texts: Where to place a capacitor to smoothen IR sensor reading?

texts:
I know this question has already been asked, but the answer I'm looking for here is different.

I found out about this forum post explaining the best way to smooth out the reading of a IR sharp sensor (it seems really great based on facts and measurements).

The thing is I don't know much in electronics, I'm wondering where should I put the capacitor and resistor described in this post: 10uf ceramic capacitor and 530 ohm resistor parallel to the capacitor.

"Where should I put it" means where do I connect it. Thanks


texts: Should we use ieee.Numeric_Std_Unsigned?

texts:
I know that in VHDl, there is a multitude of library, I have come to the conclusion that the only 2 library that should always be used are:

library IEEE;
use IEEE.STD_LOGIC_1164.all;
use IEEE.NUMERIC_STD.all;

Sometimes, I believe, we could also need some other library, for math or string purpose:

use IEEE.MATH_REAL.all;
use IEEE.MATH_COMPLEX.all;
use IEEE.STD_LOGIC_TEXTIO.all;

And that we should avoid the “false” library made by Synopsis in the early days of VHDL:

use IEEE.STD_LOGIC_ARITH.all;
use IEEE.STD_LOGIC_SIGNED.all;
use IEEE.STD_LOGIC_UNSIGNED.all;

https://stackoverflow.com/questions/45704135/when-to-use-vhdl-library-std-logic-unsigned-and-numeric-std

But, I have recently learned that other (official ?) IEEE library exist like:

use IEEE.NUMERIC_BIT.all;
Use IEEE.NUMERIC_STD_UNSIGNED.all; --seems to be VHDL 2008 only

Are those last two libraries useful? Should we use them?


texts: How to control LED brightness with mosfet as switch and potentiometer

texts:
I am designing a circuit to control a high current LED string. Most of the time the led string will be ON. Where should I place a potentiometer to control the brightness of the LED when it is on by limiting its current. I am thinking at the source to ground of the fet? LED has a forward voltage of 12V and If of 100mA at max brightness

Please excuse if I am misunderstanding anything as this is my first project.


texts:
I'm trying to add power control to a USB hub based on the Terminus Tech FE1.1s hub chip. From the datasheet, I know the chip supports ganged power control, so all ports share a single switch. That's fine for me, I'm actually planning to use the switch to control only one of the four downstream ports the hub has.

As far as I understand the datasheet, the PWRJ pin (pin 25) is a digital output pin that outputs low (<0.4V) for when power should be enabled, and high (>2.4V) when it's disabled. These levels are at 4mA.

I'm now trying to figure out what kind of transistor (and accompanying resistor) I need to use for switching the power of one of the hub's USB ports with the output of the PWRJ pin. The consumer at that port (soldered in) could theoretically draw 500mA, but in reality, I believe even 100mA could be enough.

I imagine the circuit to look like this:

I'm a beginner when it comes to electronics, and I still find the range of transistors rather complex.
I believe I need an NPN transistor (since low should enable power), and in order to get minimal voltage loss (USB needs its ~5 Volts), I probably need a MOSFET?

What transistor could fit my requirements here? What characteristics do I have to look for?

Any help is highly appreciated!


texts: Power from 2 USB ports for faster device charging?

texts: Use 2x5V from USB ports to speed up device battery charging? Do we get enough current (1A) from this 2 USB ports as well as from AC charger? I assume that voltages need to be the same, but what'll happen if they are not?


texts: 2.4 inch tft lcd with ILI9341 reset pin state and info

texts:
I am using one of those Chinese clones of the Adafruit TFT LCD and I couldn't find much information about the reset pins on these chips. The way I have it set up is that a MOSFET on the high side switches it on and off through a digital pin as it is  required in my specific application. I was able to do that and also as a word of caution to those trying to figure it out, writing all the pins LOW is a must in order to avoid powering it through its protection diodes.
It is working exactly the way I want it to but my concern is that there is not much information about the reset pins on this chip. When powered on, the reset pin is connected to 3.3V but when powered off, what state should I leave the pin in? Currently I leave it floating and since it is not receiving power in any way, the LCD is not fussy about this although I am concerned about it. Is it okay the way it is and about pullup resistors, should I care to put one on this pin?
Some info about my setup, I am using s Teensy 3.2 and the LCD is a 2.4 inch TFT LCD with the ILI9341 driver chip. A digital pin controls the MOSFET which is a logic level NDP6020P switching 3.3V.


texts: So the LF351 has an output voltage swing of typically 12V. To achieve an undistorted output waveform, output swing should be lower than Vsat. How do I know what the Vsat is? Its not mentioned anywhere in datasheets or is the output voltage swing=Vsat?


texts: How can different voltages produce the same short circuit current?

texts: I hope I’m not just thinking past something trivial but I can’t make sense of this. In this video, https://m.youtube.com/watch?v=XDf2nhfxVzg , variable voltages from .1-20V are used and when he shorts out the wires, they all produce the same amperage. How does this work?


texts: Why are the high-side and low-side outputs on this motor driver IC separate?

texts:
I'm trying to understand the datasheet for the VNH5050A motor driver. The pinout shows the high-side source (SOURCE HSx) and the low side drain (DRAIN LSx):

but after that the datasheet refers to the outputs as OUTA and OUTB.

I assume that the high-side source is supposed to be connected to the low-side drain (as the block diagram shows), so my question is: Why are they separate pins and not connected internally?
UPDATE: Here's the datasheet: https://www.mouser.com/datasheet/2/389/cd00241540-1796943.pdf


texts: Approximating a zener diode with an independent voltage source in series with a resistor

texts:
Given the following schema:

The zener diode IV-relationship is actually a  piecewise-linear approximation to a real diode.

Having the following values:

RIN = 1 kΩ
RL = 2 kΩ
VI = 9.5 V
vi = 50 mV

Apparently, the zener diode can be replaced by a 5V independent voltage source in series with a 10 \$\Omega\$ resistor. Why is this true?

What I have done

So far, I have used the Thevenin theorem for finding out in which region is the diode operating:

RL = 2 kΩ
RIN = 1 kΩ
VI = 9.5 V
vi = 50 mV

\$R_{TH} = \frac{1}{\frac {1}{R_L} + \frac{1}{R_{IN}}}\$

\$V_t = V_I + v_i\$

\$I_t =\frac {V_t} {R_{IN} + R_L}\$

\$V_{IN} = I_t * R_{IN}\$

\$V_{TH} = V_t - V_{IN}\$

\$print(V_{TH})\$

  Result: 6.36666

So, the diode is working in the region that is left to the -5 volts in the iv-characteristics, because its polarity is inverted in the circuit. I get that.

What I don't understand is how can it be inferred that the diode is actually a 5 V voltage source in series with a 10 \$\Omega\$ resistor. Why is the diode augmenting the voltage in 5 V? It is operating in that zone, true, but I don't see why the voltage source is necessary.

In addition, I don't see why the resistor is specifically set to 10 \$\Omega\$ .

Finally, it seems that the resultant voltage source would have the polarity as \$V_I\$ and \$v_i\$, that is, the + symbol near to \$R_{IN}\$ and the - symbol near ground. I don't understand this either, since the diode's polarity is inverted.


texts:
I'm facing a error when I tried to simulate a circuit. It's a parallel-to-serial converter. With the first word, the circuit works well, i.e, the conversions occur. But with the second word the simulation stop, and throws an error without information.

Here my VHDL code:

LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;

ENTITY ParalelSequencial is
  port (
    clk: in std_logic;
    data_in: in std_logic_vector(0 to 7);
    start: in std_logic;
    data_out: out std_Logic
  );
end ParalelSequencial;

architecture behave of ParalelSequencial is
  signal start_bit: std_logic;
  signal stop_bit: std_logic;
  signal buff: std_logic_vector(0 to 9);
  signal control: integer range 0 to 9;
begin
  start_bit <= '0';
  stop_bit <='1';

  buff(0) <= start_bit;
  buff(9) <= stop_bit;

  buff(1 to 8) <= data_in;

  process (clk)
  begin
    if (rising_edge(clk)) then
      data_out <= '1';
      if (start = '1') then
        data_out <= buff(control);
        control <= control + 1;
        if (control = 9) then
          control <= 0;
        end if;
      end if;
    end if;
  end process;
end behave;


texts: Override value of RFID tag from external sensor

texts: I have the following scenario, there is a RFID tag attached to a certain object which also have a light sensor on it (this is just for illustrative purposes, it could be another type of sensor), I want to know whether it is possible to tell the RFID tag when the light sensor is on/off or put another way, can the light sensor just somehow connect directly to the RFID and inform its on/off status so that whenever I read the tag with the RFID reader I could know that the light sensor is on/off, thanks in advance


texts: Noise Shaping of \$ \Sigma \Delta \$ Converters

texts:
I am currently reading the book Continuous-Time Sigma-Delta A/D Conversion to get myself a better understanding of \$ \Sigma \Delta\$ converters. Unfortunately I got stuck at the point where noise-shaping is explained. The chapter started clearly, saying that for studying the effects of noise, the quantizer can be approximated by a linear model, which then leaves us with a linearized \$ \Sigma \Delta\$ modulator as shown at the bottom.

