texts:
Considering a 3 phase inverter using MOSFETs without body diode or GAN as transistors. How can the FETs safely emulate diodes?

I mean I understand the transistors in question must be able to conduct in both direction in their on state. But is this all synchronized? Take the scenario below where M1 is ON conducting current to the motor.

simulate this circuit – Schematic created using CircuitLab

Now when M1 is OFF, I take the basic idea is to have M2 go on immediately. But before this can happen, I presume one still require some deadtime to avoid a shortcircuit. But would not this  in theory produce "infinite" negative voltage across the inductor during this deadtime?


texts: Why are MOSFETs switching at a different speed than the one they are being driven at?

texts:
I used a 555 oscillator to drive a MOSFET array for my entry-level tesla coil setup. When I measure the frequency at the driver output (Location #2) everything seems normal. When I measure it at the MOSFET output (Location #3) I get an altogether different frequency. Why could that be? What improvements can I make to my circuit?

simulate this circuit – Schematic created using CircuitLab

Here's the circuit.

Thank you,

Riccardo


texts: Alternative way to obtain h parameters without using a short circuit

texts:
I'm trying to answer the following question from a text:

  Sometimes the use of a short circuit leads to generator damage. Can
  you suggest an alternative means of obtaining data to calculate the
  h parameters without using a short circuit?

I know that to find the output impedance of a power supply we can use two resistor loads instead of shorting. How about in this case`? Can you give an example?


texts: What is the advantage of using a center tapped transformer in a full wave rectifier circuit?

texts: A half wave rectifier doesn't use it, still it shows output.


texts: Mathematical help with Wheatstone bridge

texts:
This is a homework, so I won't ask for a complete solution, but can anyone tell me how should I approach this?
I've been sitting now for hours without any progress, all that I know is the answer should be (0.01Ohm).
If someone is willing to dedicate his/her time to truly solve this I'd really be grateful!
Thanks.


texts: Carrier concentration decreasing with increase in temperature in a semiconductor

texts:
I have come across this equation in my semiconductor study $$
n_{0}=n_{i} \exp \left(\frac{E_{F}-E_{i}}{K{T}}\right)
$$ where$$n_i$$ is the intrinsic electron concentration .  This equation  gives us the electron concentration as a function of temperature.
But this equation suggests that as we increase the temperature, the conduction electron density decreases which is contrary to the fact that as we increase the temperature more and more electrons jump into the conduction band and hence increase in carrier concentration.
Where am I going wrong,please help.
Thank you in advance.


texts: Transmitter and Receiver antennas in mobile phones

texts:
I understand that in old cellular systems where FDD were employed, we used to have same antenna at the mobile phone (User equipment) for transmission and reception.Moreover, a duplexer was used to separate them.

In modern cellular systems (Say, 4G and above), do we have separate antennas for transmission and reception in the mobile phone. If no, do we still use duplexers for isolation?


texts: Control ESSP8266 IOT board over cellphone hotspot wifi

texts:
I am using the following code in order to control my ESP8266 using my cellphone hotspot.

/*
 * ESP8266 NodeMCU LED Control over WiFi Demo
 *
 *
 */
#include <ESP8266WiFi.h>
#include <WiFiClient.h>

//ESP Web Server Library to host a web page
#include <ESP8266WebServer.h>

//---------------------------------------------------------------
//Our HTML webpage contents in program memory
const char MAIN_page[] PROGMEM = R"=====(
<!DOCTYPE html>

by J.Mehdinia

Ciclk to turn LED ON

Ciclk to turn LED OFF

LED State:

)=====";
//---------------------------------------------------------------
//On board LED Connected to GPIO2
int LED=5;

//SSID and Password of your WiFi router
const char* ssid = "Jms";
const char* password = "ab12";

//Declare a global object variable from the ESP8266WebServer class.
ESP8266WebServer server(80); //Server on port 80

//===============================================================
// This routine is executed when you open its IP in browser
//===============================================================
void handleRoot() {
 Serial.println("You called root page");
 String s = MAIN_page; //Read HTML contents
 server.send(200, "text/html", s); //Send web page
}

void handleLEDon() {
 Serial.println("LED on page");
 digitalWrite(LED,HIGH); //LED is connected in reverse
 server.send(200, "text/html", "ON"); //Send ADC value only to client ajax request
}

void handleLEDoff() {
 Serial.println("LED off page");
 digitalWrite(LED,LOW); //LED off
 server.send(200, "text/html", "OFF"); //Send ADC value only to client ajax request
}
//==============================================================
//                  SETUP
//==============================================================
void setup(void){
  Serial.begin(115200);
  WiFi.begin(ssid, password);     //Connect to your WiFi router
  Serial.println("");

  //Onboard LED port Direction output
  pinMode(LED,OUTPUT);
  //Power on LED state off
  digitalWrite(LED,LOW);

  // Wait for connection
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  //If connection successful show IP address in serial monitor
  Serial.println("");
  Serial.print("Connected to ");
  Serial.println(ssid);
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());  //IP address assigned to your ESP

  server.on("/", handleRoot);        //Which routine to handle at root location. This is display page
  server.on("/ledOn", handleLEDon);  //as Per  , Subroutine to be called
  server.on("/ledOff", handleLEDoff);

  server.begin();                  //Start server
  Serial.println("HTTP server started");
}
//==============================================================
//                     LOOP
//==============================================================
void loop(void){
  server.handleClient();          //Handle client requests
}

Everything works fine by using ESP8266 IP address in an html page through devices that use my shared hotspot to connect to the Internet. But I can't access that html page by using internet coming from other internet access points. I'm new to ESP8266. What is the reason and how may I solve it? I don't have another kind of internet access to test now.


texts:
I have read many posts on this site and everyone seems very competent, so here I am... very new to this. I'm trying to learn how to convert a motor into a generator. I'm just getting a bit overwhelmed with details and specs. Sorry I'm just a carpenter that likes to mess with stuff...

I'm trying to basically build a diy generator, nothing big, mostly conceptual. I won't waste your time with my failed attempts and research. Could anyone just give me a rundown on the type of motor (bush less induction perminate magnet). Where to commonly find one (fans drills microwaves)and how to regulate the power if nessary.

If I can even run a simple led or maybe a constant 5v to charge a USB device that would be fun.

I know this has been posted before but again I'm just a hobby guy getting confused. And tips or rule of thumbs or advice or links is much appreciated. Thank you all for your help.

Update: I just found a washing machine motor if that works. Researching how to convert it. Stupid question how can I tell if I need ac or dc, sorry I work with wood... Thank you for responding I am researching your advice


texts: Time delay dpdt relay using only pot, relay, and cap (discreet components and no transistors)

texts:
I am trying to design a simple time delayed relay circuit that uses only a potentiometer, 5V dpdt EM relay, a single sufficiently large capacitor, additional resistors (if needed), and buttons/switches, powered by a 9V battery. The schematic below works to simply turn on an LED while a button is pressed and keeps it on for a moment. I have only been able to extend the time by adding more caps in parallel. I believe there is a simple solution to this logic problem that has the relay triggering itself almost as an oscillator, but when setting up as an oscillator I still can only vary the time by adding caps. How can I arrange and wire the components mentioned to allow a time delay of a few seconds to minutes, dependent upon a single potentiometer?

I thought a toaster's circuit would work, but most I see use a 555 timer or a pair of transistors and other components. Is there a simple way to use an RC circuit alone as a timing circuit without the solid state components?

I know how to do this using transistors and ICs, but that is not the point. It is an experiment to show a possible use of capacitors and RC circuits without first teaching about solid state components, ICs, etc.

The time delay can be delay ON or delay OFF.

Thanks

simulate this circuit – Schematic created using CircuitLab


texts: Expressing the current through a dependent voltage source

texts:
Consider the circuit below:

The task is to find the node voltages V1, V2 and V3 (labelled 1, 2 and 3 above). In order to solve the problem I apply the node voltage method; summing all the currents going out of each node. However, I am having difficulties expressing the current going from node 1 to node 3 and vice versa (the one passing through the dependent voltage source). This is how I attempted to express the current from node 1 to 3:

However, the mark scheme states, without any explanation, the following:

I am confused by the - sign as in my head the current is moving from 1 to 3, and the difference in potentials across the resistor must be: V1 - (V3 - 8Vb). I have tried searching for similar problems, but the problems which I have encountered have only considered the dependent voltage source on its own (no resistor etc. connected in series). It would be deeply appreciated if anyone could explain how to express the current in terms of the node and dependent voltages.


texts: 1 TTL IC -> inverter + 2-input NAND + 3-input NAND

texts:
I came across this question in my homework:

Implement the following gates using only one TTL IC: one inverter, one 2-input NAND and one 3-input NAND.

The type of IC they're talking about has 14 pins, where pins 7 and 14 are GND and Vcc respectively. Also, the rest of the pins are the in/outputs of 4 gates of the same type.
This example is given:

Using only one TTL IC (OR gates) to implement a 4-input OR gate.

So far, I can only figure out the following:

The gates inside the IC should be NAND.
1 NAND gate can be used to make the inverter:
1 NAND gate as the 2-input NAND (obviously).
3 NAND gates can be used as the 3-input NAND:

However, there are not enough NAND gates inside the IC for all of this. How do I fit them all?


texts:
Using Multisim, I was able to calculate these current values, however I can't seem to understand their correlation with the individual mesh loop current values I calculated using matrices in MATLAB.
In my calculations, i1 is 3A, i2 is 2A, and i3 is 4A. How would I show that the data in this model supports these calculations?


texts: Altium - Daisy-chaining repeated schematic sheets

texts:
Is there a more elegant way to do the following?

Essentially I am trying to daisy-chain multiple "LED" devices, each with a data-in and data-out port. So do1 will be connected to di2, do2 -> di3... etc.

The way I have it works okay, but I'm wondering if there's a less manual way to connect them. Also, the way I did it gives "multiple names per net" errors. Is there a way you're supposed to connect signals from different buses without generating this error?

Thanks!

EDIT:

It seems like the bus joiner components in the FPGA_Generic library can do what I need, but they don't work with non-FPGA projects.

I can't find any functionality like this for non-FPGA projects.


texts:
I have the following circuit which is an AM demodulator (I think). RF input is between the diodes left:

Plotting the bode plots for the negative and positive input of the comparator, I get a lousy allpass for the positive input (with a small notch at 10kHz) and a multi-order lowpass for the negative input.

What is R1+C6 for? If V+ should have the unfiltered input, why not directly connect RF?
If V- should be lowpass filtered, why not choose the components such that we get actual 2nd order rolloff rather than having the poles so widely spaced (or the zero in between)
At the input of the comparator is a high frequency signal which would toggle the bits at a high rate. Now I get it that the comparator is probably too slow for that but I feel it's odd relying on parasitic elements rather than actually creating the desired behavior.
Does the circuit work for for low modulation index, i.e. when I encode bits such that 1 represents a full carrier wave and 0 represents 20% attenuated carrier wave?
Anything else to say about this circuit? Is it well known?

