am trying to do:

V_AN will become V_AC because Phase-C is now at Neutral connection.

Here, Positive Phase Sequence is considered for calculations.
Then the Phase-A Voltage will be as following,

V_AC= V_A - V_C

∴V_AC= Phase Voltage of A,Don^' t confuse it with Line Voltage of Balanced 3 Phase System

Inserting the values...

V_AC= v_rms<0 - v_rms<-240

V_AC= v_rms (cos0+j sin0) - v_rms (cos240-j sin240)

V_AC= v_rms (1+0)- v_rms (-1/2+j √3/2)

V_AC= v_rms (1+1/2-j √3/2)

V_AC= v_rms (3/2-j √3/2)

V_AC= √3  v_rms (√3/2-j 1/2)

V_AC= √3 v_rms < 30

Similarly,

V_BC= √3 v_rms<-90

V_NC=v_rms <-60

Now it gets tricky. To get Active Power P, i am trying to calculate Apparent POwer S = VI*.

For that, according to simple conjugate and multiplication properties of Complex numbers, Each Phase Voltage and Current will be multiplies after taking conjugate of current.

S_Total= S_Phase-A + S_Phase-B + S_Phase-C

S_Total= (V_A x I_A*) + (V_B x I_B*) + (V_C x I_C*)

S_Total=(V_A<30 × I_A<∅-30)+(V_B<-90 × I_A<∅+90)+(V_C<-60 × I_C <∅+60)

S_Total=[(√3 x v_rms x i_rms) + (√3 x v_rms x i_rms) + (v_rms x i_rms)] <∅

S_Total = 4.464 x v_rms x i_rms <∅^0

So,

Total Active Power,

P_Total = 4.464 x v_rms x i_rms x cos∅

Total Reactive Power,

Q_Total = 4.464 x v_rms x i_rms x sin∅

From Here, assuming, Power Factor =1, Each Phase Voltage = 230 Vrms, and I = 10 A rms,

Power Comes 10.267 KW, instead of 6.9 KW.

Did i make any mistakes in calculations?
Why Power Increased?
It seems like the system is unbalanced now, but why there is no
reactive power, it seems like that reactive power only depends on the
power factor which is 1 in this case?
Please review my calculations and tell me if I am doing something wrong. Because I did measure power through Three Phase meter, it showed the phase voltages as I calculated but overall power was around 6.8KW while my calculation show 10.267KW??
If I am wrong, what will be right approach to calculate power in this
scenario?

Thanks and Best regards..


texts:
Can you identify this logo?
Can you identify the logo on these ICs?


texts: Simplest option for generating audio tones?

texts:
I'm looking for the simplest way to generate audio tones. Something like a square or sine wave, but I want multiple tone options. For example, two quick beeps, one at 440Hz, one at 1Khz. The tones should occur at the press of a button, and again at the release.

I am aware that a square wave can be generated with a 555 timer, but I don't know how to produce multiple tones. I also know a simple microcontroller can be used with a DAC, but I have a few requirements:

Parts count and cost as low as possible. Under $1 in higher quantities of components is ideal.
The components must not require FCC certification or SDoC, which is a concern going the microcontroller route.
The audio signal must be a mic-level signal.

Is some kind of MCU unavoidable in this situation? I've yet to find a suitable solution that covers all those bases, so any help is greatly appreciated!


texts: use atmega328p-pu to flash atmel 90usb162

texts:
I have an ATMEGA328p-pu from an Arduino that was going to be used in a company product.  We switched to a PCB that uses ATMELs 90USB162.  I would like to make a circuit board that uses the ATMEGA to store the bootloader and eeprom data for the 90usb162 so that on button press, the bootloader and eeprom is read from the atmega and written to the 90usb162.

This is desired as we currently have approx 100 90usb162 needing to be flashed with the correct bootloader and eeprom data.  Am I going about this the correct way, or is there a better way to mass flash ICs?

Project edit:

to make this project easier, i'm going to switch to the omega onion to flash the 90USB162.  The omega is a full Linux box with it's own file system where i can use C++, node js and other programming languages I'm familiar with, making this whole project easier.  If this works out, I'll post as an answer.


texts: Finding the Internal Resistance of an Ammeter using a shunt

texts:
There is this lab procedure to determine the internal resistance of an ammeter which differs from the usual process.  In this new procedure, we connect a voltage supply in series with a resistor of some known value and an analog ammeter (top image).  We increase the voltage until the ammeter reads 30mA and then turn off the supply.  Then we add a shunt (a wire) in parallel to the ammeter (bottom image).  We now use this setup and determine the internal resistance through some calculations using the formula shown in the image.

I am not sure why we would use this method compared to the usual method of connecting the circuit without the shunt and just use I_1 = V_s/(R_c + R_m) and solve for R_m, where R_m is the internal resistance of the ammeter.  Also we assume that I_1 and I_2 are the same when using this new procedure.  Is that correct?  Just need some insight into this method compared to the normal method.


texts: Serial Port Terminal transmitting at 300 baudrate

texts:
I have been using Hercules SerialPort Terminal for a while now and its pretty cool. But now, I need to send data's at 300Baud, but Hercules stops at 9600baud.

I find TeraTerm which looks okay as well, but I need help on how I can send data's in Hexadecimal, just like I can do in Hercules, as it appears I can only send ascii characters alone. Is anyone familiar with TeraTerm? Do recommend other serial port terminal.


texts: Can I create a totem-pole structure by using two optocouplers?

texts: I have two optocouplers. One of them uses NPN transistor and the other one uses PNP. Each of them explicitly give the base pin of their BJTs out. Can I make a totem pole structure by connecting them as seen in the image below?


texts: LC series circuit resonance beyond voltage limits of programmable capacitor - solvable with gain stage?

texts:
I am replicating a design where a mechanical tuning capacitor is in series with an inductor antenna, in order to achieve resonance at certain (hundreds of kiloHertz) frequencies. I am looking into options for programmable capacitors and have found the IXYS NCD2400 series - unfortunately though, its voltage limits are significantly smaller than what I'm measuring on my fixed-capacitance prototype.
Is there perhaps a way to insert some type of gain stage in between the capacitor and inductor, so that the resonance characteristics are maintained, and the voltage that the capacitor sees is lowered?


texts:
The chip I'm using is the CD4013BE. datasheet: http://www.ti.com/lit/ds/symlink/cd4013b.pdf

I'm trying to make a flip flop using this circuit to store 1 bit of information. The datasheet says Q1 (with the line over it) is supposed to be the inverse of Q1. But whenever I hook up the circuit they are always both on. I've experimented with using all the others pins too, sometimes I can get the brightness to vary across the leds but they are both always on. I can never get it so 1 is on and the other is off. Is my IC broken? If not how can I fix this circuit.

The circuit images:

And finally my horribly crude circuit diagram:

So why are both leds always on? I thought they were supposed to be inverses of eachother?


texts: Clock distribution for low-jitter audio DAC

texts: I am building a 10-channel audio DAC using 10 ES9018 converters and an ultra low phase noise clock (Pulsar) with femtosecond jitter. What would be the best way to distribute the clock's signal to the 10 converters? It is assumed that the clock's board will be mounted directly on the PCB where the 10 converters are soldered. The clock's frequency is 100 MHz.


texts: What is the role of the ROOT COMPLEX in a microprocessor system (PCI Express)

texts:
I have been learning about the Linux kernel and the most common bus type i always encounter is the PCI bus.

As an electronics Engineer, i decided to look at how this bus works as it seems to be the primary peripheral bus in a modern CPU system. All other buses (ie USB, Disk drives) seem to be connected to the PCI Express bus.