With this model we want to achieve two different transfer functions, one for \$x(n)\$ and another for \$e(n)\$.

$$
Y(z)=STF(z)X(z)+NTF(z)E(z)
$$

STF ... Signal Transfer Function, NTF ... Noise Transfer Function

Since the noise shall occur at high frequencies and the signal at low frequencies, it seems clear that the STF should be a low-pass and the NTF a high-pass filter.

Now the author states that this leads to the following concrete transfer functions:

$$
STF(z)=\frac{1}{\frac{1}{H(z)k} + 1} \\
NTF(z)=\frac{1}{H(z)k + 1}
$$

No further explanation. How is it possible to conclude that the STF and NTF need to look like that? Furthermore, how can we conclude that the simplest \$H(z)\$ is an integrator?


texts: What should I use: Hall effect sensor or current transformer?

texts:
I have to design a generalised kit for online condition monitoring of induction motor (1Hp, 3hp and 5hp) and monitor voltage, current and temperature.

I was thinking to use a Hall effect sensor/clamp on Current Transformer (clamp on CT -I to V converter-rectifier-ADC-controller) for current measurement and PT (PT-rectifier-ADC-controller) for voltage measurement.

I am not sure what will be more economical for current measurement as the kit should be portable. I also dont know what will be the rating of clamp on CT.


texts: Digital Logic current flow IFF current in different circuit

texts:
Using only digital logic gates, how do you make it so a path is only open for current to go through if there is current flowing through a different part of a circuit.

Specifically, block current from flowing through a circuit until there is (a much weaker) current flowing through a section of a different circuit.


texts: Capacitor and discharger selection for pulse discharging

texts:
I want a 100 Joule pulse in 350 micro seconds. I have 1000V nbu 1012 capacitor discharge circuit . In datasheet, Max. average power is 3000 W(page 8), however I need 100/350us= 285kW instantaneous power when pulse is activated. Does the nbu circuit can handle 100Joule discharge at 350us, (with any capacitor with maximum voltage is 1000) or should I seach for other pulse discharge circuits?

Additional info:
The resistor value is about 20ohms (but I'm not sure, I will check this within 1-2 days).
I calculated that 200uF (1000Volts) capacitor can store 100 J.
Time constant of RC circuit is 4ms.

Do these calculations say that it is not realizable to discharge 100 Joule in 350us with 1000V capacitor? So should I increase the voltage of capacitor and discharge circuit?


texts:
I have this Infra-red USB receptor with 2 broken wires, marked in the picture with circles.

What type of connector/pin are these? Both connectors are similiar, except in size. Looks like they are soldered to the pcb.
How do I fix this?
Can I replace this type of connection with a stronger one,
maybe something like a JST connector?


texts:
My instructor told me to "kill" sources (treating current sources as open and voltage sources as short). From this my third node would have to be in the top right corner.

Suppose its called A. Would the following be the correct KCL for it?

$$A: \frac{A-C}{2k} - (4mA) = 0$$

$$B: \frac{B-C}{6k} + \frac{B-Ref}{3k} + (4mA) = 0$$

$$C: \frac{C-A}{2k} + \frac{C-B}{6k} + \frac{C-Ref}{4k} = 0$$

What I am confused on is where the 12V comes in to play. Does it just get added to A (i.e \$A=(A+12V)\$ ?

$$A:\frac{A+12V-C}{2K} - (4mA) = 0$$


texts:
I'm setting an array with data from an EEPROM.
As you can see in the code below I instantiate an array, loop 16 times and fill the array with data read from the EEPROM.
I've tested the data that is read from the EEPROM which is correct, but if I print the array after the loop I get 18 characters. I can't find out where the data is coming from. Any ideas?

void send_eeprom_data()
{
  char eeprom_data[16];
  for(int i = 0; i < 16; i++) {
    eeprom_data[i] = read_eeprom(8, i);
  }
  Serial.print(eeprom_data);
}

/* READ AND TRANSFER FUNCTIONS */
char spi_transfer(volatile char data) {
  SPDR = data;
  while(!(SPSR & (1 << SPIF)))
  {
  };
  return SPDR;
}

byte read_eeprom(int ss, int address) {
  int data;
  digitalWrite(ss, LOW);
  spi_transfer(READ);
  spi_transfer((char)(address));
  data = spi_transfer(0xFF);
  digitalWrite(ss, HIGH);
  return data;
}

update

I changed the code to the following:

void send_eeprom_data()
{
  char eeprom_data[16];
  for(int i = 0; i < 16; i++) {
    eeprom_data[i] = 'a';
  }
  Serial.print(eeprom_data);
}

Ouput:

aaaaaaaaaaaaaaaaûz

(16 a's)


texts: How can I measure the conductivity of a copper rod?

texts: I would like to perform an experiment to measure the conductivity of a copper rod. What device can I use to perform that experiment? Is there such a thing as a conductivity meter? All I found was an apparatus to measure the conductivity of solutions. Please note that I need to get results as accurate as possible.


texts:
I am trying to implement a switching voltage regulator from 7.2V to 5V with LM2596 by HTC Korea. Since I don't need an adjustable regulation, I chose typical application circuit from the datasheet which is for fixed output voltage (seen below).

I use 1N5817 (20V, 1A, for testing only) Schottky diode for D1, and different values for L1 including 27uH and 33uH. I also change Cout to 100uF, 270uF, 330uF, 470uF and 1000uF (16V and 25V). No matter what I did I couldn't change output voltage. It's always around 1.25 volts, the value does not change if I remove D1, L1 or both. Changing L1 or Cout also does not affect output voltage. If I remove Cout and measure output voltage without a load, it's around 4V.

What am I doing wrong? Is there anything that I am missing here? I also attach the pictures of my test configuration on breadboard below.


texts:
What's the input voltage range for a Wemos D1 board?

I have a battery pack of 4 AA batteries. This makes 4*1.5V = 6V, but I think they can drop as low as 4*1.2V = 4.8V. Can I hook the battery pack directly to the input voltage socket? Or is this to much?

What happens when I connect the D1 to the USB to program it? Must I disconnect the battery pack first? Sometimes it would be handy to let the USB cable connected to se debug output on the serial monitor.

I'm aware of Power Wemos D1 mini from battery but that only answers whether 3 batteries are enough.


texts: Powering a load through a small switch using N-Channel FET

texts:
I want to power some load anywhere from 24-36v DC @4-7A, through a small physical slide switch rated at like 36v and only 200mA. So I need the small switch to activate a FET to control the power. The load may or may not be connected and it would be good to prevent short circuiting the load (when the switch is on or off).

Would something like this work, using an N-Channel FET? Any better ideas/ designs or improvements would be great help!

FET - FDD18N20LZ

D1 - FSV20100V

R1 - CRCW1206300RJNEAHP

R2 - CRCW1206100RFKEAHP

Sw - EG2207


texts: I have Li-ion Battery (12.6V) and 15V power supply, also DC-DC buck converter set to 12.6V as charger for Li-ion Battery. My load can take both 12.6V and 15V. I want to use Li-ion battery as power source. But when needed, i will turn on my power supply and both charge my battery and feed the load. I want to use dual schottky diode to prevent back currents and low voltage drops. Is my schematic corrent? Thank you in advance.


texts: AC Power loss of inductor in a buck converter

texts:
I have a custom piece of equipment that gives a value for AC power loss (Pac) for an inductor plugged into an internal buck converter circuit. The custom equipment has an oscilloscope which is monitoring the voltage across the inductor and the current through it. I am trying to figure out how this value is calculated using this data. Since the circuit is a buck converter, the voltage across the inductor is a PWM shape, with the voltage around Vin-Vout while the PMOS is on, and about -Vout when the PMOS is off. The current is a ramp wave with a DC bias since the buck converter is running in CCM. I am also making sure to run the circuit so that the inductor is far from saturating.

I have tried the following to no avail:

Pac = (DT(Vin-Vout)*Iripple)-((1-D)TVout*Iripple)

where D is the duty cycle between 0 and 1, T is the inverse of the switching frequency.

How I came up with this is that for a perfect inductor, all AC power that is stored during the charging period would then be discharged during the discharge period. Since the inductor has some AC losses from eddy current and hysteresis, I took the power during the charging period and subtracted the power during the discharge period and what would be left is the loss. This is obviously not correct, as I am not receiving the same values as the equipment.

Any ideas?


texts: Does anyone have a datasheet for this Arira LCD?

texts:
I emailed the manufacturer but they haven't responded to my email. I received this LCD screen in a grab bag from Jameco. Googled for a while and couldn't find anything related to the pinouts of this LCD screen. This is all I could gather.