I also simulate this system in MATLAB, creating a 1GHz RF signal with 10kHz baseband data, demodulating the RF signal with "rf*sign(rf)" and filtering with the two calculated filters and comparing the values. I cannot get meaningful results.


texts: Serial Communication between Lidar and Arduino

texts:
I currently have an existing system that communicates with a Lidar using the (White Brown) (Orange) (Yellow) wires. I'm looking to replicate the way in which the Lidar communicates with the current system using an Arduino.
The unit uses a PLC communication protocol to communicate with external devices.
Please could I have an explanation for the schematic, the communication protocol and the hardware required for this task?
Link to the data sheet here: we.tl/t-xS0BMNWP4Q


texts: Arduino i2c communication hangs while running motor

texts: I'm have a Arduino mega 2560 board connected with PCA9698(I/O expander) through i2c communication. Controlling if input and output were working correctly. The data pins from the PCA9698 is connected to the 24v DC motor driver(BTS7960) and also sensors(PROXIMITY sensors). While reading the sensors there are no issues, but While running the motor the PCA gets hangs and i2c gets disconnected.


texts: How to find the phase of this transfer function?

texts:
I have been trying to find the phase of this transfer function:

G(jω)H(jω)=0.1695/jω(5.88jω+1)

by doing this:

Phase = -arctan(0/0.1695)-arctan(w/-5.88*w^2)

PHASE = 0-arctan(1/-5.88*w)

Is this correct ? since for some reason the result does not make sense.


texts: Learning how to do DC and AC operating point biasing for a single transistor amplifier circuitry

texts:
I am trying to learn how to do proper DC and AC operating point biasing for a simple transistor amplifier circuitry before I attempt to debug https://github.com/promach/frequency_trap. Could anyone guide me ?

The output conductance angle for this class-c amplifier is not right at all. WHY ?

Why does the voltage-across-Cb or v(vin, vbase) varies sinusoidally around 85mV ?  Note: i(v_ip1) is the collector current

simulate this circuit – Schematic created using CircuitLab


texts: Messing with rgb leds and have a question

texts:
I have some LEDs that I'm wanting to use in a project. I would like to know what's the best resistor I would need to get the most light out of the 3 different colors using a 12v source. I've measured the forward voltage drops of the LEDs as:

Red: 2.17 V
Green:3.11 V
Blue:3.07 V


texts: Trouble transferring schematic (working) to actual circuit (not working)

texts:
EDIT: At this point I'm just going to implement it in software. I give up. :< Thanks though!

So I keep screwing up this circuit, and the simulation works just fine.

The simulated circuit: http://pastebin.com/fuWYgYjC

In the rest of the album now.

A sketch of how I put it onto the breadboard,

and pictures thereof (are in the album linked above)

It's color-coded, so I can find mistakes more easily (didn't seem to help though). Red = V+, Black = V-, Green = GND, Yellow = Mic Input, Orange = LED Output. The op-amp I'm using is an LM741.

It's supposed to change the peak brightness of the LED depending on the ambient sound level. The frustrating thing is that the simulator is happy with it, but on the board, the op-amp can't even keep its inputs at the same voltage (4.4 V difference). The voltage drop on the resistors is wrong too, and I think that's caused by the former.

What did I do wrong?


texts:
I am working on prototyping a gas leak detector device to be used in homes, it should have two small windows in the casing to allow sound to go out and the other window allows gas to reach the sensor.

Is conformal silicon resin enough to prevent the PCB from initiating a spark causing fire?

What kind of classification does it fall under, is it ex d class 1?

Thanks in advance


texts:
I have a 5v relay which is not working on my esp-32 dev board. I understand that there logic levels are different but i checked the seller and they say it works with 3.3 logic level. When powered by the 3.3 pin on the board, the relay light turns on however it does not work. Sometimes the green light turns on but there is no sound or vibration of the latch opening/closing. Up till now you could dismiss all of these  problems by saying that the board requires more power(5v). I thought so too. However what is bothering me is the fact that when the relays IN pin is connected too ground it turns on. Furthermore, i have also tried powering the board using a breadboard power supply(set to 5v) and triggering with esp-32 board but that too has failed? Could someone tell me If the problem is my code? relay? or mabye it is the right ammount of current/voltage?

( ik this is an electronic forum and am only asking about relays electrical side.this code is just to show it isn't a problem on the software side:) )

For testing purposes i am using this code:

void setup() {
  pinMode(23,OUTPUT);
}

void loop() {
  pinMode(23,HIGH);
  delay(250);
  pinMode(23,LOW);
  delay(250);

}


texts: Shunt Resistor on output of Voltage Regulator?

texts:
I was looking through a popular circuit on Sparkfun and trying to lower the power consumption of the device. I found that the outputs of their regulators are shunted to ground with a 300-ohm resistor.

Any idea why they shunted the output to ground with a resistor?
Does it have to be such a low resistance?

I'm trying to reduce the current consumption of this small device as much as possible. Thanks!


texts: I'm currently studying electronics for the first time. The objetive of this exercise is to calculate the current I and the dissipated power in the dependent source. However, I'm having a hard time because I believe this circuit to be a current divider, but the solution states two values (I=2A and P=560W) that are incompatible with my interpretation. I am aware of how basic this question is, but I've searched everywhere for an answer with no sucess.


texts: How to determine RC filter cutoff of an ADC reading?

texts:
I'm making a circuit where I'm voltage splitting a variable resistor and then sending the input to an ADC pin on an Arduino.

My question is, what frequency should I set a low pass filter for?  How do I got about figuring out what it should be?

For context, the variable resistor will be measuring changes in pressure from a foot.


texts: 1.5V to 30V fixed frquency PWM generator

texts:
I've need a circuit to take analogue power from a model train track (0-20V DC) as it enters an engine, then apply PWM at a reasonably fixed frequency (say 200Hz), and use this to drive the motor, so that the motor runs slower than it would strait off the track, but there isn't PWM through the tracks which seems to create dirty rails and stalled engines.

By arranging 2 NPN bipolars with a pair of diodes in reverse across each one, I can create a switch to amplify the PWM signal while retaining input direction. But I need a PWM drive circuit.

The awkward bit is, it needs to start at less than 1.5V, and handle up to 30V (should only ever reach 12V max under normal operation)


texts: Available synchronous buck converter chips are bidirectional (current)?

texts:
I was going through available synchronous buck converter ICs with external PWM capability (which can be controlled with the help of a micro-controller) and i found this one for e.g. I have read in a post here that synchronous buck converters are bidirectional in nature. So keeping that in mind this chip IR3553 should also be bidirectional (i.e it should be able to deliver current from and to both sides if required). Is it so ? For e.g if i charge a battery using this chip and after charging i simply replace my power supply with a Load, will this IC be able to supply the current to the load from the battery ?

Ive gone through its data sheets, and many other IC's datasheets, but i couldn't find any information related to its bidirectional use. So if anyone has experience with such ICs or knows about such ICs, can you please answer my question ?

Thanks in advance!. Comments would be highly appreciated

Thankyou!


texts: How to compute the charge of a required battery if I know average power usage of device

texts:
I have a device that operates on average 0.6 watts.  I want to design a battery that will leave this device on for 17 hours straight.  I know that charge(Q) = current * time.  My device has an operating voltage of 5 volts. So my calculations are:

(0.6 watts / 5 volts) * 17 hrs = 2000 mAh

I also want to charge the battery using a solar panel for 7 hrs of sunlight. So i wanted to compute the required wattage from the solar panel to charge this battery to max capacity in 7 hrs:

(2000 mah / 7 h) * 3.7 v = 1.05 watts

(3.7 volts battery)

Can someone please verify that my math is correct?


texts: I WANT at least 3 uart in interrupt in stm32

texts:
while I am using six UART in interrupt then my hardware is not working properly i.e hanging.
could you please tell me what should I do for this?
while I am using the polling method then it's ok but on interrupt, it's not working.
I am using call back function
void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)
{
  //check for global interrupt active or not
  if(huart->Instance==USART5) //for printer
  {
    if(Rx_data!=0x0D)
    {
      rx_button[Rx_indx++]=Rx_data;
    }

    if(Rx_data==0x0D)
    {
      if(rx_button[0]!=0)
      {
        for(uint8_t i=0;i<15;i++)
        {
          buffer[i]=rx_button[i];
        }
      }

      if(rx_button[0]==0)
      {
        for(uint8_t i=1;i<15;i++)
        {
          buffer[i-1]=rx_button[i];
        }
      }

      Rx_indx=0;
      for(int i=0;i<15;i++)
      {
        rx_button[i]=0;
      }

      if(huart->Instance==USART6)// from LCD TOUCH
      {
        if(Rx_data!=0x0D)
        {
          rx_button[Rx_indx++]=Rx_data;
        }

        if(Rx_data==0x0D)
        {
          if(rx_button[0]!=0)
          {
            for(uint8_t i=0;i<15;i++)
            {
              buffer[i]=rx_button[i];
            }
          }

          if(rx_button[0]==0)
          {
            for(uint8_t i=1;i<15;i++)
            {
              buffer[i-1]=rx_button[i];
            }
          }

          Rx_indx=0;

          for(int i=0;i<15;i++)
          {
            rx_button[i]=0;
          }
        }
      }

Thank you in advance


texts: Designspark Positive/Negative Setting for Gerber grayed out

texts:
i want to create gerber files for a pcb. One gerber file per layer more specifically. I have made gerber file on designspark many times before, but now the Positive/Negative option in output manufacturing plots>Settings  is grayed out. ( see picture, on the right side, Design 2).

On my 'malfunctioned Design 2', This option only gets activated when i create/Add plots by selecting the 'windows' option, while i need the "gerber/Photo plot option.
Any ideas?
Thank you.


texts:
Okay so I am working with an Arduino Uno and the uno only outputs from 0-5 volts. I am using a breadboard and I built the circuit below using a LM471 Op-Amp and I am trying to boost the voltage from 0-10 volts doing simulations it works just fine and when I input 5 volts it does 10 volts outputs and when I do 4 volts it outputs 8 volts and so on. I built the circuit but when I check the voltage it only outputs 5 volts.

