texts:
The device defaults to an inactive state (no auto conversions) unless reconfigured.
So I write to the MAX31856 config register 0x80 to setup the device to automatically read the default K type thermocouple using an 8 bit transfer 0X80 address followed by 0x80 data. CS line goes low and immediately before and after the transfer.  The timing of CS low to the first clock rising edge is 200 nsec (I have tried 400nec)
It appears to not accept the config data sent as the DRDY line never changes state after sending this data.
To verify the config data was correctly loaded I attempt a read of the config register by de-asserting CS and reasserting and then send address (0x00) followed by 0x00 to read the data, but the SDO line of the IC remains in a high impedance state (no pull up used and the pin voltage not driven high or low).
Can't seem to figure out what I am not understanding - this is not my first time with SPI.
Anyone see my error?


texts: LiFepo4 RV battery bank, charge from beefy alternator setup

texts:
What I've got
5x, 200Ah LiFepo4 batteries in a 12V, parallel bank. I'm looking at putting in a Sinister Diesel 320A alternator to supply loads of juice to the battery bank. If this is even possible, without damaging the batteries and circuit, then I figure I don't really need to go the standard roof, solar panel array nonsense.
How I understand it
Low-powered alternators can get overloaded due to the very low internal resistance of lithium batteries drawing too much current from the alternator, causing it to overheat and burnout (if there's no dc-dc charger). My batteries have a 100A max input charge and 35mΩ resistance.
Questions
Q1 - do I have this right? - the input current will divide evenly among the batteries so each battery will "see" roughly 320A / 5 = 64A?
Q2 - these batteries are equipped with an internal BMS. Does this control the battery charging such that it "shuts off" the battery from the circuit when it's fully charged? That's wishful thinking, probably, the BMS is more about internal cell balancing and not preventing harmful currents?
Q3 - overall, is what I want to do possible? I'm not going to hand-build any necessary parts, but I'm happy to purchase the proper hardware. However, as far as dc-dc chargers go, I wasn't really seeing anything above 60A. I guess that'd be OK if I put a separate dc-dc charger on each battery? ... although that'd be one charger per battery which is annoying and costly.
Thanks for any guidance!
Update:
After considering everyones' feedback (thanks!) and ruminating on it for a while, I've decided just to go ahead and get a DC-DC charger. The output voltage of an alternator isn't quite high enough to bring LiFepo's up to a full charge. It took some hunting but I finally found a single maker that has a high-amperage charger that should do the trick: Sterling Alternator-to-battery Charger. So I'll put this between the beefy alternator and the battery bank. However, I'm still unclear on how to protect each, individual battery: there will be, say, 300A feeding from the charger into the parallel bank. Each battery can't get more than 100A applied to it. Is there some hardware I can install on each battery to limit the incoming current? Is there hardware that can fully open and shut off current when the full-charge voltage has been achieved?


texts: Voltmeter measuring electromotive force of a battery

texts: It is known that connecting a voltmeter directly to the terminals(without any other load) of a battery will show you the value of the battery's EMF.However,I don't really undrerstand how this happens.The electomotive force is equal with:E=U+u(E=EMF,u=internal voltage drop,U=external voltage drop).The voltage the battery supplies is U.My question:How does a voltmeter measure EMF of a battery and why doesn't it show the value of U when connected directly to the battery?


texts: What happens on STM32 when multiple (UART) Interrupts are triggered at the same time? is there an interrupt stack?

texts:
I'm implementing a uart daisy-chain communication scheme with a Cortex M4.
When a node receives a byte over one UART, an interrupt is generated (RXNE) and the byte is written out over another UART - since I use a send and receive buffer, this places the byte in the send buffer and enables the TXE interrupt which should be triggered subsequently.

This means for every byte received, two interrupts are triggered.

Now both UARTs can receive and transmit, and it is very much possible that both UARTs do receive a byte at the same time - now both will get a RXNE interrupt and trigger a TXE interrupt on the other UART.

But only one ISR can be processed at the same time - what happens with the other ones?

Is there an interrupt stack that can get full or interrupts simply called until all corresponding interrupt bits are cleared?

The thing is that my application tends to lock up under the situation described above (with multiple bytes being received). Not however when the UARTs are set to a lower speed (this seems counter intuitive) or when there is only one side connected.


texts: Bias T to level shift output from oscillator

texts:
I am using XOR gate HMC851LC3C to get an ultra-short pulse (200ps range). This logic gate requires inputs in the range of -2.5V to 0.5V. However, RF signals from my oscillator is sine wave -1V to 1V. I want to shift the range of this oscillator output to be -0.5 offset which means to -1.5V to 0.5V in order to satisfy the requirement of the logic gate.
My question is, can I use a bias tee and apply sine waves on one side, -0.5V on the other side of the tee. Is this possible and will it change the jittering of the oscillator output after the tee?

Thank you
datasheet of HMC851 logic gate


texts: Determine the position of a ball joint by image processing

texts:
I am wondering if it is possible to sense the position of a ball joint using:

A photodiode array from an optical mouse, embedded in the socket
A specific pattern deposited onto the ball
A processor that can use the exposed part of the pattern to identify which part of the ball it is looking at and how it is oriented.

I imagine something similar to a de Bruijn Torus, that can be projected onto a spherical surface rather than a torus or plane, would do the trick.

Is there a known algorithm for generating and/or decoding such an image?


texts: Are thin connections between ground planes "islands" acceptable for ~0.5mA?

texts:
Is it okay to have a section of the ground plane connected to the rest of the ground plane through a thin trace as long it does not carry lots of current (.5 mA approximately)?

There is an example:

Does it have any bad effect I am not aware of?


texts: Are there ideal opamps that exist in the real world?

texts:
Are ideal opamps being sold? By ideal opamps, I mean those whose output can be calculated from the appropriate equations (negative and positive feedback.)
I am asking this because I am running simulations on Falstad and the real opamps (those whose supply pins are not initially connected) give very different results from the theory I know.
For example I put some negative feedback on a real opamp and I put the feedback resistor and the input resistor to be the same connected VEE to GND and VCC to 10V and input value of 3V. I expected an output value of 2V however it showed basicaly a voltage divider.
Isn't the simulator good or what?
I have designed many circuits using ideal opamps and now I need to translate those circuits to circuits with a real opamp.


texts:
I have been trying to solve this homework problem for who-knows how many hours. I could break it down enough as to specify the problem I'm facing into a single question:

For the following circuit with a charged capacitor, is \$ v_C + v_R + v_L = 0 \$ the right term? Or should it be \$ -v_C + v_R + v_L = 0 \$? Why?

I am getting really confused because everywhere, the RLC circuit is solved with a tension source, hence the formula is \$ E = v_C + v_R + v_L \$, but I have doubts if it's as simple as E = 0 since in this particular case the source itself of the power is the capacitor, entering the current through the negative side.

Keep reading only if you said the \$ v_C \$ should be negative. I explain how I tried this and didn't work at all about what I've tried in the problem and how I got to that particular question:

Here is the general circuit. The DC source charges the capacitor and in t=0 it's opened. Therefore, for all t>0, we get the simplified circuit of the previous image.

The problem considering the \$ v_C \$ negative is in the general solution of the differential equation:

From this solution, we can see that the current would increase non-stop, which doesn't make any sense (from the initial conditions \$ C_1 \neq 0 \$ and \$ C_2 \neq 0 \$). Therefore, using the right signs yelds to a wrong solution, using all v positive yelds to a good solution (both exponents negative).


texts:
I am facing a weird problem with my stepper motor when I am trying to control it with my linux computer.

As soon as the serial port is opened from my code to spin the stepper motor, my command terminal starts displaying output in Upper case letters and the output that I get is :

  I HAVE ENTERED THE MAIN LOOPSM,500,0,-400

READLINE: WARNING: TURNING OFF OUTPUT FLUSHING
SAIRAM@GTX:~/OPENCV/TRUNK/OPENCV/SAMPLES/C$

After that,I have to shut down the terminal and start a new terminal screen to control my stepper motor.

I am also attaching the code that talks to the serial port of the computer:

    void open_port(char str3[])
{
  int fd; int n;

  struct termios options;

  /*
   * Get the current options for the port...
   */

  /*
   * Set the baud rates to 19200...
   */

  cfsetispeed(&options, B9600);
  cfsetospeed(&options, B9600);
  options.c_cflag &= ~PARENB;
  options.c_cflag &= ~CSTOPB;
  options.c_cflag &= ~CSIZE;
  options.c_cflag |= CS8;
  // options.c_cflag &= ~CNEW_RTSCTS;

  /*
   * Enable the receiver and set local mode...
   */

  /*
   * Set the new options for the port...
   */

  tcsetattr(fd,TCSANOW, &options);

  /* File descriptor for the port */

  fd = open("/dev/ttyACM0", O_RDWR | O_NOCTTY | O_NDELAY);
  if (fd == -1)
    {
      /*
       * Could not open the port.
       */

            perror("open_port: Unable to open /dev/ttyACM0 - ");
    }
  else
    fcntl(fd, F_SETFL, 0);

  //str1
  //strcpy(str1,"EM,0,0");
  strcat(str3,"\r\n");
  printf("%s\n", str3);
  n = write(fd,str3,20);
  if (n < 0)
    fputs("write() of 4 bytes failed!\n", stderr);

  close(fd);

}

I am not a programming expert and hence I could not understand whats going on


texts: Need help with level shifting and amplifying a signal

texts:
I have a 1V pk to pk analogue signal and need to shift and amplify the voltage to 0.5-2V.The supply into the amplifier is ±10V. The frequency of the signal is 500 - 1000Hz.

What sort of circuit should I be looking at? Not wanting anyone to send circuits, just need some pointers in the right direction.


texts:
I bought a cheap set of remote controlled power sockets and I want to integrate them into my home automation system. So I got a 433 MHz receiver for 1€, connected it to my Arduino and tried to decode the signal from the remote using the rc switch library. This gave me ambiguous codes (and pulsewidths and "protocols") as output if I pressed the same button multiple times. My device is probably not compatible with this library.

So I hooked the receiver up to my soundcard and recorded the raw signal with 48 kHz in Audacity. This is the result for pressing the "D off" button:

1 bit = 72 samples = 1.5 ms
24 bit = 1728 samples = 36 ms

zero bit = 12 samples high + 60 samples low
one bit  = 42 samples high + 30 samples low

[3x] 010100110100100101110010 0 + 55 samples low
[4x] 010100110100100101110010   + 140 samples high + 360 samples low
[1x] 010100110100100101110010 0 + 55 samples low

[3x] 010110110000101010110010 0 + 55 samples low
[4x] 010110110000101010110010   + 140 samples high + 360 samples low
[1x] 010110110000101010110010 0 + 55 samples low

[3x] 010100001011000100110010 0 + 55 samples low
[4x] 010100001011000100110010   + 140 samples high + 360 samples low
[1x] 010100001011000100110010 0 + 55 samples low

[3x] 010101111100100001000010 0 + 55 samples low
[4x] 010101111100100001000010   + 140 samples high + 360 samples low
[1x] 010101111100100001000010 0 + 55 samples low

repeat

So I was wondering:

Why would the manufacturer decide to send 4 different codes for a single button?
Why in this weird pattern?
What's up with the extra zero on the short lines?