Arira Design Inc

800-00013-20

REV 2

800-00013-20ASSY

94V0 AB20811E

WZ-6 E170968

Someone else on reddit was also looking for a datasheet for the device. He posted pictures of it as well. If anyone has the datasheet or knows how I can connect it to an Arduino I'd appreciate it.
These are his photos of it: http://imgur.com/a/zkMHO


texts:
I need to save working configuration of my embedded application to the flash memory.

I am using STM32f746 uController. According to the datasheet. There is 8 sectors on the main block of the flash memory.

This will be my first time trying to write/read data from internal flash memory.

My question is the following:

How can I be sure what sectors/addresses are safe to use?

some sectors and addresses may be used by the HAL or any other internal mechanism in architecture or the firmware. How can I be sure that a given address is not used and will never be used by another parts?


texts: The difference between these two D latch circuits

texts: I simulated both ones and could not see any difference in functionality. So, what is the need for that extra NOT gate? When it is preferred?


texts: Where is Electric ground comes in missiles and rockets using high voltages ?

texts: I may sound silly. I think that the Rocket systems and missiles might be having high power amplifiers and circuits inside them. Then how the Electric ground is accommodated in those kind of circuits. I have heard about floating ground but I am not sure whether that concept applies here.


texts: Program to make bode plot of transfer function?

texts:
For different purposes, I sometimes have to draw an bode plot. I first of would like to know if there is any piece of software which can draw them for me. So I gave in the transfer function and then it gives me the bode plot (both phase and the magnitude). This would save some time at occasions.

Ok, so now the real question. I have the following transfer function.

$$ H(j\omega) = \frac{j \frac{\omega}{\omega_0} }{1 + 3j \frac{\omega}{\omega_0}} $$

The modulus can be calculated as follows (correct me if I am wrong):

$$ |H(j\omega)| = 20 \log_{10}(p) - 20 \log_{10} \left(\sqrt{1+(3p)^2}\right)$$

(where \$ p=\frac{\omega}{\omega_0} \$, with \$ \omega_0=\frac{1}{500 \times 6.37 \times 10^{-7}} \$).

\$ 20 \log_{10}(p) \$, would be easy, but I am not sure how to calculate the second one? How do I calculate the (magnitude) bode plot of \$ -20 \log_{10} \left(\sqrt{1+(3p)^2} \right) \$


texts:
I am dealing with a differential drive robot that interacts with several motors and actuators, all through a powerful NVIDIA Jetson Xavier. The Jetson runs Ubuntu and I use Python3 for programming all actions of the robot that go through a microcontroller via CAN bus.
Now, there are multiple parts of the robot that we need to program; chiefly navigation and arm-movement. Right now, the robot does only either of them, i.e., it can either move or perform some arm-movement. All the actions are based on the same 1D LiDAR sensor.

To boost its speed, I thought of performing both these functions in parallel, as they are almost independent of the other. Python provides two wonderful options for this: multi-processing and threading. Both of them seem equally good options with the caveat that threads cannot be killed and prove negligible improvement when compared to multi-processing. So, I am staying with multi-processing for the time-being.
Now, the way I use the sensor or lidar values is, to get them via a thread and continuously dump them as global variables.
t = Thread(target=dump_lidar_data,args=())
t.start()

Various functions defined in the same file, use these values as:
def fun():
    global lidar1
    print(f'Look, I too can access lidar 1 values: {lidar1}')

The main process or the parent process detects when its show time and spawns two child processes: p_navigation and p_arm. Both these process start together and have their own instance of dump_lidar working in their respective processors. Both terminate on the basis of the same condition. In the meantime, the parent process does nothing.

I notice that there is a considerable delay (upto 1s) between the data procured by the dump_lidar in the parent process as compared to the ones in the child processes. It is also possible that the CAN bus is giving the data after a certain delay.
Is there a possibility that the CAN or the circuit involved in getting the data to the Jetson, cause this delay ?


texts: PSpice: How do I calculate the voltage drop across a resistor?

texts: I'm searching for a tool that would display the voltage drop across a resistor in PSpice. Is there an element (like a voltmeter) that would help me able to do so?


texts: Open pin in circuit, how do I represent that in a spice model subcircuit?

texts:
I have a lm386 circuit that requires pin 8, gain8, to be disconnected in the circuit.

So how do I write the spice subcircuit to account for no connection in the 8th pin?

Example

* IC pins:     1   2   3   4   5   6   7   8
*              |   |   |   |   |   |   |   |
.subckt lm386 g1  inn inp gnd out  vs byp g8
X_U1           0   2   0   3   2   0   4  ???  lm386


texts:
We are designing a product which has to meet EMC directives. It consists of metal backplate folded into a chasis (the front is open). on the backcover there is a SMPS mounted. and on top of this we have our main PCB which has a signal ground plane on top of the PCB. the whole thing will be surrounded by a plastic cover with some space for user interface on the PCB. See image for clarification.

All SMD components will be on the back of the PCB, the front has the GND plane. The product will interface in a master-slave configuration via RS-485. because the units can be far away from eachother and be on different mains circuits, there can be big voltage differences between individual grounds so we also connect signal ground with the RS-485 connection.

My question is: (how) do we need to connect signal ground to safety ground (metal backcover)?
I understand if we connect the signal ground to the safety ground, and also connect the individual signal grounds between units, we create a ground loop.


texts: Paralel charging two Lithium Polymer batteries on a MP3 player Colorfly C4

texts:
Is it a good idea to replace a built in lithium polymer battery rated: 3.7 V, 2000 mah with TWO x brand new 3.7 V, 1800 mah (much thinner stacking them together) connected in PARALLEL and place it in my mp3 player model (Colorfly C4)? As it turnes out the built in battery is of very poor quality hence the question.

Is this perfectly safe to parallel charge two exactly same brand new lithium poly batteries, or will there be a danger of overheating/fire?
Will the capacity truly then be 3600 mah then, meaning longer playbacks as well as longer charging times?
What things should I take further into account (aside volume/packaging/fitting etc)


texts: Help identifying IC in switching power supply

texts:
I'm trying to repair an amplifier with a fault in the switching power supply, but can't for the life of me identify an IC that I need to replace. The number printed on the IC is LTBRZ 0D60 e3. I can't make out any obvious manufacturer logo, but the photo below may help:

A little background info; the amp is a 16 channel Control4 amplifier from a home automation system. The incoming mains is taken down to +/- 48VDC by a separate power supply board, and that part seems to be working fine. However, there is no life in the main amp PCB and the LCD on the front of the unit does not come on. There are 12V and 6.25V test points nearby just out of shot on the photo, and neither have any voltage on them. From the state of the board, I suspect there has been water spilled on the PCB. The only other components on this section of the board are switching devices and those check out fine.


texts: What method do you suggest for prototyping asynchronous circuits?

texts:
I got surprised and to a degree shocked by finding that there is no proper established tool for designing and prototyping asynchronous circuits.

I keep searching using google and other means to find a good method to design VLSI asynchronous circuits, but so far the searches have failed to produce an answer.

There are some abandoned tools like Balsa, etc. for automating VLSI designs, but they are totally undocumented and hard to use. What I am looking for is something like FPGAs that we have in the synchronous world.

Anyway I appreciate it if you share the name of a reliable tool, and prototyping hardware that ease the burden of asynchronous circuit design.


texts:
I have a W27C512 chip in my sights. This will be my first time using a programmable rom. I need to know how to convert any form of human-readable code into either HEX or BIN format. Here are the issues I need to solve (please correct me if i am mistaken):

I need to know the applicable addresses of the W27C512 chip. I also need to know the instruction set for this chip. ANY compiler will be handy. After spending half of today on this problem, the closest I have to an answer is this site: Proj19-EEprom programmer 27C512


texts:
I connected a DFPlayer with a PAM8403 on pin DAC_R  like this:

I also added capacitor on the supply line.

Here the sound i have from the speaker:

You can lisen here: https://www.dropbox.com/s/odw1ya0uxkn16ut/audio.mp3?dl=0

What can be the repetitive noise at the end (every .13sec or 7.7hz) and how to remove it? After the bell sound there is a a 3 sec of silent, but there is a click click click click during this time, why??

Same problem two different DFPlayer.
Same problem with battery or powersupply (5v).
Same problem with different amplifier.
If i disconnect TX and RX will the mp3 is player, i still have noise.

AND If i connect the speaker to spk_1 or spk_2, i dont have noise!


texts: Altium - create a mirror image of a board

texts:
I want to create an identical motor drive board in the right and left sides.  I just finished layout for the right side and I am wondering what is the easiest way to create the mirror image of this board for the left side?