My quesiton... is there something I can do see what I am doing wrong? why am I getting only 5 volts for output when I should be getting 10 volts. Any type of help would be great. Thank you.

simulate this circuit – Schematic created using CircuitLab


texts:
I have a class of sequence item with rand variables:

class my_seq_item extends uvm_sequence_item;
rand bit a, b, c, d;

I want to generate a random bit for 'd' only if 'b' and 'c' are 0.
How do I write a constraint for this?


texts: I'm building a lamp and want to integrate an analog voltmeter (0-300 volts AC) in to the circuit. It has an LED backlit dial that requires a separate, 6.3v power supply. Any suggestions on how an idiot (that's me) can pull this off inside a very small wooden box that I am using for the base of the lamp?


texts:
I just have a quick question. In my lecture notes, he defined the PID controller as

And then he said that this is equal to the following

How did he do that? What is k, z1 and z2 equal?


texts:
Supposing I have a discrete time signal x(n). when I pass this through an FIR filter h(n), and again pass this result through h(n) again (essentially this is a second order filtering), the group delay increases by a factor of 2. what are the practical implications of this?

The same concept is used while implementing a matched filter receiver . where the same filter which is used in the transmitter side is also used in the receiver side.

Thanks in advance

phani tej


texts:
I have this RTC module by MikroElektronika:

I need a schematic and/or user manual but it's no longer on the MikroElektronika website. (There's a similarly looking PCB but it uses a different IC than the PCF8583 used here.)
Any help would be appreciated.


texts: So basically I'm trying to figure out the distance that a person's hand is from maybe a point on the center of their chest and their bicep. I'm trying to get the position they are moving in as they attempt an exercise. I've tried using accelerometer and gyros but there error is horrible and adding a magnetic sensor and then using Kalman filtering to predict the positioning is probably out of my skill level. So I'm thinking to place magnets on the bicep, wrist and center of the chest and somehow measuring the distance between them with a magnetometer as the person is moving their arm. Is this possible? If not, are there any other options I can try.


texts:
I need to take a 12MHz AC sine wave, from around 3.3V - 10V @ 10uA, output 50V, @ 1A (or more).

I have the signal generator for signal input, but I am not certain what I need for a circuit to step that up to the appropriate power level. And what if any isolation and OCPD I might need to protect my control circuit.

Should I use a toroidal transformer? Something else? Can someone point me to a specific device or module that I can buy?


texts: How do I amplify a square wave pulse of 4 to 8 periods at 3.5 MHz from +-2V to +-60V or more?

texts:
I am working with ultrasound sensors optimized for 3.5 MHz signals, and I want to test these using my PicoScope 5000 with integrated signal generator. The PicoScope is able to generate arbitrary square waves with an amplitude of max +-2V, and I would like some circuit to be placed between the PicoScope output and sensor which amplifies the square wave to +-60V or more.

The ultrasound sensor has an impedance of approximately 41 ohm, and is connected in parallel with a TX810 evaluation board used as a T/R switch.

The square wave pulse needs to be from 4 to 8 periods long, and it will be repeated approximately every 70ms.

I've been experimenting with Microchips MD1213DB1 evaluation board, but find that it is not a perfect match as it requires a phase shifted square wave and an Output enable signal in addition to the original square wave. Since the PicoScope only has one output (being the square wave) this became difficult to implement. Also, I just fried my MD1213DB1 board and I'm hoping that I don't have to order a new one.

Is there a cheaper and easier way to achieve the pulse amplification?

Edit:

I want to test how the ultrasound sensor performs using square waves compared to gaussian sinusoidal waves. I have already tested using sinusoidal waves at +-60V, by amplifying them through ADA4870 and PA107 evaluation boards. My hope is that transmitting square waves will result in an equally good result, enabling us to design a simpler pulser circuit for the final product instead of constructing the expensive sinusoidal variant using DAC and amplifiers.

I was thinking if there were some digital / pulser solution in which the original square wave might be used to open / close some MOSFET transistors, consequentially creating a higher voltage square wave on their output.


texts: MOSFET driver IC not supplying enough current

texts:
I am designing a class D audio amplifier using an HIP4080A integrated circuit to drive an H-bridge, simulating in Proteus. My problem is that the output pins of the integrated circuit, although rated for 2A or so, only supply 300mA (peak) into the gates of my power MOSFETs (this happens for both high and low side devices). Consequently, the transistors turn on very slowly and I get some really bad shoot through (500A for 100ns).

Things I tried:

Changing the gate resistors - current peaks at 300mA below 12 ohms
Lowering the frequency of my PWM signal
Ditching my PWM signal and using separate test sources at 600, 100 and 50 kHz, 50% duty
Modifying the bootstrap capacitors
A whole bunch of different MOSFETs
Supplying the IC with a higher voltage
Increasing the dead time via the HDEL and LDEL resistors
Lowering the high voltage supply from 75 to 50 V

Maybe this is just a glitch in the software?

VBAT is 12 and HV is 75 volts. The shortest pulses from the PWM signal are ~80 ns (the IC needs at least 50).

Any help would be much appreciated!


texts: N-Channel Mosfet or NPN transistor for Low Power PWM Application

texts:
simulate this circuit – Schematic created using CircuitLab

LED:
2.05V @ 350mA
5-6 Ohm Resistor for current regulation

Hi, currently designing a circuit that controls a LED using a PWM logic level signal at 3V3. I am wanting to use a small footprint mosfet or transistor but am unsure what to use. I've looked at MOSFETS but all will operate within the ohmic region of the FET is that okay or will that eventually cause damage to the FET. Am i better to use a BJT transistor to control the switching as its a low voltage low current application but will the switching speed of a BJT be quick enough for a PWM application.


texts:
I want to reuse my old computer processor heatsinks for LED heatsinking. I think I can calculate their K/W value approximately by dividing the temperature difference vs TDP at their maximum load.

I ignore the CPU packaging thermal resistance and take it as an additional safety margin.
This way I get about 60/100 = 0.6K/W for a beefy heatsink.

The problem is, that I want to get rid of the active component and derate the heatsink accordingly. Are there any approximations I can use for derating?

I know I'll have to add a healthy safety margin, but I still need a general figure as to decide what wattage can they sink.


texts:
My question is how to read ratiometric sensor output like 5V: %10Vs to %95 Vs?

Do I need to use amplifier?
If I had an option should I choose regulated 0-5V output sensor and what is advantage of that?


texts:
So I am dismantling and ripping into a cheap Chinese counterfeit phone charger and revealing all that I see wrong with it. One thing I could do with some insight into though is the purpose of a resistor.

It is basically a 3.3Ω resistor which is in series with the mains (240V) input into the bridge rectifier:

What are they trying to achieve there?

(Mind, given the state of the rest of the circuit maybe even the designers don't know?)

Should it in fact have been a fuse?


texts: Another motorcycle project: gear selection indicator

texts:
I have another little project that I have been thinking of making, but am having some trouble with the circuit design.  In a nutshell, here is what I am envisioning:

Objective: Create an electronic solution to indicate the currently selected gear of a 5-speed transmission in a V-twin motorcycle.

Background: There are some aftermarket products on the market that claim to be able to do this for my year/make/model of motorcycle. However, I have read numerous forum reviews on these off-the-shelf products and they have been generally hit or miss in terms of the reliability with which they operate. Furthermore, these products are $$$.  I figured that with some of your help, I could make my own for much cheaper and learn a lot in the process.  One aspect of these products that I would like to use is the 7-segment LED display to indicate the gear 1 through 5. In terms of a housing, I may have access to a machine shop and some scrap materials to make a decent looking housing and handlebar mount for it.

Technical Background: In chatting on some motorcycle forums, some members mentioned that their off-the-shelf gear indicator works by using the ratio of the engine speed (RPM) to the vehicle speed (wheel speed).

On my motorcycle, I have access to these two signals.  The motorcycle is well out of warranty and therefore I am not concerned about delving in and cutting/splicing wires.

My ECM has a data output for a tachometer signal and it currently goes to an aftermarket tach (that the previous owner added) to display engine speed in RPM. The tach is an analog face and needle display. I am fairly certain that the tach signal is some form of (if not duplicate) of the crank position sensor. The crank position sensor (CPS) is a variable reluctance (VR) sensor that generates an AC signal.

The vehicle speed sensor (VSS) is a Hall-effect sensor that takes readings off 4th gear of the output shaft in the transmission.  Preliminary research into Hall-effect sensors leads me to believe that their output is some form of square wave, but I am not certain.

Note I understand that it may be difficult for you to help me since I have not measured either of those signals and only have basic electrical tools (2 DMMS) to do so.  I do have a micro-controller with which I may be able to do some datalogging...  I will attempt to provide as much info in this initial post to get an idea of this project's complexity and am willing to tap into those wires to get some data for those signals.

Main Questions:

What type of circuit is required to take the "frequency ratio" of two periodic signals?  One signal being perhaps sinusoidal and the other being maybe a square wave.
I am assuming that the frequency ratio of the two signals will correspond to the gear ratio and thus the currently selected gear in the transmission.
What circuitry would be required once the frequency ratio has been obtained to "translate" this into a digit 1, 2, 3, 4, or 5 and then display that digit on a small 7-segment LED display?
What type of "resolution" would be required in determining the frequency ratio?  The info I can provide is related to the RPM readings off the tach.  The engine idles fairly steady around 1000 rpm.  Max RPM before rev-limiting kicks in is around 6k-7k rpm.  My main concern is that changing gears only changes the rpm by a small amount it seems (at least with the resolution I have based on the analog display face)...Note After riding yesterday, I got a better idea of the RPM change when I change gears, but keep the same road speed: For each gear change, I get a 500 RPM decrease (or increase depending on whether up or downshifting) while maintaining the same road speed.

Thanks for reading this and I hope it wasn't too much text!  I have some more info that I can post as followup too if there is discussion in this thread.


texts: Can I connect a DC high voltage booster directly to my Raspberry Pi?

texts:
I have one of these modules:

Is it safe to connect it to two pins to my Raspberry Pi, directly, and turn it on by emitting HIGH on one of the pins (the other one being the ground), which is around 5V, if I am not wrong?

Will that use too much power from the Raspberry Pi or maybe burn it?


texts: Microwave detection circuit verification

texts:
I want to develop a circuit which can detect electromagnetic waves (radio wave, microwaves.)
This circuit will just act as a tamper detect and not physically measure/compute the radiation.
I have designed the circuit using a toroid ring and a few Schottky diodes.
The calculation formulas and schematic diagram are in the attachment.
After testing the circuit, I'm not getting any output.
Hence, I wanted to get the circuit as well as the calculation part of it verified.
Please note that the WAVE_SENSE signal in the design is connected to a 10-bit ADC of a microcontroller.


texts: logic level conversions for opto-isolators in digital input acquisition

texts:
This isn't my usual job, I'm not an EE, but I want to give it shot...

This question concerns developing an interface board to connect a device (DUT) to a test system in a manufacturing scenario.

The signals I have access to are a bunch of 1.8V cmos logic lines from the GPIO pins of an embedded CPU, a 5V power rail, and GND (see diagram below). Everything is in a fairly tight space, I have control over all power/ground etc.

simulate this circuit – Schematic created using CircuitLab

The 1.8V GPIO signals (s1,s2,s3...) eventually get read by a opto-isolated digital input device (happens to be a NI-6525). The opto-isolated digital inputs need at least 3.2V to sense a HIGH so I must level shift these, moreover, the current input per channel is given as "3 mA MAX"-- too much for 1.8V cmos I think?

