texts: How can I implement a SCART switch connector

texts:
I have some experience with electronics, but no experience with AV. I would love to learn how to do something like the following:

I want to build a little circuit which will do the following:

        Input a SCART(RGB signal) and a Composite RCA connection.
        ----
        Output SCART(RGB signal - passthrough of whatever signal comes in
        over the Input SCART - or Composite over scart from the composite RCA connection)
        ----
        Switch when flicked left outputs the SCART signal coming in,
        when flicked right outputs the Composite signal.

My circuit would have a switch which when flicked to the left does a SCART passthrough, when flicked to the right, it flows the composite signal over the SCART output as per the following diagram:

I have a couple of questions to help me solve this problem:

I need to know the name of the SCART IN, Composite In breakout board type connector for my circuit
How might the switch circuitry be designed

Help in these areas would help give me a starting point of actually building my little circuit!


texts: Reading motor limit switches with Arduino

texts:
I'm building a window blinds system. I have an arduino powering a motor via a DRV8833 Dual-H bridge controller. At the limits of each direction of motion, I have limit switches that kill the power to the motor in that direction. I also want the arduino to read when the limits are hit, but I can't feed the raw power from the limit switch into an input pin as it will exceed the 3.3V logic inputs.
I've got what I'm calling forward working with an NPN transistor to feed 3.3V logic when its corresponding limit switch is hit. However I'm really struggling figuring out the wiring to determine when the reverse limit switch is hit. In that case you end up with a negative voltage in a sense coming from the limit switch. I've had a couple of random configurations that seemed to work, but not consistently. I'm attaching diagram of what I have in place currently. In this diagram, I'm representing the reverse and forward directions separately with reversed voltage sources even though in practice, the two limit switches are next to each other between the DRV8833 and the motor (represented by lamp). I have diodes across the limits to allow motion in the opposite direction when a limit is hit. I have Q8 being activated when SW7 is hit and the arduino pin reads the switch activation. I need help getting SW5 to indicate to the arduino when it's been hit. Note resistors are just default ratings in diagram.

Circuit Lab


texts:
For our senior design we are designing an electric vehicle. The motor will run on 72v from li ion batteries but we have some auxiliary devices that we would like to power from the same battery. We have some LEDs that require 12v DC and probably max of 2amps. How does one basically take a branch of the main power and scale it for auxiliary uses?

My initial idea is to use a DC DC converter in parallel with the power supply coming from the batteries. The converter would essentially be a 72v max input and then be a 12v 2Amp output. Is this a good strategy?

Also I'm new to stack exchange so all help is appreciated.

Thanks for all your help. We are definitely looking at a buy option rather than make given we are a group of just mechanical engineers with limited electrical engineering experience. So I was looking on digikey and I found a 25w 12v output DC DC converter from 72v input. (Digikey part number: SD-25C-12-ND). Does that seem like it would be the right fit for our application?


texts: 0-5V Voltage controlled Constant Current Source with High & Low current Offset

texts:
I am trying to design a MOSFET constant current generator controlled by a 0 - 5VDC signal (non pwm). I have had no problems getting a nice resistor divider and an op amp to control the circuit. I am looking to get 5A through either a HBLED or a Laser Diode.

My issue is this. For the application, the 0-5V needs to be linear. The "0" volt setting needs to be adjustable as the LEDs & Laser diodes do NOT start emitting light at .01mA. I need to be able to set a "bias" or threshold current with a pot so that when the signal is introduced into the circuit, I have set the "actual current", the device will need to begin emission. Next, I need a pot to vary the top end of the circuit to stop at the max current when 5V is reached.  I use a Zener diode for over-voltage and reverse voltage protection. Overshoot in this application I really can do without. I hope I phrased this correct using the word bias.

This circuit (seen here in forum before) is a great V to I section:

For example, the laser diode has a "threshold current" of say 120mA and will max out at say 2.5A

I need the "0" volt or NO input to be right under the 120mA. so when we start ramping up the voltage from 0, the circuit immediately starts feeding 120mA. When the voltage approaches the Max setting with 5V input, I need 2.5A output. Each HBLED and Laser diode have a varying threshold & Operational current, thus the need for multiple potentiometers. Once again, I hope my question is clear. I am disabled and my brain doesn't allow the ideas to flow correctly sometimes.  Sorry, look forward to any help!! Happy Turkey Day

To obtain 2 offsets, one high one low, both corresponding to the 0-5V signal. It seems like I can imagine it, but not put it on paper.

One potentiometer sets the I threshold current when no voltage applied, second potentiometer sets the Imax at 5V. I feel like an idiot since it does not just "POP"


texts:
After reading about GSR/PUR facilities in Lattice FPGAs, I'm still a bit puzzled about how to actually get the proper GSR/PUR-based reset functionality on an actual physical FPGA chip.

In the How to Use GSR and PUR application note, they show this Verilog example:

GSR  GSR_INST (.GSR (<global reset sig>));

suggesting that .GSR corresponds to an input, thus <global reset sig> would be mapped to an external pin (as I understood it).

But then, how do I use the output of that GSR_INST ?  I distinctly remember that they say that the reset is active-low given the underlying circuitry. However, in the HDL Coding Guidelines, page 38/39, they show (Verilog version):

reg[1:0] state;
reg dout;

always @(posedge clk or posedge rst)
    if (rst) begin
        state <= idle;
        dout <= 1'b0;
    end
    else begin
    case (state)
    // ···

That rst looks like an active-high reset signal (otherwise the code wouldn't make sense / wouldn't work). So, is rst a reserved keyword that corresponds to the output of the GSR_INST, and it is implicitly available anywhere I need it?

In short: how do I put the pieces together?  (taking advantage of the GSR functionality, that is).  I'm ok with or without automatic/implicit power-up reset  (I can externally assert the reset pin of the FPGA for a few milliseconds after power-up).  But I would still like to know about how to set it up both ways.


texts: Single tone signal generation at microwave frequency with best phase noise and spurious performance

texts:
What is the best way to generate a single tone signal with best phase noise and spurious performance?

Is frequency multiplication the best way? single stage multiplication or multi stage multiplication?

I want to produce a single tone 6 GHz signal with a 100 MHz Sine Wave OCXO by multi stage multiplication.

For best phase noise and spurious performance what issues are important to notice?

Best Regards.
Thanks.


texts:
Been looking into doing from preliminary work on EMC testing in house prior to sending various bits of machinery to certification labs. One suggestion is that we carry out the testing in an EMC tent as a cheap option for the full chamber. However, even a small one about the size of my desk is around £2200.

So, how viable is a DIY version made from (at worst) cardboard with standard aluminium kitchen foil glued to it and grounded?


texts: Arduino motor shield running 2 12V 60 RPM DC motor

texts:
I'm trying to run a bot with a differential drive system and I'm using 2 12V 60RPM DC Motor and an Arduino shield along with the Arduino, along with that I'm also having an wheel position encoder which is used to connected to the Arduino motor shield:

But I'm unable to run motor or get the encoder data, I'm using ROS and rosserial_arduino to get the encoder data. I'm unsure about where to connect the 3rd pin:

I'm using a 12V power supply.


texts: Why does a circuit breaker voltage rating differ between AC and DC?

texts:
I'm looking at circuit breakers from Allen Bradley's 1492 series: (https://configurator.rockwellautomation.com/api/Doc/1492-SPM%20Specifications.pdf)
For each circuit breaker, it lists a AC and DC voltage rating. Why would the voltage rating differ between DC and AC applications?


texts: What modulation does Short wave broadcast stations use?

texts: I have small Short wave receiver for the 7 broadcast bands. (49,41,31,22,19 and 16 meters) What Modulation do they use in this? The radio is a small grundig mini 300 world band reciever.


texts:
I am designing an energy meter for electricity billing purposes by converting an analogue energy meter and counting the number of pulses given by the analogue meter's LED. Since power may be cut off any time, the number of pulses has to be stored in non-volatile memory. I saw the data sheets of Atmel EEPROM AT24C0X and inbuilt EEPROMS of ATmega328 and PIC16F877A, and found all have READ/WRITE endurance of maximum 1000000.

In this context, how is the problem of EEPROM life endurance tackled in commercial energy meters?


texts:
I would like to use a MKS TB6600 4.5A drivers together with an E-cut break out board to drive Nema 23 stepper motors (3A).
My problem is that I cannot figure out how to connect the drivers to the board. Before I fry both the BOB and the driver I would like to ask for some help.

On the driver I see there are four connections: EN, DIR, CLK, GND.

On the BoB electrical diagram I see they have used a different type of driver. The break out board has 3 connections for the driver: XD ( think is the DIR on the driver), XP (I thinks the CLK on the driver) but then I have +5V and not the GND. I will not use the Enable.

I am tempted to connect the driver to the board as following:

but I am not sure if this will work or cause the board or the driver to burn.

Some advice is be appreciated.


texts: power factor correction and switched power supply efficiency

texts: When it comes to switched power supplies, is the power supply efficiency affected by the presence of a power factor correction circuit? In my understanding power supply efficiency is estimated by measuring the ratio of power drawn from the electrical outlet when the power supply works under several loads, for instance 20,50 and 100% loads are analyzed in computer PSUs to give the 80 plus certificate, but is the presence of a power factor correction (PFC) circuit improving the efficiency? Do they take under account the reactive power drawn from the outlet to estimate the ratio to compute the efficiency or just real part and then the PFC circuit has no influence?


texts: Why can the sine wave become square wave by adding a inductor?

texts:
The key to let the sine wave become a square wave is to add a inductor,Why can the sine wave become square wave just by adding a inductor?

link:https://www.researchgate.net/publication/319034971_Real-world_Evaluation_of_a_Self-startup_SSHI_Rectifier_for_Piezoelectric_Vibration_Energy_Harvesting/figures


texts:
I face a road block with my PIC UART/USART. Previously I was working with UART in PIC18F452. But when bring my code to use with PIC16F1824, it doesn't work. I guess this is because PIC16F1824 is using Enhanced USART. Technically it should support UART. But I don't how to make it work.

I'm using MikroC Pro. It detect the incoming data using UART1_Data_Ready(), when I read the data using UART1_Read(), it seems the data is garbage.

Question:

How do I make sure the MCU read the data as it is (UART). At this moment I just want to read incoming data.
Does this has something to do with oscillator? I'm using XTAL 4Mhz.
I'm using PICKIT 3. Is there a way I can see the the incoming data?