For example: the connectors on the "top" side would now be on the bottom of the other board.  All components and tracks will also switch sides, layer stack will be inverted, etc.  Is there any command sequence in Altium that will do this without me having to manually re-assign everything to the other layer?


texts: What is the current consumed by Ultrasonic Sensors/Transducers (1-2MHz) to generate Ultrasound waves

texts:
I would like to know what is the current consumed by a 1-2MHz Ultrasonic Sensor (i.e sensors used for Clamp on Ultrasonic flowmeter) to generate Ultrasound waves. The two ultrasonic sensor specifications I've found (see below), do not mention the current current consumed, why is it ? when I've enquired with one supplier I've found that they were not sure either.

Sensor Specification 1:
 ,

Sensor Specification 2:

Edited Title of my question


texts: Can a filter change the frequency of the input signal?

texts: I am given a square wave with Vmin = 0V and Vmax=5V , T(period)=8ms and duty cycle 25%. I am asked to find the properties(low cutoff , high cutoff , bandwidth) of a band pass filter that will make the signal a sine with T=4ms. My answer would be that the Δf = 1/Δt where Δt=4ms . So the Δf=250Hz and therefore the actual value of lowcutoff and highcutoff doesn't matter as long as their difference is 250Hz. It was pointed to me that this is wrong , I don't understand why. What would be the right answer to this problem?


texts: How to choose a battery for my PCB board?

texts:
I have designed a PCB board for one of my projects. The PCB is about 60*80mm in size. I have done various tests in the lab,and now I will have to install it in the required location. However, I have been struggling to finalize the type of battery to use. I want the whole setup to be compact and not have any moving and detachable parts. The operation of the PCB and my calculations for the battery so far are:
There are two modes of operation for the PCB. They are:

Deep-sleep mode –Current consumption is about 1.5mA
Operation mode –Current consumption is about 120mA

The PCB operates once in every hour, and stays in operation mode for ~30seconds (or ~0.0084 hours). And the rest of the time it is in deep-sleep mode.
So the average current consumption is:
C=(0.0084*120+0.9916*1.5) mAhr
C≅2.5 mAhr

PCB Operating voltage is between 3.3V and 4.2V. And in the future depending on the battery I can change the Power regulation circuit.
The current consumption is measured at 4.2V. (Can I use only this for energy calculation?).
Hence the Energy required is:
E=4.2*2.5 mWhr
E=10.5mWhr

I need to choose a battery to power the PCB for about 3000 Hours. So the energy requirement is:
E=10.5*3000 mWhr
E=31500mWhr≅32Whr

If I use a Z V battery of R mAhr rating and assume the power regulator in the PCB is P% efficient, then the energy provided by battery is:
Eb=Z*R*P

Generally, for the better long-lasting performance, batteries cannot be discharged for more than 80% of its energy( So I have learned).
Hence the revised Energy of battery is:
Eb=0.8*Z*R*P

We need a battery of E energy. Assume P=80%.
Eb=E=0.64*Z*R
32Whr=0.64*Z*R
Z*R=50 Whr

If Z=12V, then R~ 4.2Ahr
If Z=24V, then R~2.1Ahr
If Z= 5V, then R~10Ahr
If Z= 3.7V(Typical Batteries) , then R~13.5Ahr

I can see many batteries online which , I think, can server my requirement. However, due to None-Little experience in this field, I am unable to consider the practical aspects. And also most of the batteries for this requirement seems to be little bigger. I am aware of the fact that I need to consider shelf-life of a battery and C rating as well, but don't know how to do it.
Can anyone please suggest me which type of batteries will suit my project well?
I hope all my calculations are correct. If there are any mistakes please consider correcting them.
Thanks in advance!


texts:
I'm looking into doing a Bob Smith termination for a Power over Ethernet (POE) PSE. The TI app note shows the following termination:

But all of TI's reference designs (and later figures in the same document) use the following termination with two ESD capacitor:

Are these circuits equivalent? What is the purpose of having two ESD capacitors?


texts: What is the basic definition of an amp-hour?

texts:
What's the basic definition of an amp-hour? For example:

A 12V battery is rated at 100Ah.

Does this mean that the battery will be discharged in 1 hour if the load is 100A@12V?

Thanks.


texts:
Can anyone please explain how does megohmmeter (insulation tester) work.
Here is what I don't I don't understand:

These little tester can produce e.g. 1000V, how is that done? What are the  internals that can produce I assume from 9V battery 1000V?
How can something generate 1000V at very low current? Internal resistance? From what I understand if you increase voltage you also increase current. If you trying to produce 1000V and put a big resistor in the front of it to lower the current, don't you immediately lower the voltage as well?

Two basic questions how does the internal of the meter work and how can you produce 1000V with little current.

I am clearly missing some basics.


texts: Designing an over voltage protection for really low voltage

texts:
I'm working on time lapse photography projects and one of the main problems is the voltage supply. So, using a couple of hot glue tubes I was able to create dummy batteries for my camera to connect an external power supply.

I'd like to go further now and use a voltage regulator in order to leave the camera on for longer periods. The problem is that I don't know the maximum voltage nor the current the camera can handle (my camera is a Canon Powershot SX150IS and it works fine with 2 AA 1.5 Volt batteries), so I want to build an overvoltage protection, so whenever the voltage goes over 3V, the power goes down and protects the camera.

I have seen this:

http://www.brighthubengineering.com/consumer-appliances-electronics/68396-over-voltage-and-low-voltage-protection-circuits-easy-home-projects/#imgn_3

as a starting point, but it doesn't seem to fit my needs (high voltage). Do you guys know where I should start? or maybe a better web site I can look at?

Best,

Charlie


texts:
I'm working for the first time on eMMCs and there's something not completely clear to me in their addressing system [explained in section 5.2 of JEDEC 5.0 standard]

JEDEC says that, depending on the size and the 30th OCR bit, you can have a byte access mode or a 512B sector access mode. So if I understood well in byte access mode the address structure starting from the most significant bits is:

write protected group-erase group-write block-single byte of interest

and the last bits express the memory position for a single byte inside a given write block while in the second:

write protected group-erase group-write block-512B sector

with the last bits identifying a single 512B sector

1) are them the right address structures? how does it work when I need just few bytes from a 512B sector [if partial retrieval is not supported of course]? it seems like if having to ask for an entire block discarding most of its data with a consequent great loss of time [a practical example with a fake address decoded in both ways would be very appreciated] 2) if the mechanism of taking the full block is right then who provides the offset for the bytes of interest once the whole sector is retrieved?

Thanks in advance to those who will try to help


texts: For MMBT2222; How to get hfe value to calcluate minimum base current to drive transistor in Saturation?

texts:
If my collector current VCC = 3.3V & Ic = 31.82uA then how to calculate minimum base current is required put transistor in saturation mode? Depending on it I will calculate base series resistor

As per my understanding hfe varies drastically in saturation region. Which hfe value to put into Ic = hfeIb formula?


texts: Ideal operational amplifier resistor question

texts:
My question is: since the same current flows through R1 and R2 the input current is 0, so can we treat them as resistors in series and add them together? If yes, what would be the expressions in terms of Ohm's law?

Example of the situation:


texts: How many times can an IC be desoldered and resoldered?

texts:
For a long time now, I had a fear, that when you solder a SMD IC to a PCB, that you won't be able to desolder and resolder it again without destroying it. Recently, I did just that, but it didnt damage the chip, so I feel a bit better. I used a hot air gun at my college. I did it because not all pins were soldered proper before.

Q:

What is the rule of thumb, how many times can I desolder and again solder the chip, to save the cost on testing?

Can it be infinite or will it start producing magic smoke after a while?


texts: I have this relay circuit to cut the ignition power of a vechile. Can someone please explain how this immobiliser                 circuit is working.


texts: Why does the load resistance has to be >100*Source resistance in case of a stiff voltage and <0.01*Source resistance in case of a stiff current?

texts:
I am using Albert Malvino's Electronic Principles and while i understand the equations to find load resistance the book does not explains the fundamental reasoning behind it.

Can anyone do better?


texts:
I have a question regarding ferrite beads. I have this kind of circuit:

Where IC1 and IC2 are digital ICs. The voltage supply for the opamps is obviously analog. I want to place a ferrite bead between the analog and digital side. I heard that it is best to place a ferrite bead between two decoupling caps (B). But in a lot of datasheets they place the ferrite bead between analog and digital supply (A).

Should I place the ferrite bead in point A or should I use multiple ferrite beads and place them in B?


texts:
I have been playing around with a ASC758 in a PSS Leadform package. After reading the datasheet I am still thoroughly confused. Can someone please help me understand this sensor.

What I am confused about is how to connect the sensor in the first place (weather or not to put the wire that I am sensing in between the terminals, or to connect it to them).

I am also getting approximately 1.6v when the sensor is not connected to anything. I know this has a bi-directional and uni-directional setup, but I cant figure out how to configure the sensor for either setup. It would appear from this voltage that the sensor is in bi-directional setup.

My last issue is that I am not sure of the equation to calculate the amperage.


texts: Can I use rectifier diodes with DC (1N4002)?

texts:
I have an HTronic 19 00 33 AC/DC converter. I would like to use it as a DC/DC step down converter to transform 12V DC into 5V.