I'll probably be able to do this analysis for each button and get the transmitter to send the codes. (Although it's a lot of work.) I'm just curious if there is a logic or a pattern behind this that I'm not seeing. Maybe someone has a hint to how I can achieve my goal more easily.

Also maybe interesting to know: The sockets "learn" which of the buttons (A-D) they are associated with. They listen to the first ON button you press after plugging them in. To unset the link, you have to press the OFF button after plugging them in.


texts: Change capacitance or resistance in RC circuit

texts: When tuning an RC circuit you can choose either to tweak the resistance or the capacitance.  I was wondering if there are any benefits for choosing one over the other depending on what you are trying to achieve?


texts:
I need to power up a grid of 20 RPi3. Each RPi3 required 5V 2.4A. So, in total is it about 50A.

According to my tests it doesn't drain more that 1.2A. I think it is because I don't use any USB or WiFi.

So, I want to have one or two power supples for all of them. Since I have very little EE experience I just made a simple search in internet for 5V 50A power supply.

So far I like power supplies from company called: MEAN WELL.

I like these:

SP-240-5
RSP-320-5
HRPG-300-5

Questions:

Please tell me where it is ok just wire up my RPi3 in parallel with 18 AWG via Micro USB to one of the power supply of my choose above?
What I should consider additionally, maybe I am missing something important (very little EE experience and very serious amperage)?
If you know better solution - please tell.


texts: Two ways to understand bypass capacitor to reduce supply ripple

texts:
I knew two ways to understand how bypass capacitor reduces ripple, but I don't know how both these ways are related:

1)  A large capacitor stores a lot of charge; when supply fluctuates, the capacitor gives the charge and keeps the voltage almost constant.
2) A large \$C\$ means very less reactance. Thus all the ac is grounded.

I understand each of above two explanations very well. But I don't seem to see the connection between them. How are they same? In particular, how storing a lot of charge is same as grounding ac? Any help?


texts:
I have a device that takes two AA batteries and I want to replace it with my own external power source and regulation circuitry. Instead of clipping or soldering wires to the device contacts, I would rather plug in a dummy battery shell that has the appropriate contacts on the end to make the whole project cleaner and more prototype friendly.

Does such a thing exist?


texts: Can I apply 12V intermittently to a 5V 28BYJ stepper motor?

texts:
As the title suggests, am I able to apply 12V to each winding of the 28BYJ (5V version) to increase the torque?

I understand that it's not ideal as it will overheat, but it won't be running non-stop. It will run on average 2 seconds out of every 12, which I figure will cool down a bit between rotations.

Or is there a way to increase the torque on these motors? They are running half steps already and are unable to move the load.

Am I likely to get shorting between windings if I increase the voltage, as it's a proportionally large increase in voltage?


texts: Using an op amp to balance a Wheatstone bridge by heating a sensor wire

texts:
I'm attempting to create my own hot wire liquid water content sensor, the control circuitry of which is similar to many hot wire anemometers:

simulate this circuit – Schematic created using CircuitLab

RS, the sensor wire, is a 5 cm long, 125 micron diameter platinum wire with a resistance of 0.5 ohms. RT, the temperature compensation wire, is an 8 cm long, 25 micron diameter platinum wire with a resistance of 17 ohms. My understanding of how hot wire anemometers are supposed to work is this: as air flows over the electrically heated wire RS, its resistance goes down, making the Wheatstone bridge unbalanced. This increases the difference between the two inputs of the op amp, which then outputs a higher voltage, increasing the temperature and resistance of RS until the bridge is balanced again.

The issue I'm running into is that the op amp is unable to provide enough power to heat the sensor wire, which needs to be about 50°C. Im using a LM358P op amp. I think that part of the issue may be that because the resistances in the bridge are so low, the op amp needs to deliver more current than it is capable of to supply the output voltage expected. I've been supplying the op amp with between 3-32v single supply, and the output voltage and current have been around 30 mV, 30 mA respectively.

I study mechanical engineering so the workings of op amps is something I've been trying to teach myself, any suggestions for increasing the power through the sensor wire to heat it properly would be greatly appreciated!


texts:
I have a wireless remote control for a light.
It runs with a 12V battery.
It has two mini Omron type B3F momentary ON switches (mini push-button switches).

One button is for Light ON, the other for Light OFF.

I wonder how to connect my Arduino to that switch so I can control the on/off states.

I was wondering about relays, or maybe hacking direct the board which seems pretty rudimentary (was a cheap control system).

In the picture, you can see 6 switches because it controls 3 receivers.


texts: Trouble finding an NJM2360D Boost Converter EAGLE library

texts: I am doing a Senior Design Project for my Electrical Engineering degree. This project involves making a PCB. I am having trouble finding a specific library for EAGLE 7.7.0 software. The library that I need is for an NJM2360D Boost Converter. Does anyone know where I can get a library for this component? Please and Thank you!


texts: Connecting a CAN node results in infinite errors on the bus

texts:
I'm developing a device which is controlled by the received CAN messages. The device should be eventually mounted in a vehicle. The device receives messages only. It doesn't send any messages on the bus.

The device was tested in HiL successfully.

Once the end customer connected the device in the vehicle, more than 3000 errors were detected on the bus in short time.

As far as I understand, if my device detected 127 errors while receiving the messages, it should go "error passive" and after 255 errors it should go "bus off". Isn't it correct. My device is not configured to automatically re-transmit after entering "bus off" mode.

My question is, what can cause those many errors once my device is connected on the bus? The bus had no errors before connecting my device.

My assumption is that the senders on the bus don't have the same bit-timing as my device. But even if this is the case, the maximum errors detected should be 255, right?


texts: Is it possible to measure phase margin with the loop closed?

texts:
Everything I read on the web, concerning this question, says that in order to measure or set the phase margin of an amplifier the loop must be opened and the phase lag around the loop measured when the gain around the loop equals -1 (unity loop gain).

This seems to be almost universal advice with its resulting practical problems such as DC offset across the break and creating the correct load for the output of the opened loop.

My question - Can the phase margin be measured in a closed loop setup, why is an open loop always recommended for this?

Classical amplifier theory says that for an amplifier to be stable the loop phase must be less than 180 degrees lag by the time the loop gain gets down to 1 (unity). To give sufficient phase margin the value of the compensation capacitor is often set to give a loop phase of, say, 135 degrees at unity loop gain (phase margin = 45 degrees).

Consider the following amplifier:-

simulate this circuit – Schematic created using CircuitLab

Loop Gain = BAol

where:-

Aol = Vout/Vdiff

and

B = Vfeedback/Vout

Therefore loop gain = Vfeedback/Vdiff  (using pk to pk values).

Loop phase is the phase of Vfeedback to Vdiff.

It appears that I can measure both loop gain and loop phase in a closed loop configuration.

Why can't I just increase the input signal frequency until Vdiff = Vfeedback (unity loop gain) and then measure the loop phase with a 2 channel oscilloscope (phase of Vfeedback to Vdiff) to determine or set the phase margin? (How short of 180 degrees the loop phase is).

Is there anything with this apparently very practical closed loop method of determining (or setting) phase margin. Why is such a much more practically difficult open loop technique so commonly recommended?


texts:
I am looking to interface a Melexis IR sensor to a AVR micro(ATmega2560). The sensor has an SMBus interface. The datasheet of the micro does not explicitly state that it supports SMBus. But it has a TWI interface which is compatible with I2C.
 1. Has anyone achieved this?
 2. If yes, what is the maximum frequency of communication
 3. Have anyone interfaced the sensor with a different micro which does not explicitly state that they support SMBus?

Related links

 Maxim app note
Question at Stack exchange


texts: Why is there voltage out of the gate of my transitor

texts:
I'm a big beginner in electricity :-D I just discovered the "Circuit wizard" tool and I'm drawing a circuit with a "MOSFET n channel" transistor. As I understand, when there is voltage on the gate, the transistor is "open" and the current can flow "through" it. So I did the following schema:

Behind the tooltip, there is a switch, open. Thus, I expected 0V on the wire between the gate and the switch... And I expected that if the switch was closed, the voltage would be 5V.

Only the second assumption is correct. Indeed, I really don't understand why there is 3.33V on the gate of my transistor. As the switch is open, the wire is like... not connected to anything so where does this voltage come from ?

The answer is surely obvious but I don't know what to look for on the internet to find it :p


texts: How does armature reaction affect brushes in DC generators?

texts:
"Due to armature reaction, the natural direction of the magnetic field of the poles is distorted.  Thus the neutral plane is also altered.  Therefore, the armature conductors are not at zero potential when they come in contact with the brushes.  This leads to sparking across the brushes and loss of power."

I've seen that statement in various different videos regarding the subject. However I'm confused. I understand how the neutral plane shifts due to armature reaction, but I'm wondering why the armature needs to be at zero potential when it comes in contact with the brushes?

Aren't brushes supposed to transfer the current generated in the armature to the load? Why would the armature have zero potential, when in contact with the brush?

Any help would be appreciated, thanks!


texts:
I want to have the PIR Motion Sensor:
https://www.adafruit.com/product/189

Used to turn on a light whenever it detects motion.

Simple enough, but would it be possible to have this done wirelessly?

I.E. PIR Motion Sensor detects motion, sends a single high to a transmitter, signal is sent to receiver, receiver has output signal to blink an LED.

Note: The transmitter and receiver will only be about 5 feet away from each other, so hopefully all of this can be low power.

Any help would be appreciated. Thank you.

(Raspberry Pi is tagged because I wasn't sure if one would be required to implement what I want)


texts: What do the colors of resistor bodies mean?

texts:
I don't mean the colored bands, but the colors of the bodies themselves.  They come in brown, blue, green, etc.  Is there a standard?

For instance, epanorama says:

  But there are two resistor body colors which you should know what they need if youre fixing some electronics circuit. Resistor body colors white and blue are used to mark non-flammable resistors and fusible resistors. If you encounter tjis type of resistor in the circuit do not replace it with normal reistor because this would cause fire danger is something goes wring in the circuit.