Useful links:

PIC16F1824 datasheet
PIC18F452 datasheet
Documentation for MikroC Pro UART Library

Code

void main()

{

ANSELA = 0; //Digital I/O for PORTA
TRISA = 0b00100001;
PORTA = 0;
APFCON0.RXDTSEL = 1;  //0:RX is on RC5 1:RX is on RA1
TRISC = 0;
PORTC = 0;

RCSTA.RX9D = 0;
RCSTA.ADDEN = 0;
RCSTA.CREN = 1; // eneble reception.
RCSTA.SPEN = 1; //Serial port enable
RCSTA.RX9 = 0;

T1CON = 1;          // Turn on timer TMR1
PIR1.TMR1IF = 0;    // Reset the TMR1IF bit
TMR1H = 0xFC;       // TMR1H and TMR1L timer registers are returned
TMR1L = 0x18;       // their initial values
PIE1.TMR1IE = 1;    // Enable an interrupt on overflow
INTCON = 0xC0;      // Enable interrupt (bits GIE and PEIE)

PWM1_Init(4000);    //initialize PWM at 5Khz

UART1_Init(9600);

while(1)
{
  if (UART1_Data_Ready())
  {
    //Blink the LED, indication data is coming in.
     PORTA = 4;
     delay_ms(50);
     PORTA = 0;

     sVal = UART1_Read();

    //My debug code to see what character coming in
     EEPROM_Write(0x00+ii, sVal);
     ii++;

      if (sVal == '3')
         motor_run_fast();
      else
          motor_stop();

  } //UART ready
}

}


texts: I need to measure a new temperature device called and ICTD but no meter exists, can I make one with an FET Circuit?

texts: I need to measure a new temperature device called an ICTD but no meter exists, can I make one with an FET Circuit? This device scales a variable microamp signal of .000233 amps DC at -40C to .000375 amps DC at +100C. The device I am working with is an Opto22 ICTD-P3. I hope to simulate a standard RTD to an off-the-shelf temperature controller input to get a direct temperature readout. A RTD has a normal resistance that varies around 90-110 ohms for a simalar temperature range. A VOC seems to be the general idea but I have not found anything that operates at about 100 ohms for the output. Thank you all in advance for your insights.


texts: Accurate Static Pulling (with electric motor?)

texts:
I am trying to see if I could accurately apply a static pull to a cord to create tension.
I should not be measuring the tension directly, only be sure that the pull I apply is the force in Newtons that I want.
The range is from a few tens of Grams to 7 kG. Either in one range or in several sub-ranges (say, 80G - 500G, 500G - 2kG, 2kG - 7kG) or such. With say, accuracy of 1% of the value.
I do not specialize in drives so I do not know how accurate a, say, BLDC motor torque could be when applying current, and what range I would get.
Any ideas? Any that have been tried?


texts: Why do only high-end phones support a lot of LTE bands?

texts:
Most lower and middle end phone only support 3/4 LTE bands. High end phones, like the iPhone, or flagships from Samsung and LG also support a lot of bands.

iPhone 7: 1, 2, 3, 4, 5, 7, 8, 12, 13, 17, 18, 19, 20, 25, 26, 27, 28, 29, 30
LG G4: 1, 2, 3, 4, 5, 7, 8, 20, 28
Samsung S7: 1, 2, 3, 4, 5, 7, 8, 12, 18, 19, 20, 29, 30 and the S8 has 22/24 of them.

Meanwhile, every lower-end smartphone (in my region) only has 1, 3, 7, 20. Not a stupid choice because it gets LTE service in almost every European country, but you don't get complete coverage.

And it's not only a choice of modem capability. Even the newly announced Xiaomi Mi6 only supports those four bands. And it has the latest and greatest of Qualcomm. Same SoC and the same modem as the Galaxy S8.

These high-end smartphone don't have 35 antennas. I don't think there are 35 different signal paths.

I understand that a higher-end smartphone could have more antennas with several distinct front-ends, allowing using multiple frequencies at the same time, but I don't see why a phone with only two antennas that support 800, 1800, 2100, and 2600 MHz would not be able to work with all those frequencies that are in between.


texts:
Is this the correct convention for providing power to IEC cables/connectors in USA?

If your immediate reaction is "google it", I'm finding many diagrams online use somewhat ambiguous drawings instead of actual pictures of these things. It seems the "plug/pins/male" and "receptacle/sockets/female" words are often used incorrectly or it's unclear.


texts: Better resolution with photodiode (LTR-536AD)

texts:
I want to build something like a fog-sensor.

I'm using a laser and on the other end (~20m) I have a LTR-536AD photodiode. I hooked the photodiode to an arduino and was monitoring the voltage.

My problem: When there is ambient light the analog reading is ~640. When I hit the sensor with the laser it is about ~620.

How can I increase the resolution?


texts: Relay to connect a DC motor to Arduino using external DC power supply

texts: Trying to control a 12 V DC pump using an Arduino. Got a relay that has just the labels 10A 250 VAC, 15A 250 V AC, 10A 250 V AC. So does this mean that this relay would not accept a DC source as an external powersupply?


texts: Where can I find projects that are more tutorial than "copy-paste"? Some thing that talks about the math and analysis of it as well.

texts:
So, I'm taking 6.002x which is basic circuit analysis of resistor networks, MOSFETs, capacitors, inductors, diodes, gates, amplifiers, etc. and while I enjoy this I'm not learning anything about designing circuits in both the analog and digital contexts.

Where can I find projects to build that aren't just here's a circuit diagram; it does this; go build it type projects? I want to learn about some aspects of design as well as build projects.

I'm a software engineer by trade, but I'm trying to learn electronics too, so I have a full stack understanding.


texts: I've spent a load of time looking for the answer to this question, but I cannot find it. What is the official name of this connector?


texts: What are some techniques to lower noise on a mixed-signal analog-to-digital converter board?

texts:
I'm building a 24-bit ADC board for Arduino that can sense microvolts (biological signals). What are some good techniques to lower the noise that will negatively affect the ADC resolution?

What I've done already:

made a 4 layer board, with internal ground plane and digital power plane
added separate analog and digital power supplies
kept high-frequency digital signals away from the input lines, and also from the ADC except where they enter the ADC
most ground connections go to the ground plane using vias
there is one single ground for both analog and digital ICs
RC filtering on the input signals

Are there other techniques that would be more effective? Are any of the ones I used counterproductive?


texts: Energy direction in an electronic circuit

texts:
I've been reading a number of materials trying to understand the physics that allow electricity to be possible. I'm confused by this virtual positive [charged] particle (often called a test particle) that is used to explain the direction/properties of an electric field and thus the movement of energy in a circuit.

Specifically, I recognize that the energy is loaded onto this virtual positive particle by the virtue that Work and thus a gain of Energy is required for the positive particle to move from the anode side of the battery back to the cathode side of the battery (where the energized ions are present). From this point the positive particle (now energized and at the point of high energy at the cathode) move to the point of low energy (the anode) offloading their energy onto a load which transforms it into some other form of energy (thermal in the case of a short circuit or resistor load).

I'm curious though how does this positive particle move in any direction? With a classic electronic circuit (copper wires) the electrons are the charge carriers and thus form the charge highway/sea of electrons allowing energy to move (in response to a induced electric field). i.e electrons move, atoms/ions do not.

Is this simply a convention (much like conventional current vs electron current) in that the ions are not moving but the illusion is given that they are by virtue of the electrons moving and leaving holes/positive charges in their wake (in the opposite direction)? Is so why was it chosen instead of using a negative charged particle and thus being easily traceable by the movement of electrons?


texts: Pull-up/ pull-down resistors in CMOS gates

texts:
Can someone help me with understanding why the next two circuits have those outputs?
My initial schematic contains only one inverter, and the signal is 5V for output high state, and 0V for low.
Now, using one grounded resistor (that I think is pull-down resistor), my output values are 4V in HIGH, and 0V in LOW. Why does it work like that, and is it really a pull-down resistor as i think?

The second one is

and its output states are 5V for HIGH and 1V for LOW level. Why is it like that and is that a pull-up resistor?
Thank you for your help!


texts: Transil probably, but google, vendors do no know this part


texts: Difference Between Contact and ContactLess smart cards

texts:
What's the difference between the contact and contactless smart cards more technically and physically is there identification to distinguish them ?

EDIT: Some smart cards like debit card will have magnetic strip also if magnetic strip is there then it can be  contact/contactless i.e. can be read by any reader ?


texts: 4 digit 7 segment CC - all digits count the same number

texts:
Ultimately I'm looking to build something that's going to count revolutions as part of a guitar pick up winder.

I've got a circuit hooked up with 4 x 4026 counters going into a 4 digit 7 segment display. I believe I have the correct linking of the chips withe carry from one going into the clock of the other. But every time I provide a clock pulse all 4 digits on the display increment by 1 rather than just the least significant.

I have the pin outputs from each of the chips going into the corresponding cathode of the 7 seg display but I just cannot get it to count more than 0 - 9.

What am I getting wrong?

This is my first question on here. I'm new to electronics and have been working at this for a few days but always run into the same problem. Really appreciate any help.

Thanks for the comments and answers so far. I've added what I hope passes for a circuit diagram...

I think I've got the clock in and carry out (/10) connected correctly and I think I've got the right outputs going into each of the common cathodes on the display. I'm not worried too much about re-setting or inhibiting the clock right now so I've put them to negative. I'm not doing anything with Pins 4 and 14.

The LED on the left is just another method of me knowing a clock pulse should be going in


texts: Aluminum Electrolytic Capacitor - current, power, efficiency

texts:
How to find out the efficiency of an aluminum electrolytic capacitor like this one.

How to find out resistance of such a cap in order to calculate the time it takes for it to charge up or discharge?

The resistance would also allow to account for power loss as stated above.
Is there any hint in the datasheet enabling me to calculate the desired values?

@ Christian B: Thank you but the ESR or dissipation factor is given just for 100 Hz. What if I wan to discharge the cap just once a day (-> low frequency)?

$$ESR = tan\delta * \frac{1}{2\pi fC}$$

If I assume f = 1 Hz for example and C = 2 mF, I will get approx. an ESR = 10 Ohm.
But assuming f = 1 Hz seams not reasonable to me though.

@ Marcus Müller: The efficiency I am looking for is basically the equivalent ohmic resistance during charging and discharging. Once having that number, together with charge/discharge time and current/voltage, I could calculate the power dissipated in that resistance. Of course the leakage current is important too. At least when the cap stays charged for "longer time".

Or is there a different approach? I simply want to intermediately store energy in that cap.


texts: Relay : what is the difference between Low level trigger and high level trigger

texts:
I am selecting relay for A micro-controller project and I am electronic beginner so I faced an issue when I had to choose between low-level triggered and High-level triggered

As far as I understood :

Low-level triggered will allow the current to go through the power line when the control signal is below a certain voltage.
High-level triggered will allow the current to go through the power line when the control signal is above a certain voltage.