To perform level shifting, I was thinking about the MAX3000E because it is designed for things like cellphone cradles, smart card readers, etc. It has ESD protection and it can handle 8 signals and I can use it to level-shift from 1.8 to 5.0, all I have to do is provide voltage rails for 1.8 and 5 from my test system. No problem, I thought...

BUT looking at the datasheet for the 3000E it seems that the output current I can provide from the 5V (Vcc) side is only 10uA max! That isn't enough to drive the diodes in the digital input device.

So now, I am thinking about adding mosfets to each output of the level converter so that I can deliver enough current to the opto-isolators.

Questions:

Am I even using the right level converter for such an application? I
get the feeling I am doing this wrong. The test system uses
opto-isolators but it is a good pick for other reasons.
I thought about ditching the level translator entirely and just
using mosfets to drive the optoisolators from the 1.8V signals. But
then, there's the problem of ESD protection, losing the nice
"enable" pin, plus I don't feel confident with with just naked
mosfets. Is this easy to do with mosfets in this scenario where
DUT's are going to be constantly plugged and unplugged into the
system? Should I invest the time in trying to do this with just
mosfets? Will it be reliable in a factory system?

Looks like the moral of the story is that "self-configuring" bidirectional logic translators can only deliver a very small amount of current on the output side (~uA's). In my scenario, I am using the output side to drive opto-isolator inputs on the system side which require ~mA's of current. This requires using an additional buffer of some kind, or, selecting a different logic level translator. Since I don't need to change direction in-situ (never be tx'ing and rx'ing on the same line), selecting a translator that has fixed or settable direction solves the problem because these don't seem to have the extremely small max current spec on the output.


texts: From Li-Ion to Li-Po battery: design a new battery pack for old mobile phone

texts:
I have an old working mobile phone. The battery, a compatible 3.6V 500mAh Li-Ion is almost dead (the original one was 800mAh). Is it possible replace the battery pack with a 1200mAh or so Li-Po battery?

I attached the pictures of the Li-Ion battery pack

The original phone battery charger has an output of 7.5V 880mAh


texts: Relays making TCA9534 I2C bus expander reset when driving AC inductive loads

texts:
I have a PCB which uses a TCA9534 as an IO bus expander. It has four relays interfaced via MOSFETs.
This board is connected via ribbon cable to the main board, which contains the main MCU that controls this TCA9534. Main board also provides stabilized +5V for TCA9534.
Everything works fine when no external load is connected to the relays. However if an inductive load is connected, when the relay contacts open and close, the TCA9534 loses configuration bytes from configuration registers, and all interface pins become inputs. I guess that the chip is being reset.
This is the schematic fragment including TCA9534:

And this is the circuity of one of the relays:

This is the designed layout:

As you can see, I placed a bypass capacitor near the TCA9534 to avoid incoming noise.
Note that there are more chips in the design, but they are not causing problems. They are not being used at the moment the problems occur.
As a workaround, I placed a MOV in parallel with relay switch and apparently the problem disappeared. As best as I can understand, the MOV is limiting high voltage spikes caused by the relay contact arcing.
Even though the problem might been solved, I have seen tons of control boards in real world applications which have relays driven from MCUs and controlling any kind of AC loads, but without MOV or other type of filters.
So, this is the question:

Why is my design not working as expected and I need to place MOVs, but similar boards from real world work perfectly without preventing relay contact spikes? What kind of magic are manufacturers doing?


texts:
Friends, I am very new to electronics and I am trying to design a simple switch with a transistor. Following is the circuit:

The input is a square wave generator with positive and negative cycles but the output current is zero when the cycle is negative. Can anybody please help me redesign this to switch a negative current in the output when the input is negative? ie, the output current should be positive when the input is positive and the output should be negative when the input is negative.


texts:
My excercise is the following:

Make a circuit which outputs X^3 of two bit input of X.
Use the lowest number of HALF ADDERS as you can.

I don't really understand how to compute x cubed with half adders.

Any hints or help is appriciated.


texts: Which Layer should be considered for Characteristic impedance for 4 layer PCB?

texts:
I am developing 4 layer PCB with following general stack up:

Layer 1: Signal Layer (top side)
Layer 2: Ground Plane
Layer 3: Power Plane
Layer 4: Signal Layer (bottom side)

For Layer 1 & Layer 4 which internal layer to be considered as a reference to calculate characteristic impedance?


texts: Override One Lamp in a Four-Lamp Circuit Using Transistor?

texts:
simulate this circuit – Schematic created using CircuitLab

I have a circuit of 4 light bulbs, with single switch on the positive terminal that will turn all the 4 bulbs at once. EDIT: Light bulbs circuit is parallel design. source is 12V DC and all bulbs are running 12V DC.

I want to be able to still have the original switch to turn on all 4 bulbs, with a new switch that overrides bulb #3 to keep it turning on. Essentially, when bulb #3 is switched on, the original switch ignores bulb #3.

To solve this I go with installing a diode at the positive terminal of the bulb #3. When original switch is on, electricity will go thru that diode and then turns the bulb on; when new switch is turned on, electricity will go to bulb #3 thru new line but will not go to the original circuit because of the new diode.

A friend said this might be able to be done with a transistor but he couldn't figure out the solution. Is that true we can use transistor for this? it's for automotive brake lights.


texts: How to split uint32 into four uint8 in efr32

texts:
i have uint32_t data but my SPI transfer function command can send 8 bits at one time.
i want to create uint8_t array.i tried the following but i am not sure about & * adress game.
Is this the correct way to split uint32?
uint8_t arr[4];
uint32_t Tx_PP= {0x02F003E7};
arr[0]=*Tx_PP
arr[1]=*(Tx_PP+8)
arr[2]=*(Tx_PP+16)
arr[3]=*(Tx_PP+24)
SPI_tranfer(USART1,arr[0]);


texts: LTSpice: How can I specify a constant-dependent delay?

texts:
I am defining a voltage source that depends on the voltage at another point in the circuit.
B1 N1 0 V = if ({dly}> 0, delay (V (In), 2m), V (In))
This works perfectly! If I do dly> 0, B1 has a 2 ms delay. However, I want to make the delay dependent on dly. So, I try this.
.params dly = 2m
B1 N1 0 V = if ({dly}> 0, delay (V (In), {dly}), V (In))
So, I get an error message. "A constant delay must be specified as positive definite".
What am I doing wrong?
Here is my complete subckt.
.subckt Ultrasound In Out Ref
.params Ind = 0.04*(40/{f}) Cap = 2/({Ind}*(2*pi*{f}*1000)**2)  Res = .1e6
.params Amp = 10*({Res}**-0.5)
.params dly=0 dly2 = if(dly>0,dly,1)
* I also tested it as follows. Did not work.
*.params dly=0 dly2 = if(dly,dly,1)

* Model
B1 N1 N3 V=Amp*if(dly>0,delay(V(In,Ref),dly2),V(In,Ref))

C1 N1 N2 {Cap}
L1 N2 Out {Ind}
C2 Out N3 {Cap}
R1 Out N3 {Res}

* Noise
B2 N3 0 V=30e-3*white(1e6*time)

B3 Ref N4 V=V(N3,0)
R2 N4 0 0.1

.ends

Here is the asy file, where dly is defined.
Version 4
SymbolType CELL
LINE Normal 48 112 48 80
LINE Normal 96 32 64 32
LINE Normal 32 32 0 32
RECTANGLE Normal 32 -16 64 80
SYMATTR Value Ultrasound
SYMATTR Prefix X
SYMATTR ModelFile Ultrasound.cir
SYMATTR SpiceLine f=40 dly=0
SYMATTR Description
PIN 0 32 BOTTOM 8
PINATTR PinName In
PINATTR SpiceOrder 1
PIN 96 32 BOTTOM 8
PINATTR PinName Out
PINATTR SpiceOrder 2
PIN 48 112 RIGHT 18
PINATTR PinName Ref
PINATTR SpiceOrder 3


texts: How to protect the circuit from Ethernet ESD, overvoltage, etc

texts:
Creating a carrier board for a RPI Compute Module4, I am not sure how to protect the circuitry from possible ESD /over-voltage coming through Ethernet connector.
In normal circumstances, I would apply some zener diode and in-serie resistors, but I don't think this will work with a 1Gbps Ethernet (response time, impedance, etc).
I also looked for optocouplers IC, but all what I seen works only up to few MHz.
Looking at the Development board, it has a couple of IC protecting the input, unfortunately, no label for this 2.5mm IC:

Is there any "standard" IC to protect the board from Ethernet? I am not necessarily looking for a specific part number, but rather a IC type name or family.


texts: THD calculated with amplitude instead of RMS

texts:
I have a digitized sinewave, and want to determine the THD of this waveform.
This is the equation I am familiar with for calculating THD:
$$
THD=\frac{\sqrt{\sum_{n=2}^{\infty}V_{n_{rms}}^2}}{V_{fund_{rms}}}
$$
A colleague of mine has been using a solution that substitutes the RMS voltage of the harmonics and fundamental with the amplitude. My colleague claims this is acceptable because \$ V_{rms} = V_{peak} / \sqrt2 \$ (for a sinwave), and we can simplify to the \$ V_{peak} \$ because \$ \sqrt2 \$ occurs in all terms.
Being able to skip calculating RMS seems like a nice performance improvement, but I am concerned as I can't readily see what it is costing me.
What do I lose using this method, are there any "gotchas" I am missing?


texts: Difference between rising edge falling edge D flip flop (asynchronous reset)?

texts:
I am answering a question about a D Flip-Flop with Asynchronous Reset with the reset output '0', that is set to be rising edge triggered. What i don't know is the difference between a rising edge triggered and a falling edge triggered Flip-Flop?

If possible try to provide a schematic of what this would look like. i.e., i already know the clock, data diagrams, but i don't know how the Inverters, Transmission gates, NORs and NANDs are hooked up and if there is any difference in hooking up the Clock signal. If you can, try to provide an answer in the form of this type of diagram, ->not block diagrams<-.

This here is the diagram for a falling edge D Flip-Flop, with what i'm guessing is reset output '1'? I'm not sure on the reset either. All i know is that it's negative edge triggered.


texts: Is there any standrad that specifies max voltage at earphones output in netbooks? What values can I expect, can it be 5V or rather 1,8V ? Is there any way to monitor current (current I mean adjective, not noun) Voltage for left and right channels of that output?


texts: Reducing jitter and improving speed of accelerometer output

texts:
I'm not sure if this is an EE question or a StackExchange question due to the programming involved, but anyway here goes:

I just built a tilt sensor for my tractor's front loader.  I wanted something easy to read in bright daylight, wireless, magnetic attachment, and reasonably accurate to indicate the tilt and level of my front loader so I can use it to level some ground easily.