My confusion stems from the role of the ROOT complex. It appears to sit between the CPU and the PCI express ports. Also from a diagram i saw on Wikipedia, it also sits between the CPU and memory.

Does all memory access from the CPU pass through the Root Complex ?
Is the root complex the main facilitator of memory mapped IO. As in, is the root complex responsible for detecting addresses that map to devices and in turn forward said data to the right PCI express endpoint ?
From the above, is it safe to assume that physical RAM is treated as an endpoint ?


texts: lpddr2 interface differences between different memory controllers?

texts:
The way LPDDR2 connections are done with CA bus is different between these two processors. I thought since LPDDR2 is a JEDEC standard, these schematics should be interfacing with the same lines from their respective memory controllers. How would I figure out what lines from my processor to connect on the CA bus?

The main differences are in the CA[3:6] lines. This is what I feel like should be standard and having a hard time interfacing with my chip which provides no guidelines.


texts:
This is my first attempt at making a really simple audio amplifier. The schematics are below:-

First I tried connecting the circuit to a 9V battery. (Multimeter reads around 8.3 Volts, which is in the operating voltage range of the LM386 as per datasheet) The result I have is lots of noise, sometimes cracks and pops and a barely audible sound of the audio input (it feels like highly attenuated form of input which is very bad). It doesn't even sound at least equal to the input! I want the gain to be around 200, so I do have a 10\$\mu\$F capacitor across pins 1 and 8 of the LM386.

I've also tried connecting to a 9.6V - 250mA rated unregulated DC adapter. The results are almost the same... (though I seem to get a higher voltage here..)

Initially I simply used a in-ear earphone to pick up the mono output. I also tried connecting a small speaker (pictured). It's apparently a 0.2W 8\$\Omega\$ speaker. The output is low, but the end result is similar to the earphone output..

Here's a snap of the breadboard.. Sorry for the bad quality pic. This config used the DC adapter and a 0.2W 40\$\Omega\$ speaker. I even checked all parts for continuity using a multimeter. I'm also open to tips on troubleshooting this, since I'm new.

Top bus is the Vs and the bottom bus is the common ground. Input audio is connected to the left end of the 'green' 1k resistor. Its a very thin wire since its from a small 3.5mm TRS cable.

I don't want anything super loud, just audible maybe like 2x of the input signal. If so, what kinds of speakers would this amp be capable of driving? What would I need to make it sound acceptable? Basically, what's wrong with this circuit?

UPDATE: I followed all of your suggestions and my setup now consists of an additional 100\$\mu F\$ capacitor in parallel to the power, a 100nF capacitor in series to the input audio signal and a 10\$\mu F\$ capacitor connected to the bypass pin.
There was a problem though, the 9.6V unregulated adapter I use seems to show 22 Volts on the power rails (under load).. this seemed to make the LM386 run really loud. I seem to hear the amplified audio at times when I nudge some parts here, but anyhow after sometime, the IC got too hot and so did the 100\$\mu F\$ capacitor at the power supply.

I can't really tell if it's all because of a bad quality adapter or the IC or breadboard or capacitors..
The capacitors were salvaged from an old PCB board of another circuit.
Also since I think the last LM386 got fried, I desoldered another LM386 from another board and I'm keeping it in stock. This is the last 386 I have in hand now and I don't wanna screw this up.

Now for safe testing, I drew power from laptop USB (5V regulated).. the volt at pin 6 of the new 386 shows a solid 5V. Speakers were really quiet so I hooked this up to an AUX cable and listened to it.. The output is weird and not satisfactory.. The sound seemed to be amplified when I nudge the power cable at pin 6 (ie, peaks of loud sound happens only at the beginning and then it fades to a point; see attached image/sound of the Line in recording)

(Using no cap at pin 1 and 8)

Sound Clip

UPDATE-2: I seriously doubt the volume level output of this amp.. through the speakers, I don't think it plays it loud enough.. the signal sounds sort of 'amplified', but the speaker doesn't seem to output it loud.
Btw, I tried 9V batteries, 9V battery with 5V DC, 7.8V DC, 5V DC all sound the same. Is it because of my speakers?
Also thanks to everyone who suggested adding extra caps to the power rails.. that part really helped in filtering a lot of noise. I used a 10\$\mu\$F cap there along with the 100nF cap. Or does adding more caps cause power loss or something?


texts: Glowing two leds alternatively in a given ratio of time

texts:
I want to design a circuit for glowing two leds for alternate intervals for different input voltages.
For example:
Consider two LEDS Red and Green. When the input voltage to the circuit is 0-5Volts then the two LEDS should glow for 50:50 time and when the input voltage is 5-10Volts the two LEDS glow for 20:80(RED:GREEN) time. I just need a basic circuit to implement this task.

I was thinking of using 555 timer IC but no solid configuration seemed working.


texts:
I have researched and I understand why there are no 32 bit Analog to Digital converters; it is because basically when you go beyond 24 bit, you begin to pick up on the noise generated from the vibrations of the atoms. With that in mind, I predict that the same or similar would be true for Software Defined Radios.

Question: There are 16 bit ADCs for software defined radios. Why aren't there 24 bit ones?

-- Thanks in Advance--


texts: Making combinational component synchronous

texts:
I have an combinational entity that is implemented with a lot of combinational logic.  Synthesis (using Xilinx ISE) indicates:

  Maximum combinational path delay: 62.367ns

When placed into a synchronous (clocked) design, the maximum frequency the entire system (clock domain) can operate at is only ~16 MHz.  Essentially this one component would drive the entire system's maximum clock rate down.

What I want to do, is wrap this combinational component up in some synchronous logic (with start input, done output), that essentially "waits" on the propagation delay of the async component.  Basically it just latches in the input, waits N clock cycles, and then latches the output to a register.  However, after synthesis ISE still says Maximum Frequency: 16.975MHz.

How do I get ISE to ignore the propagation delay of this device?  Or, how else can I attack this?

EDIT:

I mean combinational instead of asynchronous.

This is part of a homework assignment. We previously were to implement a factorial module in each of "iterative", "low-latency" (combinational), and "high-throughput" (registered stages). Now we're using the first two of those in IP cores for Xilinx XPS system builder. The synchronous implementation was a piece of cake to get working (probably because that's how it should be done!) Of course, the timing constraints aren't met for the low-latency version, so I have to add logic to address this.

Now that I know the term is "Multicycle Path", the following resources are helpful:

http://www.xilinx.com/csi/training/vivado/setting-multicycle-path-exceptions.htm


texts: PLL - why compare phases not frequencies

texts:
I have a question about PLL's. The aim of PLL is to get two signals with the same frequencies (there can be a shift in phases, as I understand). So, in this case, why do you use a phase detector to compare phases, and NOT just compare frequencies?

thank you


texts:
I'm trying to tackle a problem where I want to wall-mount a USB device on a brick wall that only has a single 2-wire (14AWG) cable available, and no room / capability to run a new cable or remove the current one (have tried both - it's an old house, who knows what is happening in the wall...
I plan to plug a 240V AC (Aus) to 5V DC transformer (can be another transformer - the cable is NOT rated for 240VAC however) in the roof space, and connect it to the cable. The other end of the cable comes out of a small hole in the wall (probably around 70mm high x 50mm wide x 30mm deep that I can put a small circuit board into.
The problem is that, as I am sure everyone here knows, you can't charge a modern usb device (based on my tests) using just 2 wires, a USB cable for charging these devices has 4 wires, it needs "something" on the two data (+/-) cables. It is that "something" that I want to put in the wall, where there is limited space. I assume that this will be some sort of circuit that convinces devices that they are OK to charge, simulating (??) the communication that would normally happen on the 2 data wires inside a USB cable, effectively a very small DC-to-DC usb charger.
Is there anything off-the-shelf that can be bought to go from 2-wire to a (4-wire) female USB Type-A plug that allows the device to receive power? I'm also happy to put something together myself if anyone can point me at a circuit diagram :-)
Thanks in advance, hope all that made sense!


texts: What MCU-type hardware is needed to read 12-110MHz pixel data from a video decoder?

texts:
The goal is to display PAL/NTSC (576i/480i) video on 32x16 RGB LED matrix. Scaling down the video is thus needed. From that point it is fairly easy – 32x16 image used to drive the matrix.