Am I right?


texts: Timing complexity for correlation implementation on FPGA

texts:
Let's say we have a database of five thousand 512 point discrete signals. Each database entry is unique in itself. The important point to note about the signals in the database is that out of the 512 points, more than half of the points are zero for all the signals. Now, we capture a 512 point discrete signal from the outside (details need not matter).This signal corresponds to one of the signals in the five thousand entries of the database. I compare the acquired signal by taking the Spearman Correlation of the acquired signal with each of the five thousand signals and the entry which gives the highest correlation coefficient is the closest and depicts the acquired signal. This operation of correlation, especially the 512 point correlation, consumes a lot of time on MATLAB. Obviously, there is latency on the PC, which is the main reason for consumption of time. The time consumed is 2.3 seconds on an average for calculating the correlation of the acquired signal with each of the 5000
database entries.

Now, let's say that I want to implement the exact thing on an FPGA (Virtex-7 Xilinx Family). I think that the operation of correlation can be done in parallel because the acquired signal is only one and the database entries can be stored in the FPGA. So, not all the 5000 signals can be correlated parallelly, however, if at least 1000 can be correlated parallelly, then the time will reduce considerably on the FPGA. So, my question is how many signals could I correlate at one time on this FPGA and what will be the approximate time taken for this 512 point correlation in total if implemented on this FPGA.


texts: HDL Designer: What's the difference between a project and a library?

texts: Which should I use? I'd like to use it to model circuits for homework and to possibly reuse parts circuits in other designs.


texts: How to identify this particular SMD component?

texts:
It is used on a small board RFID antenna circuit based on the TMS3705:

At the first check it seems to be a 0 ohm resistor, but the dimension 4x4mm its strange.

Any ideas?

L.


texts: Which type of amplifier has feedback? BJT, FET or both

texts: The answer to this question is given in the picture shared but I am not able to understand the answer or rather I would prefer to say I do not agree to the answer given. So I need to know what will be the right answer.


texts: RTD reads differently with different monitors

texts:
I have an RTD that I am reading with a Jenco 77A  4-20mA converter and a reliable 4-20mA supply/display. When I turn on a nearby AC electric motor, the indicated temperature jumps 50°C (which is clearly not actually happening).
However, when I disconnect the RTD wires from the converter and read them with a mulitmeter, I see a steady resistance reading.
I have confirmed that the converter works with other RTDs, and that the same problem occurs with the same RTD on identical converters.
Why would the resistance measurement be so wrong on one measurement system but accurate on another? Are there any commons means to fix this problem?


texts: What is the brightest, biggest & baddest white LED to date?

texts: I'm looking to make a DIY LED projector with a single LED (even if its a very small projector, might make an array of projectors with edge-blending, don't have the specifics yet, but it has to be energy efficient) and I was wondering who makes such a LED or if there is experimental technology in the works to make brighter LEDs.


texts: Need to replace a surface mount fuse. T10 L AC250V. Please help

texts:
Basically I have a device which seems to have blown a fuse. I've done some research and found that it's a "surface mount fuse" or smd fuse. My main questions are where can I find this fuse(or is any 10A 250V fuse ok) and how can I replace it. Also, are the metal ends something I can solder off solder on the new one?

I'm from Canada so I found this one by mouser. Shipping is expensive so I may look for another. (https://www.mouser.ca/ProductDetail/Bel-Fuse/SMM10)


texts: Resistor Load Effect on inverting op-amp

texts:
I was reading through some notes a while ago and am struggling conceptually with the ideal op-amp philosophy. This started when I looked at the top figure below, I originally solved it using basic voltage divider/thevenin equivalent techniques. But when I looked at how my professor did the problem, he used the fact that the virtual ground at the inverting terminal means R3 is || with R2. Again this made sense to me, but I wanted to look at some other problems to understand this result which leads to the middle and bottom problems. I wanted to know why the load resistor on the op-amp in the middle problem isn't the same as shorting it to the virtual ground, sort of like we did in the top problem? Also, why does the professors technique in the first one work whereas it doesn't work in the middle/bottom?

simulate this circuit – Schematic created using CircuitLab

simulate this circuit


texts: AVR Excitation System and Generator in SimuLink

texts:
I am designing in simulink cooperation of synchronous machines with the grid.
The main blocks are Excitation System which is AVR [link1] and Synchronous Machine [link2].

On the site we can find

  "Regulator output limits and gain
  Limits Efmin and Efmax are imposed on the output of the voltage regulator. The upper limit can be constant and equal to Efmax, or variable and equal to the rectified stator terminal voltage Vtf times a proportional gain Kp. If Kp is set to 0, the former applies. If Kp is set to a positive value, the latter applies. Default is [ -11.5, 11.5, 0 ]."

but those coefficents are nowhere properly explained.

I tested it and it limits the output of the regulator to the defualt value which is 11.5 and then the referal value of Vf is straight line (on Efmax level) until the regulator starts to lower down the field current and voltage.

For safe reasons I need to know:

where this values (Efmin Efmax) comes from in means of finding the formula for them?
how to set it properly for specific AVR model or Generator?

Schematic of the regulator:

I also have found that the values of limitations for different models of Excitation Systems varies from ~2-15 (pu)


texts: Isolated vs non-isolated boost converter for LED (12v to 24v)

texts:
I have a 12v system in my motorhome and planning on installing 24v LED strips, however, I'm unsure whether I would need an isolated or a non-isolated boost converter.

I'll be using roughly 5 meters of LED (24W per meter).

If I would have to choose all by myself after reading on StackExchange I would go for a non-isolated converter as this is not a critical application and we're only talking about direct current. However, I'd like somebody to confirm my thinking.

So my questions.

Isolated or Non-Isolated 12v to 24v Boost Converter? (Victron Orion)
I might add a PWM Dimmer in the 24v circuit. Does that change anything?
I do have 230V AC in my motorhome (from an inverter). Would it be a better choice of using a simple LED Driver that converts AC to DC?

Thanks in advance


texts: Erratic MCU behavior while switching from wired to wireless UART

texts:
I have an Arduino that accepts its UART I/O from a wired and a wireless connection. The wired portion is a standard CP2104 USB to UART bridge and the wireless portion is done, for now, through an HC-05 BT module. The two are switched using a MUX/DEMUX scheme in which the USB 5V acts as the select line. When the USB is unplugged, the BT module is turned on. While the USB cable is plugged in, the BT module is turned off. The MCU is used to control 4xTB6600 stepper drivers.

Here is the weird bit: When the motors are plugged in to the drivers, and the USB is unplugged to allow the BT module to take over (when the motors are off and there is no software actively using the USB), the MCU behaves very erratically constantly switching ON and OFF the enable pin (The MCU runs grbl. A video showing this behavior is shown here). This does not happen when the motors are unplugged and it works fine. I'd really appreciate it if anyone can help me understand why this is happening and give me some ideas on making this work.


texts: Why would a pin not go high on an Arduino?

texts:
I'm using a SparkFun-built Arduino Pro Mini 3.3V / 8MHz. One thing I need it to do is toggle the gate pin on a MOSFET, and that's not working for some reason. Getting in there with a multimeter, I see that the voltage on the pin never goes HIGH. The only thing I have running on there is the following bit of code:

void setup()  {
  pinMode(A7, OUTPUT);
}

void loop() {
  digitalWrite(A7, HIGH);
}

Any thoughts on either configuration or electronics that could be causing this?

The pertinent part of the schematic is:


texts:
This is my first post, so hello all :)

I have a tungsten wire thats wrapped around a crucible. I want to send ~20A through it in order to heat the crucible.

Now the tricky part. Since this is part of a delicate setup, I don't want to use solder or glue in order to minimize contamination through evaporation (this is a physics experiment).
At the same time the setup has to fit inside a 10cmx10cmx5cm box.

Any ideas on components I could use to make these connections?
Is using crocodile clips to connect the tungsten wires a completely stupid idea? :D


texts: I got a L317T voltage regulator. I connected it to a 12V input, but the output which i get is only ~0,32Volts instead of ~5Volts. Why is that happening. Its not a problematic regulator. Every one of them did the same thing. With or without the capacitors, the regulator gave me a very low voltage


texts: Non-ideal inductor effect on inductor current in a quadratic boost converter

texts:
I'm studying a quadratic boost converter and I'm expecting to see in the lab a constant current in the inductors, with a small ripple associated with energy exchanges between the capacitive and inductive elements.
However, I already know beforehand that in fact, the inductors are not ideal, having a small resistance associated with them. My question is if I should expect to see the currents decrease?

My line of thinking is this.
In the ideal case we would have input power equal to output power. Now we have input power equal to output power plus the power losses. (NOTE: in the image the output voltage should be in the opposite direction).

$$P_i=P_o+P_{losses}$$

$$V_iI_{LB1}=V_oI_o + r_{LB1}I_{LB1}^2$$

Now because $$I_o=(1-\delta)I_{LB1}$$, we will have:

$$V_iI_{LB1}=V_o(1-\delta)I_{LB1} + r_{LB1}I_{LB1}^2$$

$$V_i=V_o(1-\delta) + r_{LB1}I_{LB1}$$

$$V_i=V_o(1-\delta) + r_{LB1}I_{LB1}$$

$$I_{LB1}=\frac{V_i-V_o(1-\delta)}{r_{LB1}}$$

Therefore, should I immediately conclude that the current decreases? But does that make sense? What about the ripple? I'm not able to realize if it will increase or decrease, but I suppose it will increase? Since it's already an undesirable effect on my converter?
Can someone please clarify me?
Thanks in advance


texts:
I see several options for this; there is the TI's application bulletin (originally a Burr Brown App. Bull. from 1997) --- www.ti.com/lit/an/sboa068/sboa068.pdf

There's LT's LT1001-based circuit: http://cds.linear.com/image/416_circuit_1.jpg

Then, there is the simple circuit shown in Wikipedia's Precision rectifier page:

simulate this circuit – Schematic created using CircuitLab

which I can combine with the original signal (i.e., its output + Vin/2) to obtain the absolute value of the input signal:

simulate this circuit

Notice that I indicated LT6237; among other things, I need moderately high bandwidth (I want the absolute value of signals going up to 10 or 20 MHz).

I find this the simplest option, and can't see any obvious disadvantages --- are there any important advantages in the other designs with respect to this one?

All circuits are sensitive to resistors mismatch;  I'm planning to use 0.1% resistors either way. But I wonder: are some of the circuits especially sensitive to resistors mismatch?

I believe that one advantage of this one is that neither of the two op-amps has the other op-amp in its feedback path (which the other two designs do, at least for a fraction of the input signal cycles), so if we have stable op-amps, then we do not need external compensation capacitors.  Is my intuition correct?

With the above said: I run a simulation with LTSpice, selecting LT6237 for the op-amps, and the circuit behaves wildly different depending on the diode that I select.  For the resistors, I use the ideal/generic resistor from the LTSpice tool bar.  If I select the generic/ideal diode, then the circuit oscillates when the output goes positive. With 1N4148, it does not.  With fast-recovery diodes (the first fast recovery from the list), the output is wildly distorted (no oscillation, but the output is quite deformed), for Schottky (e.g., 1N5817), the circuit oscillates.