I could not find the datasheet in English, here is the German version.
As far as I understand, it uses 4 M7 1N4002 diodes and a 2000uF capacitor to convert AC to DC, and then a LM317T to step down the voltage.
With my very little and new electronics knowledge, if I connect DC to the input it should just work and two of the four diodes will let the DC flow, and the others two will always block it. My concern is that I might be missing some parameters in my limited logic.

Is there any problem if I connect DC to the input?
Can the M7 diodes receive constant 12V as an input instead of AC?
In case there are problems, can I connect the DC after the diodes or I should remove the diodes and capacitor instead?


texts: Soft-latch auto-reset OFF (hold) / ON (press) button, is the schematic correct?

texts:
I'm looking to make a soft-latching interface with a single momentary push button.

Required features for my build are (edited, sorry for bad description)  :

Circuit should always start in OFF position (hence auto reset) ;
Should work as press to power ON, hold to shut down ;
Must be compatible up to 60V ;
Must be able carry the battery's nominal voltage to the module it switches ON and OFF (said module needs high voltage to go HIGH else it stays LOW)

Can you please tell me if anything is wrong ? How should I solve it ?

Thanks

Edit (2) : For the 5v regulator I use a LM317HVT with a pair of resistors. NAND used is a CD4011 and mosfet used to switch ON/OFF is an irf510.


texts: finding the voltage gain for an amplifier

texts:
simulate this circuit – Schematic created using CircuitLab

Hello all
the circuit provided represents the small signal model of a MOSFET amplifier.
I am being asked to find Vo/Vsig which is the total voltage gain of this amplifier. My analysis is below:

\begin{equation}
v_{sig}\:=\:-i\left(\frac{1}{g_m}+R_D\backslash \backslash \left(R_1+R_2\right)\right)
\end{equation}
\begin{equation}
v_o\:=\:-i\left(R_D\backslash \backslash \left(R_1+R_2\right)\right)
\end{equation}
Therefore
\begin{equation}
\frac{v_o}{v_{sig}}=\:\frac{R_D\backslash \backslash \left(R_1+R_2\right)}{R_D\backslash \:\backslash \:\left(R_1+R_2\right)+\frac{1}{g_m}}
\end{equation}
but the problem is that the book answer is this:
\begin{equation}
\frac{v_o}{v_{sig}}=\:\frac{1+\frac{R_2}{R_1}}{1+\frac{\left(1+\frac{R_2}{R_1}\right)}{g_m\left(R_D\backslash \backslash \left(R_1+R_2\right)\right)}}
\end{equation}
The problem seems simple, but I don't know what am doing wrong. Any help please?


texts: What would cause streaking in graphics LCD display?

texts:
I am using a 128x64 graphic LCD module that uses either NJU6676 or ST7565P similar to this Zettler module. I am getting vertical streaks as pictured. They appear to be most pronounced when the topmost pixel in the column is dark.

When I use a different module, I get no streaks. However, when I use the demo board sent by Zettler, there are no streaks with the Zettler board, but there is slight streaking and blotchy contrast with the Kyocera board.

I have varied the V5 ("electronic volume") level with minimal changes to the streaking, and I have varied the C2 caps (see schematic below) from 0.1 µF to 1 µF (there is disagreement on the values and range of these caps on various internet sites). The refresh rate has been slowed to once per 2 seconds per the manufacturer's advice. The streaks are still present.

In my current hardware, the topology of the circuit is basically like so, but with the common C2 node being tied to +3.3 V:

Unfortunately I am not set up to change the firmware right now, so I'm a bit hamstrung, which is why I'm exploring hardware fixes first.

Has anyone seen this and know what causes it?


texts:
I'm designing a product that will be powered by a single 18650 cell.

Specifically, I am basing my numbers off this cell in particular:

Samsung INR18650-25R

It has a typical full voltage of 4.2V and cut-off of 2.5V.

I've looked through TI, ABLIC, Diode Inc. and a few others for battery protection ICs for single cells and noticed that the OVP parameter for offerings that have a UVLO of 2.5V are typically higher than 4.2V by anywhere from 0.075V to 0.125V. Is this so the chip does not cut out too early when the battery reaches a full voltage of 4.2V?

If so, would an IC with a OVP of 4.325V be safe to use with a cell that has a full voltage of 4.2V?

Sorry if this question has a simple answer, this is my first time designing a full product, and want to understand fully before moving forward with my design.

I am also using the BQ24075 with the BQ27441 for charging and fuel gauge. This is from the reference design of the Battery Babysitter breakout from Sparkfun:

Battery Babysitter from Sparkfun


texts: Does the twisting in a twisted pair reduce attenuation?

texts:
i'm doing networking and trying to understand if the twisting in  twisted pair reduce attenuation. I know that the cable can't be longer than 100 meters and the book says this

From Microsoft Windows Networking Essentials
Twisted-pair cable is the most commonly used cable type in networks
today. It comes in multiple categories with different speed
capabilities. A twisted-pair cable used in a network includes four
pairs of copper wire. Each wire in the pair is twisted around each
other, and the four pairs within a cable are then twisted around the
other pairs. The four twisted pairs are then wrapped in a polyethylene
or polyvinyl jacket. The number of twists per meter in these cables is
different for different categories of cables. Twists in the cable help
minimize both cross talk and EMI. Additionally, the number of twists
per meter determines the speed and frequency capabilities of the
cable. Higher speeds and frequencies allow the cable to carry larger
amounts of data. However, all the twisted-pair categories have a
maximum distance of 100 meters. In other words, the cable can’t be
longer than 100 meters between any two components. It is possible to
extend this distance by using a repeater. The repeater amplifies the
signal, allowing you to run the cable another 100 meters.

So this means that if i have higher frequency i have less attenuation? I mean i thought attenuation is the distance the data goes not how much data there is, so i think the answer to my question is no, but am i right or wrong?
Thank you


texts: Can I make a hole in a touch screen without ruining it?

texts:
I need to make a big capacitive touch screen with holes inside it, can this be done without ruining the whole screen?
Thanks in advance.


texts: I need to convert a 4v peak to peak signal (-2v to +2v) into a 0 to 3.3V signal to get it into my ADC on LPC 11u24. I have tried several designs but the problem is that all of the designs I found are based on single rail op amps. I only have dual supply op amps. Any suggestions?


texts: Problem in configuration of Tiva TM4C1294NCPDT on Code Composer Studio

texts:
I am using code composer studio and using the microcontroller below, I used Energia software to run a simple program and it runs, but when I use CCS and try to flash an example program for this MCU provided by ti , it gives me an error message .
I think that problem is from target configuration file .

In the target configuration file :
I set the connection Stellaris In-Circuit Debug interface,
and Board or Device : Tiva TM4C1294NCPDT.

Then this window pops up:


texts:
I just got a Ultrics FBA-0021-YB multimeter and tried to measure some currents. This multimeter has 2 modes of measuring current, one is by connecting the red lead to the 10ADC (10A max) slot, and another by connecting the red lead to the VΩmA (200mA max) slot.

The first method works perfectly but has less digits of precidion so I wanted to use the second method. I tried measuring the current through a LED strip, then a small DC motor, and also a LED backlight. The first method worked always, but with the second would simply almost all of the times not work at all, and give "0.00" with the selector on 10A or "1" on 200ma, 20ma and 2ma.

I read through the manual - it doesn't specify anything in particular about this.

Any help?


texts: How do I define solar irradiance in the context of a solar cell?

texts:
This is homework. I've tried my best to find the best answer that I could understand and could be accepted by my lecturer.

I've searched my lecture notes, wiki and google to find some good explanation defining solar irradiance. But somehow I still don't understand how I should 'define solar irradiance'. Can someone give me a few good sentences explaining solar irradiance.
What are the changes, if any, in a photovoltaic cell (in terms of short-circuit current and open-circuit voltage) if the irradiance is reduced by 50%?


texts: So in a transformer, when an alternating current flows through the primary, thanks to the Ampere's law, a changing magnetic field is produced around it. This induces an alternating current in the secondary. So far so good. Now my question is, does this induced AC not create a changing magnetic field in the secondary, which in turn induces current in the primary (just like the primary did to the secondary)? And thus, won't we have a self-sustaining circuit where the primary and the secondary took turns to induce each other?


texts:
"During the interval that p is negative, power is being returned to the load. (This can only happen if the load contains reactive elements"

Can someone explain to me why this is the only case P can only be negative. (Please provide a practical application for the idea behind it).

Referance http://imgur.com/Ynr9XIm


texts: Make a 9v battery power USB powered light?

texts: I am somewhat of a noob to electric circuits. I bought a USB powered light off ebay for fun (link to the item), and I want to somehow make it powered off a 9v battery instead of a computer. I understand that I am going to need some kind of resistor to drop the voltage, but I am not sure what kind to get, and if that is the only thing I must do. I have access to many tools and electic stuff, so no worries there. I am basically asking what parts I need to do this and how to hook it up? Thanks!


texts: microcontroller is "hanging" when it is feeding PWM to a DC motor controller

texts:
I am using linear potentiometer to control the speed of a DC motor. I am using the following schematic.