I used my own custom-built wireless MCU as the controller, interfacing via I2C with a GY-521 accelerometer/gyroscope module.

The display is just a servo motor connected to an indicator hand and a laser-printed dial face, and 5 LEDs also.

Here's a video of the device working:
https://www.youtube.com/watch?v=xWT8AyE1JLU (sorry about the noise, I was trying to show how jitter doesn't seem to affect it as bad!)

In testing, it worked great.  But as soon as I snapped the sensor to my tractor's bucket, the vibration from the engine caused the accelerometer readings to go crazy.  The needle basically jumps from one end to the other, making the readings useless.

So first I tried to average the output.  (I am sampling at approx 5-10 samples per sec)
That still yielded shaky results.

So I implemented a low-pass filter, using a coefficient of 0.1 for new readings.  As you can see in the video, this helped to eliminate the jitter, but now the readings are too laggy.  Turning the device from one end of its range to the other, it takes several seconds for the needle to catch up to the input.  This also makes it unusable, as it needs to be more realtime.  And as you can see, it takes a long time to get back to zero.

Does anyone have suggestions/ideas on how to reduce jitter from the engine vibrations and bumps/thumps experienced by the bucket, while yielding a fairly fast and accurate output?

Note that my MCU won't be able to handle lots of math for each sample, so don't know if that eliminates FFT or not - it's only a basic 8051 running at 16MHz.

Here are the links for spec sheet/register map for the Accel/Gyro:
https://www.cubby.com/pli/Spec+Sheet.pdf/_506bd71d53d3454282f06fa698666f04
https://www.cubby.com/pli/Register+Map.pdf/_17685da9808c42099c5ebdc1058c63b3

Any info appreciated!


texts: 7 Segment Display - Hiding the electronics

texts:
I'm building a basic thermometer that displays the temperature on 4 seven segment LEDs. I want to put the circuit in a box with a clear plastic lid.

I'll mount the LEDs on the PCB around the other components, and fix this flat against the base of the box so the LEDs shine up through the clear plastic lid.

My question is how can I hide the electronics (i.e. the MCU, temp sensor, resistors, etc) but still be able to see the LED display, by some how darkening the clear plastic lid, and make it look more professional?

Alternatively, can you get enclosures with a translucent lid? I've searched but can't find any.


texts: Dealing with digital circuits and their associated switching speed?

texts:
When designing a digital one-minute counting circuit I came across a difficult problem.

Basically, I designed the circuit to drive the (normally HIGH) clock of the 10s slot low if the 1s slot's current state was 9 (actually, just if the first and last bits are HIGH -> 1001)

The devices I am using are positive edge, so when the 1s slot returns to zero the condition is no longer satisfied - therefore the clock returns to a HIGH state and increments the 10s slot.

The problem is that I was getting double clock problems(7->8 transition and the designed clock mechanism).

It turns out that there was just enough delay in the switching between 7 -> 8 (0111 -> 1000) that the first/last bit HIGH condition is satisfied:

i.e., some combination occurs in the transition period to register a logical HIGH at the output

1001 1011 1101 1111

The temporary solution to the problem I came up with was to actually keep the clock for the 10s slot LOW until the condition where the 1s slot equals 0 (0000) is satisfied(So, essentially clock WHEN we get to the state as opposed to before). However, this solution requires too many gates (a 4-input NOR minimum). My previous design was actually fed from another part in the design that is already present, so it didn't require any additional circuitry.

Any ideas on a more efficient solution?

The IC's used in this design are the 74LS47 (7Segment decoder) and the 74LS163 (4-bit binary counter). The pull-down resistor inclusion is a mechanism to set the counters to 00 and hold while the switch is closed.


texts:
I am using a bipolar stepper motor with Fs = 238Hz, I want to ramp it up above its Fs, for this purpose I am stepping it up with an interval of 100ms but as soon as the motor reaches 240Hz it starts vibrating on its place and the motor stops, what am I doing wrong here? I am following TI's application note here.

http://www.ti.com/lit/an/slyt482/slyt482.pdf


texts:
i have two 18650 batteries of this type (but with one 1500mAh and one 2000mAh)
and i need to charge them with two (or more if needed) 6v 1A solar panels.
I was looking around and found this  but this one is 4.2v instead of 3.7, and i'm reading mixed things about if this would work


texts: How to plot the open-loop gain of an inverting amp, difference amp, and low pass filter?

texts:
For example, if we are using the ADA4004-1 op amp in all these circuits, the open loop gain is 400000 as shown in the spec sheet (Table 2): ADA4004 Datasheet

The open-loop breakpoint is at 30 Hz (GBWP=12 MHz, also in Table 2) so the plot should be constant at 112 and then fall off at -20dB/decade after 30Hz.

However, how do you plot open loop gain for an inverting amp, difference amp, and low pass filter? Shouldn't it just be the same plot for all of them?


texts: How to use Ebers-Moll equation to calculate collector current?

texts:
The Ebers-Moll equation is given by:$$I_C = I_S(T) * (e^{V_{BE}/V_T})$$
where \$V_T\$ = \$kT/q\$ = 25.3mV at room temperature. In TAOE (2.3.1), it mentioned

  \$I_S(T)\$ is the saturation current of the particular transistor (which depends strongly on temperature, T ... \$I_S(T)\$ approximates the reverse leakage current (roughly \$10^{-15}\$A for a small signal transistor like the 2N3904.

I ran a simple simulation just to test the Ebers-Moll equation, where \$I_C\$ is just approximated to \$10^{-15}\$A, and taking \$V_{BE}\$'s value directly from the simulation:
$$I_C = 10^{-15} * e^{0.727330 \div 0.0253} = 0.003A \ \ or \ \ 3mA$$

The value is over two orders to one simulated by the program iCircuit (427.267mA). If I just use KVL and multiply the default \$\beta\$ of 100, I get \$I_C = (5-0.727330) \  \div \ 1000 * \beta = 0.427262A \ \ or \ \ 427.267mA\$ matching that in the simulation.  How am I supposed to use Ebers-Moll equation and why is it more accurate to determine collector current by base-to-emitter voltage. I just plug in some basic values in and the result did not even turn out close.


texts: Solar with dual battery setup - keeping both charged?

texts:
My setup in my motorhome is 240W solar panels connected to 200Amp Hour house battery through an MPPT solar controller. The starting battery in the cab has a constant current draw around 200mA, flatting it if not used after a month or two.

The problem seems simple to solve on the surface - connect the solar to the starter battery, but it turns out to be a bit more tricky than that. I don't want one battery going flat dragging the other down, so can't just connect them.  My question is what is a good (as in simple and cost effective) way to connect the solar output to the starter battery so the starter is maintained in a charged state.

What I have considered so far (an within my limited electronic skill range)

Replace the controller with on specifically capable of solving this. Best, but expensive
Connect though a low value resistor (say 3 Ohm, 50W ) as a current limiter - Cheap, easy but could flatten house batteries if cab lights left on etc, and flatting the house battery could drag down the starter.
A second small solar panel - costs add up by the time you factor mounting and wiring it in, and there is not much space left on the roof anyway.

Although I am OK with a soldering iron, ideally I could do this with one or two the shelf components for a few 10's of dollar.

I am looking for suggestions that I may not have come across.


texts:
I am in a muddle here, so thanks for making the effort to have a read.

I understand that electrical power going into motor is given by:
\$P_e=I^2R\$

I understand that mechanical power out is given by:
\$P_m=\tau\cdot\omega\$

Where \$\tau\$ = Torque at motor output shaft

Where \$\omega\$ = Speed at output shaft

I understand that for a DC motor, torque is proportial to current:
\$\tau=k_E\cdot I\$

Therefore if current is proportional to voltage via resistance, and electrical power in is proportional to current, power is proportional to current.

Then imagine that a motor is reacting a fixed torque value, and the supply voltage is increased to raise the output speed. A fixed torque and a rising speed means a rising output power. However input power is fixed, since torque is fixed because current is fixed. Graphing this (x-supply voltage, y-Power) gets you a flat line for electrical power in and an angled line for mechanical power out. Therefore the lines must intersect and therefore on one side of the intersection point, output power must be greater then input power, which is impossible.

I am clearly overlooking something so any pointers would be greatly appreciated.
Cheers now, all the best.


texts:
reference:https://www.analog.com/media/en/technical-documentation/technical-articles/D61_EN-Convert.pdf
The above circuit take input voltage of range 1-5V and gives the corresponding current output of 4-20mA .I got the circuit reference from analog, i understood the functioning of the first stage that the current following through R1 is Vin/R1,the same current flows through R2 therefore voltage at bottom of R2 is 24V-voltage drop across R2 but it is written in the reference sheet that the voltage across R2 and R3 is equal ,i didn't understand how the voltage across R2 and R3 can be equal?


texts: 0-380V Dimmer Circuit using MOC series Optotriac

texts:
I want design a dimmer circuit that have output voltage of 0-380V(rms). I didnt see any application about 380 V dimmer circuits and there is no information about 380V application in MOC series opto datasheets. But some optotriacs allow application for 380 V such that VO3062 or IL410 in their datasheets.

The 380 V (single phase) is produced from 220 to 380V transformer in my application. I have designed a dimmer circuit for 0-220V before and it worked perfectly. This circuit is below. I want use again these components and this circuit.

But now I want control 0-380 V output and I dont know what will be resistors of circuits. I think they will not change because of resistor value is related with input voltage of MOC3061 (VCC is 5V and current must be 15 mA for MOC3061 series ). Can I use again MOC3061 and BT137 for control of 0-380 V dimmer circuit?


texts: I have a coaxial cable whose length is $$L=10m$$, working at $$f=1GHz$$ frequency and i need to determine it's attenuation coefficient (if that is correct term), however i cannot find any relationship between these three values anywhere on the internet so i would appreciate if someone could help me! Thanks in advance!


texts: How to amplify the output of a digital low pass filter?

texts:
I have used the transfer function of a RC low pass filter to design a IIR Digital low pass filter.
\begin{equation}
H(s)=
\frac{1}{sRC+1}
;First
\space
order
\end{equation}
\begin{equation}
H(s)=
\frac{1}{sRC+1}
.
\frac{1}{sRC+1}
;Second
\space
order
\end{equation}
As the readings of ADC are discrete signal, so I have used the Bilinear Transform to find the Z-transfom and did the inverse Z-transform to find the input-output relationship in time domaim.

In the first image, I have used a pure 50 Hz signal as input. The peak-peak amplitude has reduced a little in the output of the first-order filter. It has reduced a lot in the output of the second-order filter.[Cutoff 60 Hz]

In the second image, I have used a mixed signal of 50 Hz and 1000 Hz signal as input. Output peak to peak amplitude is reduced as before but the amount is different.[Cutoff 60 Hz]

My objective is to amplify the output. I cant simply multiply it by 2. Because if an 8-bit DAC is coupled to my microcontroller then anything above 255 will be out of its range. I want to eliminate the offset and amplify the signal as much as possible. Is there any way to find the approximate offset voltage and the maximum possible gain.