Are these simulation artifacts?  What should/could I expect in practice when assembling the actual circuit?

Thanks!


texts: Issue reading pressure transducers and getting floating value

texts:
So I'm trying to read a Honeywell pressure transducer off an Arduino Mega and I'm just getting floating values. I've tried ground the line straight to the Gnd and then I get a consistent 0 but otherwise it just floats. I have the excitation (positive) line for the transducer connected to the Arduino 5V output, the common (negative) line connected to Arduino Gnd, and the output line is connected to analog pin A8.

The code on the Arduino looks like:

#include <Arduino.h>

int pressInput = A8;

void setup() {
  Serial.begin(9600); // set the baud rate
  pinMode(pressInput, INPUT);
}

void loop() {
  String input;
  if (Serial.available()) { // only run through loop if data has been sent
    input = Serial.readString(); // read the incoming data
    if (input == "press") {
        int pressValue = analogRead(pressInput);
        Serial.println(pressValue);
    }
  }
  delay(100); // delay for 1/10 of a second
}

And I'm communicating with the Arduino via python and that code looks like:

def read_press():
    #Command to get the pressure value
    pressure_in_voltage = send_arduino_cmd("press")
    pressure_in_psi = 75.0 * (float(pressure_in_voltage)/1023.0) * 5.0 - 37.5
    #pressure = max pressure/(4.5V-.5V) * (voltage/max voltage) * 5V - offset (max pressure/(4.5V-.5V))
    return (pressure_in_psi)

With this code I'm getting random pressure values for example:

133.321
102.529
165.945
93.365
117.558

Any thoughts on how to debug this or what could be going wrong in my Arduino code? I've tried this with three of the same transducers and gotten the same result so I don't think it is an equipment failure on that side. I've also tested voltage across the + and - and it is 5V UNTIL I connect the output line and then I can't see any voltage across any of the lines. I've also connected the ground and common lines to a 5V power supply to ensure it wasn't an issue with the Arduino power and got the same result.


texts:
Is it possible to build a DC-DC converter by means of a piezo crystal followed by a voltage multiplier? The crystal would supply the AC voltage needed by the voltage multiplier. I'm looking to get around 60~70 V from an Arduino 5V pin, and don't require much current(around 0.5mA).

Specifically, I'd use 5V to excite the crystal and use the AC output as the input of a voltage multiplier.


texts: What is the purpose of this simple 1 capacitor 2 resistor high pass filter?

texts:
I have seen the standard high pass filter with the -3dB cutoff frequency =  \$ 1/2\pi RC\$.

simulate this circuit – Schematic created using CircuitLab

However I have seen this particular circuit which I'm seeing here and there, especially on the inputs and outputs of ADCs DACs etc. Is the resistor there to limit the input/output current? Would the -3dB cutoff frequency change at all? If so, what frequency would the new one be at?

simulate this circuit


texts: How to compute the throughput varying the bandwidth

texts:
Let's say that I have two different wireless technologies, A and B.

A has a bandwidth of BA MHz, B has a bandwidth of BB MHz. I can compute the capacity of (for instance A) with Shannon:

CA = BA * log(1 + SNR)

but what if A is on frequency band FA, and B on FB? If, for instance, B is on a higher bandwidth, the total amount of information that B can transfer would be higher compared to A. How could be possible to compute this? I'd like to compute this regardless of the technology, whether FEC is implied or not etc..


texts: Protecting LEDs driven by pulse generator via coax cable

texts:
I am a student in physics, and I have a project where I need to pulse LEDs with short pulse widths. I have a SRS DG645 pulse generator and using these LEDs.
I have an RG58 coax cable with a BNC fitting on one connected to the pulser output. The other end I've cut and joined the central conductor to the positive lead of the LED and the grounding braid to the negative lead of the LED. This works, but my advisor suggested adding a series resistance to protect the LED. For testing purposes, I can do this with a breadboard, but what options are there for a more "production-ready" product? And what about reflections? How would I handle the 50 ohm termination in this case?
My understanding of electronics and circuits is pretty limited, and my advisor does not answer questions he thinks we should already know and instead tells us to go find the answer for ourselves.
Thank you for any help you can provide.


texts: Need help understanding PNP,NPN dual transistor

texts:
Hi, i need help understanding how this NPN,PNP transistor work because it make me really confuse from what i'm understand. The circuit is from laptop motherboard schematics.
The transistor is IMD2AT108 .
Datasheet is here : http://rohmfs.rohm.com/en/products/databook/datasheet/discrete/transistor/digital/emd2t2r-e.pdf

Voltage on pin 1&2 is 19.36V
Voltage on pin 3 is 19.46V
Pin 5 & 6 is connected to ground.
Pin 4 is 3.25V

My question is :

Please explain why voltage on pin 1&2 is 19.36V ?
Suppose for PNP transistor in the circuit is in situration mode because Vbe is -ve but from measurement the PNP transistor is in cut-off mode. Please explain.

Thanks all for your help.
Ryan


texts:
I am trying to implement an sd card reader on lpc43xx devices. For this I can make use of the LPCopen examples that use the ROM based drivers. However for some reason the ROM based driver example states that it only supports sd cards up to 4Gb.

So now I probably have to port the outdated LPCUSBlib drivers in order to implement the sd card reader. Of which a specific bug discussed in this question:
SDXC Card Reader with LPC1822

In this question it is replied that the LPCUSBlib version only worked up to 4GB initially as well. And a fix is proposed to accept sdxc cards of up to 64GB. (However it seems like in his pre fix code it should already accept up to 32GB) So I am confused whether this same fix was used to solve the initial issue of only supporting up to 4GB.

My question is, does anyone know the exact bug fix that got it working for >4GB. And would this solve the same problem for the ROM based rivers? The reason for asking is to prevent me from porting the LPCUSBlib drivers and then finding out that it only supports up to 4GB as well.

Thanks a lot.


texts: Capacitive touch screen sensitivity question

texts:
I have a question about capacitive touch sensing. I have read a few related questions already (here, here and here) and I think I understand the basics.

From my understanding, when a human uses a touch screen their body acts as one "plate" of a capacitor and the screen acts as the other (with protective screen coatings, glass etc. in between). They are connected though a common ground (e.g. earth ground). The touch controller can sense the capacitance at different points on the screen and determine where the touch happened.

I have been experimenting with a touch stylus (like in this question) in two different setups:

Off-the-shelf touch stylus held by me
Off-the-shelf touch stylus held by a plastic clamp and connected to earth ground

I have found that the touch screen is much more sensitive to the stylus in Setup 1 compared to Setup 2, however I don't understand why. I understand there are a few differences between the setups

The human body has capacitance and so the total capacitance that the screen "sees" in Setup 1 is different
The ground that the circuits (below) see may be different

simulate this circuit – Schematic created using CircuitLab

This answer suggests connecting the stylus to the metal housing of the device to create a good common ground. Unfortunately my device is plastic. I think it is unlikely that any ground connections I have access to are the same as the screen's ground.

How can I improve Setup 2's performance? Would building a human equivalent circuit to add to Setup 2 help?

For example this from here:

Cheers

EDIT

I simplified and built the "human body" circuit and updated my equivalent circuit with Kevin's suggestions. However, the performance isn't any better.

simulate this circuit


texts: Multimeter not showing same current as bench power supply

texts:
I’m getting a different reading on my multimeter for current than what shows on my bench power supply.
The bench power supply shows 5 mA. This makes sense with the displayed volts and watts- 2V*.005A=.010W

The multimeter shows 11.58 mA.

The multimeter is older than the bench power supply. I’ve heard that you can break the multimeter by using the current setting incorrectly, something that I could have done in the past unknowingly.
What could cause this discrepancy? Does it look like I broke my multimeter? If so is it possible to fix it easily?


texts: Why do simulated results differ to calculated results?

texts:
Why, when using a program such as multisim, do the simulated results within the program differ slightly to those calculated analytically.

Would there be any reasons other than rounding errors in calculations and the fact that multisim uses ideal components?

For example, I have a circuit; a 3 phase unbalanced load connected up in star, with one leg having a resistor and capacitor, one leg having a resistor and inductor, and one leg that has only a resistor. In multisim I have used z blocks for the 2 legs and a resistor for the leg with no xl or xc.

I've calculated the I through each phase, I for the neutral, and the total power dissipated. My simulated results for the currents are around 1-2mA out (which would be accepted as correct), and the power dissipated is about 200W out (again would still be accepted.)

For distinction criteria I am to compare the results and explain why they are different, and apart from the reasons listed above I cannot think of any, however for a distinction I would be expected to write more than just a paragraph.


texts:
(source: ecetutorials.com)
This is not an assignment.

Calc Maximum output offset voltage caused by the input offset voltage Vios

Calc Maximum output offset voltage caused by the input bias current Ib. For an inverting amplifier with R1 = 100 k and Rf = 10k . Here 741 Op amp is used with Vios = 6 mv and Ib = 500 nA.

In this question Vin is given in inverting end only.
In the book Roy Chaudary Linear Integrated Circuit. It is given that No matter where the input is given the resulting formula for the V0 will be V0 = (1+ Rf/R1) * Vos.
Roy Chaudary Go to page 122
However, in the solution set of this question it is given that V0s = - (Rf/R1) * Vios. What am I supposed to do which one is correct? What am I not considering


texts:
The “abc <-> DQ” transformation matrix used for transforming currents, voltages and magnetic field
can they be used for transforming inductances also?
as given below-


texts: How to hook digital input to remote control buttons?

texts:
For a DIY project I would like to adapt a remote (RF) control

to accept digital signals from MCU. I am not quite sure how the buttons in question work: Are they normal buttons which make near 0 ohm connection or something advanced (it's part of the question).

If I will be able to tap into the button terminals, which circuit would be suitable to "emulate" pressing the button? Can open collector / open drain on from the MCU side work (using common ground with remote control circuit) or additional components are needed? Maybe there are ICs to provide open collectors for 8 connections in at once (would be interesting to know how those might be called)?

For example, http://www.penguintutor.com/electronics/simple-homeautomation-raspberrypi uses relays, which I do not like.

(I can see similar questions like How to "push buttons" on voltage ladder? , but the answer does not contain more detail on transistor approach)


texts: Why doesn't my multi-meter diode tester work on this LED?

texts:
I own a TENMA 72-7720 Multi-meter with LCD/continuity tester:

I've used this on other LEDs to test, no problem, using the diode tester setting (approximately 2:00 on the dial by the hold button)

I purchased a large quantity of Purple (UV) LEDs that arrived yesterday.  When I tested them using the above tester, I got nothing.  I tested about half a dozen of the 600 I ordered and none worked so I decided to test them using another means.  I hooked one up to my current project (8x8x8 LED cube) and the LED worked fine.

Since I'm going to be making over a thousand solder connections with these things I want to make sure they're good before I use them and to test periodically during assembly.