An ATmega328P receives the value from linear potentiometer via analog read. This ATmega328P transmits the value via CAN. Other ATmega328P receives it and analog writes the values via optocoupler (4N35) to the motor controller (Kelly's KDH14601E). The motor controller uses this value to control a 110V DC motor (lynch LEM 200 D135 RAGS). The High voltage and low voltage sides are completely isolated in the motor controller.

When the motor is disconnected or is in no load condition, everything works fine. But when there is load on the motor, both the microcontrollers stop responding. They basically freeze and the motor rotates at a constant speed. Sometimes the value fed to motor controller is corresponding to the last read value and sometimes a value which is not possible according to the code of microcontroller. I made some changes in the setup and have achieved following results-

Initially I was not using the optocoupler and the microcontrollers were hanging in no load condition also.
If I use a different LV (Low Voltage) supply for motor controller and optocoupler, everything works fine but I cannot do this in my final setup (I must use only 1 LV battery). In this case, both low voltage sources are completely isolated.
If I use a different LV (Low Voltage) supply for motor controller and optocoupler and connect the ground of both Low Voltage batteries, everything works almost fine. Sometimes the microcontroller reads a value which is not practically possible, but there is no hanging of microcontrollers.
I put a diode in the path which connects optocoupler output to motor controller, but observed no change.

Please help me out with this.

P.S.: The motor controller manual states that a potentiometer should be used to feed the controllers, but I cannot directly feed the value of linear potentiometer as I have to make certain modifications to the values.

Thanks.


texts:
I am a trying to design a design an Electrosurgical interference suppression (ESIS) protection layer to filter out high frequency noise caused by Electrosurgical equipment during surgery. I am using ADAS1000, an electrocardiogram AFE.

I understand inductors can be used to block certain frequencies in a circuit.

My question is how do I go about designing a circuit to block 100kHz-5MHz noise on a electrode?( Single conduct line)


texts: How is an LED constructed, is it possible to build my own

texts:
I wondering if it would be theoretically possible for me to build my own led or oled. I am aware that this is not very practical, I'm more interested just as an exercise. I understand the basic theory behind leds and the materials necessary, but I'm not aware of the process required.

My environment is neither. It's hack space in NYC where we build a variety of things. My budget could potentially be a few hundred dollars. I've been looking a bit into semi conductor inks thinking perhaps that is the easiest route. I was really just looking to see if anyone has attempted this.

If anyone can point me in the right direction it would be appreciated.

Thanks


texts: How to forward the body diode of the mosfet without triggering the parasitic bjt?

texts:
For some applications the body diode of the mosfet is desired but how to make it forwarded without turning the parasitic bjt on ? The bjt's base is the body and to turn the diode on we must give its anode a voltage higher than its cathode and the diode's anode is the body so we must give the body a voltage to turn the diode on but that will turn the bjt on too and the mosfet will not operate correctly then how in some applications the body diode turns on ??
Edited :

This is the same structure TemeV used and here is my question : if the substrate for some reason wasn't shorted to source because some mosfets have a substrate terminal non shorted now that means the anode of the diode and the base of the transistor will have the same voltage on them and if the diode turned on wouldn't the bjt turn on too ? If it does then turning the diode means that no current will pass from d to s and it will all pass through the diode


texts: Remagnetizing a BLDC magnet from a floppy drive

texts:
I am attempting to rejig a brushless DC motor to work as a dynamo - I am unsatisfied with the paltry 3W output max of my most powerful hand-crank dynamo and am trying to see if I can get something with a little more power by using a larger rotor and gears, ideally more than about 10W.

I have salvaged this from an old floppy drive:

I attempted to figure out the number and position of poles yesterday on the rotor. Unfortunately, thanks to my impatience I used a neodymium magnet to do this, which has significantly decreased the rotor's field strength. As a rough indication, the maximum open circuit voltage i could get by spinning the rotor with my finger was around 1.5V, whereas now it is just under 0.5V. I would like to be able to remagnetize the rotor if I can. Some research has led me to How to re-magnetize a permenent magnet motor of small size (model railroad)? which answers my question qualitatively, if not quantitatively - namely, passing a pulse of sufficient current for a short period of time through a coil can remagnetize any adjacent magnets. I have made a small capacitor bank, 5x 100uF:

which is charged up to 30V (the max my power supply outputs). I haven't yet added the diodes for preventing ringing and freewheeling. Given each coil has a DC resistance of ~1.7ohms, this should give a max current of about 17A, assuming I can minimize resistance. Would this be enough to have any appreciable effect on the magnetization? If not, is there any way to get sufficient magnetization back or is this a lost cause?


texts:
Look to this figure:

i have doubt in finding effective resistance b/w the terminals of this type of connections, during my school classes when I study to find effective resistances. When I study about wheatstone bridge. A method get me to find it, provided the relation $$frac{R_1}{R_3}=\frac{R_2}{R_4}$$ satisfied. Then there is no current through $R_L$ and circuit is simplified. But when the above relation does not satisfied, then how I find effective resistance? Is there any analytical method to find such solution or is this values only determine experimentally?


texts:
I would like to know what is the name of these type of Cable Connector's please, and where do I get them? and do they come in various sizes for the same Pin Count? also, I have another one with 4 Pins inside.

thanks.


texts: Is there a table that shows how 8b/10b encoding tries to ensure running disparity on a transmission line?

texts:
In telecommunications, 8b/10b is a line code that maps 8-bit symbols to 10-bit symbols to achieve DC-balance and bounded disparity. In this case we take each 8-bit data and map it to a 10-bit symbol. Now long time ago some humans sat down and thought about which 8-bit value corresponds to which 10-bit value/values. They also decided to create some special symbols e.g comma symbol.
As far as I know, there are many 10-bit symbols which are not used and I assume that 0000000000 and 1111111111 are included in it. Which 10-bit symbol shall be transmitted next also depends on which 10-bit symbol was transmitted last time and also on the current 8-bit data to be mapped.
Is there a table that can show me which 8-bit symbol is mapped to which 10-bit symbols such that running disparity is maintained?
In simple words, I want to understand how does 8b/10b encoding ensure running disparity.


texts: I am trying to build a portable Geiger-Müller tube that is run on 4x AA batteries. However, the tube runs on 300 volts. What is the most efficient way to do this? I have looked for a transformer that I could drive with a 555 timer, but I couldn't find any transformers meeting my specifications.


texts: DDR4 reportedly uses something called pseudo-open-drain-logic or PODL. How does it work?


texts: Is there a way to protect RS-232 Transceiver IC from static death

texts:
My company sells devices many devices that use RS-232 line transceivers like the MAX232 chip. In many cases our users run their RS-232 cables in the range of 30 to 50 feet to connect our device to their PC. Over the years we have seen many boards come in for repair because the serial communication stops working and the problem can often be fixed by simply replacing the MAX232 line transceiver.

My guess is that the long serial cable is acting as a giant antenna for EMI or static and the transceiver can only take so much. In our next board design we want to go with a surface mount chip which will be much more difficult to "pop-out" and replace if the problem occurs again. Is there a way that I can protect this chip against such problems without increasing the cost of the board/components greatly?


texts: Difference between types of transistors?

texts:
I am new to transistors and I need help finding the type that I need. I am looking for a transistor that allows current to pass when the base is connected to ground, and doesn't allow the current to flow when it is connected to power. What transistor would this be?
Edit: looking to connect to positive line


texts: I2C read from write-protected EEPROM using STM32

texts:
I have been trying to read from write-protected area of Microchip 24AA02E48 EEPROM.
I am able to do I2C write and I2C read in the same EEPROM. However, when I want to do a read of the MAC ID I am seeing continuous read, whereas I am not able to do random I2C read.
buf1[0] = AA;
buf1[1] = BB;
ret = HAL_I2C_Mem_Write(&hi2c1,(0x50<<1),0x0042, I2C_MEMADD_SIZE_16BIT,(uint8_t *)&buf1,0x0002,HAL_MAX_DELAY);

ret = HAL_I2C_Mem_Read(&hi2c1,(0x50<<1),0x0042,I2C_MEMADD_SIZE_16BIT,(uint8_t*)&buf2,0x0002,HAL_MAX_DELAY);

The above continuous read works.
The random read from address 0xFA where MAC ID is stored, is not working.
ret = HAL_I2C_Mem_Read(&hi2c1,(0x50<<1),0x00FA,I2C_MEMADD_SIZE_16BIT,(uint8_t*)&buf2,0x0006,HAL_MAX_DELAY);

Not able to get the MAC ID.
Kindly let me know any pointers to this.


texts: Single cell Li-ion battery doesn't charge with PMIC, but does charge without

texts:
I'm trying to charge an Adafruit 500mAh battery with a custom PCB I made. However, when I include the AP9101C protection IC (with accompanying DMG6968 common-drain MOSFET pair), it fails to charge. This is the circuit as it's meant to operate:

USB_HALF stays at 2.5V, indicating No Battery Present. The battery discharges fine in this configuration (as tested with a few LEDs, 30mA draw), which implies that the MOSFETs are ON.
I can get the battery to charge correctly (and USB_HALF subsequently is pulled low) in this configuration without those 2 ICs:

Note that the wire running off to the left leads to the load on this PCB, which isn't soldered on these test boards. So save for the temporarily connected LED load, the parts shown in the schematic are the only parts present.
Any ideas?


texts: Using bi-directional logic level shifter for SWD.

texts:
I have a SWD emulator running on a cypress FX3 board where two of its gpio pins emulates SWDCLK and SWDIO pins. The board runs at 1.8V.
These pins have to be connected to target - spansion FM4 which runs at 3.3V or 5V. I got this logic level converter.