Additional information:
1. The screenshots are from an MS-Excel file. I've already tested it using ATMEGA 16.
2. I will analyze the sound waves less than 120 Hz. Any sound wave above 120 Hz has to be eliminated. I will use two microcontrollers. One for low pass filter and another for FFT. Communication will be 16 bit parallel.
3. Filter Equation:


texts:
Just recently got interested in starting up a new project out of my area of knowledge.

Basically I'm going to buy a 3v 200ma solar panel that I want to use to power a small light in one of the rooms in my basement.

I plan on buying this one:

http://www.amazon.com/gp/product/B00IWZWT6S/ref=oh_aui_detailpage_o00_s01?ie=UTF8&psc=1#Ask

My question is, what else do I need besides the solar panel to get going on this?  What exactly do I need in between this solar panel and the light bulb?  Any resources would be great to help me start up on this new project.  Thanks in advance for the help!


texts: Switching between circuits, transistor-based SPDT?

texts:
I want to use a piezo buzzer alternatively as a sound detector and as a sound emitter, on the same circuit (be gentle, this is my first attempt to electronics since the university long years ago).

I want the piezo to monitor the ambiant sound level, then emit sound for a while when the sound level is above a given threshold (typically, play music when baby cries during the night).  I'll use an Arduino for the processing part.

For the sound detector part, I plan to reproduce NerdKits' tutorial.  I hear the sound emitter part is much more simple as far as electronics is concerned (just plug the buzzer between input and ground, is that it ?), and I don't fear the programming part.

Now what bothers me is how to switch between the receiver/emitter setups.  I understand I'm looking for a kind of transistor-based SPDT.  Is a push-pull setup the way to go, or am I on the wrong track ?

NB : Yes, I could just use a second piezo buzzer or whatever, but I find it somehow more satisfying to use the same device both for input and output, provided it's doable.


texts: Import PCB outline made from connected lines from Inkscape

texts:
I have designed an outline for a PCB in Inkscape and wish to import it into Eagle, but the guides I have found leave me with lots of little lines in Eagle, not a continuous line, what's more is there are gaps between the lines, and as this is for the dimensional layer, not ideal. 1

Is there a way to modify the file so the import is made up of connected lines? Or another way to get this to work?

Also tried this with similar disappointing results 2


texts:
I was asked to design a EMI-protected button. A schematic below.

Let me explain all that stuff

a C39 capacitor suppresses high voltages
an R44 resistor limits the current coming from an ESD discharge
a D29 diode is a TVS diode

Did I place the TVS diode correctly? I placed it behind the resistor so that the current that has lower value and then the TVS diode would deal with lower energy.
What do you think?


texts: Powering ws2812b led strip with ATX power supply

texts:
So, I'm planning on doing a little project. I have 8years old ATX power supply from an old PC, and I want to use it to power my LED strip (ws2812b). It is a 300 led strip (5m strip). I know for that length I will need 5V/18A of current but my PSU is only rated to do 5V/16A max. *Note that I will be using these LEDs for decoration only so low/medium brightness.
Another thing that is my concern is wiring and powering LEDs. I have some ideas about that.
I will cut the strip into 2 pieces. (3m and 2m).
Now comes the fun part. On my ATX PSU, I have 5x18AWG 5V wires and 3x20AWG 5V wires. I've read somewhere that 18AWG wire is capable of maxing 2.3A, so I was thinking shorting 3x18AWG and 1x20AWG wire for my 3m strip, and rest shorting for my 2m strip.
Of course, after shorting these wires I would use separate 14AWG wire (so 2x+5V and 2xGround) to transfer power to the LED strips. ( I will try to draw all of that so you can understand what I think)
Another note - PSU will be roughly 5m away from strips in other room.
Now check up the wiring

The red wire is 5V, Brown is ground, Grey is a data line
I'm going with this controller simply because I know just little about programming in Arduino and I think it is much easier for me just to buy a complete one. I'm also concerned about that 10A going thru the controller to the 3m LED strip because I haven't found anywhere about what amps can that controller take.
Do you even think all of this wiring is a good idea? Because I'm no expert and I need the second opinion.
Do you maybe think I should somehow do separate powering of the controller (So it gets its own power and smaller amps), if yes can u suggest me how because there is no scheme anywhere about that.
I'm a student and that is why I went cheap on this but I think it could work. If someone can help and tell me if something is wrong I will appreciate it a lot. The LED strip and controller haven't arrived yet so I'm open to all suggestions.
Thanks. And btw sorry for bad English ;)


texts: Solving an RL Circuit with an Inductor in Parallel to Resistor-Inductor in Series

texts:
I tried to look through my textbook to find anything similar to this one and have tried every solution I can think of to no avail. For now, I settled on the fact that I may be over complicating the solution so I calculated the initial and final current of each and used those to find the forced response for t > 0.

The function \$ u(t) \$ is a piecewise function with a value of 0 when \$t < 0\$ and 1 when \$t \geqslant 0 \$. My intial conditions and final conditions are as follows:

$$i_1(0) = i_2(0) = 0 A $$
$$i_1(\infty) = 5A \ \ , \ i_2(\infty) = 2A$$
$$\tau_1 = 0.5\ \ , \ \tau_2 = 0.2$$

These yield the final solutions:

$$i_1(t) = 5(1-e^{-2t})$$
$$i_2(t) = 2(1-e^{-5t})$$

This seems too simple to be true though. I've also tried an approach using mesh analysis but that resulted in constant answers (which seems wrong because it should be a time varying solution?). I also tried using nodal analysis with the node between the 4 and 6 ohm resistors but had no luck.

What approach would be the "correct" one? I don't actually know the correct answer either so any help is greatly appreciated.

P.S. sorry if my math formatting is wrong or if I did not ask my question properly. It is my first time posting on this board and I tried my best to make everything as clear as possible :)


texts:
I am trying to switch 12V using a Transistor and an Arduino, which outputs 5V. When I connect the Arduino to the Transistor base and 12V to the collector, I get 4.2V on the Emitter, and I don't understand, why. The Transistor is a C9014. Why is the output 4.2V and not 12V, as I expected?

simulate this circuit – Schematic created using CircuitLab


texts: Why is there a delay in a common anode 7-segment display?

texts:
I have a common anode 4-digit 7-segment display.  I have each segment cathode connected to a 330-ohm resistor, and the resistor is connected to a shift register.  Each segment cathode is connected to the same shift register.  Each common anode is connected to a second shift register.  Right now, I am using an Arduino to multiplex the display to show a number.

This works great, but there's a problem.  The display isn't bright enough!  I assume because this is a common anode configuration, and that the shift register can only provide about 40mA of current for 8 segments (A-G and the decimal point).

I have decided that I need more power.  My first thought was to try to use 4 PNP transistors.  I hook them up correctly, and the segments get brighter.  Great!  However, there is a problem.  It seems like the transistor is slowing something down!  There is a nasty glow of segments that are used by other digits!  I have the microprocessor set to show each segment for 4 milliseconds. The datasheet claims that the transistor should switch on and off faster than that.  Why is this faint glow happening?

Here's what it looks like when 1111 is displayed:

Here's what it looks like when 1112 is displayed:


texts:
In a project I'm working on, I am designing a Totem pole PFC, and for the controller (using a digital controller) I need to sens the input voltage, which is an ACvoltage and feed it to the ADC of the digital controller and do the necessary calculations.

My question is regarding a circuit that senses and scales down the input voltage so I can feed it to the controller.

I tried this circuit:

Idealy the results will be as follows:

And the output voltages are:

V1 = VN * R2/(R1+R2)

V2 = VL * R2/(R1+R2)

The problem is that I don't know the voltage of the phase VL and of the neutral VN in regard to the ground GND, so I don't know how to choose the right resistors R1 and R2
and secondly the input of the op amp IN+ can't have less than (-V)-0.1V = -0.1V, so I think it will burn out if V1 or V2 goes under -0.1V.

Should I be worried about these problems and how can I find solutions for them, and is there any circuit with similar behaviour that I can use.

Thank you.


texts:
What is an easy way to do this? I'm really going in circles and would need an overview:

There is a certain input line, output line, a high voltage, a low voltage - and a reference voltage.

Now if the input is higher than the reference the output will be "high voltage". If the input is lower than the reference the output will be "low voltage". How can this be achieved?

I've only got diodes, transistors, resistors (and capacitors/inductors etc) to do this. If I would use an amplifier I need to build one myself.


texts:
I have been told that in order to not damage a battery is better to connect it to a capacitor, to deliver current in a smooth way. This is because we are using a circuit where a peak of current is delivered periodically (16Hz) and this is about 60mA and last 25ms. When the device is not sending a peak the current leech is about 20mA. So the peaks damages the battery. The question is, what type of capacitor I need to choose in order to prevent damaging the battery, what is your basis?. The battery nominal voltage is 3.6V.
The battery's datasheet can be found in: http://www.eemb.com/Download/Primary-Battery/Li-SOCI2-Battery/Energy-Type/ER341245.pdf


texts: A circuit similar in working to a NOTC relay?

texts:
How do I build a circuit that gives out a "high" only when given in a "high" continuously for a preset time period? The input is actually the out from a logic gate.

The following details have been added considering the suggestions from Andy Aka.
The rate at which the output goes from high to low once the input is low, need not be fast and a delay up to a few seconds is tolerable. Also if the input is not high long enough to set the output high, the timer should be reset, which could also be non-spontaneous and could take up to a few seconds.


texts:
Sometimes, if the sum of two digits are < 10, BCD addition is similar to binary addition.

But sometimes if the sum > 9, the result requires a correction. This corrections is +( 0110).

Why do we add 6? Why not some other number? I searched the web, but I don't understand.

If you want links of this question that have been asked in the past:

http://answers.yahoo.com/question/index?qid=20070930062637AAzyBlv
http://www.physicsforums.com/showthread.php?t=639798


texts: Building 3-8 decoder with two 2-4 decoders and a few additional gates

texts:
I am trying to build a 3-8 decoder without an enable by using two 2-4 decoders (that also don't have enables), two chips that each contain 4 AND gates, and one chip that contains 4 NOT gates.

I have tried to base my solution on this answer:
Design a 3-to-8 Decoder Using Only Three 2-to-4 Decoders

but I have not been able to figure it out.

Thanks in advance.


texts:
Is it possible to switch two master SPI lines using Quad 2:1 multiplexer like (74HC257)? I want my two Master devices to access a single SPI slave (Flash). Please see attached schematics. SPI speed is 4MHz.