I have chosen 80 MHz ARM Cortex controller from Texas Instruments – Tiva C 123GXL. Block diagram looks like the following:

ADV7181C is Analog Devices video decoder. It allows very flexible outputs:

There is LLC pin with clock of the pixel port, 12-110 MHz. Is the 80-MHz ARM Cortex enough to somehow read video frames at say 10-20 FPS? One idea is to connect LLC as interrupt to the MCU. I assume that LLC will be at ~60 MHz max for PAL/NTSC input. Can I connect at that frequency? What about 110 MHz, maximum LLC, what do I need (which other MCU) to read and down-scale the frames in such situation?

I'm not sure if the Tiva allows some kind of parallel bus. There is uDMA: "ARM® PrimeCell® 32-channel configurable μDMA controller". But I also need to down-scale online, because of 32 kB SRAM memory available. Maybe this is on-topic: "PCF8575C, Remote 16-bit I/O expander for I2C-bus"?

MCU features: imgur.com/a/jHxOJ

MCU datasheet: www.ti.com/lit/ug/spmu296/spmu296.pdf

ADV7181C datasheet: www.digchip.com/datasheets/parts/datasheet/041/ADV7181C-pdf.php


texts: Why do some PCBs put vias around mechanical through-holes?

texts:
I've noticed this more and more now that I'm designing PCBs often.  Below is one example, from a motherboard.  Note the eight vias around the through-hole used for screw mounting.

  What is the purpose of these vias?

I'm sure the vias are connected to the PCB's ground plane, but if their only purpose is to make a ground contact to the chassis (through the screw in the hole), why not just pull back the soldermask?  That would provide even more contact with the screw.  I've also seen this configuration in situations where the mechanical hole was plated-through.  So I can't see grounding being the entire reason.  Do the vias have some beneficial mechanical property?


texts:
I am a physics student at a university and because of the pandemic, I and my classmates have to simulate our electronics lab exercises in Micro-Cap (version 12). We've got schematics like in this picture.

Our goal is to find the right resistance of potentiometer RP, so that the voltage in point B will oscillate.
However, it looks like the voltage in the point B is independent of the resistance of RP. It oscillates with a resistance of 1 ohm as well as with a resistance of 58 kohm.
What is some information about this type of oscillators?
P.S.
I have little experience with oscillators and op amps.
Many of you pointed out that V4 and V5 should not be sources and that I confused them with meters. This is the symbol used in the original schematics in places of V4 and V5:

Update
I edited my schematic: removed the voltage sources and connected the X2 op-amp in inverting input. Here is an image:

Also, I tried to set an initial voltage on C1 capacitor to 1 V (link to manual). Here is how my transient analysis looks like:

I used these settings:

The maximum resistance of the potentiometer RP is 200 kΩ and the wiper is in the 50% position.
Update
Now it works! Here is my final schematic:


texts: I am building a CRO. I made a circuit for it but I am not able to figure out which parts to use. Can anyone suggest low noise high frequency (at least 1 MHz unity gain) op amp which can give at least 15 mA output ? Also I am finding IC capable of producing 100 kHz PWM signal at 1% or lower duty cycle.


texts: Finding Zin of non ideal non-inverting amplifier

texts:
I would like to know how to solve for Zin of the non ideal non-inverting amplifier shown below:

I wonder how to get to this expression:
$$
\beta = \frac{R_1}{R_1 + R_2}
$$
$$
Z_{in} \approx 2R_{icm} || (R_{id} + \beta A(s) R_{id})
$$

Where A(s) is the gain of the op-amp in the s-domain (again, it's non-ideal).
Obviously there are some approximations I do not see.
I know \$R_{icm} > R_{id}\$, and probably \$R_0 >> R_1 \: or \: R_2\$, but otherwise I'm in the dark, totally in the dark in fact.

Thanks!

EDIT: Maybe I should have been more precise regarding my question. I'm dealing with a textbook not really showing anything. Of course I can use shortcuts regarding negative feedback, I can also use google (altough I haven't found any links properly explaining what I'm seeing here), and I understand the basics of negative feedback.

I want to solve it simply using standard analysis method, \$Z_{in} = V_{i}/I_{i}\$.
The author does the following steps:

\$V_x = V_o \frac{2R_{icm} || R_1}{2R_{icm} || R_1 + R_2} \approx \beta V_o = \beta A(s) V_{id}\$
\$I_x = V_{id}/R_{id} \$
\$ Z_x = \frac{V_x}{I_{x}} = \frac{\beta A(s) V_{id}}{V_{id}/R_{id}}  = \beta A(s) R_{id} \$
\$ \implies Z_{in} = 2R_{icm} || (R_{id} + Z_x) = 2R_{icm} || (R_{id} + \beta A(s) R_{id}) \$

What I don't understand is:

I don't even know where is \$V_x\$ because no schematics show it. I guess it's the voltage at \$ V_{IN-} \$, and I also guess they approximated the current entering \$V_{IN-}\$ to be zero in order to get that relation (but again, why is it a valid approx considering we assume finite resistances, because \$R_1 \: or \: R_2 << R_{icm} \: or \: R_{id}\$?). For the rest I understand, including the simplification to \$ \beta \$.
What is \$ I_x \$? The current flowing in V_{IN-} seems to be approximated to \$ V_{id}/R_{id} \$, correct? But why? Is it because \$R_icm >> R_{id}\$ (so that the current in the icm resistors are negligible)?
I don't have any idea what is \$Z_{x}\$ at this point? What is this equivalent impedance, or what is the equivalent circuit with \$Z_x\$?
I have no idea why \$Z_x\$ is in series with \$R_{id}\$. And why \$2R_{icm}\$ is in parallel with those 2.

If someone could explain these steps that would be really useful to me so I can get on with my reading. I'm more interested into the analytical solution than why I get the final result.

Thanks!


texts: Buck converter, duty cycle has inverse relationship with Vout?

texts:
I've been trying to design a DC-DC step down (buck) converter for a school project, and have been getting unexpected results. I'm using a PWM signal from an arduino to step down the voltage, and have been working with the assumption that the duty cycle (that is, TimeOn/Period) is equal to the ratio of Vo/Vs.

However, after testing with an oscilloscope (to view duty cycle of pwm) and multimeter (to view output voltage), it turns out that my output voltage is decreasing with an increase in duty cycle. Vo/Vs has an inverse relation to the duty cycle. What could I be doing wrong? Thanks in advance


texts:
I new to electronic engineering and am trying to learn electronic engineering by creating little projects. I have a few questions about powering my Raspberry Pi (5 V DC @1000 mA) from a 12 V DC 1000 mA power supply. The 12 V power supply will provide power to the TFT monitor, and I want to also power my Raspberry Pi from the same source.

After doing some research, I can make a 5 V regulator using a 7805 voltage regulator and two 100 µf electrolytic capacitors. The plan is to put a heat sink on the 7805 to help dissipate the heat. My goal is to have one source of power input for my project.