Is this always true?  Only with certain manufacturers?


texts: On an AVR (ATtiny2313), which is serviced first when TIMER0_OVF and TIMER0_COMPA are due at the same time?

texts: If an AVR's 8-bit timer compare register is 255 and the timer overflows (according to the datasheet, the compare interrupt happens on the next timer clock cycle) then both the overflow interrupt and the compare interrupt should be due at the same time. Which will be serviced first?


texts:
I'm trying to understand this application note from On-Semiconductor regarding the loop control design of buck converter Designing Stable Control Loops for High Current Voltage Mode Synchronous Buck Converter with the NCP323X
I'm referring to the design example in pg.5
I'm just curious how they got open loop gain value, Gde = -10.13dB.
Please correct me if I'm wrong, from my understanding, this value is supposed to be equal to the modulator gain, Fm where Fm = Vin/Vp
Based on input specifications,

Fm = Vin/Vp = 12/6.6 = 1.818
20 log Fm = 5.19dB

But from the design example (pg.5) , it shows it shows that the open loop gain deficiency, Gde is -10.13dB.
Could anyone explain why?


texts: In the above problem for t>0 the inductor can be modelled as a short circuit and therefore the current flowing through it is -4/8 or -0.5 A, as no current flows through the 4 ohm resistor. But to determine the Thevenin equivalent resistance as seen through the inductor the 4 ohm resistor must be considered as being in parallel with an 8 ohm resistor, so that the Thevenin equivalent resistance is 8/3 ohms. But if no current flows through the resistor, V = 0*R = 0 and R*0 = 0 so R can have any value, so why is a value of 4 ohms used to calculate the Thevenin equivalent resistance? Is this because the inductor must be viewed as a load rather than as a short circuit and the result is independent of whether an inductor or another element is connected, or because Ohm's law does not apply or I am interpreting it incorrectly?


texts: Can somebody identify these missing parts at the input stage of a Red Pitaya?

texts: The board is from Red Pitaya. The chip AD8066. It is being used as unity buffer. The components I have marked with black boxes are kept at input pins(3 and 5) of the chip.


texts: Does humidity relate to static sensitive?

texts: Are components more static-sensitive in drier places or vice versa?


texts: Simplifying a Boolean expression that has 3 variables in it

texts:
Problem:
Simplify the following expression using Boolean Algebra:
$$ z = (B + \overline C)(\overline B + C) +  \overline{ \overline A + B + \overline C} $$
Answer:
\begin{align*}
z &= (B + \overline C)(\overline B + C) + A \overline{B} C  \\
z &= \overline C \, \overline B + BC + A \overline{B} C  \\
z &= \overline B \, \overline C + C ( B + A \overline B ) \\
z &= \overline B \, \overline C + C ( A + B ) \\
z &= AC + BC + \overline B \, \overline C  \\
\end{align*}
However, the book gets:
$$ BC + \overline B ( \overline C + A ) $$
I believe both answers are right but I would like to know how to get the book's answer.


texts: US/Can - Maximum current in a single circuit in a 100A panel

texts:
I hope this is the right sub...

I have a 100A pony-panel in the garage. I'd like to have someone add a wall plug for EV charging, ideally a 14-50, but I'd settle for a 14-30 if need be.

I seem to recall there is a rule that any circuit can only be x% of the total supply. I further recall this being 25%? So in this case, I'd be limited to 25A?

Is this correct, or am I having a senior moment?


texts:
Can you point me to a good online resource to learn how to understand and design LC filters?

The goal is digital forward phase control to dim a light bulb. I've read that the EMI produced by the voltage spikes when a TRIAC goes into the "on" state can be bad news for other electrical devices nearby on on the same supply circuit.

http://www.epanorama.net/documents/lights/lightdimmer.html gives an example circuit with a 50-to-100 microhenry inductor in series with the TRIAC, and a 100 nF capacitor in parallel with it, but I don't know how the author came up with those numbers.


texts: I'm trying to identify what this type of connector is. The first image is the male connector, attached to a flex ribbon. It has 20 pins on each side. I thought it was an FFC connector, but can't find anything remotely like it in Digikey FFC connectors. The closest match I can find is an Apple LCD flex cable "grade R" replacement. Any ideas? Thanks!


texts: Can air itself be used as a magnetic core in CT (Current Transformer)?

texts:
I would like to measure a current flowing on an RF power line in ICP (Inductively Coupled Plasma) system. The frequency of RF is 13.56 MHz.

So, I'm planning to construct my own CT (Current Transformer) for the current measurement. I originally thought that I have to choose some ferromagnetic material as a magnetic core in CT, But I'm curious what happens if I use a non-magnetic material such as a plastic or even an air. I read some paper which looks to use the air as the core. What are the advantage and disadvantage if the non-magnetic material is used in CT, instead of using the magnetic material?

The primary aim in constructing CT is that CT must not give non-ignorable influence on the power line under the measurement. As CT is nothing but a  transformer, so many winding on the secondary side reduces an impedance seen by the power line (the primary side of the transformer) according to \$\tilde Z_L^\prime  = {\left( {\frac{{{N_P}}}{{{N_S}}}} \right)^2}{\tilde Z_L}
% MathType!MTEF!2!1!+-
% feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
% 4rNCHbWexLMBbXgBd9gzLbvyNv2CaeHb5MDXbpmVaibaieYlf9irVe
% eu0dXdh9vqqj-hEeeu0xXdbba9frFj0-OqFfea0dXdd9vqaq-JfrVk
% FHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr0-vqpWqaaeaabiGaci
% aacaqabeaadaqaaqaafaGcbaaeaaaaaaaaa8qaceWGAbWdayaaiaWa
% a0baaSqaa8qacaWGmbaapaqaa8qacqGHYaIOaaGccqGH9aqpdaqada
% qaamaalaaabaGaamOtamaaBaaaleaacaWGqbaabeaaaOqaaiaad6ea
% daWgaaWcbaGaam4uaaqabaaaaaGccaGLOaGaayzkaaWdamaaCaaale
% qabaWdbiaaikdaaaGcceWGAbWdayaaiaWaaSbaaSqaa8qacaWGmbaa
% paqabaaaaa!4DCC!
\$ where \${\tilde Z_L}
% MathType!MTEF!2!1!+-
% feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
% 4rNCHbWexLMBbXgBd9gzLbvyNv2CaeHb5MDXbpmVaibaieYlf9irVe
% eu0dXdh9vqqj-hEeeu0xXdbba9frFj0-OqFfea0dXdd9vqaq-JfrVk
% FHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr0-vqpWqaaeaabiGaci
% aacaqabeaadaqaaqaafaGcbaaeaaaaaaaaa8qaceWGAbWdayaaiaWa
% aSbaaSqaa8qacaWGmbaapaqabaaaaa!42A8!
\$: secondary side load impedance, \$\tilde Z_L^\prime
% MathType!MTEF!2!1!+-
% feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
% 4rNCHbWexLMBbXgBd9gzLbvyNv2CaeHb5MDXbpmVaibaieYlf9irVe
% eu0dXdh9vqqj-hEeeu0xXdbba9frFj0-OqFfea0dXdd9vqaq-JfrVk
% FHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr0-vqpWqaaeaabiGaci
% aacaqabeaadaqaaqaafaGcbaaeaaaaaaaaa8qaceWGAbWdayaaiaWa
% a0baaSqaa8qacaWGmbaapaqaa8qacqGHYaIOaaaaaa!4439!
\$: impedance seen by the primary side, \${{N_P}}
% MathType!MTEF!2!1!+-
% feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
% 4rNCHbWexLMBbXgBd9gzLbvyNv2CaeHb5MDXbpmVaibaieYlf9irVe
% eu0dXdh9vqqj-hEeeu0xXdbba9frFj0-OqFfea0dXdd9vqaq-JfrVk
% FHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr0-vqpWqaaeaabiGaci
% aacaqabeaadaqaaqaafaGcqaaaaaaaaaWdbeaacaWGobWaaSbaaSqa
% aiaadcfaaeqaaaaa!4263!
\$: number of primary winding, which is 1 for CT, \${{N_S}}
% MathType!MTEF!2!1!+-
% feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
% 4rNCHbWexLMBbXgBd9gzLbvyNv2CaeHb5MDXbpmVaibaieYlf9irVe
% eu0dXdh9vqqj-hEeeu0xXdbba9frFj0-OqFfea0dXdd9vqaq-JfrVk
% FHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr0-vqpWqaaeaabiGaci
% aacaqabeaadaqaaqaafaGcqaaaaaaaaaWdbeaacaWGobWaaSbaaSqa
% aiaadofaaeqaaaaa!4266!
\$: number of secondary winding. Is this idea correct?

Thanks for reading my question and I'm looking forward to replies.


texts: How do I get a firmware .hex running on a PIC18F2550?

texts:
I've been playing with this data logger board that's based on the Microchip PIC18F2550, but my application requires a lot of analog front-end signal conditioning.  I would like to combine everything on one custom board, but I can't tell if it's possible to get the data logger firmware running on a virgin PIC18F2550.  The data logger contains a bootloader that allows firmware updates via USB; the firmware .hex is available for download, but no bootloader code is available.

I haven't used microcontrollers before, so I have several questions that I haven't been able to answer from the data logger website or the PIC18F2550 datasheet:

Is the bootloader something that is pre-loaded on the PIC18F2550 by Microchip, or must it be installed by the developer?
If the bootloader is pre-loaded, then I presume all I need is a USB connection to the PIC (as on the original board) and the "Microchip USB HID Bootloader" utility to install firmware the first time.  Correct?
If the bootloader is not pre-loaded, then may I use a programmer via the ICSP header to install firmware, without a bootloader?  If so, what hardware and software do I need, and what is the process to do this?

Thank you!

Here's the data logger schematic:


texts:
How accurate can I get temperature measurements if I repeatedly sample the data from a PT100 sensor. [Assuming I have a 16 bit converter]?
What are the limits on accuracy and repeatability? Does the accuracy increase as the square root of the number of samples?


texts:
I've been researching switchmode regulator ICs recently, and I've been doing some searches on Digi-Key. When I do my searching, three main types of regulators are listed:

Buck
Boost
Inverting

I know what buck is (step-down), and I know what boost is (step-up), and I believe I know what inverting is (negative output voltage from positive input voltage).

Besides these main types, "flyback" variants of each are listed. What is a flyback power supply, or flyback regulator?


texts: What is the name of this springy type oscilloscope probe accessory?

texts:
Exactly what it says on the tin.

How is this pictured accessory called? The obvious place to look for a name would be the probe manual, but it looks like they decided to add the accessory to the package after making the manual, since it's not on the component list.


texts:
I'm writing an app, that most of its time will spend in STOP or STANDBY mode (battery powered microsystem). I'd like the internal RTC to wakeup my STM32 every 5 minutes, enter the ISR, do its tasks in ISR (ADC measurement and send it over) and enter back the STOP mode.

My question is: how to do it nice and simple?

I tried with RTC alarm interrupt, but when I set 5 minutes in the alarm register, the interrupt run every 10 minutes (5 min, 15 min, 25 min and so on... - actually I had tested with 5 seconds). I tried to reset the time register in the ISR, but it works only sometimes.

Could you give me some advice what's the best way to do a periodic wakeup in STM32F30?


texts: Direction of winding (clockwise/anticlockwise) in flyback transformers

texts:
Here is a circuit of offline switching power supply based on Viper22a IC:

In this circuit and many other similar circuits, they denote the starting of a winding by a "dot". However they never mention the direction of the winding - clockwise or anticlockwise.