The reason for this is that, I have an MP3 module (master2) which already has a flash that I want my MCU (master1) to access the data from. I don't have control on SPI lines of MP3 (Master2).


texts:
Thanks to the help I've received on here the last few days I have been able to put together a schematic for a project I am planning.

The project itself is lighting up a 1/400 scale model of the Cunard Queen Mary 2.

I will be running this from a 3amp 12v power source using a range of mostly 3mm LEDs along with some 0402SMDs. They will mostly be in series chains of 2 or 3, with each chain having its own direct connection. I've grouped the LEDs into like for like, so no chain is made up using different colours or types/makes.

I've broken this all up into 5 layers, depending on where the lighting sits within the model vertically.

Below are 6 images. The first 5 are each layer individually, with the final one a combination of all 5. (Please Note: There may look like there are some broken or random wires, there isn't that is just me making crude use of the software to create an outline of the model)

(The software states I will require 1.89A but my calculations come closer to 2.5A)

Should I fit a fuse? If so, what value?

I'd appreciate any input, but please keep in mind my knowledge is absolute minimum, especially where terminology is concerned, thanks.

Edit: I've corrected the resistor value on the single red LED on layer 3, to 560ohm.


texts: Why doesn't this RC circuit simulate as expected? (i.e. what am I doing wrong?)

texts:
I am trying to learn about RC circuits.  As I understand it, the indicated point in the basic RC circuit below should produce a current and voltage curve like this.
However, when I attempt to simulate the circuit in the embedded CircuitLab and (other online simulators also) I get nothing.  I also tried in Digikey's Partsim and got the same results. So it must be something I'm doing wrong...

I chose Time Domain simulation with the following parameters:

(I assume the Time Constant for this circuit is about 1 second, so 2 sec should generate a nice curve...)

I'm measuring V and I at the point indicated.

Here's what I get.  Notice the scale shows 9.000V top and bottom, and current 0.000A top and bottom.

It makes no sense!  Please tell me where I went wrong!  Thank you!

simulate this circuit – Schematic created using CircuitLab


texts: DS1307 RTC module using without arduino?

texts:
Is it possible to use RTC module DS1307 to schedule swtiching lights on and off? I am not supposed to use arduino but all tutorials on internet are with arduino.

The main problem for me is power consumption. I need to reduce it as less as possible. Well, my circuit needs about 30mA for normally working. That is (30*24)mAh on daily base, but I need to power it for 2 years with 10000mAh battery. My goal is to every 8 hours turn on circuit for 1minute and turn it off.

I was searching for different 12V timers but I didn't find anything useful.


texts: I am a second year Electrical Engineering major. I have done a little with the Arduino, but it is not powerful enough to handle video (from what I understand). I would like to capture video from something like a webcam and send it over Bluetooth to either a computer or phone/tablet. Does anyone have any suggestions on how to approach this? I have not found a PCB with a microprocessor powerful enough to handle this that includes Bluetooth. Will I have to make the circuit on my own? I have not designed circuits yet, so I would have no idea on how to design the circuit and handle the transmitter. Any suggestions and help would be greatly appreciated, thanks!


texts: Binary Data encoding and decoding format

texts: I am trying to understand what is the meaning of this data coding format as shown in the following image. It is not simple binary to decimal conversion. Can anyone tell how this conversion formula works?


texts: How does this circuit work? (TP4056, DW01)

texts:
Why are capacitors C13, C12, R20 used here?
And why resistor R18 and C5? (What function do they perform?)
I don't understand why they are installed there.

Datasheet:
TP4056,
DW01,
FS8205A.


texts: do two I/O microcontroller pins that are connected to each other require an external resistor?

texts:
I'm trying to make two atmel AT89C2051's communicate with each other serially but the serial ports on either won't be available because one serial port on one chip connects to the computer and the other one on the other chip connects to a radio unit.

So my thought is to connect an output port (like P1.5) on one microcontroller to P3.2 on the second one to act as a clock, and connect an output port (like P1.4) to P3.7 on the second one to act as data.

I use P3.2 as clock input since its supposed to trigger interrupt 0.

My question is will an external pull-up resistor be required even though I'm not using P1.0 or P1.1? and if so, what is the maximum value the resistor should be?


texts:
I stumbled across a relatively simple FM radio transmitter online.

Credit: makezine.com

I wanted to understand how it works (it is called "super simple" on the website), but several hours I have nothing but a vague understanding.

I believe R2, L1, C3 form an oscillator, and then the transistor Q1 is used to modulate the signal. C1 would just be used to remove any DC offset. However, this leaves R1, C2, C4, C5, and R3 and,  for these components,  I have no clue what they do.

Could someone please explain how this "super simple" transmitter works?


texts: Why are words in reverse order when reading from a flash?

texts:
I dumped the contents of a NAND flash chip, and do not understand why would each of the words in the image be in the reverse order. This CFI-compatible flash is connected to a TI AR7 SoC that integrates a MIPS 4K core.

I am dumping the flash using OpenOCD connected to the board's EJTAG port. I have done this before with very similar boards with AR7s and have never seen this.

Just to clarify, I am not speaking about endianness, every single 4 byte sequence seems to be reversed, including strings, ie: 'CTAWGODHRAW GNIN' instead of 'WATCHDOG WARNING'. ('0123' becomes '3210')

Are there reasons for the data to be inverted like this? How is the processor able to boot from this data if the flash is, for reading, just mapped at an address?


texts:
This might be the noobest question ever, but I'm actually really having trouble understanding at times how to orient a pot from a schematic in the case I don't fully understand the circuit. Maybe I'm just thick as a brick, but I haven't been able to google this satisfactory.

I have made do with just breadboarding and testing or just using front panel mounted pots with the possibility to reverse by a simple twist of the connector, but I really would like to know this better so I can do PCB mounted pots even of circuits I haven't tested on breadboard.

So to exemplify, say I have an ADSR envelope generator and know that I want fully CW to represent long times and CCW short times.

I read a schematic looking like this:

but from the same page I also have an older version (where this part should be identical) where the wiper arrow was pointing the other direction but also connected to the other end-pin:

Both come from http://www.schmitzbits.de/adsr.html

This makes me think that the way the wiper arrow points is the CW side? Is that always so?

Also, at some point I was pretty sure that for straight wiper pins, the right pin when looking from the wiper pin's perspective was always meant to be the CW pin, but now I'm not sure at all.

Just to be clear, I fully know the pinout of my physical pots, that's not the problem. It's just the schematics standard I'm wondering about.

Update:

KiCad's only pot schematic in standard lib looks like this:

Combined with the at least decently common 1(CCW),2(wiper),3(CW) pinout of the physical pots, that plays well with the schematics for this ADSR making the resistance of the rheostat configured pots have max resistance -> longer times when pot is in CW direction.

Can someone confirm similar findings for Eagle standard lib or other standard software? If that is the case, I will at least try to adhere to it myself when drawing a schematic.


texts: Returning from interrupts at a different location from where the interrupt occurs. (PIC16F877A)

texts:
Is there a way to return from interrupts at a different location from where the interrupt occurred in Microchip PIC16F877A?

I have a problem where I need my code restarts at a specific point always an external interrupt occurs and the ISR is just finished.

I'm thinking in use in-line assembly instructions in my C code to get the address I want to return and to change the top of stack to that address, but I guess the PIC16F877A doesn't support that.


texts: Choosing an SMD Resettable fuse for a 2.5 Ampere USB charger port

texts:
So I have googled for more than an hour, trying to find the specific answer for this, and maybe Im searching all wrong, but here comes my question.

I have a USB-hub combined with one fast charging port, with ONLY power, and no data. The other day the fuse from the DC transformer (transfomer is at 5 volt, 3.5Amps) and the port failed after I connected an apperently faulty powerbank. The fuse is located right next to the USB port in the hub.

All the other, data-USB ports work just fine, even with only power from the DC transformer, but the 2.5 Amp charging port is dead.

The fuse on the board is marked with "J". But this gives me results of a 32 volt 1.25 Amp fuse... Is this the one I should go with?

I dont really get how the voltage and amperage of the SMD fuses coincides...

I would be so happy if I could get some help in findig a suitable small fuse for the job.

Best regards, Fredrik

EDIT

I have a resettable PTC, 6 volts with a tripping current of 3.5A and a holding current of 2A (it seems on the documentation Ive found) on another board that I dont use, marked with K. Is this a good alternative?


texts:
I have a PCB that's designed to output 3.3V from a 5V source. The 5V source I'm currently using sources several amps (3A), though I only need about 100mA. I based the schematic on "Ultra-Low-Noise Fixed Voltage Application" circuit in the datasheet for MIC2505. For some reason when I plug in the power, I'm showing only 1.5V on the multimeter. Any ideas why this might be?

Regulator: MIC5205-3.3BM5
C1: 1uF / 16V ± 10% X7R Capacitor SMD-0603
C2: 2.2uF / 16V SMD Tantalum Capacitor ± 10%
C3: 470uF / 16V SMD Aluminum Capacitor


texts: Why can this ignition coil driver circuit not produce high voltage but only ~ 300 V?

texts:
Why is this ignition coil driver circuit not working correctly? (The coil is of this type, but used the model shown in the photo below.)

The coil is driven with 16 V @ 5 A @ 540 Hz but I cannot get high voltage between the top connector and the bench supply ground. The voltage is only about 300 V.

What could be wrong with the circuit?


texts: Connecting Attiny85 to nRF24IO1: How can I get 2 free IO pins in attiny85

texts:
I am trying to connect an Attiny85 to an nRF24L01. I tried the library NRFlite from the Arduino IDE libraries and it works fine. The problem is that I end up with only 1 free analog pin (pin 4) in Attiny85 (see below). However, I need 2 free pins.
Radio  --  ATtiny85

CE    ->  Pin 3

CSN   ->  Pin  3

MOSI  ->  Pin 1

MISO  ->  Pin 0

SCK   ->  Pin 2

IRQ   -> No connection

VCC   -> No more than 3.6 volts

GND   -> GND

I remember reading an article sometime ago about this same issue, but I cannot find it or remember any detail...
Any help is appreciated.
Zak


texts: Can i wire two switches so that the circuit is closed when one or both switches are thrown?

texts: I basically want my switches to act like a logical OR, so that when one, the other, or both doors are opened, a common light turns on.


texts: How can a signal itself have a high impedance?

texts:
Observation: Recently I worked with a piezoelectric sensor and read that the sensor itself has a high impedance. Because of this, an op amp of high impedance was required to amplify the signal.

Question: How is it possible for a signal to have high impedance? How can the signal itself have resistance / reactance (I understand there will be very low amounts of resistance in the wire that the signal travels across.) Shouldnt the signals resistance / reactance be determined by which circuit is connected to?