My schematic:

And a Fritzing diagram on the hook up:

Is this the correct approach?
Is my schematic correct?
Is my hookup correct?


texts: What other problems can be caused when using the JMP instruction to navigate through subroutines instead of using the instruction CALL/RETURN?

texts:
I've been creating a report on why the JUMP instruction shouldn't be used in the piece of code above and instead CALL/RETURN instructions should be used to navigate through the subroutines.

I understand that the code will never reach back2: because it is using the jump command and would continuously loop between back1: and the calculateNextPower routine.

Would I be correct saying that:

the jump instruction doesn't push the instruction onto a stack and results in you not being able to return to where you've jumped from.
When using call, it prevents you from pushing to many addresses to the stack by recursion like the JUMP instruction would. This can cause a stack overflow/tail recursion and can result in you not getting the result of the calculation until you have returned by using the call and return?

I think that I've made this way more complicated than what it is, read way to many sites and have confused myself on the reasons why it should be used instead of the jump instruction, other than it not being able to get to the "back2:" routine.

Appreciate any help on clearing this up, I'm new to this type of work


texts:
I have a DC motor, which is used as an electromagnetic brake. However I want to leave certain frequencies uninhibited, so I thought this should be possible by adding a shunt filter on the DC motor mains. The Idea is that if I high-pass the current through the shunt, that for a sinusoidal velocity input below 3 Hz no current flows through the motor coils resulting in no back-emf torque.

The circuit below consists of a sinusoidal voltage source as a result of the emf of the DC motor, the armature inductance (L1) and resistance(R1) and a still unresolved shunt circuit across the actuator leads.

What I want to accomplish with the shunt is to obtain a certain frequency response of the current in the shunt circuit, but I'm struggling with the design. Most of what I've found describes voltage filtering behaviour and I'm wondering if it's possible to filter the current in a shunt circuit.

The schematic currently shows a low pass filter arrangement, which in my understanding will result in a high current for high frequencies and a low current for low frequencies as the capacitor will have a low and high impedance respectively. The inductor acts as a low pass filter on the current, but it's filtering higher frequencies I don't really care about.

simulate this circuit – Schematic created using CircuitLab

What I would like to achieve is a frequency response somewhat like the picture below. The important part is the relatively close proximity of pass and stopband frequencies.

I would like to know if it is possible to obtain such a filter on the total current and whether this could be done without any need for active control (aside from opamps and "dumb" active components)


texts:
I'm designing a simple circuit which will
charge a big capacitor for 3 seconds,
then pass a 5A current for few microseconds,
then charge again the big capacitor for 3 seconds,
then pump again 5A for a few microseconds, and so on.
And now I test it on a breadboard and I'm convince that its working.
So I started to do a PCB layout.

Questions are the following:

Do I need to concerned on the EMI emission?
What design techniques can you recommend to me or PCB guide layout on this specific PCB.
Any precaution that I need to do in the circuit or even PCB layout?


texts: Looking for capacitance and voltage rating - How to read electrolytic SMD capacitor labels

texts:
I need to replace an SMD capacitor on a board. The printing on it says

F1
560
2.5z

I have googled intensely but have been unable to find information on how to read such a codes.

I need to find out its capacitance and voltage. I think it could be 560uf, but I need to be sure of that and still have to find out the volatage rating.

Also would it be ok to replace an SMD  electrolytic capacitor with a standard through-hole  electrolytic one of the same capacitance and voltage rating?

I am adding picture of the relavant part below:

Inside the red square is the capacitor I need help with

Inside the red reactangle on top there are two other SMD capactor presumably from the same manufacturer. I posted these as well in the hope it may help to find out the manufacturer of the cap I need to replace.

Can somebody please help me?

Thanks.


texts:
As far as I am aware, this is an incorrect implementation of an AND gate, as when out is logic high, the two N-type FET transistors will go to an open state, leaving it floating. I am doubting my understanding, can someone clarify?

From Building Logic Gates from Silicon (CS 441 Lecture, Dr. Lawlor).


texts:
How would do I add additive white guassian noise for an input SNR, without using the awgn() function on mat-lab?

Are there any resources available that can help me to solve my problem?


texts: How to maintain EMI shielding whilst penetrating the shield with cables?

texts:
I'm trying to shield an ip camera from EMI generated image noise for low light photography.  It's enclosed within a metal box that is then grounded.  The subject is also inside the box.  The camera needs a power supply at 5V and an Ethernet cable connection.  These obviously have to pass through the box via small holes.

How can I ensure that the shielding is as effective as possible?  Do I have to take special measures to prevent EMI propagating along the cables into the box?  Or, doesn't it matter?


texts: Diode Selection for 12v motorcycle lighting application

texts:
I've wired up a pair of 10w (each) LED aux lights to my motorcycle (a Kawi KLX250S).  I wanted to run them off of the high beam switch.  That part was easy.

I replaced the headlight bulb with a low-beam-only HID kit.  With this installed, hitting the high beam switch turns off the headlight (while turning on the aux lights).  I would like to keep the headlight on.

What I did was run a 12v line off of the relay powering the aux lights (it's a relay with twin 87 outputs), but it's backfeeding and causing the aux lights to be on all the time.  I'm told I need a diode to correct this, but having no electrical training (I can solder and follow directions but can't read a schematic to save my life), I don't know how to select the proper one.  Any help would be very much appreciated! :)


texts: Two separate heatsinks leads to less volume than one?

texts:
I am currently designing a heatsink to handle the heat from a diode and a MOSFET. I can pick either two or one heatsink, and my goal is to minimize the volume of the heatsink.
Intuitively I would think that one heatsink for both the MOSFET and the diode would lead to the least amount of volume, but my results show that two separate heatsinks (one for the diode and one for the MOSFET) results in the least amount of total volume, can this make sense? If so, I would appreciate it very much if someone could give an intuitive explanation of it.
To obtain my results I used the following procedure:
To obtain the R_ha=R_heatsink_to_ambient when MOSFET and diode share heatsink the following thermal equivalent circuit was used:

By calculating the heatsink temperature that guaranteed MOSFET and diode junction temperature lower than rated values R_ha was found.
When the diode and MOSFET did not share heatsink, the following thermal equivalent was used:

Then R_ha_diode and R_ha_mosfet was calculated to satisfy rated temperature of the diode and MOSFET. Here is where I think I am doing the procedure wrong, because the heat from the MOSFET does not influence the diode and vice versa.
By using heatsink data sheet I found the volume for different switching frequencies (the minimum feasible volumes were picked from the datasheet):

As you can see from the scatter plot in all cases where two heatsinks were used the total volume of the two heatsinks was smaller than using one heatsink. I am of course not asking if my numbers are correct what I am wondering about is:

Is my result logical, does it make sense that the total volume is smaller with two heatsinks?
Is the thermal modelling correct?


texts: dimensional analysis of the Shannon-Hartley theorem

texts: In the infamous Shannon-Hartley theorem the bandwidth of the channel is measured in Hz (Hertz) but the channel capacity is measured in bps (bits per second). So, either I'm missing something obvious or there's a dimensional mismatch in the equation.. Can somebody please help me understand?


texts:
I've been taught that electrons move from cathode to the anode (negative and positive). But what happens when I apply positive voltages at +10V at one end of the circuit and +6V at the other? How would electrons flow if both terminals are positive?
Could some please clarify how we determine the sign that we put before the value of a voltage?

Also, why does current not flow in an open circuit? If I connect one end of a wire to a battery and let the other hand hang without any connection, what is the potential at the loose end, the one that is in contact with the air? Is it 0V?