While I2C works with this converter, SWD doesnt seem to work. This converter uses pull-up resistors on each channel. SWD requires pull-down on its clock and pull-up on its data. Is there any way to connect this 1.8V emulator to the 3.3/5 V target using this converter or some custom circuit?

I am an electronics newbie so please give specific directions for a custom circuit. Also Cypress FX3 supports 1.8 V and 3.3 V, but for some limitations, I can use 1.8 V only.


texts: Current sense magnetics with critical/boundary conduction PFC chips

texts:
I was thinking of using a critical/boundary conduction PFC controller in a boost PFC.

I'm not sure how convenient it is to find an inductor with an auxiliary winding.

I can find lots of choke type inductors in the inductance and current range I need.  I do not know much about chokes.  Is it feasible to use 1 winding of a choke as my inductor, and the other as a current sense winding?

If I use a choke or inductor without an aux winding, have I removed the opportunity for designing a critical/boundary conduction PFC?


texts: How to detect AC or DC voltage from 9V DC to 250V AC?

texts:
I have a device that needs to detect the presence of voltages from 12V DC up to 240V AC RMS (Absolute maximum of 9V DC to 250V AC RMS) This device is going to have up to 8 channels that should be able to work independently with complete isolation between them.
I started working on a circuit that could accomplish this but can't seem to find a fit that wouldn't burn up with high heat dissipation or fail to trigger with low current.
The 2 options that I was thinking of were:

Use a small value capacitor or high-value resistor to limit current to an optocoupler. A capacitor wouldn't work with DC voltages, (if I am not mistaken) and a high-value resistor would not be able to drive enough current to pull down a 100k resistor on the transistor side of the optocoupler at low DC voltages. If I lowered the resistance there would be enough current at low DC voltages but my calculations show it would be in the order of 2 watts of dissipation at the resistor.

Use a high-value resistor with a Zener to limit voltage to around 9V on the sensing side. This should have the added benefit of triggering at a set voltage rather than varying based on the current transfer of the optocoupler. My issue here is that I then need to get the signal back over the optocoupler, there is not enough current left in the single to drive the Opto without some buffer that would require an additional isolated power supply. This could work but having an isolated supply per channel is quite of bit of wasted space and value. The stepping nature of the supplies would add a lot of noise too.

Possible solutions:

Is there a better circuit or IC that could accomplish this task?

Is there a low cost, low current (< 100mA), small footprint isolated DC-DC power supply available? I found the RFM-0505S, it an isolated 5V -> 5V supply at 200mA, much more than required and relatively large but could work.

Would there be enough current available after running 12v DC through a 300k+ resistor to drive the base of a transistor or would I need an op-amp to buffer the voltage?

Thanks in advance for your help!


texts:
What is going on here? According to the circuit diagram there are two microcontrollers (U1 and U2, with slightly different partnumbers) on the Arduino Leonardo, but when I take a look at the PCB I can only find one. Is it a common way of drawing things and how does Eagle know it is one and the same device?

Unfortunately the project files only open in Eagle, so for what it is worth I included two screendumps. There is a pdf version of the circuit diagram too.


texts: Where to start on creating radio circuits

texts:
I'd like to interface with a legacy system that uses BPSK at ~5MHz to transmit data. I understand the basic idea of BPSK - that it's a 180 degree phase shift to represent data - but I'm having a hard time finding examples that take an Arduino or something and create a BPSK radio.
Most of the documentation I find online shows a basic block diagram like this:

I understand we're mixing sine phases based on bits from a processor, how would I implement this with OpAmps?


texts: how do they make travel adapters so small?

texts:
How do they make cellphone adapters, especially "travel adapters", so small?

I once peeked inside an old Nintendo adapter, and it had (among other circuitry) a rather-bulky step-down transformer to bring the voltage down from 220V mains to 12V, and a diode-based rectifier to convert AC to DC. This is my limited knowledge of how power adapters work.

I'm really curious how they manage to fit a transformer inside such the tiny travel adapter - so I tried to google it, and found this disassembly of an Apple adapter. I'm not sure if the thing with the yellow tape around it (towards the end of the vid) was a transformer - is it possible to make transformers so tiny these days?

Or is there some other way to reduce the voltage (apart from using a transformer) that is used in travel adapters?


texts: Weird behavior of the MLCC capacitor after soldering

texts:
It's my first time using this capacitor. Before soldering, the capacitance measured only around 6uF. But after soldering and desoldering, the capacitance became 9uF around, and stable.

I tested several, all behave similar.

So, is this normal?


texts:
Does anyone have a Altium query/selector that targets vias in SMT pads? I'm routing a very dense HDI board, and would like to make rules that exclusively target vias that are inside a component pad and not normal vias or offset (dog-bone style) vias next to BGA pads.

(I'm aware of the tradeoffs involved in putting vias in pads, and the board house is going to fill and plate over them. I'm using Altium Designer release 27009 (Dec 2012)).


texts: Problems with a CD4060BE ripple counter not counting

texts: I have been trying to trace the fault in the circuit in the image below for the last 3 hours and I have exhausted the possibilities. The problem is that the CD4060BE ripple counter is not counting. The crystal clock signal fed to pin 11 on the chip is fine and is oscillating at 1 Hertz, but I get no output from the binary count pins. My question is: Do I have the chip connected up incorrectly? Also, should pins 9 and 10 be left unconnected?


texts: Can I replace a fan with a lower-rated fan?

texts:
I have an old RadioShack inverter / battery device that seems to have died because the fan seized up. The original fan is labeled DC 14V 0.09A. The battery in this unit puts out 16V according to my multimeter, and I read 15.37 volts at the leads that power the fan.

I can't seem to find an identical replacement online, so I am wondering if it is possible to substitute a fan rated for a lower voltage. Would a 12VDC fan work if the dimensions were the same? (This is mostly what I can find online.) What would be the down side? Shorter duty cycle?

Thanks!


texts: While determing the AC load line, the author takes Rc to be parallel to Rl. How is it possible since the two resistors have different nodes?


texts: Calculating required delay before pin value is recognized in 8051

texts:
I looked at the following in hopes my question will be answered:

can we use 8051 pin as Input and output at a time?

But the answer was vague. It stated:

"though there is a 'strong' source transistor that comes on briefly when the pin is switched from '0' to '1' in order to charge stray capacitance connected to the pin quickly"

This suggests to me that as soon as I set a GPIO pin value to high on my AT89C2051 (assuming the external thing connected to it is high impedance or nothing), there is a delay I need in my code before the pin is officially recognized as high.

I included a basic skeleton of my code below. Basically an "ack" pin follows the clock when operations are complete. If that "ack" pin is forced low externally then a reset bit is forced on. The problem is I don't know how much delay to include in my program.

What I do know is each "nop" takes about 0.54uS to execute because I'm using a 22.1184Mhz crystal on my AT89C2051.

clr 20h ;turn reset off
clr P1.1 ;turn ack off
setb P1.2 ;allow clock as input only

mainloop:
    main1:
      acall someasyncfunction
      clr P1.1     ;ack=current clock state
    jnb P1.2,main1 ;wait till clock switches

    netmain2:
      acall someasyncfunction
      setb P1.1          ;ack=current clock state
      ;how many nops???
      jb P1.1,notrip     ;If user pulls ack low then set reset
        setb 20h
      notrip:
    jb P1.2,netmain2    ;wait till clock switches

    acall postprocessing
sjmp mainloop

My immediate guess to the calculation is to find the biggest capacitance value mentioned in the datasheet and multiply by the resistor connected to the GPIO pin (or if no resistor is connected, then multiply by whatever the internal resistor is?)

I'm also powering the thing with regulated 5VDC.

Anyone know the math to this so I know the minimum number of "nop"s I need to add between when the pin is internally set high and when valid data can be read from it?