So why isn't my tester working?


texts:
I'd like to track a ball during a game using wristbands on players and a chip in the ball. I'd like the type of ranging given by Bluetooth low energy (immediate, near, mid, far) so that I can tell post-game who had the ball at a given time.

If BLE is the right solution I'm trying to figure out how chips would exchange the ranging distance. Would the chip in the ball need to be smart-ready (dual mode)? The phone would be on the sideline, so it can't be the in-game tracker of the ranges.


texts: is it possible to connect two I2C busses on one board, one at master mode and the other in slave. I am just trying to learn some I2C stuff, but I have only one board.


texts: Reverse signal protection for two devices with different voltage levels

texts:
I want to design a circuit that is capable of blocking reverse voltage signals but allowing forward voltage signals to pass through.

The original problem and solution:

I was designing an Arduino to ESP8266 interface with a pair of the Arduino pins as a serial port. For the Arduino TX to send data to the ESP8266 RX, the circuit was a very simple resistive divider to divide 5V to 3.3V, which worked well. The problem came when I needed to do the same for the ESP8266's TX pin. As the ESP8266 operates on 3.3V voltage levels, feeding 5V by mistake into the ESP8266 would certainly mean disaster. Therefore, I was trying to figure out a way to let the ESP8266's 3.3V signal pass through to an Arduino IO pin without being distorted or its voltage decreased by a drastic amount while still protecting the ESP8266 in case the user on the Arduino makes an error and feeds 5V into the ESP8266.

The solution I came up with originally was to use a Schottky diode like the 1N5817, as shown in the schematic below, to prevent the Arduino IO pin from back feeding into the ESP8266:

The new problem:
In my tests, it turned out that the Arduino was completely incapable of receiving serial data from the ESP8266, most likely because the voltage level was too low. If I short a wire across that diode, the serial data gets through with no problems.

Is there any way to properly prevent voltage back feeding from a 5V IO pin to a 3.3V IO pin while still preserving the original voltage when the 3.3V side is transmitting a signal to the 5V side?

A few requirements for the solution:

The components used must not be too large, as PCB space is precious
Would prefer hand-solderable components (e.g. for resistors, 1206 is a good size)
Prefer SMD components


texts: How can I interface a Raspberry PI GPIO to an open collector circuit to send / receive data?

texts:
I have a GPIO from a Raspberry PI connected to a Nintendo 64 system like so:

From what I've gathered and observed, the data line on the N64 system is an open-collector output. The line is tied high when data is not being transmitted and pulled low to transmit.

The PI supports pull up/down configurations for the GPIO pins, but I don't see anything about an open-collector configuration.

With my current setup, I am able to read data from the N64 with the PI. However, I'm completely stuck on how to pull the data line low in a non-destructive manner using the GPIO pin, and also read from the same pin.

Is this something I can accomplish without additional hardware? Or do I need to add something like a transistor that I can switch with the PI to connect the data line to ground? If I do that, how will I read data?

As you can see, I know just enough to thoroughly confuse myself, but not enough to solve the problem.

Thanks for your help!


texts:
Given a function, e.g. \$y = f(x_0, x_1, x_2, x_3) = \sum m(0, 3, 4, 5, 6, 7, 8, 9, 11, 15)\$. How can i find the minimized function without hazards?
I see this can be minimized using a Karnaugh map:

\$\Rightarrow y =  (x_1 x_0) + (\overline{x}_3 x_2) + (\overline{x}_2 \overline{x}_1 \overline{x}_0) + (x_3 \overline{x}_2 \overline{x}_1)\$
To make this function hazard free the implicants \$\overline{x}_0 \overline{x}_1 \overline{x}_3\$ and \$x_0 \overline{x}_2 x_3\$ need to be added right?
\$\Rightarrow y =  (x_1 x_0) + (\overline{x}_3 x_2) + (\overline{x}_2 \overline{x}_1 \overline{x}_0) + (x_3 \overline{x}_2 \overline{x}_1) + (\overline{x}_0 \overline{x}_1 \overline{x}_3) + (x_0 \overline{x}_2 x_3)\$
How can this function be minimized? Because by reducing it, hazards could be created again, couldn't they?


texts: IRFZ44N for PWM replacing my TIP3055 BJT

texts: i am currently doing a PWM circuit using NE555 to drive my DC motors rated at 24V and 12.5A under load(3A during no load), connected to my mini electric solar car im doing as a project. I have got myself a TIP3055 and used it for my circuit, during no load(motor shaft spinning freely) it works fine but when i attached the shaft of the motor to my tyres while me sitting on the car(loaded), it wont even run at 0 ohms pot and one of my TIP3055 got fried. Then i searched for MOSFETs and came across the IRFZ44N and was wondering if it was a good replacement. Additional Notes: a linear 12V voltage regulator is connected to the Vcc of my NE555(which i forgot to include in this diagram) while the motors are connected to my 24V batteries.I changed the 1k ohm resistor connected to the base of the BJT to a 220ohm to allow more current but still it doesnt work and ended up frying another one. My PWM will be running around 14kHz, the diodes i used are the 1N4004. So if anyone got any good MOSFET recommendations im all ears or will the IRFZ44N suffice?, thanks :)


texts: Solving Open Circuit Voltage and Short Circuit Current

texts:
In the two images presented below, I need to solve for the 'Open Circuit Voltage' and 'Short Circuit Current' in loop 1 at the first LED String (Consisting of 10 LEDs in series) circled in red.

I have a base understanding of how to go about solving this, but it hasn't provided a solution thus far. I was hoping someone could explain the steps on how to solve these two problems. My ultimate goal is to the create a load line so that I can compare it to another LED light and find an operating point. If someone could help that would be much appreciated.

Open Circuit Voltage

Short Circuit Current


texts: I've found my self very interested on Raspberry Pi. Although, I think it's not powerful enough for my project, so I was wondering how could I build a more powerful SoC computer, with a bigger board, more RAM memory and an ARM chip as powerful as current tablets and smartphones. Is that possible? Do they sell those chips to normal people? How can I build a SoC computer?


texts: What QSPI chip is on ItsyBitsy M4 Express?

texts:
I'm trying to find out the name of the QSPI chip that is used on ItsyBitsy M4 Express boards.
On the image below is very faded:


texts: Complex conjugate poles for OTA unity gain

texts:
So I am designing an OTA, exactly like Miller OTA, but I tried to see the behaviour without Miller compensation. The circuit diagram is shown below

As seen there is no compensation network, neither is the output loaded.
If connected in unty gain configuration i.e Vout shorted to Vin- then I get a frequency response with gain peaking as shown below

This suggest that there is complex conjugate pole. So I went ahead with the small signal analysis.
The input signal is connected in Vin+ hence
$$ \frac{Vo}{Vin} = \frac{1}{1+\frac{1+sr1C1}{gm2\cdot gm6\cdot r1\cdot r2 - (sCin \cdot r2)(1+sr1C1)}}$$
where \$ r1=ro2 \parallel ro4 \$ ;\$ r2=ro7 \parallel ro6 \$ \$ Cin \$ is capacitance between gate and source of M1 and C1 is capacitance between gate and source of M6. This equation checks out because for DC, the gain is \$ \frac{Vo}{Vin} = \frac{1}{1+\frac{1}{gm2\cdot gm6\cdot r1\cdot r2}} \$ and assuming \$ gm2\cdot gm6\cdot r1\cdot r2 >> 1\$ the gain is roughly equal to one. Now to find the complex poles I would like to get the equation in the standard format which is

And this is where I am stuck.
So my questions are as follows:

Is the gain equation correct?
Can anyone show me how to get this in standard form? I am guessing there will be a zero as well with a value r1C1.

EDIT:
I end up with the following equation which does not make sense to me:
$$ \frac{Vo}{Vin} = \frac{gm2\cdot gm1\cdot r2\cdot r1 -s\cdot Cin\cdot r2 + s^2 \cdot r1\cdot r2\cdot C1\cdot Cin}{s^2 \cdot r1\cdot r2\cdot C1\cdot Cin +s\cdot (r1c1-r2cin) +gm2\cdot gm1\cdot r2\cdot r1 +1}$$
EDIT:
Added small signal model for reference


texts: Does spice model saturation recovery of bipolar transistors?

texts:
When a bipolar transistor is driven into saturation, it builds up charge which slows the recovery time when it is switched off. What I would like to know is, how well is this behaviour captured in spice models? Does spice model this? If I pick any given transistor from the library, how accurate is the recovery behaviour likely to be?
I am using LTSpice. I ran a quick sim (results below) and I can see some difference in recovery time for saturated vs unsaturated. But the difference doesn't seem large, and I'm not sure if it is due to other factors such as different collector currents.


texts:
I want to display a 4 digit number on a small device that fits in a hand.
I have a CR2032 3V battery at around 230mA, my microprocessor is a 8051 (in a BLE112) usually uses about 0.9µA and I want the device to last as long as possible.

I've looked at the typical seven segment displays, which typically uses a few mA which is too much.

A alternative is the Sharp LS013B7DH01 which is used in Pebble and uses 5 µA, but seems a bit complex for my microprocessor (and expensive)?

There should be some simple low power 7 segment display which has a average power consumption measured in µA (not mA), but I simply can't find it or think of some other solution.

What alternatives do I have?


texts:
I am trying to design a grounding plan for an RF transciever system. I dont want to go into the component and part details. The basic system is as shown below

simulate this circuit – Schematic created using CircuitLab

My doubt pertains to different grounds and their importance or significance during layout. The basic components in my system are —

Battery that will give about 20V,
2 buck regulators that step down 20 to 5V and 3V3,
Microcontroller,
RF ICs, Converters ADC and DAC.

Now, the different grounds in my system will be, if I am right, PGND,DGND and AGND.
My understanding of the different grounds are as stated —
PGND or power ground — It is the ground return path from the Vcc lines and to the ground.
DGND — The ground reference for digital signals. The signals being most GPIOs. Now, how can the MCUs have a PGND and DGND. The MCU has many GND pins which are PGND. Then where does the DGND come up and which pins should be considered as DGND.For eg  if I have 6 GND pins in MCU how many will be DGND and how many are PGND. Then, how will the 2 be connected. Will it be a star connection. Then this will be true for all digital or linear ICs.

AGND — analogue ground in ADC and DACs. The same principles will apply there as well. Then a good PCB will end up with a multitude of star connections. And finally somewhere I must connect it to the PGND. How is that done. And god forbid I have any differential trancievers, I will have another ground line for them.

Is my understanding right please? Kindly comment.

Now, the whole system is enclosed in a box that has a chassis ground. How is this brought into the whole picture ?


texts: Unrecognized and ignored parameters in LTspice while adding a Third-party model

texts:
I have tried to add a third party model to my LTspice program (2016 version) but when I run the simulation many errors show up.
The model is made for PMOS and NMOS ( saved at the same link)
Link of the models:(http://ptm.asu.edu/modelcard/180nm_bulk.txt). I have followed this tutorial (http://www.linear.com/solutions/1083) to add the models.
Here is the circuit that is needed to be simulated to find the DC operating point and the AC gain.