The second question may seem like a dupe but I looked it up and it was slightly different from what I've asked, the answer for the other question slightly differs too and it didn't clear my doubt either.


texts: Can I use two 10 ohm 5 watt resistors instead of one 5 ohm 10 watt resistor?

texts: I am working on converting an old ATX PSU to a lab bench power supply, and the guide I follow is putting a 5 ohm 10 watt dummy load resistor on the 5 V supply line. I don't have resistors of this value right now, can I instead put two 10 ohm 5 watt resistor instead? Or do I need a dummy load resistor at all?


texts: Help convert this charging indicator circuit

texts:
I have found this schematic to track when a battery is being charged, but I don't know how to convert it to work with a different voltage.
The charging voltage is 25.2V and the lowest the battery can go is 22.2V. I want to charge it with up to 2 amps.

I am not very good at electronics and the best I can do is change the resistors values, but I have no idea about the diodes or the comparator.
Thank you for your help in advance!


texts: Connecting Ashtech antenna to mobile device

texts:
Just recently I got my hands on some old GNSS survey equipment from Ashtech, which was originally brought to the market around 2010.
It consists of two ASH111660 antennas with corresponding two Ashtech Promark 100 devices, each connected by TNC/m LEM/m cables.  They were used in a rover/base configuration.
My problem now is that the handheld Promark 100 devices are quite worn down (e.g. very bad batteries,) are no longer supported nor updated, there is no option to expand licenses, etc.
I would like to discard them and ideally just use the two antennas as external GPS antennas on my smartphone (or other suitable and affordable modern mobile device.)
On the software side this does not seem to be much of a problem, but first I must find a way to physically connect an antenna (TNC-f) to another mobile device.


texts: How do electrical arcs carry less or more current with same supply voltages?

texts:
With a powerful microwave oven transformer, big bright white arcs with more current are created.

With small flyback transformers driven by a simple oscillator, at the same voltage, arcs are thinner, purple, and have less current.

Assuming both devices are the same output voltage rating, how is it possible that one arc in the same air environment can "carry" more amperage than another arc knowing ohms law, with the same supply voltage, the current will stay equal with the same resistance independent of how much current I have available.

So I thought the only answer to this could be internal resistance, but wait that means the voltage decreases, thus a smaller arc, which is not true.

So how exactly can electrical arcs have higher current yet a constant supply voltage?


texts: How to use an E-Stop rated at 10A for higher current application?

texts:
Most of the E-stops are rated at 10A or less. The following blog has explained how to wire an emergency stop http://www.ehow.com/how-does_5151421_do-emergency-stop-buttons-work.html.

But from my understanding of this circuit, the E-stop is still in series with the power-supply. Given the fact that the amount of current most E-stops can handle is so less (~10A), How is it possible to wire them so that they can be used for high-current electrical system?

Also, by wiring the emergency stop in series with the main power source (batteries) would violate the safety principle that resetting the emergency stop should not by itself turn on the power again.


texts: Inconsistent performance of circularly polarized antenna

texts:
I have a circularly polarized patch antenna for an RFID reader, with a gain of 8dBi and bandwidth from 914MHz to 919MHz and an axial of 0.34dB. I have read that using a CP RFID patch antenna means that the RFID tag will still be detected no matter the orientation of the RFID relative to the CP RFID patch antenna. But when testing this I see that there is a difference in terms of the detection of the RFID tag when I change the orientation of the RFID from horizontal orientated to vertically orientated. I connected the antenna to the reader and then to my computer where the software shows the retrieved data from the RFID tag.

For example, I placed two tags at a distance of 1.5m away from the reader's antenna at the same height in free space (outdoors). One RFID tag was horizontally orientated while the second RFID tag was vertically orientated. When testing these tags the horizontally orientated RFID tag showed to more stable because the reader's antenna picked it up continuously and I could see the data from the RFID tag using the software. However, when testing the vertically orientated RFID tag I noticed that the vertically orientated was barely detected by the reader's antenna, in that one second, the data appeared on the computer and next minute the data was not there. This does not make sense because the CP polarized suppose to detect the RFID tag regardless of its orientation. However, I did notice that when I brought the vertically orientated RFID closer to the reader's antenna the antenna started to pick the RFID tag in a more stable manner. Why does this change in performance exist?


texts: Why are op amps used so frequently in analog electronics?

texts:
I've read in several books and papers the observation: "Op amps are the bread-and-butter of analog electronics", or "... op amps are the most commonly encountered building block in analog circuits ..." and to that effect.

Although my experience is not broad enough either to concur or to refute that claim, it's certainly borne out in the circuits I have seen.

It makes me think I'm missing something fundamental, to explain why a component like this would be perhaps something like a "for" loop in programming or something, a fundamental pattern, that once available, finds pervasive application.

What is it about the fundamental nature of analog electronics that makes an op amp the fulfillment of such a basic and versatile pattern?


texts: Choosing the right stackup for 6 or 8 layers

texts:
I am designing a PCB with RF (~3 GHz), analog/mixed-signal (ADC, DDS) and some high speed digital lines (ADC outputs, DDS input; ~100 MHz).

There are very few RF lines which I can have on one layer.
But digital may be more which I need to route in different layers.

I decided to use just one single ground (due to added complexity, issues with return currents and questionable benefits). On the PCB I use 6 supplies all over the place (1V, 1.2V, +/-3.3V, +/-5V ... and also 2.5V and 1.8V but they are more localized).

My previous prototype was 4 layer and for that the one "correct" way was: 1 - important signals, 2 - Ground plane, 3 - supply plane (all supplies on same layer), 4 - less important signals.

Now I want to upgrade to 6 or 8 layers (cost is secondary). Assuming 8 layers bring signifiant benefits - what is the best stackup?

Two possible options:

Signal: Biases, references, less important stuff, high speed digital (short lines)
-5.0V, -3.3V
1.0V, 1.2V
GND
Signal: stripline (RF, high speed digital)
GND
5V, 3.3V
Signal: Less important stuff, high speed digital (short lines).

Advantages: GSG for stripline

Disadvantages: -5V/-3.3V no closeby ground, high speed digital couples into supplies, Layer 1+8 problematic for high speed digital since no ground plane.

Signal: RF (uStrip), high speed digital
GND
1.0V, 1.2V
GND
Signal: high speed digital
5V, 3.3V, -5V, -3.3V
GND
Signal: high speed digital

Advantages: All signals and supplies have ground nearby

Disadvantage: uStrip (no stripline)

Many possible combinations are possible but none of them seems really too great. Ideally I would have 20 layers and separate each layer by ground. But since this is not possible with 8 (this is about max for me) - maybe better start off with 6?

For all options, I would create a polygon pour to GND net on all signal layers where there is no signal routing to add additional grounding.


texts: How does an output switching from HI or LO to HI-Z affect an input in CMOS?

texts:
Let's say we have a tri-state buffer output connected to an inverter input, implemented in 7400 series CMOS chips.

If the buffer output is HI, the inverter output is LO. If the buffer output is LO, the inverter output is HI.

But what happens if the buffer output goes tri-stated (HI-Z) and we are not using a pull-up or pull-down resistor? Is the inverter input now floating and its output can vary? Or will the inverter output be stable and hold its logic level?

Do TTL chips behave differently?


texts: The purpose of capacitors C1, C2 and C3 in this audio amplifier

texts:
I am trying to analyse this amplifier circuit and I can not understand what the purpose of the 3 capacitors C1, C2 and C3 are if anyone could explain that would be much appreciated.
Thanks in advance.


texts: Can I connect multiple bare wires to one DC Power connector?

texts:
I need to install a HDCVI CCTV system which comes with 4 male DC connectors )left in the image below) and 1 female DC connector (right). Supposedly, the 4 cameras the system has all use the same power supply, to which the female connector attaches to. The system uses UTP cables.