Does the direction of winding not affect the circuit in any ways?

I tend to believe that polarity of induced voltage should be dependent on the direction.

In case the direction of winding changes the polarity, is there is a standard winding direction to be followed while making the transformer? Example - Does the circuit given above assumes this pattern?:

Primary: start at 2 - End at 1 -> Clockwise

Auxiliary: start at 3 - End at 4 -> Clockwise

Secondary 1: start at 5 - End at 6 -> Clockwise

Secondary 2: start at 8 - End at 7 -> Clockwise


texts:
How to calculate the Starting current of an induction motor if I have the power in kilo watts and the voltage? I have looked up formulas , but I got confused.

I calculated the full load current by dividing the power by the voltage (p=VI). I'm not sure about the full load current calculation as well.

Also I know that the starting motor current is higher than the full load current, is that correct?


texts: Why input combinations producing output '1' constitute a standard SOP expression and those producing output '0' constitute a standard POS expression?

texts:
Why input combinations producing output '1' are picked for forming a standard SOP (Sum of Products) expression and input combinations producing output '0' are picked for forming standard POS (Product of Sums) expression? Is there any specific reason behind it?

From the sample truth table,

Standard SOP expression is formed by picking the input combinations that produce an output of 1. (For an SOP expression input 1 is considered as A and input 0 is considered as A')
i.e., Using the input combinations 011, 101, 110 and 111, SOP expression will formed as F = A'BC + AB'C +ABC' + ABC,
where A' denotes A complement.
Standard POS expression is formed by picking the input combinations that produce an output of 0. (For a POS expression input 0 is considered as A and input 1 is considered as A')
i.e., Using the input combinations 000, 001, 010 and 100, POS expression will formed as F = (A+B+C)(A+B+C')(A+B'+C)(A'+B+C),
where A' denotes A complement.

Why the terms producing output 1 are being selected for SOP form and those producing output 0 are being selected for POS form?


texts: Arduino vs PIC nop. Is this the same thing?

texts:
If I have the following line of code in an Arduino based project:

__asm__("nop\n\t");

Will this have exactly the same effect as nop in PIC12F675? Does it matter that the PIC in question and the Arduino may operate at different speeds?


texts: MAX743 unstable with load (5 to +/- 15V)

texts:
I have constructed the circuit outlined in the MAX743 datasheet however the negative rail seems to be spiking 8Vs @ roughly 135khz in 15V mode. When I change the chip to 12V mode the spike is reduced to 4V.
I have played around with the capacitor values and found that increasing the capacitors value attached to FB- managed to fix this issue... until I decided to apply a load.

When Applying a load of 470ohm (much less than the maximum load) the whole circuit's voltage drops significantly.

Any suggestions on how I could go about fixing this? I have been trying to get a stable +/- 15V for a around a month now to power an OP-Amp (OP-07x). Could applying only a resistance load make the circuit freak out? Do OP-amps have fancy circuitry inside that prevent this issue from arising in practice?

Thank you for your time everyone! :)


texts:
Does the sampling clock rise/fall times for ADCs matter, or they can be virtually 0 seconds? Can they be slow? In particular, I could not find anything about rise/fall time constrains for AD9235.

EDIT: (after reading the answer)
Given that the rise/fall times are not that crucial and the fact that sample and hold periods matter the most, please, correct me if I am wrong on the following:

According to the timing diagram below, the best time to start sample would be on the falling edge of the TRIG or CLK clocks because after first half cycle (when any of the clocks go high) the VIDEO signal is still not reset?

Currently, I drive the ADC with TRIG clock and sampling starts on the rising edge of the TRIG. Therefore, after half cycle of the TRIG when it goes low and the ADC switches to 'hold' state, the VIDEO signal is reset. This might not be enough time to charge the SHA capacitor?

EDIT2: added a sampling clock for ADC.
Which clock would be safer to drive the ADC with: SAMP or TRIG (SAMP is inverse of TRIG)?


texts: A question about digital transmission from a microcontroller

texts:
For a half km digital transmission I want to use RS485 protocol. I want to sample an analog voltage by an uC like arduino and send this data digitally for half km to a receiver. I want to poll/retrieve the data by sending a character to the uC via the RS485 protocol. So for instance if I send character 'D' it I will receive data. This is to synchronize with the other com port inputs.

But the uCs dont have RS485 interfaces.

My questions are:

1-) Is RS485 a good choice for such long distance?

2-) First thing came to my mind was a TTL to RS485 converter. Does anyone have experience with that? Or is there simpler or better way?

edit:

I might need more than 5 of this setup and I want to receive the data synchronous at the PC end. So not a single port. I'm not experienced whether a wireless or wired digital protocol suits more for this. Would polling data solve the synchronization latency issues?


texts: Input Protection Diodes Functioning with Circuit Breaker?

texts:
I was wondering if I was correct in assuming these diodes were being used for ESD protection on the input of a power circuit. I'm a little bit confused what the point of the diodes are when there's a circuit breaker before them too if anyone has any idea.

The breaker is rated at 5 amps which is less than the maximum rating of the diodes. The only thing I can think of is the diodes are handling up to a certain level of transient and if the transient becomes too large the circuit breaker will kick in and protect the diodes and obviously the rest of the circuit as well.

I know usually there is a resistor in this type of network from what I've read online but there doesn't seem to be one in this setup which I was also confused about.

simulate this circuit – Schematic created using CircuitLab


texts:
RAM (8KB, requires 13 bits A0-A12)
Start: 0110 0000 0101 0000 (6050h)
End:   1000 0000 0100 1111 (804Fh)

ROM1 (8KB, requires 13 bits A0-A12)
Start: 1000 0000 0101 0000 (8050h)
End:   1010 0000 0100 1111 (A04Fh)

ROM2 (8KB, requires 13 bits A0-A12)
Start: 1010 0000 0101 0000 (A050h)
End:   1100 0000 0101 0000 (C04Fh)

Above are the address maps. Now, how to design an address decoder when all of the 16 bits are changing?


texts:
Currently I am trying to connect my LCD to my laptop through a VGA connector. The LCD has 6 wires out of it which I am trying to solder to a VGA male connector, But the laptop doesn't detect the LCD. What is wrong?

I noticed that the laptop can detect other screen even if they are turned off (no power cable attached), so I think the trick is in the wiring.

What I want to know is how a PC detects the VGA monitor once its connected.
Does it send a signal that the monitor respond to?

My LCD 6-wires are labled [HOUT - ROUT - GOUT - BOUT - SYN - VC0].
I assumed ROUT, BOUT and GOUT are the RGB signals, SYN is the VSYNC and HOUT to be the HSYNC. (Not sure of that though).


texts: Power mux LTC4412HV not doing what I expect

texts:
I have created the following circuit:

Following are the variables:

VPOE: 12V supply
VEXT: external supply between 10VDC and 34VDC
VSWITCHED: any voltage between 10V and 36VDC that goes to the load.

My goal is that VPOE is always supplying all current to the load (VSWITCHED) in case it is present. As soon as VPOE is not present any more the load should be supplied by VEXT. This means:

VPOE smaller than say 10VDC --> Go to VEXT
VPOE larger than 10VDC --> Go to VPOE

From reading the datasheet I thought that whenever CTL is asserted high, the mosfet Q1 should switch off. This is not happening. The circuit only works when VPOE is about the same as VEXT, than VPOE is the only supply which feeds current to the load.
What am I missing?


texts: What is wrong with the MOSFET IRF540N ? Even with the zero gate voltage, why current is still flowing through drain to source?

texts:
Actually I was developing the overcurrent protection using op amp LM-358 as described in the second picture . I made the circuit as described on this link https://circuitdigest.com/electronic-circuits/overcurrent-protection-circuit-using-op-amp, But I am facing the problem that using comparator I am able to achieve about 0 Volt at gate of mosfet but still I can not switch off the load

I only performed the simulation , I have not done it practically


texts: How are opcodes decoded at hardware level in any controller?

texts:
I know that any compiler will convert human readable code to binary.
This binary code is a opcode which has instruction+operands in it.
I do not understand how this opcode is decoded at hardware level.
For example: If I have below line of code in C
a = 8;

Lets assume this is converted to assembly as below
mov a,#8h

Finally, the compiler has generated below opcode (I am not sure I have converted this opcode correctly)
74h 0xE0 8h

So my question is when we flash this code to flash of controller, how does the controller understand and perform only "a=8" and not a=b+c ?
I also wants to know how it differentiates between different peripherals like register,RAM ,counters or ports?
I came across some c programs where we refer these peripherals with some address (0xE0 for acc ,0x80 Port0) , but how controller fetches/outputs to that particular peripheral or a register bit which was referred in our code.


texts: Equivalent circuit composed entirely in NAND gates

texts:
Summary / Instructions

I was given this problem in a test paper:

Take this circuit

and make an equivalent one only with NAND gates.

The problem

I've tried, with multiple combinations but almost always the result is in this form:

X+X+X

Where it's supposed to be in this form X*X+X, the function of the above circuit.

NOT A AND NOT B AND C , ~A*~B + C (~ = NOT, * = AND, + = OR)

Statement

I know I'm not supposed to just throw the problem ( like asking others to get it solve ) but I'm feeling frustrated and I have a final exam soon and I know this kind of question will be in, any help is greatly appreciated.


texts: How does series parallel combination of LEDs affect the temperature rise?

texts: I was designing the LED light of 200 W with LED combination of 9 series / 8 parallel, each LED is 6V thus total output voltage is 56V. I am using Meanwell xlg 200 W driver. But this resulted in high temp rise and blinking of LED after some time. Does making an LED combination of 8 series / 9 parallel solve the problem without affecting light output?


texts: How can I modify this circuit for a higher gain?

texts:
Here is an image of an amplifier circuit.

How can I modify this for a 10-50 times more gain. I put a wire from pin 1 to 8, but I didn't get enough gain.


texts: MPLABX : How to Read/Write 4 bytes unsigned integer to EEPROM?

texts:
My question looks simple but still I lost my way to get the issue resolved. Discussion might show me the way.

I am using Pic16f877A microcontroller to write EEPROM using I2C ( 1 Byte at a time ). I need to write 4Bytes integer value (lets say 4284967295 ~ 0xFF67697F). I want to write this value to the EEPROM and Read this value from EEPROM whenever needed.
I am unable to find best possible ways to write/read this value.

I tried approaching following way :

unsigned int a = 4284967295;
unsigned int result1, result2, result3, result4;
result1 = (( a & 0x000000FF ) ); \\ result1 = 127
result2 = (( a & 0x0000FF00 ) ); \\ result2 = 26880
result3 = (( a & 0x00FF0000 ) ); \\ result3 = 6750208
result4 = (( a & 0xFF000000 ) ); \\ result4 = 4278190080

but lost the way.
And reference, link, and your guidance will be appreciated.