Here is my schemetic:

I have used .inc order and I have used the SAME link for each of NMOS and PMOS. I In the model text file:

   .model NMOS NMOS
    +Level = 49
        bla  bla

    .model PMOS PMOS

the words NMOS and PMOS are repeated twice. I think one of them will be set as value for NMOS/PMOS in LTspice and the next word must be set as prefix in Ltspice as I understood. However, the program does not recognize the elements if I change the prefix part of NMOS/PMOS from "MN"/"PN" (original prefixes) to "NMOS"/"PMOS". And if I don't change the prefix a long list of errors shows up too.
Here is my error for DC sweep for example:

(https://textuploader.com/dlynf)

Why are these errors happening? Are there built-in errors in the model file?
How can I set W/L for the MOSFET? The errors occur also When I give DC voltage the source "V2". Should I use the models in separated files for each? In such a circuit to determine the input impedance I should apply Vin/Iin when Iout=0 and for output impudence I should apply Vout/Iout when Iin=0 and deactivate all the independent sources. Can I do this in LTsipce?


texts: overcharging issues in MPPT solar controller with NO output leads

texts:
My MPPT solar controller has no output leads. It contains only the (+,-)leads for battery and solar panel. Input is from the solar panel and output goes to battery.Therefore, I have to connect my load to battery connections. Output from 2 PV is 23 V and output from 60 A rated charge controller is 13 V. MPPT controller doubles the current from the PV's.

I want to know, how solar controller will manage overcharging/discharging related tasks of battery. What are the chances that my battery will not be overcharged. Can I take any other measures. My load is 12 V dc.Thanks


texts:
I am having trouble identifying this potentiometer. I am 99.9% sure it is made by Alps, less sure but somewhat thinking it is an RK097 series. It is about 25mm long overall with a roughly 12mm long shaft.
My other question is, what is my best path to clean it out? It has a little bit of static sound when I pass through a certain point in the rotation, so I am guessing it is a little dirty. It appears there is an anchor (maybe a ground? I'm not an EE or even close) wrapped around the knob, so it may not be possible to remove it.
I have contacted the manufacturer, but it is a small operation and wait times are incredibly long.
Thanks in advance!


texts: 1968-ish Philips radio components question

texts:
I found a Philips radio/record player from I believe 1968 at a garage sale. I picked it up for $5. Sweet deal for me! I researched the cabinet to find it's general manufactured time frame. I've already repaired the record player but the radio is somewhat dysfunctional. Dysfunctional in that only the left side of the unit has sound while the right does not. I checked the speakers, and the balance selection knob works. I then started looking over the PCB board for burnt out components to which I found two ceramic cylinder type components that look like resistors. I thought maybe they were capacitors, but I'm really not sure. They have "M1" stamped on them (i'll attach a photo) and a diagram that looks like an AC voltage source diagram. Circle with a squiggly line throw the middle.

I'm not too familiar with components, just getting started with this radio cabinet. I'd like to replace these but I don't know what they are exactly?

Any help would be greatly appreciated. If any further pictures are required I'd be more then happy to upload. Thanks

Edit:
Thanks Sparky256, no I haven't tried an ohmmeter as of yet.
user2943160: I'll attach some photos for location.

[


texts: How do I get the transfer functions of each channel for a control system?

texts:
Consider acontrol system with the following transfer matrix:

\$G(s)=\begin{pmatrix}
G_{11}(s) & G_{12}(s)\\
 0&G_{22}(s)
\end{pmatrix}\$

and suppose I want to get the transfer functions for the two channels in order to do some analysis in Matlab, for example look if there are pole at the origins or RHP zeros, or look at the effect of coupling, I am not sure if I should do as follows:

\$y_{2}(s)=\frac{G_{22}(s)}{1+G_{22}(s)}u_2(s)\$

and for the first channel is:

\$y_{1}(s)=\frac{G_{11}(s)+G_{12}(s)}{1+G_{11}(s)+G_{12}(s)}\$

Or I have to do something like:

\$y_{1}(s)=\frac{G_{11}(s)}{1+G_{11}(s)}u_1(s)+\frac{G_{12}(s)}{1+G_{12}(s)}u_2(s)\$

I ask because I have not clear how to deal with the effect of coupling when  I want to define the transfer functions for each channel.

Using Matlab, I have done:

F4_cross = (F4_min(1,1)/(1+F4_min(1,1)))+(F4_min(1,2)/(1+F4_min(1,2)));

where I considered \$F4_{min}(1,1)\$ as \$G(1,1)\$ and the same for \$G(1,2)\$ for reasons due to previous code. The problem is that \$F4_{min}(1,1)\$ has a pole at the origin, while \$F4_{min}(1,2)\$ doesn't. The controller then should have a pole at the origin for \$F4_{min}(1,2)\$ and for the other one not, if the steady state error has to be zero. Moreover, the step response for the coupled system F4_cross is :

so it is present a steady state error.

If I consider for example:

\$F4_{min}(1,1)+F4_{min}(1,2)\$

as open loop, I think this is wrong since it is a system with two inputs which are differents.

If I plot the step response I have two different step responses, one with infinite steady sate error and one with zero steady state error.

The way of operating should be to apply the decoupling, bit if I don't want to apply it I donìt see a way out.

I have tried doing:

loopsens(F4_cross_min,k1_1/s)

and this gives me zero steady state error, since F4_cross_min does not have a pole at the origin, but the syntax for loopsens is loopsens(plant,controller), and it closes the loop. But in this case F4_cross_min it is a closed loop, but this is the only solution I have found that works at least on the calculations, but I think it is conceptually wrong.

Can somebody please help me?


texts: Is there any 8080 Series Parallel Interface standard?

texts:
I want to know whether there is a standard for 8080 like parallel interface. What I want to do is connect LCD driver to MCU(stm32). Some doc told me how to connect MCU to the drivers via 8080 like interface here But it didn't tell the detailed meaning of CS,RD,WR lines. I searched some LCD driver datasheets but found contrary info:

SSD1289 use CS as clock signal(page 51) while ILI9340 use WR/RD as clock signals(page 29). So, is there a official standard for 8080 like interface? Or do I have to read the datasheets in detail each time when I want to use a driver chip?


texts:
I have a super simple question about solenoids.

If I wired this, a 120v solenoid valve, to a 3 prong male plug would this cheap chinese humidity controller be able to control it?
My assumption is yes, but I am mainly wondering if there is anything egregious that I am missing.

edit:this and that clarification


texts: Choosing the right Schottky for the voltage/amperage

texts:
What do these ratings mean when it comes to reading datasheets for Schottky and how do you pick a diode based on these ratings:

Current, Forward, Continuous

Voltage, Repetitive Peak

Voltage, Forward

For example, I have a 12V / 3A line that i would like to put a Schottky diode on to prevent backflow but have no idea what any of the above ratings have to be so that i get the right one.


texts: Measure voltage when battery is connected to lead without resistance

texts:
When we use voltmeter without resistance,(parallel connection) I thought it might have potential difference between two points, because of this equation
V=Ed
I thought There should be small difference 'd' between two points. So i connected what i said and I was embarrased to see "0" on my voltmeter.
So i wonder why this happen although V=Ed says there might be potential difference between two points.
I'm not a English user, so I'm sorry for my bad English.
But I hope someone could help me get out of this chaos.


texts: Stabilising a constant current load opamp feedback loop

texts:
I designed a constant current load around the ACS712 Hall-effect current sensor (module from eBay). This module gives a voltage output of 185mV/A superimposed on VCC/2. Its current range is +-5A altho I'm only interested in +I for this design. The schematic below shows the basics of the design.

simulate this circuit – Schematic created using CircuitLab
I had some trouble stabilising the feedback loop. The "error amp" (OA3) was open loop and gave a bang-bang output. The loop was unstable producing an oscillation in the 100's of Hz. Then I added C2 and increased the value of R13 to 100k. This reduced the oscillation to a great extent but there was still a low-level less than 100Hz oscillation producing a sawtooth gate drive on the MOSFET. After poking around adding bypass and roll-off caps to the opamps without much success I instinctively added C1, bypassing the "Gain Amp" OA2 and this completely cured the oscillation. My question is why did these changes kill the oscillations? I'm not the best at this kind of circuit design but my instincts led me in the right direction and I would like to understand why adding caps C1 and C2 made the difference. Also, do I have them in the right place or what other changes would you recommend to ensure stability.

I have not checked the impulse response of this loop nor how it behaves under dynamic conditions. I would appreciate some guidance on how to approach such tests.


texts: Detect the colour of an LED (Red Blue or Green)

texts:
I am trying to find a way of determining the colour of an LED without an electrical connection to it, i.e a sensor pointed at the LED. I can place the sensor quite close to the RGB LED I intend to measure, but i'm struggling to come up with something that will do what I need.

I will be using the sensor with a micro controller of some kind, probably an arduino, or the ti myRIO.

I found this Colour sensor however it looks like it might be overkill for my requirements.

Many of the other sensors I have come across work by shining RGB LED's on the object and measuring what is reflected back. I don't think they would work when the object I am measuring is a light source in itself. Am I correct here?
For example

Are there any other solutions that I am missing?


texts: What capacitor needs to be used for a circuit that limits the current?

texts:
I have the following circuit that is intended to limit the current that passes through diode D1

In this case, we can see on the graph that the current is limited at 5.31mA

We can see on the graph what happens to the voltage at the cathode of D5 (blue line) and the current at D5 (green line).

The input voltage is red line.

Instead of R8 i will have the IC BD9G101G that gives me an output voltage of 3.3V, and from the datasheet it says that it's input will need to be between 6V to 42V.
I actually have it connected in the following way:

Will i need to be careful with the value i choose for the capacitor in a way that it gives the desired voltage?
Another thing that i believe it's not good is that at the terminal of R8 the voltage will not be stable and that doesn't seem to be good for the IC that will be there instead of the resistor.
Or even if there is a better solution than using a BD9G101G that gives me the desired 3.3V output i'm open to replace it.

EDIT: i edited the circuits to be similar to what i really have.
The ideia of the current limiter is to make the circuit draw as little current as possible from the voltage source.


texts: Why are cables only made of round shapes? What is the advantage of it? Why aren't there triangular or quadrilateral or pentagon shapes of cables?


texts:
I have a query on (7,4) Hamming code.