My question now is: Do I connect all cameras UTP bare wires to the female connector just by twisting them together (minding + and - of course)? I have googled it, but all I can find is tutorials with one camera, not 4. Thanks.


texts: Mean Well power supply voltage adjustment

texts:
I am using a Mean Well RD-125A dual switching power supply which supplies both 5 V and 12 V. It has a screw that adjusts the voltage for both. My issue is it doesn't give an exact 12 V AND 5 V. It looks like I'll have to choose between below voltage or above.

My question is what would be the safest option for my 12 V and 5 V devices? I am worried about damaging them if the voltage is higher or lower over time, but maybe the increased/decreased amount is safe enough, I don't know hence the question.

Using the voltage adjuster here are the values for 12 V, 5 V, and a somewhat middle range.

12 V
5.8 V

11.2 V
5.5 V

10.23 V
5 V

For reference, here is the data sheet for the Mean Well RD-125A.


texts: Voltage drop over MOSFET controlled by microcontroller

texts:
I made the circuit below to power a microcontroller and a load from one power source.
But looking at the voltage drop between drain and source of the IRLZ44N MOSFET, instead of 12 V I got only 3.1 V when the MOSFET is opened by ATtiny85's 4.5 V signal.
What am I doing wrong that lets 3.1 V drop instead of 12 V between drain and source?


texts: 5V Step Up Converter Drops Voltage to 2.3 Volts when Connected to Device

texts:
Recently I combined two 18650 batteries in Parallel, and attached the output of the Paralleled 18650 batteries to a 5V Step UP Converter.

Device draws 5V 4a.

Here is a picture to the step up:

While the Paralleled batteries are the input, when I set the output on the adjustable converter to 5V and connect my battery powered device, the output Voltage drops to 2.3V and 1.3A.

I am not sure why this is happening: immediately when I connect the battery powered device to the output with AWG Gauge wires, the Voltage I set is seemingly overriden.

Thanks!

Here is the data sheet:


texts: Circuit problem with Zener diode acting like an open circuit due to voltage being less than breakdown voltage

texts:
Find the current through Zener diode?  - JEE mains 2019

In the solution, initially, the same circuit without the Zener diode was taken and it was found that equivalent resistance is given as 1250 Ohms and hence the current through the whole flowing through the battery would be .01A.
From this, the voltage drop along the parallel resistors of \$R_2\$ in the same circuit was found as 7.5V.  Then it was said that due to this the Zener diode would act as a open circuit as the voltage is less than the Zener break down voltage of 10V (i.e: zero current).
I don't understand how we can make a statement on the circuit with Zener diode from a circuit without Zener diode/follow the last lines of the argument. I hope someone can give a more detailed explanation of what was going on there.


texts: Turns ratio of transformer not on datasheet

texts:
I'm currently looking for transformers to generate high voltage spikes (several kV) on the secondary by suddenly changing the voltage (and therefore the current) on the primary. Ideally, I'd have a transformer with a turns ratio of 1:100 or more so that the voltage induced on the primary coil doesn't damage any low voltage components.
My issue is that I have no idea of how to find an appropriate transformer for this. Specifically, most of the filter options on sites like Mouser and Digikey do not allow you to select the turns ratio. The only transformer that seems to provide the turns ratio are current sense transformers, but I don't that those are appropriate for generating high voltage spikes.
Some datasheets, such as this one*, don't even list it either.
My question is: is there another way to determine the turns ratio from the datasheet? For instance, in the datasheet above, is the turns ratio 6.3:230 (because those are the voltages given in the Electrical Specifications section)? Or, is there a different type of transformer that I should be using?

I should mention that I'm aware of this question, however, I'm not even looking for a specific turns ratio (the only requirement is that it's greater than 1:100). My design will be built around whichever transformer I get.
*I have no opinions on this product. This is just one I found while looking for transformers.


texts: What considerations should I have when selecting a microcontroller for fast read and throughput?

texts:
For a project at work I am tasked with selecting a microcontroller to facilitate video transmission.

The microcontroller will read H.264 encoded 1080p30, 30 to 40-second, video files (~500 MB) from an external FAT32 storage (Currently a MicroSD UHS-1/Class 10) and send them to a communication component, with a WiFi module as most prominent candidate. It is impossible to use a wired connection in the context of this project. The data is sent over short range and during transmission the microcontroller is completely dedicated to transmission. It will have no other tasks running in parallel.

Timely transmission of video data is the most important quality attribute and we're aiming at a timeframe of around 1 minute or less.

I saw many questions about processing video that were about raw signals or output from camera modules, but did not find a case where there is just a microSD file system to read encoded video from and how this relates to needed capacity.

What should be my most important consideration when selecting a microcontroller to achieve an optimal data read speed from a storage device such as MicroSD, to route this data through the microcontroller and submit it to the communication component for transmission? Should I be looking at processing power, pins, RAM or other specifications?


texts: Can someone help me to identify the IC marked A105 T44A MUGL 0J2785 in the picture? Is it a kind of liquid sensor?

texts: It's a 20-pin SMD chip on the right side marked A105 T44A MUGL 0J2785


texts:
Pardon my noobness. I'm trying to set up a simple IR LED - Phototransistor pair but am having difficulties. My setup is just as in the following link, except my resistor values are 1K.

http://www.nerdkits.com/videos/theremin_with_ir_distance_sensor/

I'm using an Arduino to read the value of the voltage at the emitter but it does not change no matter what I do. I know I'm using the Arduino correctly because I can change the analog pin around and get expected values. I'm guessing I have some fundamental misunderstanding. Is it perhaps where you place the IR LED in relation to the phototransistor? They are right besides each other and I moved them around a bunch with no change. I will post a picture when I get home.

Also, what does varying the amount of current through the IR LED change? The wavelength is always the same, right?

Another question, this is the datasheet for the phototransistor: http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_373001_-1

A red LED will work to, since this is somewhat sensitive to red light, right?


texts:
May be a very basic question, I am a chemical engineer with limited electronics knowledge.

The circuit is a potentiostat with the current source \$I\$ being a sensor electrode.

I was looking for a way to calculate output of stage 2 as a function of \$I\$. I was wondering what kind of opamp configuration the first stage has? What is the best approach to solve this?


texts:
I have a system error pop-up on an HMI of one of my machines. Since it only had a number, I tried to reach the manufacturer for the error code description. They said that this error usually is the result of a bad analog input (in my case, one of the thermocouples). I have regular J-types, which are connected directly to PLC. Here's the thing: they all read exactly what you'd expect, but the manufacturer's techs tell me that it could read OK and still be bad, which I don't understand.
Suppose "+" wire's insulation is damaged and there's a short to the ground, then there would be no reading. And if "-" wire is shorted to the shield, and, let's say, it picks up some EMI, but then, it would either get filtered inside the PLC or it would effect the reading.
So, my question is: How can a thermocouple give a good reading and still be bad?


texts: Checking how many inputs (reed switches) are active using minimal GPIO pins

texts:
I've been a programmer, for a while, but I am new to the hardware aspect of things so I apologize for my lack of knowledge.

Just for a fun project to try to get better with hardware, I've decided to make an electronic chess board that records your moves.

I'm using reed switches for this project (they activate when they are near magnets) and I have a question.