Disclaimer:
My background is in computer science and my knowledge of electronics is pocket sized. Sorry in advance if this question is based of misconceptions on my part.


texts:
i'm using a 2,4GHz transceiver with a differential output. A Balun with 50Ω Output is connected. I have 3 free places to add matching Components in π Topology.

The antenna is placed on the other side of the PCB connected to a Via where i tried to match 50Ohm. The Antenna also has 50 Ohm.

I have a SignalHound Tracking Generator and SignalHound Spectrum Analyser.

I Recorded the folowing Diagramms for the Reflection.

I got the best Result with the last SetUp. Do you have any idea how to improve the process of matching. I'm not able to measure the SmithChart.

Greets,
Andi


texts:
I am experimenting a bit and have built the circuit shown below to mix two input signals. It works great across the full audio spectrum.

Now I’m trying to figure out a way to switch the signals so that one or the other can be switched off/on individually without any strange artifacts/pop from DC/audible distortion, etc. at the output, while still allowing for removing any large DC bias at the inputs.

I have tried numerous attempts at placing switch contacts, and this is made a bit complex by the single supply.  The requirement to bias the summing amp adds DC to the right of the 220uF caps, so while adding large resistors to ground to the right of the caps doesn’t affect the bias or response much, if the switch is placed after the large resistors and before the 1k resistor, every operation requires the cap to recharge, and distorts the signal until it is charged.  Placing the switch before the caps means if a long time goes between switching, the signal is distorted until the cap fully charges.

Can someone give me some suggestions on how I might accomplish this?

UPDATE: Thanks to the replies, I have modified the circuit as follows, and tested successfully with pushbutton switches.

Regarding the type of contacts for S1 and S2, assuming use of an analog switch or other FET type: Which would give better muting performance without unwanted side-effects, using an SPST switch and simply breaking the connection, or would it be better to use an SPDT switch and both break and shunt the input signal through a resistor to ground? As recommended in various locations on the web, I have tried simply shorting the input directly to ground, but I've never gotten satisfactory performance this way, probably due to the lower input impedance of the next stage.


texts:
I want to achieve a specific temperature using a semiconductor or an electrical resistance in general. The temperature I want to achieve is at about \$30^oC = 86^∘F\$. This experiment consider it to be local in space, just the semiconductor and me with a battery. The starting temperature is about \$24^oC−25^oC\$

  Can you suggest any semiconductors that can do the job and are cheap?

  How can I achieve this temperature? How much voltage, current should I use?

  I don't want to use coolers to drop the temperature.


texts: Measuring power factor of a single phase motor on a three-phase service

texts:
I am trying to measure the power factor of a single phase, 208V compressor motor that is connected across phases B & C of a three-phase service and drawing 8-10A. My first attempt using a Fluke 345 set to measure single phase is reading 0.997 power factor. If I set my meter to measure as three-phase, I see 0.07 power factor.

Neither of these can be correct and I'm not sure how to measure the true power factor for this setup. Is this even a reasonable measurement to ask for from this configuration?

(If it matters, there is another single phase motor connected across other phases (A & B) that is active at the same time and if I attempt to read it I get 0.47 or 0.88 power factor as single phase or three-phase measurement.)


texts: How to calculate Fundamental Input Power Factor

texts:
I am really confused with the concept of fundamental input factor. What was taught to me in class was the below formula
IPF(Input Power Factor) = IDF(Input Displacement Factor) x CDF (Current Distortion Factor)
Input Displacement Factor was defined by my instructor as the cosine of angle between the phase voltage and line current
So, I tried to apply this 2 things to this problem.
I did the same steps as given in the solution and got Vo = 531.19V and cosu = 0.967. [Here u is the overlap angle]
Now I tried applying the formula taught in the class and got wrong answer. Steps are shown below.

So, source line current (iR) leads the line voltage (vRY) by (0.5u+30). So, it will lead the phase voltage by (0.5u+60).

Please help me understand this problem.


texts: What determines the amount of current that can be drawn from a generator?

texts:
I tried searching this site and the internet for answers to my questions but found only partial answers.

I am experimenting with generator design. I am using only one pole of the magnet so as to get pulsating DC output. My question is; What determines the maximum amount of current that a DC generator can deliver to a load? Does the resistance of the generator coils determines this?

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

Guys, I am very grateful for your response to my question. My background is in Digital Electronics; My knowledge of electromagnetism is not thorough and so I would like to get answers to a few more questions.

1)  Autistic, you mentioned that " ....inductive term vector adds to the DCR" What is DCR?

2) I am using one pole only of the magnets to get a DC output. However, I am reading the output voltage as AC. Why? When I set the multimeter to DC it displays milivolts; This makes sense, since no smoothing capacitor was added.

3)  This is unrelated to the current discussion. When a voltage is applied to a coil (wound on an iron core), how long does it takes to becomes fully magnetized? When the current flow stops, how fast does it take for demagnetization to occur.


texts: Early Deadline First (EDF) scheduling in real-time systems feasibility test proof

texts:
I am trying to prove Theorem 6.2 on page 127 of the book Real-Time Systems by Jane W. S. Liu:
http://www.cse.hcmut.edu.vn/~thai/books/2000%20_%20Liu-%20Real%20Time%20Systems.pdf
It is based on Early Deadline First(EDF) scheduling.
It says on the book that the proof is similar to the proof for Theorem 6.1 on page 124-126. However, I am still stuck.
Here is what I have so far:


texts:
For https://www.design-reuse.com/articles/34973/low-power-high-density-clock-gate.html ,  could anyone explain how the following newly proposed clock gate circuit architecture works ?

How does it reduces the clock-to-out path by merging the internal latch sequential loop and clock inverters ?

How does it saves an area of equivalent to 2 inverters ?


texts: The picture shows the truth table of control operation of a RAM. If you disable the OE pin the output can not come to the bus because of high impedance, now the question is, is the impedance unidirectional like a diode? if not how can write data function still be possible when OE is high? because in this situation the data input should not reach the ram. in other word is the tri-state switch bi-directional or unidirectional?


texts: CC1120 does not receive upon software upgrade

texts:
Note: only read if you have experience using Texas Instruments CC1120 modules earlier.

I am using this development board by Texas Instruments with a CC1120 module hooked up on it.

I have been using the TrxEB RF PER Test Software (Rev. C) on it and I have been able to transmit packets to another module in the RX Sniff Mode successfully. However, today I upgraded to the CC112x Software Examples (Rev. E) software which allows me to directly enter RX Sniff Mode (there's a separate app for it) instead of having to navigate through a menu. Both of these firmware can be found here (scroll down to the Software section).

Note: Rev. E firmware is a bit difficult to compile because of it's folder hierarchy, I have uploaded a cleaner version of it here.

The transmitter is working fine and I can see transmissions at 868 MHz using a lab spectrum analyzer, however, the packets do not show up at the receiver end.

I had issues transmitting at high frequencies earlier so I switched to 434 MHz in Rev. C firmware (which had a menu). However, I must change some registers in order to do the same in Rev. E firmware.

I have been searching around and the registers that control the transmission frequency appear to be controlled by the following set of values:

    //Register Settings for different frequency bands.
    static uint8 freqSettings[5][3] =
    {
      {0x69,0xF1,0xFF}, // 169.5125 MHz
      {0x6C,0x80,0x00}, // 434 MHz
      {0x6C,0x80,0x00}, // 868 MHz
      {0x72,0x60,0x00}, // 915 MHz
      {0x77,0x60,0x00}  // 955 MHz
    };

I'm surprised that 434 MHz and 868 MHz use the same values (these values are from the Rev. C firmware. Then there is this:

    //Band select setting for LO divider
    static uint8 cc112xFsCfgs[5] =
    {
      0x0A, // 169 MHz
      0x04, // 434 MHz
      0x02, // 868 MHz
      0x02, // 915 MHz
      0x02, // 955 MHz
    };

Unfortunately, the register this array controls is CC112X_FS_CFG which is set to 0x12 by default in the newer firmware, a value that matches neither 434 MHz nor 868 MHz.

Anyone who has successfully been able to transmit at a different frequency using CC1120 wireless module?


texts:
I wonder how a mobile phone (handset) sends signals to the Base Transceiver Station (BTS). The BTS is obviously quite large and, thus, possesses much more power than a phone does. So, how is a phone able to send information?

Receiving is quite clear but I don't get the other way around. I couldn't find any detailed explanation on that. The only hint I've discovered is that the signals are overlapped to a carrier frequency. But, as far as I understand, this does not touch or even explain the mentioned "power"-issue. I often read that most mobile phones use the same antenna for receiving and sending. If that's possible then why are the BTSes so large when such small ones like in our handsets are sufficient?

My questions are intentionally naive, since they are fundamental questions. And because I do not really know it better.


texts: How do I automate the size setting (or any property) of both NAME and VALUE in a PCB BRD file?

texts:
I would like to set the size parameter of both value and name of components on a PCB layout to have a readable silk screen. Now it seems that I have to smash everything and go by them one by one.

Is there an ULP or something that iterate through every component and let you set one of the properties automatically?


texts: MH-Z19 CO2 sensor giving diferent values using UART and PWM

texts:
I have a MH-Z19 CO2 sensor, according the data-sheet I can obtain PPM values via UART and PWM. The difference between both method is the limit in the CO2 concentration, where UART I should have readings between 0-5000ppm, and via PWM I should have readings between 0-2000ppm.

I just wanted to know if I can have the same readings using both methods, but after tried I'm realized that I'm having different values.

I'm using the following code to test:

#include <SoftwareSerial.h>
SoftwareSerial mySerial(A0, A1); // RX, TX

byte cmd[9] = {0xFF,0x01,0x86,0x00,0x00,0x00,0x00,0x00,0x79};
char response[9];

#define pwmPin 10
int prevVal = LOW;
long th, tl, h, l, ppm, ppm2 = 0.0;

void setup() {
    Serial.begin(9600);
    mySerial.begin(9600);
    pinMode(pwmPin, INPUT);
}

void loop(){
    mySerial.write(cmd,9);
    mySerial.readBytes(response, 9);
    int responseHigh = (int) response[2];
    int responseLow = (int) response[3];
    ppm = (256*responseHigh)+responseLow;

    //CO2 via pwm
    do {
        th = pulseIn(pwmPin, HIGH, 1004000) / 1000.0;
        tl = 1004 - th;
        ppm2 = 2000 * (th-2)/(th+tl-4);
    } while (ppm2 < 0.0);

    Serial.println(ppm);
    Serial.println(ppm2);
    Serial.println("-----------");
    delay(5000);
}

The readings that I'm getting are the foolowing:

643
356
-----------
643
356
-----------

Any idea what could be going on here? Should I suspect that the sensor is damaged? Or, I'm doing something wrong?

Thanks and best regards.

BTW: The test is done with an Arduino Pro Mini ATMega 328, 3.3v, 8Mhz. The sensor is being powered by 5v from a NodeMCU (lolin).