The generator polynomial for this is \$g(x) = x^3 + x + 1\$. The non-systematic code for the message signal \$m(x)\$ is \$c(x) = m(x)g(x)\$

The above procedure is giving a different answer from what is given in many of books. The (7,4) Hamming code is given as:

\$\{P_1 P_2 M_1 P_3 M_2 M_3 M_4\}\$ is the code word for \$\{M_4 M_3 M_2 M_1\}\$ message signal where

\$P_1\$ is even parity bit for \$M_1M_2M_4\$

\$P_2\$ is even parity bit for \$M_1M_3M_4\$ and

\$P_3\$ is even parity bit for \$M_2M_3M_4\$

My query is that the above mentioned is not obtained both by systematic and non-systematic coding procedures. Can you please explain me where am I going wrong. (is it the generator polynomial or coding procedure ?)

I don't know whether it is the correct stack to post this question. Couldn't find one for communication engineering hence posted here.

Thanks in advance.


texts: What's causing the audible 7/8th rhythm in Qi chargers?

texts:
I have a wireless Qi charging system for my mobile phone.  When I put the phone into the cradle it starts getting charged and I can hear a very quiet noise coming from the arrangement.  Other questions (like What might cause audible noise in an inductive charging system?) are dealing with why there is noise at all, and that's understood.

I am curious why the noise (at least in my case) is so strangely rhythmed.  It is not a constant squeal as the author of the other Q described.  It is rather a repeating rhythmic tic pattern with a period of just under two seconds.  I can reproduce the pattern by saying something like

chip-chip-chip-chip-chip-chip-tatata

and repeat this right away (so it goes ...-chip-tatatachip-chip-chip-...).  The delay after each chip is around 0.27s, the delay after a ta is around 0.09s, so that as a whole the pattern has a period of 6×0.27s + 3×0.09s = 1.89s.

To the musicians among us:  The rhythm sounds like six 8th notes and then a triplet of the length of another 8th, so it is a 7/8th rhythm.

Can anybody explain what't going on in these circuits?  I have been searching for an answer for quite some time now but I found no mentionings of any rhythmic aspect in combination with wireless charging in general or Qi specifically.

It might be a special property of my charger of course, so I am not sure that this is reproducible for others.

EDIT: I managed to create a recording of the sound.  It is very silent, so there is a lot of noise captured as well.  Especially a wall clock in ~1m distance is clearly audible over the signal.  Here is a spectrogram of the recording over several seconds in the range 4kHz - 20kHz.  The pattern is clearly visible (and on the bottom you see the ticking of the wall clock).

I would love to upload an mp3 of the recording but this site doesn't make it as easy for sounds as for images.  Does anybody know of a equivalent of Imgur for sounds?

EDIT 2: I uploaded a recording to YouTube as a commenter suggested: https://youtu.be/xKPyiHGkoks


texts:
Simple question really.  Can I use Atmels Qtouch library with non-Atmel MCUs (such as an STM32)?

It seems like Atmel has a solid line of capacitive touch ICs, which come coupled with an API library for interfacing with them.


texts:
I found the following board in random research. Can anyone explain the reason for etching the green mask in red color circled area and that too patterned?

The other side of etch is the processor IC.


texts: Debugging with Blackmagic probe and platformIO undefinedError

texts:
As stated, was able to debug using this setup but suddenly I started getting errors. I am able to upload firmware to the target board (STM32 Bluepill) but when I start a debugging session I get the following error!
undefinedError: Traceback (most recent call last):
File “/Users/engmoh/.platformio/penv/lib/python3.8/site-packages/platformio/main.py”, line 109, in main
cli() # pylint: disable=no-value-for-parameter
File “/Users/engmoh/.platformio/penv/lib/python3.8/site-packages/click/core.py”, line 829, in call
return self.main(*args, **kwargs)
File “/Users/engmoh/.platformio/penv/lib/python3.8/site-packages/click/core.py”, line 782, in main
rv = self.invoke(ctx)
File “/Users/engmoh/.platformio/penv/lib/python3.8/site-packages/platformio/commands/init.py”, line 44, in invoke
return super(PlatformioCLI, self).invoke(ctx)
File “/Users/engmoh/.platformio/penv/lib/python3.8/site-packages/click/core.py”, line 1259, in invoke
return _process_result(sub_ctx.command.invoke(sub_ctx))
File “/Users/engmoh/.platformio/penv/lib/python3.8/site-packages/click/core.py”, line 1066, in invoke
return ctx.invoke(self.callback, **ctx.params)
File “/Users/engmoh/.platformio/penv/lib/python3.8/site-packages/click/core.py”, line 610, in invoke
return callback(*args, **kwargs)
File “/Users/engmoh/.platformio/penv/lib/python3.8/site-packages/click/decorators.py”, line 21, in new_func
return f(get_current_context(), *args, **kwargs)
File “/Users/engmoh/.platformio/penv/lib/python3.8/site-packages/platformio/commands/debug/command.py”, line 117, in cli

    server_executable = debug_options["server"]["executable"].lower()
TypeError: ‘NoneType’ object is not subscriptable

============================================================

An unexpected error occurred. Further steps:

Verify that you have the latest version of PlatformIO using
pip install -U platformio command

Try to find answer in FAQ Troubleshooting section
https://docs.platformio.org/page/faq.html

Report this problem to the developers
https://github.com/platformio/platformio-core/issues

My Environment:
-Mac Os big sur.
-vscode (Version: 1.54.3).
-PlatformIO (Core 5.1.1 - Home 3.3.4).
-BlackMagic probe clone (bluepill converted!) <-- Used to be working before the latest update.
This is the platformio.ini configuration:
[env:bluepill_f103c8]
platform = ststm32
board = bluepill_f103c8
framework = cmsis
board_build.mcu = stm32f103c8t6                 ; change microcontroller (override)
board_build.f_cpu = 8000000L                    ; change MCU frequency   (override)
upload_protocol = blackmagic                    ; SWD interface
debug_tool = blackmagic
debug_port = /dev/tty.usbmodem7BBB54AD1
upload_port = /dev/tty.usbmodem7BBB54AD1

What could be the issue here?


texts: Are all voltage reference ICs able to sink as well as source current?

texts:
I'm looking at the REF30xx series of precision voltage references from TI.  The datasheet lists a maximum output current of 25mA.  Every specification and figure on the datasheet (e.g. load regulation on pages 3 and 5) shows only positive output current (0-25mA).

This concerns me, because datasheets for other devices such as op-amps tend to have bipolar current ranges (-25 to 25 mA) and figures either have an axis that goes negative for output current or else shows absolute output current (using +/- mA).

Can I expect these voltage reference ICs to operate correctly in a circuit that requires them to sink as well as source current?

If not, can someone recommend a buffer circuit that won't ruin the low-noise characteristics of the reference voltage?


texts: If I'm correct that FPGA lookup tables usually have one output, is it the routing structures that would be used to duplicate them? Wouldn't that mess with input voltage requirements for other LUTs?


texts: How fast may I trickle charge a full LSD NiMH battery?

texts:
I've bought two packages of low-self-discharge nickel-metal hydride AA batteries, each made by a different well-known battery manufacturer.

Sadly, the datasheets aren't very detailed:

• One datasheet is just a single page long. It says that I should charge the batteries at between 0° Celsius and 40° Celsius. But it says nothing else about charging, let alone trickle charging.

• The other datasheet is two pages long. It discusses charging at a charge rate of 0.1C. It also discusses fast charging at 0.5C or at 1C. But it doesn't mention trickle charging at all.

Let's assume neither brand of cell has any gas-recombination capabilities. When a battery is fully charged, may I trickle charge it? If so, what's the maximum charge rate I may use? I don't want to damage the cell.


texts: Help me clarify this really unclear diagram?

texts:
5.2 Reduce control IC exposure

2a. Connect VS and COM as shown in Figure 6.

http://www.irf.com/technical-info/appnotes/an-978.pdf

(H-bridge application notes)

Do they want me to connect the VS pin to the COM pin, or is that some sort of typo?

EDIT: Please note there is literally no VS pin in this diagram. VSS doesn't mean anything when using the 8-DIP package, and COM does not look directly connected; so what the hell am I doing when it says to connect them, just taking a wire and soldering it to both VS and COM? Or do I run it through a decoupling/low-pass filter, a resistor, what exactly do I do.


texts: What is the value of this shunt resistor from a drone power distribution board?

texts: What is the value of the shunt resistor shown below? It is from the drone power distribution board, rated for up to 120 A. I am guessing, that the value is 0.25 mOhm. However, even with this value, at max current, power dissipation is ~3.6 W, which is way above the typical 2 W power rating.


texts:
I'm trying to set up an lm2734 to regulate a VIN of 9V - 12.6V down to 5.0V. I'm a bit of a noob, and the sample configurations they provide don't have the 5.0V output scenario. My specific question is around configuring the VBOOST pin - they define it as needing to be 5.5V > VBOOST – VSW > 2.5V for optimal performance, but my understanding is that the VSW pin goes back and forth between VIN and 0V (that being the theory of operation here). In another spot, they talk about using a zener in series with VIN to drop the voltage down. There, they talk about the limits on VBOOST needing to be

(VINMAX – VD3) < 5.5V
(VINMIN – VD3) > 1.6V

Where VD3 is the breakdown voltage of the zener.

What am I missing here? How do I figure out VSW? I'd like to understand the theory here, beyond just "use this configuration," though I do ultimately need to pick how do set it up. My hunch is that given VOUT of 5.0V, I can just run VBOOST directly off VOUT, without any additional circuitry, but I'm not sure why.

EDIT Elsewhere in the datasheet, I see a reference to

VSW can be approximated by:
VSW = IO x RDS(ON)

RDS(ON) is 300mO and IO would be somewhere between 500mA and 1A. It seems like this may be the answer, but I would still like confirmation / clarification from those better educated than I.


texts:
In the context of building PID controllers for very large heater systems (ovens, kilns, etc.) nearly all the designs I encounter use an SSR to switch the load, a choice I don't understand.

The power requirements can top 50A at 250V, where even a reasonable-quality SSR would be expected to dissipate something like 40-70W. By comparison a mechanical relay for the same capacity and quality is dramatically more efficient, doesn't come with inconvenient cooling requirements, and is 5-10x cheaper even on a bad day. Plus, EMRs generally fail open, which is a plus for heaters.

You could argue that SSRs have the upper hand on longevity and moving parts, but certainly not to a degree that justifies the price differential and special cooling requirements.

So... what's the benefit for SSRs here that I'm missing? Why are they preferred in so many designs?


texts:
In a single ended data acquisition system a DAQ board is sampling channels in a multiplexed way. The DAQ is single ended as well as the input signals.
When I use two analog transducers coupled to two channels where ch0 is accelerometer and ch1 is an ultrasonic proximity transducer; in this case I see noise in ch0.

And this noise shifts with the sampling rate. And if I remove the ch1 (ultrasonic sensor), then the noise disappears from ch0.

Obviously ch1 (ultrasonic sensor) is causing aliased noise in ch0. But can this be a common mode noise? What could be happening? (At the moment I'm not able to provide more quantitative data.)