In chess, there are 64 tiles which means I need 64 reed switches. I realized that connecting each reed switch to its own GPIO pin is inefficient and annoying considering that I'll need to get more pins (I'm using a RPi B+, so I have 27 pins to work with currently). I decided to check if anybody else has done what I'm trying to do using reed switches to see if they had any workarounds to this. Nobody has gone into too much detail about how they did it, but it appears that some people have gotten away with using 16 pins (one for each row/column).

All I really need to know is how many reed switches are activated on each row and column. I'm assuming there is a way of connecting everything in such a way where every activated switch adds to the voltage, and then I can read the voltage for each input. However, my RPi only allows me to see if there is a high or low voltage supplied to the input.

Any tips? Thanks!


texts: Piezoelectric showing strange, slowly fluctuating periodic background noise

texts:
We are trying to detect mice's licking using a piezoelectric attached to a metal spout tube that delivers water.

It's kind of working in the sense that we can detect licking, but it suffers from strange slow oscillations in the baseline (see screenshot 1 below).

The sinusoidal or spindle-like shape is the baseline signal without licking, and larger spikes are the detected licking of a mouse. As you can see in this image and the one below without licking, the frequency of the spindle-shaped oscillations is slowly fluctuating between <0.1 to 0.25 Hz.

The readout of licking is still visible, but it looks as though the amplitude of the signal is proportional to the amplitude of the spindle-shaped baseline oscillation. The licking spikes are smaller at the edge of the spindles, but become larger at the belly of the spindles.

So we cannot really know the exact amount of deflection of the piezoelectric by the mouse's licking. It appears that the signal gain of the piezoelectric is fluctuating, rather than the fluctuating noise is simply added to the signals.

We have tried to fix this problem by trying various ways of grounding, but so far not working.

Couple of things we've considered/tested are:

The piezoelectric attached to the metal spout tube is not insulated from the metal tube, and the metal tube is creating problems?
Is this still a grounding problem? How can grounding affect the gain of piezoelectric?
Could the metal tube or piezoelectric work as an antenna and pick up signal/noise from distant objects?
What is the source of this weird rhythm?
The sampling frequency of the piezo readout is 100 Hz.
Mains frequency is 50 Hz.

If you have any advice on this, or have seen something similar, let us know, please! Thanks.

Added on 30th October

There were comments about the gain change or piggybacking on baseline noise.

I can do a proper analysis using the recorded data later, but for now just a quick look at the screenshot above demonstrates that the amplitude of licking "spikes" subtracted with the "spindle shape baseline noise" is increasing towards the belly of the spindle (see the red numbers; they would be more or less constant if it were piggyback and if the pressure given by licking is stable, but it steadily increased).

We can't be sure about whether the pressure of licking is constant from this small example, but I've seen this pattern of evolving spike height in relation to, or in the spindle-like baseline, and that's why I think it is not piggyback for the moment.


texts: I'm finding it hard to understand. What is the difference between PLA and ROM? Can somebody please provide a link or explanation?


texts: 12V Car headlight halogens vs. 240V mains golf balls (longevity)

texts:
The halogen headlights on my car must be about ten years old; I've never changed them and they put up with vibration, extremes of temperature etc.

Yet the 40W mains ones in my house (normally dimmed) typically last probably ~3 months before failing.

Is there any reason for this? Are automobile bulbs made to a much higher spec, and if so is it possible to get household bulbs made to this spec?

I just hate throwing out perfectly good glass and metal on a regular basis!

Cheers in advance if anyone can impart any wisdom on this.


texts:
How do I solve
$$(X+Y)(\bar X+ \bar Z)$$

My take:

$$X \bar X+ X \bar Z+Y \bar X+Y \bar Z = X \bar Z+Y \bar X+Y \bar Z$$

But what after this? Its for sum of products


texts: Does performance of PV inverters degrade over time?

texts: Does anyone know if the performance of solar inverters degrades over time?  If so what is the mechanism?


texts: How does Internet communication work on a coaxial cable?

texts:
In buildings, it is common for the same cable (coax) to be used for pay-TV and the Internet.

It makes sense that I can transmit several TV channels on the same cable, since it can be modulated by the frequency and sends them. However, in Internet communication, data must be sent and received. There is no cable for the transmission and another for reception. So how is Internet communication on a coaxial cable?


texts:
I read that the h-bridge driving a transformer primary of an inverter whould benefit from a phase in which the primary is short circuited, before being switched to the opposite current.
How much this affect the overall performances of an inverter? Which are the reasons?
Is there any chip providing such a driving strategy?

REFERENCE
A Review of Inverter Design and Topologies page 8, see the figure:
"Off time shorting"


texts: How to apply Ampere's law with the integration path crossing a permanent magnet?

texts:
I read several books on permanent magnet synchronous machines (PMSM), and they tend to describe the relationship between H and B as \$B_{mag}=\mu_0\mu_{r,mag}H_{mag}+B_{rem}\$.
Then when they apply Ampere's law \$\nabla \times H=J\$ with the integration path crossing this permanent magnet as \$2H_{mag}\delta_{mag}+H_{external}\delta_{external}=0\$ because there is no current circled by the integration path.
However, I could not understand why the effect of \$B_{rem}\$ is excluded in the application of Ampere's law. Why is \$H_{mag}\$ used in the equation but not \$\large\frac{B_{mag}}{\mu_0\mu_{r,mag}}\$?


texts:
I am trying out the UART on the PIC18f45k50 for a project but when I try to transmit, it seems that the PIC keeps on transmitting "Hello World" indefinitely. I have tried turning off the transmit enable bit but this doesnt seem to have any effect. I then added the while(1) loop to trap the microcontroller in it to keep it busy however even with this it transmits the data twice before stopping.
I am viewing the transmitted data on my PC with termite and am using an rs232 to usb converter. The code is as follows:
UPDATE: The issue was that when it finishes executing the main method, it restarts the code execution and it repeats twice only when it is reprogrammed.
// Configuration Bits
#pragma config FOSC = INTOSCIO  //OscillatorSelection
#pragma config WDTEN = OFF      //WatchdogTimerEnablebits
#pragma config LVP = OFF        //Single-SupplyICSPEnablebit

#define _XTAL_FREQ 16000000

#include <xc.h>
#include <string.h>
#include <stdint.h>

void USART_Init(long baudrate)
{
    float temp;
    unsigned int Baud_Value = (_XTAL_FREQ - baudrate*16)/(baudrate*16);;
    BRGH = 1;
    TRISC6=0;                       /*Make Tx pin as output*/
    TXSTA1bits.SYNC = 0;                                    //Setting Asynchronous Mode, ie UART
    RCSTA1bits.SPEN = 1;
    temp=Baud_Value;
    SPBRG=(int)temp;                /*baud rate=9600, SPBRG = (F_CPU  /(64*9600))-1*/
    //TXSTAbits.TXEN=1;                     /*Transmit Enable(TX) enable*/
}

 void USART_TxChar(char out)
{
    while(!TRMT);            /*wait for transmit flag*/
    TXREG=out;                 /*wait for transmit flag to set which indicates TXREG is ready
                                    for another transmission*/

}

void USART_SendString(const char *out)
{
   while(*out!='\0')
   {
        USART_TxChar(*out);
        out++;
   }
}

void main(void) {

    uint32_t dly;
    OSCCONbits.IRCF = 0b111;
    OSCCON2bits.INTSRC = 1;
    OSCCONbits.SCS = 0b10;
    ANSELD = 0; //digital
    TRISDbits.RD1 = 0;