Thanks in advance!!!!!!!


texts: Determine Vt and k from given transfer characteristic

texts:
Hello there sorry to post an example like that but i am out of ideas can you tell me a way to figure it out i am always finding 2 unknown variables like

Id = k.(Vgs-Vt)^2


texts: Why can't I power a brushed DC motor from a powerbank?

texts:
Today, I've tried powering an 8520 coreless brushed 3-5V 0.15A DC motor from a 5V/1A power bank. The powerbank is unfortunately unspecified (its old and was originally a part of a company gift bag, so no receipt or model number, anything).
This is the PB's power management chip:

This is the bottom view of the same chip:

This here is the motor in question:

And this is how I connected the motor to the PB (I've tried both polarity directions).

The blue light indicates that the PB is on. I suspect a part of the circuitry checks whether the PB is completing a circuit and only then turns on the PB (no idea how that might work). When I short those two USB contacts with my finger, the blue light turns on for cca. 10 seconds and then turns off. When I connect a DC voltmeter, it shows 5V, as advertised, and the blue light stays on for cca. 10 more seconds after the circuit is broken, exactly the same as with my finger. When I connect the motor, however, it spins for a fraction of a second (jerks, more likely) and then immediately stops. The blue light turns off immediately as well.
I've tested the resistance of the motor at standstill and it turns out to be around 0.8 Ohms. The PB is nearly fully charged (very recently charged & corresponding to the LED charge-information lights, which are all on).
I possess a very, very surface-level knowledge about brushed DC motors (and electronics in general), so I've come here for advice. Could this be caused by some sort of mechanism protecting the batteries from a reverted voltage (such as the back electromotive force generated by the motor)? I've also tried connecting a smaller, similar motor (including a propeller, salvaged from an old RC plane, I have no information about it though except its visual properties), and it spun without issues (it has 6.2 Ohms at standstill). Maybe the missing core has something to do with it? Anyway, I'm at a loss. Can anyone give me any hints about what could be going wrong? Thank you very much.
EDIT: I've tested the motor on a cellphone 3.7V battery (no controller) and it runs fine. Keeps going until I break the circuit.


texts:
Will a PINMODE register in lpc2468 affect the status of an input pin i.e can we enable

an internal pull up for an input pin,or it is only possible for output pins.


texts: I'm working on a home automation setup and I'm trying to find the best way for the system to know when I'm home. A motion sensor won't work because my wife or my dogs may be home when I'm not. The two things I almost always carry with me are my keys and my cell phone and I liked this solution which pings the phone to see if it has joined the home wifi network. The only problem is that my phone goes to sleep very quickly when not used. This would make it good at detecting when I get home (if I just wake the phone for a few seconds on entering), but not when I leave. My other thought would be a bluetooth tag on my keys with a reader near the door, but how could it tell arriving from leaving? Anyone have any suggestions?


texts: thevenin equivalence of wheatstone bridge load

texts:
I'm trying to figure out the Thevenin equivalent as seen from the load of a wheatstone bridge... however, I think the model example in the book is wrong:

Here's what the book has to say:

Here's my work:

Which is the right answer?


texts:
the MAX856 says it has a low-battery indicaitor. My setup has a single 3.7v nominal LiPo pouch and I want it to trigger the low-battery at 3.4V.

Datasheet: https://datasheets.maximintegrated.com/en/ds/MAX856-MAX859.pdf

Does this mean that I should take my battery + terminal, put it through a resistive divider and choose the resistors such that 3.4V at BAT+ gives 1.25V at the resisitve divider output ?


texts:
In a simple inverting amplifier I've seen the below topology in my text book, where R3 is said to be R3=R1||R2.

However, every time I see this, all three resistors are the same values!  From Forest Mims, to op-amp app-notes.
When I run the simulations in LT-Spice the equal value version has the lowest Vos, followed by R3 = R1||R2 followed by direct connection to ground.

So my question(s) are:

Why use this topology instead of a simple follower (no resistors), when the op-amp is unity gain stable.
All the academic texts say to use the parallel equation for the value of R3, but I never see it in the wild. Why?


texts: Electric speed controller (ESC) interruption with FET

texts:
I would like to develop power distribution board for quadcopters. One of the task of this board is to interrupt power from battery going to ESC when the copter sleeps. The battery will never unplugged from this board.

There are 4x 40 A ESCs, so theoretically the maximum current will about 150 - 200 A. But probably it will use much less, the hovering amperage is about 20 - 30 A. Moreover, the battery will provide power only for some minutes (~5000 mAh).

I choosed two NFETs (NVMTS0D4N04CL) with Rds = 0.3 mohm, the maximum dissipation will be 5-6 W. Probably these FETs do it without heatsink. The size, weight and reliability are extremely important.

In the default state the FETs are pulled high with resistor (in case of program or microprocessor failure).

I designed two solutions:
SOLUTION A: The FETs are controlled by  VOM617A optocoupler with 2N7002-7. With these elements the two FETs are pulled low and turn off when the NFET_EN is high.

SOLUTION B: The two FETs are turned off with CPC1117N solid state relay when the NFET_EN is high.

In both cases the purpose of the  zener diode is limiting the voltage going to gate when the circuit is powered from more than 20V (5S or 6S battery). Each FETs has one flyback D1 and D2 diode.

My questions:
Do both circuits work?
Which one is better solution?
Is there any difference in reliability of two circuits?
Are diodes D1 and D2 required? I guess the ESC already has many of these.
Is there anything that can I improve in this circuit?


texts:
simulate this circuit – Schematic created using CircuitLab

I'm having trouble getting these motors work. sometimes they work fine and sometimes they just run without giving any gate pulse at all. Is there something im missing in the circuit?.
The same circuit works perfectly when only one motor is connected. but sometimes the circuit works perfectly all of sudden even with both the motors. what can be cause of this behavior...
How can i make it a solid circuit for my project.


texts: Can FOC be done with only one PID controller and a lookup-table that determines phase-offset?

texts:
Normally two PIDs are used to do torque-control with FOC -- one for the direct torque and one for quadrature torque.
The reason for this is described here:
Why are two PID controllers needed for FOC (Field Oriented Control)?
Assume that I characterised a particular motor so that for any given speed and torque (as measured by current and speed sensors) the ideal phase-offset was known (or interpolated) by a lookup table.
If I used this lookup table combined with sensors for rotor-position, torque, and speed, would I be able to dispense with the second PID loop and only use one for determining the quadrature (torque) force?
I believe this question is equivalent to asking whether the phase-offset depends on anything other than the speed and measured current.  If there's no other forces that might affect the phase-angle, then the PID for direct torque can be removed.


texts: Why is input impedance matching done for amplifiers?

texts:
I am trying to design a single transistor RF power amplifier. For a single transistor amplifier, the voltage at the base/gate of the transistor determines the current through the transistor and ultimately the output power. Then why is power input to the transistor maximized by impedance matching. Why can't impedance bridging be done to increase the voltage at the gate/base of the transistor and hence increase the collector/drain current?

Edit: If your answer is maximum power transfer, I dont understand how impedance matching ensures maximum power transfer. I understand that impedance matching ensures that maximum power enters the transistor but the transistor is not a power amplifier. It is usually a transconductor or a voltage amplifier. How does the output power maximize when the input power is maximized?

Edit again: I realized that this question Why do we care about matching the input impedance of receiving RF amps? is very similar to the one I am asking. The accepted answer there is that maximizing the power input to the amplifier through impedance matching increases the SNR of the input signal thereby increasing the SNR of the output signal too. Is the same argument applicable here too? Is maintaining the SNR of the signal the sole reason to maximize the input power to the amplifier by impedance matching?


texts: Expected peak-to-peak output voltage of satellite LNB

texts:
Anyone know what the output voltage of a typical DirecTV LNB might be?
I've converted an old dish to be a backyard radio telescope and I'm hoping to record output levels with a USB oscilloscope, as I find the results of using an SDR dongle to be less than optimal.
Thanks!


texts: Charging 12v batteries with direct connection to 20v solar panels

texts:
I want to charge a 12v Sealed Lead Acid car battery off of a solar panel (20v) and then draw about 10-20W of power from it via an inverter (the load).

I'm wondering if its okay to connect it together like this:

And what downsides, if any, are there and can I avoid them? Is it a problem hooking up the battery to solar panel without a load?

Thanks!


texts:
This spice file

.include ntyp.md
.include ptyp.md

vvdd VDD GND_ 5
vgnd GND_ 0 0

vin IN GND_ pwl(0 0 100n 0 101n 5 200n 5 201n 0 300n 0 301n 5 400n 5)
.tran 1p 400n
.print tran v(IN) v(OUT)

M1 OUT IN GND_ GND_ EN l=5e-07 w=1.2e-06  $ (44 7.4 44.5 8.6)
M2 OUT IN VDD VDD EP l=5e-07 w=2.4e-06  $ (44 12.1 44.5 14.5)

gives the error unknown parameter ($) when I run it locally. I've tried this on AIM-spice and LTspice. However, when another person runs the same code on another computer it doesn't give this error. ntyp.md & ptype.md are located in the same folder as the spice file. I also tried an absolute path to no avail.

What am I doing wrong?


texts: Metastability Deserialization and clock crossing domain

texts:
I have a question on metastability and clock crossing domain.
I need to deserialize a bitstream out of an ADC.
TXCLK, TXOUT1, INCLK are the outputs of the ADC.
So the idea was to register the DATA TXOUT1 on a shift register clocked by TXCLK then capture the parralelized data on every rising edge of INCLK and then write the captured data on an asynchronous FIFO (two independent clocks).
My problem is that the module SHIFT REGISTER is clocked on TXCLK and the module CAPTURE is clocked on INCLK.
INCLK is way slower than TXCLK and i don't know if i will face metastability problems crossing from a fast clock domain (TXCLK) to a slow clock domain (INCLK)


texts:
Just to give a little back ground on the project - I am currently building a buck converter linked up to 2 * 250W solar panels in parallel, then use an MPPT algorithum to track the max power.  I will be using a TI Stellaris microcontroller to control the PWM, and will be using a synchronous buck topology with possibly a multiphase design to reduce the current through each mosfet (as well as lower output ripple).

The question relates to which is the best frequency to use for a buck converter?
How to determine the best frequency?

I have experimented with 15-24kHz on a synchronous buck circuit already, and am aware most smps designs use 50kHz and upwards.
My aim is to make the system as efficient as possible, and I seem to remember reading somewhere that lower PWM frequencies are more efficient, but cannot seem to find any literature on this after extensive searches online.

Any input would be appreciated, and if there is source information you can point me to even better.


texts:
I am working on determining the specs needed for an induction heater I plan on buying or building. However, I’m having trouble calculating the potential current draw and wattage needed for my application.

The use will be for brazing copper to brass with silver solder. The melting point is around 1200 F. The copper is a 3” diameter hollow pipe with about 0.079 wall thickness. And the brass is about 0.5” thick and a 5” diameter.