EDIT UPDATE:

Noise appears at ch0 even if I only connect the ground of ch1.

I could now draw the complete system:

simulate this circuit – Schematic created using CircuitLab


texts: In amplitude modulation is the carrier wave multiplied by the radio signal wave to form the equation of the resultant wave to be transmitted?

texts:
I understand how to add sinusoidal waves. They use the priciple of superposition and the original waves are not affected. However in amplitude modulation the radio wave that is transmitted is a result of a modulation of a carrier wave and a signal wave. However I do not understand how these waves are "blended" together. I am struggling with different articles.
Are they multiplied together perhaps? But how? It appears remarkable to me that electrical signals would multiply together. Perhaps someone understands the math behind this and could offer a clue.


texts: Thermal considerations for electronic measurements

texts:
Background

Generally components behaviour changes with respect to temperature, e.g. a resistors resistance is a function of temperature, as is the saturation current of a BJT.

When putting a current through a component this can cause the temperature of the component to change.

Question

Given that a circuit is driven with a repeated periodic signal, will the temperature of the components approach a constant temperature over time? (For arguments sake consider room temperature constant and the circuit is in free air).

Application

I want to measure the behaviour of a circuit, and want for example the resistance of a given resistor to be as constant as possible for the duration of the measurement. Is it wise to drive the circuit for a period before taking the measurement such that the change in resistance due to heating is minimal? This would include enabling power supplies etc.


texts:
I came across this package

Never saw anything like this before. Does anyone know what it is and how it's supposed to be mounted?


texts: Syntax error near "else" in Verilog, in an initial block, next to assert

texts:
I'm trying to make a self-checking testbench for an ALU I'm designing for an extra credit assignment. Here's what I have:

module testbench();
    wire [31:0] a, b, y;
    wire [2:0] f;
    wire zero;

    alu test(a, b, f, y, zero);

    initial begin
        a = 0; b = 0; f = 3'd2; #100;
        assert (y === 0) else $warning("0 + 0 failed");
        a = 0; b = 8'hFFFFFFFF; f = 3'd2; #100;
        assert (y === 8'hFFFFFFFF) else $warning("0 + FFFFFFFF failed");
        a = 1; b = 8'hFFFFFFFF; f = 3'd2; #100;
        assert (y === 0) else $warning("1 + FFFFFFFF failed");
        a = 8'h000000FF; b = 1; f = 3'd2; #100;
        assert (y === 8'h00000100) else $warning("FF + 1 failed");
    end
endmodule

I'm getting four critical warnings, all of them saying 'Syntax error near "else".', for each of the lines with the assert statements. I don't know why that's happening, I have the statements in the initial block. Does anyone know if I'm missing something here?


texts:
I am trying to synthesize around 3000 different modules. The verilog codes for these were generated using a python code.

Is it possible to automate the synthesis and compile the results such as number of LUTs used and critical path?

NOTE: I am currently using Xilinx ISE.


texts: How does this Logic Analyser front end work?

texts:
Hi I was reading on EEVBlog, some guy has reverse engineered the Logic Analyzer within the new Hantek MSO5102D MSO. I had a question about the front end part:

This is a 4-channel section of the front end. I understand that VT1 is used to control the threshold voltage by scaling the incoming signal through a voltage divider. But why are the capacitors needed?

Is this something to do with the inductance of the probe wires? How does this help if the user can conceivably attach any wires to the logic analyzer? - so the designer can't know what the inductance will be.

Or is this some kind of band limiting filter? If so, why is there a resistor in parallel with the capacitor?

I would be much obliged if someone could enlighten me about the design of this high speed circuit.


texts: Startup and auxiliary/station transformer power parallel to bus

texts:
This question is in regard to switchyard/electrical distribution operations in a utility power plant.

During a startup, the electric distribution system is lined up so that the startup transformers will power the various 4.16kV buses. The startup transformers are 230kV/4.16kV.

When one of the main generators at the station synchronizes, it can provide station power to the 4.16kV buses via the auxiliary/station transformer (24kV/4.16kV).

For most of the 4.16kV buses, there are breakers for the startup supply, aux supply, and sometimes a diesel generator.

For one of these buses, is it expected that equal current will come from the startup and aux/station transformers when both are paralleled to the bus?

Usually the transfer for startup to aux/station power does not take long, but as I understand there is still time when the two sources are powering the distribution system in parallel.

Is there a good design/operation reference for explaining this?

I have been getting explanations involving circulating current with parallel transformers, but I believe the case I am looking at is different. There are two transformers from different supplies, and they are feeding a bus in parallel.

Also, there are synch switches and fast bus transfer on these feeders but there are interlock switches to override that logic and keep both supply breakers closed in the parallel arrangement. This override allows for testing of the supplies from the startup transformers.


texts: How is High Precision in Op-amps based in BJT accomplished?

texts:
With BJTs there is always an associated Vbe. So when designing with them and taking output from emitter, I simply add a tiny offset so the signal lower than Vbe won't be clipped below ground, then clamp to ground any excess offsetting. I also employ few simple rules together with this so that I encounter fewer Vbe and Vce's. But sometimes I just can't avoid them without making the implementation messy or costly.

Since there have High Precision Op-amps out there (I'm sure some are BJT based), are there any techniques used by Microelectronic Engineers that can more cleanly mitigate these forward voltage drops?

EDIT:

To be specific, I need to balance 2 sides of a circuit. I've settled on raising the effective ground of the other side, but I can't design a simple voltage follower (that will be the effective ground) that is accurate enough and does not disturb the opposite side.


texts: fpga gpio pins as uart pins (tx and rx)?

texts:
I am trying to use fpga de2115 and (ftdi ft232rl usb to serial)  to communicate with pc.
Can the tx/rx pins from the adapter be connected directly to the fpga gpio pins?
The board has rs232 port , but i don't have the rs232 cable and also want to avoid this.
So can i assign uart hdl assigned pins to fpga gpio and connect them to the adapter tx/rx pins?

thank you.


texts: Data received when earpiece connected to audio jack?

texts:
I'm still new to electronics and signals.

I'm currently doing a project, and i have to detect the type of earpiece connected to an audio jack. So far, i found out that when you plug in your earphone/headphone, your mobile device detects that a earphone is connected, meaning, there is some sort of data being transferred when connected. Is it possible to detect the type of earpiece(or any sort of info) through the audio jack.

Thanking in advance.


texts:
So do electret mics have polarity?
The following circuits seem to contradict each other...

1)

2)

Now the problem is one image shows polarity while the other one does not!!
What's the holdup here?


texts: I have one question. Refer Image attached by me. There is Main Motor M1 connected by star delta starter and M2 is fan motor whose connection is taken from Delta contactor. I have question here IF there is short circuit happen in fan motor/ In its connection will that short circuit current will flow through M1 Motor stator winding?IF No then Why?


texts: What exactly does the frequency spectrum represent?

texts:
The signals in the image represent a low pass signal and its Hilbert Transform. I know that a plot for a signal's magnitude with reference to frequencies can be found by applying a Fourier Transform. However, I've always read that the frequency plot can contain only the magnitude or only the frequency at a time. If it's only a magnitude spectrum, the values must all be positive. However, the second plot in the image has the positive frequency components in the fourth quadrant.

So my question is, what exactly is the plot representing and how is the plot made?


texts: Windmill generator voltage-regulation with clamping diode

texts:
I am making a windmill powered generator. The charge controller I have is rated for a maximum input of 15V. I want to protect the controller in the event of high voltage spikes produced in a wind storm (50 V max from generator motor, for example).

I am wondering if/how I can use an avalanche (clamping) diode to shunt excess voltage away from the controller, to ground. Under normal circumstances, the charge controller will charge a 12V battery bank.

The general schematic is attached. The exact parts could be:
Avalanche diode
Resistor

Note: Since the diode is rated for 5W peak continous, at 50V I think I may actually need 500 ohms resistance although the picture shows 200.


texts: 4 cell bath scale to Arduino what is circuit?

texts: A bath scale has 4 cantilever beam load cells; one at each corner. Each beam is fitted with 2 strain gauges glued to one side of the beam and three lead wires, Red, White, black, go out of the cell to the pc board (12 leads in total). Resistance r-b=1K ohm; r-w=1K ohm;w-b=2K ohm. What is(are) the Wheatstone bridge(s) and circuit for the voltage as a function of total weight?


texts: programming a BEKEN BK3431 bluetooth 4.0 ble tag chip

texts:
I have few BLE tags, with button+led+buzzer (AKA "iTag"),
I opened them up and saw it's based on one chip: BEKEN BK3431.
I have access to the following JTAG/test pads:

VCC3V |
GND |
P05 |
P04 |
P06 |
P07 |
PROG |
RSTN |
TXD |
RXD

I searched online and could not find an references for programming it.
I want to build a simple costume firmware (in c/c++), and make the tag broadcast custom data.
What development tools/hardware and software do i need to upload my own firmware on this BK3431 tag? Is anyone familiar with this chip?
Thanks


texts: Is a NAND flash chip better for power saving purposes as a micro SD card?

texts:
I know, they are technically the same, but from what I read, NAND flash chips can be controlled better like putting it into standby and waking it up in the matter of a few nanoseconds, which could be useful for recording projects that need to transfer the RAM buffer every few seconds.
I would need at least 128GB / 1TBit, so NOR flash chips are unfortunately not an option.
It would be worth it to implement a BGA package, but only if that saves more power than a micro SD card which is typically designed to be as fast as possible for the end consumer.
Also, I was not able to find out much about that, but I read that NAND flash chips have two modes: SD and SPI. Does that mean they can be connected just like a micro SD card via SPI protocol to a MCU just with the addition of more pins like chip enable, etc.?
Unfortunately, it is pretty hard to find any datasheets of bigger NAND flash chips, so maybe some people with experience on that matter can help. :)
And besides all of this, is there any other method to save data more efficiently on battery powered devices?
I apologize for any spelling/grammar errors - I'm not a native English speaker.


texts: Why does a timing light connect to 12 V?

texts:
I'm curious why an ignition timing light needs to connect to the battery to work.

I may not be fully understanding how they work, but I'm guessing there's an inductive pick up and that illuminates the bulb.

So couldn't just that inductive kick be enough to light the bulb?


texts: How should I design a heat sink for an SMD power mosfet?

texts:
I really like the specs for the Infineon OptiMOSPower-Transistor IPT007N06N, but how would I keep this beast cool? Usually I use regular aluminium heat sinks (with water cooling or a fan) for MOSFETs in this power category, but this has to be soldered onto a PCB. Would I create a larger copper area and then attach a heatsink to this, or is there a way to keep the PCB itself cool? What is the usual the strategy here and are there any sample designs?
Datasheet of IPT007N06N (pdf 1.2 MB): https://datasheet.octopart.com/IPT007N06NATMA1-Infineon-datasheet-43351903.pdf