    USART_Init(115200 );

    for(dly = 0;dly<100000;dly++);
    USART_TxChar(0x22);           /*Transmit character '"'  */
    USART_SendString("Hello World");    /*Transmit String*/
    USART_TxChar(0x22);           /*Transmit character '"'*/
    for(dly = 0;dly<100000;dly++);

    RCSTA1bits.SPEN = 0;
    TXSTA=0x00;
    while(1){};

    return;
}
```


texts:
I have a circuit with a 220uF capacitor and a resistor is used to limit the inrush current
I stupidly fitted the wrong power rating resistor and (no surprise it failed) its taken me a while to realise my mistake. I believe the correct resistor is fine (it ran for a significant amount of time and is double the power) but I am a little bewildered as to how I calculate the rating and prove it theoretically
The resistors (I used two in parallel) fitted were 3R3 1.5W 2512 package
TE Connectivity CRGS2512J3R3
There is even a graph in the datasheet telling me the surge rating isnt adequate and I am interested in how they calculate these curves so I can apply the calcs to other resistors where they arent so helpful to provide a graph.
Here is the plot:

I measured the inrush with a scope (100VDC supply) and its a little over 40A, the theoretical max is over 60A but there is a reverse polarity protection   diode and fuse and PCB trace and cap ESR  reducing this.

That's the total inrush which passes through two resistors in parallel so approx 20A each resistor
As can be seen the surge has decreased to 50% of the peak after approximately 0.5ms so I believe I can treat this as a square wave with a width of 0.5ms as a decent approximation (like the EMC standards advise for TVS diodes etc)
There are app-notes online like
Vishays Pulse Load on SMD Resistors: At the Limit (again not enough repuation to add link)
I understand that periodic pulses require more derating than a single pulse (thats logical) at what point a single pulse becomes periodic is another topic as probably all electronics needs to be turned off at some point!
Using the calculation in vishays datasheet for periodic pulses with a 1 second period and using my inrush measurement data
P = (V^2/R)*ti/tp
V =100, R=3.3, ti = 0.0005, tp = 1
Gives me a value of 1.515W (absolute max) and I can see if applied surges more frequently then the power increases (which is what happened when the resistor failed)
Looking at the graph from the datasheet (isnt easy on the eye) but with 20.1A through the 3R3 resistor then thats a peak power of 1333W
The graph from the datasheet doesnt seem to agree for example derating for a 0.001 pulse time (for a convenient point to read off the values) the graph says approx 1kW max peak pulse power where as the calculation says that the average would be approx 3W which is double the rating of the resistor
I think I have spent too much time looking at this and simply need to go to bed and wake up fresh, I am confused if I am doing this right or do I just not have a clue!
I can calculate the energy into the capacitor but not sure what I would do with that, is the method right? is there a better way? Is this the way to do it when the manufacturer dont specify pulse/surge ratings?
Any advice is much appreciated


texts: How to get immediate state of DYP-ME003DD PIR sensor?

texts:
I am trying to detect movement for a project and have a DYP-ME003DD PIR sensor.
It has 4 pins, +,-,CDS (I think this is what it says, it's hard to read) & OUT.
When I connect it to my arduino and it detects movement it set the CDS to HIGH.
However it stays HIGH for ~10 seconds.
The OUT pin also goes HIGH on movement and seems to match the CDS pin in waiting for ~10 seconds before returning to a LOW state.
I see online that there is a couple of triggering modes for this PIR but I have been unable to find how to change between them.
Can anyone explain why this PIR has two output pins and how to get an immediate reading. i.e. If I move it detects but if I stop it also detects and doesn't wait for the ~10 second delay it currently seems to be stuck on.
UPDATE: Image & Link to specifications added.


texts: Save Audio ADC samples in SD Card in STM32

texts:
I use STM32F7 and I want to save Audio as ADC samples in SD card, continuously in 50K sample rate that is made by timer.(Same as voice recorder)
I use DMA to save data in SD card.
During read ADC, I put samples on the buffer and after 500000 sample ( about 10 seconds), I try to save them in ADC. My problem is during this process, I cant save any sample and I lost them.
Please Help me!
Thanks a lot!
uint8_t MIC_Voice_Store[200000];
    long int MIC_Store_Counter=0;
    int MIC_flag=0;

    char Name_buffer[30];
    int MIC_File_Counter=0;

    char buf[4];
    char try[4];
    int savecounter=0;
  extern char SDPath[4];
  extern FATFS SDFatFS;
  extern FIL SDFile;
   UINT myBytes;
  FRESULT result;

sprintf(Name_buffer,"MIC_%d.TXT",MIC_File_Counter);
result=f_mount(&SDFatFS,SDPath,1);

 while (1)
 {

            if(MIC_Ready==1)
                {

                    HAL_TIM_Base_Start_IT(&htim1);
                    if(MIC_flag==1)
                    {
                        if(f_open(&SDFile,Name_buffer, FA_WRITE | FA_OPEN_APPEND) == FR_OK)
                            {
                                for (savecounter=0; savecounter<100000; savecounter++)
                                {
                                        buf[0]=((MIC_Voice_Store[savecounter]/100)%10)+48;
                                        buf[1]=((MIC_Voice_Store[savecounter]/10)%10)+48;
                                        buf[2]=(MIC_Voice_Store[savecounter]%10)+48;

                                        result=f_lseek(&SDFile,f_size(&SDFile));
                                        result=f_write(&SDFile,buf,sizeof(buf),&myBytes);

                                }
                                result=f_close(&SDFile);
                            }
                        MIC_File_Counter++;
                        MIC_flag=0;
                        MIC_Store_Counter=0;
                    }
                MIC_Ready=0;
             }

}

}

void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef *htim)
{
if(htim->Instance==TIM1)
  {
      if(MIC_Ready==0)
      {
          HAL_ADC_Start(&hadc2);
          MIC_Voice=HAL_ADC_GetValue(&hadc2);
          if(MIC_Store_Counter<100000)
          {
              MIC_Voice_Store[MIC_Store_Counter]=MIC_Voice;
              MIC_Store_Counter++;
          }
          else
          {

            MIC_flag=1;
          }

          MIC_Ready=1;
        }
   }
}

Thanks a lot.
Because of sample rate is so important for me that have specific and constant value, I use timer to implement that. because of this I don't use DMA for ADC, and it doesn't  cause any problem. But I use DMA for SD card and my main guidance for that, is this tutorial:
YouTube
And, Start DMA in this tutorial has ambiguity for me too.  And I think it make problem. Can you help me more about that and start DMA with SD card?

Furthermore, you should not use f_open(), f_lseek() and f_close() on every write operation, they take an awful amount of time. Open file once at the beginning and keep writing data blocks until the end, then close file once. This way you have much better chance of keeping up with the incoming data flow.

Actually I use it at first, But this way change my sample rate because of  f_write() slow response.  That it related to use DMA with SD card, that I think is my problem now.

Finally, using f_printf() instead of f_write() may or may not be more efficient for writing bytes as text, but it sure will make your program more readable.

I will do that and tell you about that result.


texts: I got this question as a school assignment (1st year electrical engineering). I have to calculate the 3 unknown resistor values. The values which were given are in the schematic. Further \$\beta = 100\$ and the transistor is an NPN BC547B. The problem for me is the negative \$V_{EE}\$ voltage and the \$V_x = 0\$V. I don't really know where to start (already stuck for an hour). Can you give me some hints or an example so I know how to go further? I have already looked at a lot of BJT biasing examples but can't find one (I think) which really fits my problem.


texts:
I read the Christophe Basso APEC 2013 and on page 90 I have some questions:

1.) How to get equation 2, because I don't know where B1 current comes from.
2.) what is B1 current meaning