I understand the resistivity of copper to be 1.7*10^-8. But with that value I am coming with extremely small numbers for resistance of my target hearing area and it just doesn’t seem correct.

How can I accurately determine my power and current needs for this application. The plan is to use 48VDC supply but that can be changed.


texts: Help me find the device based on its label

texts:
I have an SMD component containing two pads (probably in a SMC case). There is a label on the surface of the component: fAC15 in one row and MP in second row.
I suppose the component is a Transient Voltage Suppression (TVS) diode.
Am I right?

Thank you very much for your time and effort to help me.

Sincerely,

Bojan


texts: Help me decode this mechanical drawing of an SD card PCB layout

texts:
I'm trying to understand this mechanical drawing so I can create a layout for it in gEDA PCB.

Specifically on page 4. I've already managed to place GND 1 and GND 2; those were fairly simple to work out. But GND 3 confuses me, because it's apparent from close inspection of the drawing that it doesn't quite line up with GND 1 and the offset doesn't appear to be given. The same is true for GND 4 which doesn't quite line up.

Also on a semi-related note it is unclear whether the pins are in the order as they are on the SD card or if they are numbered arbitrarily - that is, does pin 1 correspond to pin 1 on the SD card?

While this isn't strictly electronics, I think it passes as an appropriate question because it is an electronic connector and it requires a PCB layout.


texts: Does the current supplied to the load doubles when the voltage is doubled

texts:
Let's say that the load is connected to a 12V battery consumes 3A current. When the 12V battery is replaced with 24V battery causes 6A current flow for the same load.

I'm just trying to understand if the load consumes only the required amps from the source battery regardless of the voltage of the battery or does the change in voltage has direct impact on current flowing through the load


texts: connect computer to magnetic exercise bike

texts:
I recently bought a york 3350 exercise bike.

I would like to get more information out of the system than is currently displayed in the console (totals etc, so info that can be obtained from the current system).

The online manual is here (poor images, sorry).

I was hoping it might be possible to use the cable connections that are current on the bike.  I.e. where it connects from the front post to the console there is a connection, could I get a cable that would go into that,  split into two, one for the computer and one for the console.  This would hopefully mean I would still be able to use the console to use the bike at all times, just as before.  I would also be able to, (in a read only fashion, at least), get the information into the computer to read out the results as they are created.

As I side note, I am a C# (.net) developer, not sure what other language I would need, assembly / c / C++?

Regards

back of console where it connects.

back of console where it connects.

cable that goes into back of console

join in cable between base unit and front stem to console

join in cable between base unit and front stem to console opened.


texts: Input clock of a Direct Digital Synthesizer

texts:
I need to create a circuit based around one of Analog Digital DDSs (AD9102) to create a sinusoidal signal at 150kHz. For this purpose I think that a clock line at around 10MHz would be sufficient. I don't fully understand how the input clock works. By looking at the component's datasheet (@pag 20/36, CLOCK INPUT) I can see there are multiple possibilities for driving the chip. There are few things I don't fully comprehend.

When they say "In applications where the analog output signals are at low frequencies, the AD9102 clock input can be driven with a single-ended CMOS signal". What do they mean by "low frequency"? Is 150kHz considered a low frequency output signal, or they mean something more like 100Hz signals?
If solution 1 is not suitable for my case, I'd need to use a differential signal for the clock distribution. Let's suppose I will use the solution that includes the LVDS driver, what do they mean by CLK+ and CLK- (input signals of the AD9515 driver)? Assuming CLK+ is a 50% duty cycle squarewave @10MHz, does that mean CLK- is a 90° shifted version of CLK+ signal?
If this is the case, why can't I simply put these signals into the CLKP and CLKN inputs, in order to avoid the use of the driver?

Hopefully everything makes sense! Thanks for the responses.


texts: Need help with power supply in my project

texts:
I am a mechanical engineer.
I need some help with my project
I am building a water sampling device that has 11 solenoid valves and a vacuum pump to distribute water to various containers on the device.
I have a single battery, and a microprocessor (Arduino).
I am not sure how to do the wiring here.
How can I supply power to all the 11 solenoid valves and still control the valves using an Arduino.
Thanks for the help.


texts:
I need to use a LM7809 to reduce 12-14V to 9V  , the device is using 40mA at normal state
when I search google for application circuit -  I got all kind of valus for Cin , Cout.   use this datasheet
LM78xx datasheets
I saw in page 22 to use 0.33uF and 0.1uF - so can I use this ?
what is the thumb rule for it? and what is the formula I need to use?
Thanks ,


texts: Constant current LED driver min / max current rating explanation

texts:
I currently have a 150-1500mA led driver that I sue to power a 30W LED. Driver has adjustable maximum current pins that I can use to change to match the maximum current. I have it set to 1050mA.

I am now considering another driver. Looking into Meanwell LDD-350L datasheet there is this line at the top of the first page:

  constant current output: 300mA to 700mA.

This confused me since what use is PWM dimming if you cannot get the full range of values? My current driver has minimum of 150mA but I am able to PWM the LED at very low levels, certainly below 150mA unless the driver is using up the remainder of the power.

How does min / max current specification work in constant current drivers?

Edit:

To add to the answer already accepted, the reason why my current LED driver was rated 150-1500mA is that it has max current select jumpers with 150mA being the smallest selection.


texts:
I have this circuit and I must represent it in state space. I know the process because I have done similar ones but having trouble with this one. I have found the Kirchhoff equations for the 2 loops and for the upper junction, whatever I do after that I can't end up with two equations x'1 and x'2.

First loop: V(t)=V(R1)+V(c1)+V(R2)
Second loop: V(R3)+V(c2)=V(R2)+V(c1)
Junction: i(t)=i(R3)+i(c1) or i(t)=i(c2)+i(R2) => i(c1)=i(R3)+i(t) and i(c2)=i(R2)+i(t)

I know that V(C1)=x1 ,and V(c2)=x2 and i(c1)=c1*x'1 , i(c2)=c2*x'2

Whatever replacements I cant find X'1=V(c1)+V(C2)+V(t) and X'2=V(C1)+V(C2)+V(t)


texts: I lost the remote of an RC helicopter. I want to make a remote and know about the circuit. I am searching for this component which has three legs beside the LED in the pic. Would someone help me determine what it is?


texts: How does this continuity/mains tester work?

texts:
Many years ago I bought a multi-function testing screwdriver, the instruction sheet (which I have mislaid) claimed you could use it for a surprising number of tasks:

Continuity of fuses
Mains voltage present (barrel marked "70-240V" and, amusingly,  "CE")
Locating a conductor break inside a mains-lead
Checking your microwave oven for microwave leakage

If you hold the blade and place the top near a wall it lights up near buried 230V wiring
(e.g. for light switches) but isn't very reliable.
If you touch the blade to an earthed condcutor (e.g. radiator or water-pipes) and press your finger on the metal cap, it lights up.
I took it apart, there is a 3-pin device in a TO-92 package labelled
   KSP
    13
  -135

I guess this is some sort of transistor.
There is also what seems to be a very high value resistor (too high for my cheap multimeter to measure)
Inside the capsule are also a LED, a small resistor and two small button batteries.
Here are some photos

Surprisingly, it still works after I reassembled it.
I don't use it to test for 230VAC (I plan to get a non-contact tester for that)
I assume it relies somehow on AC and human capacitative coupling to earth? How does it work?


texts: Operation of BJT with low values of Vbe ("cutoff" region)

texts:
Many sources claim that when the base-emitter voltage becomes smaller than approximately 0.6V-0.7V, the bipolar junction transistor goes in the cutoff region and there is zero base and collector current.

Of course this is not completely true, since there will be some (exponentially decreasing) current for lower values of Vbe, and this exhibits the characteristics of diodes operated at low voltage (with an exponential I-V characteristic).

Does the Ebers-Moll model accurately predict the behavior of the BJT in cases where Vbe is so small that the base current becomes on the order of pA (10e-12 A)? In general there is a current gain parameter called beta ~ 5 - 100 which relates the collector current to the base current, but does this beta decrease if the base current becomes extremely small?

I am asking this because I have a particular application where I need extremely low currents, and I am not sure if the simulator (Cadence Spectre with foundry-provided npn models) is reliable in this unusual region of operation. I know that it uses the Gummel-Poon integral charge model, but this should be close to the Ebers-Moll model at low currents, I expect.


texts:
I was trying to calculate the voltage drop of a copper wire due to its length,
given that it has a fixed size and it transmits DC current.
Anyway when trying to calculate it with one of this online-calculators,
it asks me about a load current.  The voltage drop seems to vary dramatically in relation to this paramenter but I still haven't completely understood its menaning.
I know what an electrical load is : an electrical component that consumes electric power", but I couldn't find a detailed explanation for what a load current is.


texts: How do the open loop voltage gain and closed loop voltage gain differ?

texts: The closed-loop gain of op-amp is calculated by the ratio of Vout/Vin. What about the open-loop gain? How does the value of open-loop gain and closed-loop gain affect the performance of op-amp ? What is the relationship between open-loop and closed-loop gain of op-amp?


texts:
I was wondering about refresh management (RFM) in DDR5.
The JEDEC DDR5 standard says that RFM can be controlled via the MR58 OP[0] Register (0 = RFM not required, 1 = RFM required). It also says that periods of high DDR5 DRAM activity may require additional refresh commands, which suggests that the value in the MR58 OP[0] register is changed at run time (e.g., by the DRAM chip itself or the memory controller).
Is this correct, or is MR58 OP[0] only set during manufacturing (i.e., indicates whether a DRAM DIMM supports RFM) and then not changed anymore?


texts: Finding ground in a battery powered circuit?

texts:
I don't know if this is an obvious question.  I'm powering my circuit (that's used to amplify an EKG signal) by a ±5V battery supply, the amplifier I'm using the ina129 needs a voltage reference that's midway between my voltage supplies.

I considered using a simple voltage divider circuit but found that it becomes unbalanced. Could I use something like the Texas Instruments virtual ground splitter (tle2426) or does it only work for positive voltage supplies?


texts: How to design the footprint when the pin positions are slightly different for each part?

texts:
I'm a beginner of electronics. I have several IN-12A nixie tubes. I want to mount the nixie tube on the PCB. However, the position of the pin in the datasheet is out of the position of the pin in the nixie tube.

Also, since the pins are slightly twisted with each other, adjusting the library to one nixie tube can cause problems when replacing nixie tubes. How do I arrange holes to design a library that fits all IN-12A Nixie tubes?(I use the pins of D'SUB instead of Nixie Socket.)


texts: IR2110 Simulation not working in LTSPICE

texts:
I am trying to implement a half bridge topology as shown in the figure below:

I have replaced the IRF450 with STGW40H60DLFB IGBT.
I have also replaced the 11DF4 with UF4007.
My LTSPICE schematic looks like:

My VDS and VGS in the high side and low side is:

When I run my LTSPICE simulation with a pulse with 100K frequency, I get:

I can't spot a error in my LTSPICE, please let me know if you have any idea what it might be.
MODEL Used for UF4007:
.MODEL UF4007 D N=3.97671 IS=3.28772u RS=0.149734 EG=1.11 XTI=3 CJO=2.92655E-011 VJ=0.851862 M=0.334552 FC=0.5 TT=1.84973E-007 BV=1000 IBV=0.2 Iave=1 Vpk=1000 type=silicon

Spice Model for IR2100 was downloaded from:
https://www.infineon.com/cms/en/product/power/gate-driver-ics/ir2110/
Spice Model for STGW40H60DLFB  was downloaded from:
https://www.digikey.be/product-detail/en/stmicroelectronics/STGW40H60DLFB/497-14364-ND/4696260


texts: Identify dead component in notebook battery

texts:
Battery name is GARDA31, based on bq29330 and bq8030.

Most probably I killed it myself when soldering by shorting terminals with solder wire :( Controller is alive (communicates through SMbus), but shows "critical" and 0% charge in the OS.

The marking seems to be

R005
FZ81

but I am not sure in first 0 as the defect is exactly in its place.

It has relation to the - terminal of battery. I would think it is a current sense resistor Rsns (see circuit diagram of page 4 of datasheet), but my colleague says that it does not look like resistor but rather like semiconductor; I measured it to be a short (voltage is 0 across it and Ohmmeter shows the shortage), and if it would be a current sense resistor then battery would start or/and catch fire?

Battery pack was replaced and is fully charged.

I have another battery controller with current sense resistors, and they really look differently:

I did not desolder the battery pack yet, seems will have to do it to perform signal tracing.

Update:

I removed the batt pack, and desoldered the device. It appeared to have two terminals. Also found out that fuse is blown - and that's why there's no further damage.

This "resistor" is going to the notebook battery connector. I can not trace it more precisely because I have no datasheet for bq8030.

Update 1:

I shorted the fuse with solder (expected to melt in case of emergency), and replaced defective current sense resistor with two R010 resistors in parallel.

No change. OS still says 0%, and "Online, Critical". There's something else, up to gas gauge chip's firmware defecting the assembly because it thinks pack is damaged.


texts: Capacitor in series with capacitors in parallel?

texts:
What is the equivalent capacitor when identical capaoacitors are combined in series and in parallel unevenly, like shown in the diagram.
Is it all the same as capacitance i.e just divide ESR of parallel caps and add all series ESR and voltage ratings, the position of the single, higher ESR cap makes no difference?


texts: Voltage scaling of analog signal -10 to +10V to 0 to 3V inorder to give it as input to ADC using opamp TL082 and TL431

texts:
I have a sensor which gives an  output of -10 to +10V, I need to scale down it to 0 to 3V in order to give it as input to ADC of microcontroller.

I have opamp TL082 and TL431. I have attached a reference circuit as well, but when I simulate I get wrong output. Please share your ideas, what do I need to change in the circuit.

Simulation of the model in Ti tina software.

Vin = 5v (sine)
Vref= 1.5v (sine)
vout= 3.66v


texts:
So I live off grid and have a 12v solar system with an array of batteries and a 12v 45amp MPPT controler. I also have a 1000w inverter for things such as powering my laptop and things.

I have recently bought a fridge however I am having some issues powering the device as when the compressor starts it will surge at around 750w. My MPPT controller does not go this high (and I have not been able to find any that will) and so the compressor will not start correctly and just make clicking noises while the inverter complains that it does not have enough power.

I have tried removing the MPPT from the circuit and just having the batteries go directly to the inverter which seems to work fine however it means I will have no undercurrent control over the batteries. Ideally I would like everything to go though the MPPT controller.

I am looking into soft start devices such as this one to slow the start up draw of the compressor however I am not sure if this will allow the compressor to start correctly.

I was wondering if anyone has any ideas or solutions to to this problem.

Thanks!


texts: What is the purpose of carbon brushes in an electric motor

texts:
I just took apart our washing machine to replace the carbon brushes.

Was wondering why the machine stopped working when the brushes were worn down?

Also if the engine makes a wuring noise after you put it together, does that mean that the brushes have been put in the wrong way?


texts: Proper PCB grounding with several general purpose ICs

texts:
I'm designing a general purpose Arduino shield pcb and right now I'm struggling to find a proper ground layout.

ICs on the board: 12->5V and 12->10V @5A switching DCregulators, several H-Bridge motor drivers (rated at a max 1.8A), a TEC driver (rated at max 3-6A ),a pair of octal-switch SPST, a pair of shift registers and a DAC among some op-amps, FETs and BJTs.

I'm following Ott's guide for grounding mixed signal pcbs. I've got the basics down, but the main issue is that the TEC driver's datasheets implies the existence of a Power Ground on the PCB and considering all the large currents flowing out of the DC regulators, I realize it can be quite relevant. I'm also not sure if the motor drivers should be part of this power ground plane (the 10V rail is supposed to power DC motors driven by the H-Bridges).

My questions: are the digital ICs (Shift registers, SPST switches, digital side of the DAC) really that noise sensitive that a noisy ground would compromise their behaviour? (I suspect only the DAC). If that was not the case, I could just use a common Digital/Power ground.

I'm considering a power ground (DC regulators, Motor drivers) with two bridges: to digital ground (SRs, Switches) to an analog ground (TEC driver), and additionall a bridge between the digital ground and a second analog ground (with the DAC and analog input pins). Would there be any ground loops with such a configuration?


texts:
This is my first electronics project, I'm really new at this and struggling to understand everything, just learned so solder a few days ago.. :)

I'm using this circuit as my starting point

I'm using a 12V power supply, and a 12V LED strip. Instead of TIP31 I have TIP35 (guys at my local electronics shop said that in my case they don't really make a difference..)

I hooked up the schematic but I had problems with audio output splitting, not enough was passed to the TIP35, so I added an amp circuit with LM386 something like this

Having read that powering the LM386 with 12V results in heat and stuff, I wanted to be safe(er) and I'm passing 5V to it with a TO220 regulator that drops 12v to 5v. I'm not using the Gain pins, because I noticed that it doesn't influence brightness, only the "sensitivity", and the LEDs would flash to the smallest sounds (which is not what I want). So I'm passing ~70% volume and amplifying that, so my LEDs react to more lower sounds.

The problem I am facing is that the LEDs do not blink at full brightness. That was the problem I had without having the amp in, I though that might help but it doesn't. The LEDs I believe never reach ~60-70% of brightness compared to just passing 12v and having them on. I thought it might have to do with the length of the strip (5 meters), I cut it down to just a 9 LED length strip - same result with low brightness.

I've stumbled across this pdf  that shows different pins for input/ground/output. I've hooked up in this order: input/output/ground while this pdf ground/input/output. Could that have anything to do with it?..

I'm sorry for the newb questions - I am one..

Edit: Here is how I've connected everything (sorry if it's messy..)

Oops I messed up the colors of the output to the LEDs, they should be switched (blue-red, red-blue)


texts:
I want to build a DIY RFID reading system that can read a wide surface area. My idea is to connect one single PN532 chip with multiple RFID antenna using multiplexing.
The antenna must be as thin as possible and flexible.

After after having removed the IC from a RFID sticker, can the sticker coil be used as a RFID reader antenna? Is there another cheap way to build 10 to 20 RFID reader antenna?


texts: How do single-phase inverters know if they're in sync with the grid after they're in parallel?

texts:
How can one inverter, once its output is already in parallel with the grid, measure the phase difference between the grid and itself?

Any current or the variation in the current flowing on its output could happen due to the load on the grid, once its impedance varies erratically (different things being turned on and off, not to mention equipment that changes its impedance by itself).

Also, a variation in its output current could also happen due to a voltage mismatch rather than a phase mismatch.

So, how does it measure that? More specifically: Is there a simple solution for it that doesn't require computing?

I've come to a solution, but its quite complicated (although completely feasible): An inverter that, after first synchronizing and paralleling to the grid, works like an FM voltage source, and uses something like a lock-in amplifier to measure variations in the output current that happen with a known frequency (due to the FM modulation).

In this FM voltage source, the carrier signal would have the same frequency as the grid (like 60 Hz) and a modulating signal of much lower frequency and low amplitude (causing the carrier signal to vary just a little bit around 60 Hz, like +-0.01Hz, and with a low frequency, like 3 Hz).

Considering that the inverter and the grid are in phase at the very "middle point" of the modulation cycle, then the output current will have have 2 variation cycles per modulation cycle: It will have a minimum each time the modulation is at the middle point and a maximum each time the modulation is at a extremum.

Note that these current variation cycles I'm talking about are the variations caused by the effects of this modulation, and once they happen at a known and low frequency (much lower than the grid), you can measure the current and use something like a lock-in ampifier to amplify only these variations and filter out the rest.

The filtered measurements can then tell how much it is deviating from the grid. If, for example, the inverter is not in phase with the grid at the middle point but in another point inside the modulation cycle, the 2 current "variation cycles" that happen at each modulation cycle will have different amplitudes and lengths (one will be shorter and lower than the other).

And if they're not in phase at any point, then there will be a single current variation cycle per modulation cycle: A minimum when the inverter is closer to be in phase with the grid and a maximum when it's farther from being in phase.

The inverter can also use that to deduce if the grid is down (as it would suddenly be no longer in phase in any point of the modulation, without first deviating from the middle point).

But I find this way quite complicated. Is there any other, simpler way?


texts: What is the difference between RS-232 and RS-232-C?

texts:
I know about RS-232. Later, I heard about RS-232-C.

Are these two standards the same or not?
If not, what are the differences?


texts: MII/GMII switch for 10/100 Mbps vs 1Gbps

texts:
The lack of search results I've got so far suggests that I have a fundamental misconception here, but: for a PHY with a MII/GMII interface such as the KSZ9031MNX, how does the MAC decide whether to use MII or GMII signaling?
Should I wait for the PHY to signal that autonegotiation is complete, then read PHY status registers and reconfigure accordingly, or is there a more direct method?


texts: Design 1-Wire slave device to get the state of a switch

texts:
I have an MCB (Miniature Circuit Breaker) whose state has to be communicated over 1-Wire. I can get the MCB state as 0/5V signal. How can I develop this to act as a 1-Wire Slave device so that it can communicate with a 1-Wire Master device?
Please give me some hints/guidelines as to how to achieve my goal.
EDIT 1
I have previously done communication over 1-wire by interfacing a 1-wire temperature sensor with an Arduino. But my requirement is to design a 1-wire switch state monitor device which can act as a 1-Wire slave.
EDIT 2
I am looking for something like a small uP so that I can connect HIGH/LOW input to it and the uP then transmits it to the 1-Wire bus. I am looking for this kind of solution. Only READ operation has to be supported. I cannot use an Arduino as a slave due to cost constraints. There will be 5-8 MCBs whose statuses have to be recorded.


texts:
What options do I have for isolating the input and output of a switch-mode power supply?

I think one method could be to use a transformer.

I have read that many SMPS designs use a high-frequency transformer. What does this mean, and does this provide isolation?


texts: MOSFETs Gate Driver: Current drawn from the Power Supply

texts:
I'm going to use a L6491 High voltage high and low-side 4 A gate driver  to drive a half bridge made from two IPW65R019C7.
I'm going to use a +15V to supply the L6491 MOSFET Driver.

How can I have an idea about the current drawn by the L6491 from the +15 power supply?

I don't know exacly which is the parameter on the datasheet which gives me this infomation. Is it the supply current Is, Sourcing Output Current ISrc or the Sinking Output Current ISNK?

Thank You.


texts: Change resistance value after starting a circuit

texts:
I am trying to build a simple LED blinker as a nightlight for my son's bedroom, based on this circuit.

But my knowledge of electronics is basic at best. This circuit has a 10k pot that was supposed to control the blinking speed, but for some reason I don't understand it has to go to 0 to start the blinking. After that, I can turn it to the maximum value to get the slow steady fading I wanted.

But I don't want to have to turn a potentiometer manually every time the circuit starts. I'm sure there's a way to make this happen automatically using a capacitor somewhere, but as I said I'm not good enough to figure that out by myself.

Edit to add: Tried changing one of the 10k resistors (I actually put a potentiometer there to try several different resistances) but didn't work. I also tried changing one of the capacitors by a 33uF one, and then a 470uF one. The circuit simply doesn't start if I don't turn VR1 to 0.

Edit 2: I didn't have access to the CS9013 transistors, so I used a S9014 instead( the datasheets seemed similar enough for me) Also, for testing purposes I'm using a 9V power source instead of a battery.


texts: Push to talk (PTT) to Bluetooth intercom system

texts:
I want to build a push to talk button or a workaround for similar implementation to an existing Bluetooth intercom system. It is a Bluetooth headset from Schuberth (SC1M) at one end and a Pelstor intercom system at the other end. Obviously they both connect using Bluetooth and are powered using batteries built into them.
Basically, I want an implementation in which the Bluetooth headset can always hear from the intercom system and I should be able to transmit audio from Bluetooth headset to the intercom system only when I want.
I know that push to talk button enables audio output when the button is pressed and the circuit is broken when the button is left which disables audio transmission.
How to implement something similar in a Bluetooth intercom system. I have seen Bluetooth PTT switches available in the market but I am not sure how these are implemented.
Any ideas will be appreciated.


texts:
Given the following circuit,

I need to redraw it as a Series Shunt feedback amplifier, i.e. with the following topology:

Identifying the AC equivalent circuit seems to be easy: 12V and -12V become GND and current generator turns into an open circuit. However I have troubles identifying the amplifier net and the feedback net and the series shunt topology. Could you help me redrawing the circuit?


texts: Need help with selecting an antenna for PCB

texts:
I have designed a pair of circuits which utilize the QAM-TX2-433/QAM-RX2-433 transmitter/receiver.
So far everything is hooked up on solderless breadboards, with just a length of wire for antennas.
The next stage is to design PCBs for these circuits and to find an appropriate antenna to extend the communication range. As I learned in the past few hours, antenna design is a very complex field. I am not trying to understand the subject in depth, but I would really appreciate answers to a few questions that I feel are crucial to my understanding, however vague it might be.

My understanding is that antennas require a closed circuit from the RF signal to ground in order to work. This connection is made wirelessly through EM radiation. So, in case of just a wire hanging in the air, the circuit is inefficiently closed to the ground terminal of my battery, which is why a wire antenna can transmit at all. Is this correct?

In order to increase the efficiency of an antenna, a ground plane larger than lambda/4 is required. On a PCB, this ground plane can take the shape of a large conductive area connected to the ground terminal. Correct?

For 433MHz, \$\lambda/4 = 17cm\$. However, this length can be shortened by providing an inductor in series with the antenna. A helix antenna combines the antenna and the inductor in one length of wire, so it seems like a very good choice for my project. I am looking at this part here: PHC-M4-433.
Would you agree that this is an appropriate antenna to try?

I also found this antenna: ANT-433-HETH, but I do not understand how to use it. It is really attractive for its size - it looks like I could put this one inside my plastic case and hide it entirely. But why does it have 2 connection points? What do I connect the other end to?

Is there any reference material available that can explain to me exactly how to lay out the ground plane on my PCB, and where the antenna is supposed to be in relation to the ground plane? For example, should the antenna be centered above the ground plane?

It is also possible to make an antenna with a long trace on the PCB. Would this trace have to be 17cm long? What happens if I put it into a spiral to fit on a small PCB? Where does the ground plane go in this case?

I know that these are fairly broad questions, so I am mostly looking for practical advice on some of the options available to me for this project.


texts:
I'm working on a Microblaze-based system.  I'm using FSL to shuttle data directly from an AC'97 controller core to my custom DSP core.  The FSL buses are clocked at the 125MHz system clock. The DSP components have been designed with a 48kHz clock in mind (the codec sampling rate).

How do I go about clocking the samples through the DSP components at 48kHz?

FSL bus is essentially a FIFO, that signals when data is available for the slave to read.  Through some experimentation, I'm seeing samples arrive at approximately 48 kHz (I was using a timer interrupt in the uBlaze to monitor this, hence the "approximately").  Is there any way I can generate a sane "clock" from this fact, and also allow XST to understand the timing requirements of what I'm doing?


texts: Daisy-chaining two ADC with SPI protocol

texts:
I'm trying to configure and read two ADCs (MAX11156) with a RaspberryPi. The ADCs are daisy-chained together. For the communication, I'm using python code with the spidev library. The driver is properly installed and SPI0 is enabled. However, the received data doesn't make sense to me at all and I'm trying to figure out, whether it's a software or a hardware issue.
The data I have received, resembles what I measured with an oscilloscope. Having nothing connected to the analog input, I receive following raw bytes for a period of 10 samples:
[63, 255, 0, 0, 0]      decoded: -2.0481V -4.0960V
[192, 1, 63, 255, 255]  decoded: 2.0481V 4.0960V
[192, 1, 63, 255, 255]  decoded: 2.0481V 4.0960V
[192, 0, 31, 255, 255]  decoded: 2.0480V -0.0000V
[63, 255, 32, 0, 0]     decoded: -2.0481V 0.0000V
[63, 253, 224, 0, 0]    decoded: -2.0483V 0.0000V
[63, 254, 0, 0, 0]      decoded: -2.0482V -4.0960V
[192, 3, 223, 255, 255] decoded: 2.0485V -0.0000V
[192, 3, 31, 255, 255]  decoded: 2.0484V -0.0000V
[192, 3, 223, 255, 255] decoded: 2.0485V -0.0000V

For the configuration, I'm sending two times the same configuration byte (1,0,0,0,0,0,0,0).

After configuration I give the ADCs some time to convert. To read the data, I'm transferring 5 bytes of 255 (since the register is expecting a logic high during transmission). I'm expecting 5 bytes, since the ADCs have a 18bit resolution, so 36 bits in total. The last 4 bits are ignored.

This is my code:
import time
import spidev

def configuration(b7,b6,b5,b4,b3,b2,b1,b0):
    msg = (b7 << 1)  + b6   #first  2 bits: 10 - MODE: Daisy-Chain Mode, no busy indicator
    msg = (msg << 1) + b5
    msg = (msg << 1) + b4   #next   2 bits: 01 - REF:  Reference Mode 1
    msg = (msg << 1) + b3
    msg = (msg << 1) + b2   #next bit:       0 - SHDN: Normal Mode
    msg = (msg << 1) + b1   #next 3 bits:  000 - Reserved
    msg = (msg << 1) + b0
    return msg

def decodeDaisyChain(ans):
    #accepting list of 5 bytes for two 18 bit in a range of +-5V chained together
    val1 = ((((ans[0] << 8) + ans[1]) << 8) + ans[2]) >> 6
    val2 = (((((ans[2] & 0b00111111) << 8) + ans[3]) << 8) + ans[4]) >> 4
    val = ([val1,val2])

    # convert to voltage (-5,+5V)
    Vref = 4.096
    step = Vref*2 / 2 ** 18  # in Volts
    zero = 2 ** 18 / 2
    ans = [(x - zero) * step for x in val]
    return ans

spi = spidev.SpiDev()
spi.open(0,0)
spi.mode = 1    #polarity: 0 phase: 1
spi.cshigh = True

# ADC Configuration
msg = configuration(1,0,0,0,0,0,0,0)

try:
    while True:
        spi.writebytes([msg,msg])
        time.sleep(0.0027)
        ans = spi.xfer([255,255,255,255,255])
        #ans = spi.readbytes(5)    # optional method. Didn't work either
        val = decodeDaisyChain(ans)
        print("%6.4fV %6.4fV" % (val[0],val[1]))
        time.sleep(0.1)
finally:
        spi.close()


texts:
I want to have two switches controlling my lights room that works like a XOR gate, does anyone know how to do it? I have a very simple switch for testing and I tried many times and couldn't do it as I don't know too much about electronics.

This is the switch I am using:

I was wondering if there is a way to wire it to another one that looks the same that works like a XOR gate.
I found this diagram online but I don't understand it, here it is though:

Cheers.


texts: Microcontroller with Video input preferably composite

texts: I am looking to build a project that will take video input from several different cameras that have composite output. I am wondering if there are any micro controllers or shields out there that will allow the micro controller to accept composite input? Even if it only were to accept one input I can setup a system for switching cameras. I would prefer to stay away from the usb capture devices.


texts:
After nearly two weeks of testing, STM32L MCU suddenly stopped working.
It is not recognized by ST-LINKv2 debugger (tried connecting using stlink under Linux and STM's ST-LINK utility under Windows).

MCU power is OK, ground and SWD pins are connected.

I did not do anything special with device when it suddenly stopped working
software does not redefine SWD pins
device is powered from battery, so do not expect that MCU was burned by some voltage spike
MCU was bought from local reseller that seems to have original parts (but not sure)
although present on schematic, quartz crystal and capacitors are not soldered. Device is driven from internal clock (HSI).

It seems that MCU is dead. The only explanation that come to my mind is EMI.

Please help to understand what could be the source of problem.


texts:
I have a problem i'm trying to get to the bottom of. I am basically trying to find the secondary line voltages of a three phase delta primary, with a six phase forked star connected secondary transformer. The link shows the configuration of the forked star connection, and the phasor diagram to aid it
http://www.vias.org/matsch_capmag/img/matsch_caps_magnetics-936.png

My issue is that using the normal equation of root 3 x Vphase/n gives doesnt give me the line voltages for all 6 phases, and looking for line to line voltages I really dont know where to start and there isnt much documentation available on these systems. Any help would be appreciated for me to understand this.

If i had say 11kV primary line voltage (delta) with a turns ratio of 100:1, how would i work out the secondary line voltages of a 6 phase forked star configuration as shown in the link?

Thanks for any help in advance.