And please be more specific than just a 2 * R * C because I need to know the R and C you refer to.


texts:
Background:

I have a Minseg [M2V3] two-wheeled robot.
It uses a battery pack as follows:

6 x AA battery (1.5 [V]) in series (9.0 [V] net).
The current batteries are Duracell Procell AAs. [datasheet]

The device passes the battery pack voltage to an Arduino Mega 2650,
which regulates the voltage to power several IC chips.

The device also passes the battery voltage directly to a DC motor driver:
TI SN754410, a quadruple half-H driver. [datasheet]
This receives a pulse-width modulated signal from the Arduino controller,
which states whether to pass or null the source voltage at any given time
to each of two DC motors:
Lego NXT DC motor [datasheet]

My controller specifies a desired voltage.
This voltage is normalized (divided by) the assumed source voltage,
yielding a number ranging from 0 to 1.
This number is converted into a PWM signal,
which is on for the yielded factor of time and off for all other time
for each sample interval.

Original Problem:

The source voltage from the battery packs droop proportionally with motor speed.
At zero speed (zero voltage applied), the battery pack provides 8.5 [V].
At max speed (constant voltage applied), the battery pack provides 7.5 [V].

Recall from above that the calculation for passing voltage to the motor
is dependent on an assumed value.
(I measure the battery pack leads at full speed before use, and use that value.)

I realized I could slightly improve performance,
either by sensing the actual voltage dynamically during operation,
or by holding the source voltage to a constant value.

For the first method:
The Arduino analog input is able to read up to 5 [V].
Thus, using a voltage divider (two resistors from + to -)
to multiply by a factor of R2 / (R1 + R2),
[in this case, approximately 10k / (15k + 10k) = 0.4],
over the battery pack terminals (up to 9 [V]),
can serve as a fair voltage sensor.
(Some filtering would likely be necessary?)

But I wanted to go with the second method:
I purchased a premade (hobbyist) voltage regulator [datasheet]
(Yeeco Ultra DC to DC Buck Boost Converter Adjustable Voltage Stabilizer 5.0-25V to 0.5V-25V Automatically Step-Up/Step-Down Car Power Supply Module Voltage Regulator)
I did put the aforementioned voltage divider across its output (for later use); however,
I do not believe this has much of an impact on performance.

Actual Problem:

When I turn on the device, there is a 2 second delay without motor use.
It thus turns on as normal.
After the two-second window is passed, when the motors would begin to activate,
the Arduino shuts off (self-protects?).

It is my thought that the series AA batteries cannot handle
the pulse requests from the voltage regulator at its input.
I do not believe that the datasheet provides adequate enough information
to know if I am bypassing a limit.

It does state "2 [A] / 1 [s]";
does that mean a near-linear relationship and maximum of "0.02 [A] / 0.01 [s]"?

If this were the case,
which types of battery material are best suited for such pulses at a AA size?
It would be nice to not go over 9 [V] such that I could demonstrate behavior  with and without the voltage regulator using the same set of batteries; however,
I'm not averse to hearing all of the options.


texts: Does anyone have any suggestions for C/C++ compiler/debugger for this chip, initially via ST-LINK on a Discovery board? I am currently using IAR EWARM but am not particularly happy with it.


texts: Dielectric break down of stacked glass layers

texts:
We have a capacitive touch panel with 1 mm thick cover glass.

Currently it is failing at 15kV ESD.

I am assuming that dielectric breakdown of the glass occurred and the touch driver is exposed to higher ESD and failed.  To increase and finalize the thickness of glass, I am doing a test.

Questions:

If I add a another 1mm thick glass sheet above the panel and test, how does the ESD voltage get divided between the glass layers?

Will it be divided equally or
if the first glass dielectric breaks, will its resistivity be reduced?

Can you please share links to any literature to understand better?


texts: Question about voltage in the open circuit

texts:
I have this circuit here, and I'm trying to its Thevenin equivalent voltage and resistance, using superposition. When I "kill" the \$V_{0}\$ source, it becomes a wire and the voltage across the gap is the voltage across the network containing R2, R3 and R4.

I'm having a hard time understanding why that's the case.


texts: My treadmill connects to its controls via a DE-9 port interface and I'd like to reverse engineer it so I can control and monitor it via my computer instead.  I would hope it perhaps uses RS232, but given that the only hardware solutions I've found for passthrough monitoring of serial communications are a bit expensive to purchase on a guess, does anyone have any recommendations on the cheapest way to get started on such a reverse engineering project?


texts: How to select resistor with specific package size

texts:
I have some SMD resistors in size 1812. How do I select this package size in the part library? I see all the other sizes, 2010, 1210, 1206, etc, but no 1812. I'm new to Eagle, and the interface is a bit confusing to me but searching 1812 produces nothing. Searching for "resistor" produces a lot, but there's a ton of nested results that are tedious to scroll through.

What's the proper way to find a specific part in a specific package size?


texts:
I am planning to migrate to the NXP Cortex M3 architecture and I'm a little lost between the existant development tools.

Keil is expensive and I don't know if it's worth it.
Anyone who has tried some compiler can give any advice?

I found this compiler http://www.code-red-tech.com/red-suite-2.php it seems good and not expensive.
Anyone who tried it or know about it can give me more info?


texts: Would it be considered good practice to match the lengths of UART's Tx/Rx traces?

texts: I am assuming the answer would be yes since Tx/Rx pins are used to send data back and forth, or is it of such a low frequency that such thing is not required?


texts: Calculate the input voltage for this circuit if Vo = -11V

texts: I just want to clarify something. I don't know why my answer is wrong. My solution is attached in the problem


texts: Controlling AC motor with relay vs. switch on motor

texts: Is there a difference in terms of operation between switching a relay connected to mains for an AC motor versus opening/closing a switch on the motor? Would the internal protection circuitry containing the switch be useless if a relay was used to switch power instead? I'm asking for how something like this would affect operation of something like start/run capacitors and thermal protection.


texts: Can a Zener diode that protects a switch against inductance when the switch opens, affect turn on speed of the valve when you close it again?

texts:
As you probably know, in the applications that the turn off speed of the solenoid valves are crucial, the simple flyback diode is not effective. Some people put a resistor in series with the flyback diode to alleviate the problem, but for real fast applications the Zener diode is suggested.

You can see it in the picture (third one from the left).

I think (but I am not sure and please correct me if I am wrong) that the current flows through the loop only when the voltage is higher than the Zener voltage V_z.

What I don't understand is:

What happens to the voltage in the coil that is lower than the V_z?  Is it going to remain there? I mean at some point, the voltage drops under V_z and the leg that contains the diode is out! But how can the remaining voltage is going to affect everything in the circuit? and the next turn on command?
The most important question: Is it going to affect the next turn on command in a negative way? For my application I need to turn it on and off 10 times per second (about 5 cycle of on/off)
And what is the trade off between choosing a higher value of V_z against lower value?! Assume it never reaches the switch (MOSFET) safe voltage? Does lower V_z means slower turn off? How can V_z affect everything in positive/negative ways?

FYI, I want to turn  Airtec 2P025-08 on/off with an Arduino. 12Vdc, 0.5 Ampere, Don't know the inductance/resistance of the coil!


texts: If I supply 24v to a 50v rated 22000uf electrolytic capacitor, does that mean it will store 44000uf at 24v?

texts:
Is the higher voltage just a safety thing, or can the capacitor actually store more charge?
Also, if I supply it with 24v, will it output 24v or 50v?

I read the wikipedia on capacitors, watched a few youtube videos, and read a few other articles, and they were all very vague about this.


texts: Configuring LPTIM Parameters with the STM32L4

texts:
I bought an STM32L433 Nucleo-64 board (STM32L433RCTxP) and I am trying to learn more about the LPTIM peripheral. I am experimenting with setting up the LPTIM1 peripheral so that it generates an interrupt every 1 second, and the LPTIM1 interrupt handler would do some trivial task.
This is how I am setting up my LPTIM1:
/* Note: SYSCLK, HCLK, PCLK1, PCLK2 are all 16MHz running on HSI */
static void MX_LPTIM1_Init(void)
{
  hlptim1.Instance = LPTIM1;
  hlptim1.Init.Clock.Source = LPTIM_CLOCKSOURCE_APBCLOCK_LPOSC;
  hlptim1.Init.Clock.Prescaler = LPTIM_PRESCALER_DIV128;
  hlptim1.Init.Trigger.Source = LPTIM_TRIGSOURCE_SOFTWARE;
  hlptim1.Init.OutputPolarity = LPTIM_OUTPUTPOLARITY_HIGH;
  hlptim1.Init.UpdateMode = LPTIM_UPDATE_IMMEDIATE;
  hlptim1.Init.CounterSource = LPTIM_COUNTERSOURCE_INTERNAL;
  hlptim1.Init.Input1Source = LPTIM_INPUT1SOURCE_GPIO;
  hlptim1.Init.Input2Source = LPTIM_INPUT2SOURCE_GPIO;
  if (HAL_LPTIM_Init(&hlptim1) != HAL_OK)
  {
    Error_Handler();
  }

  HAL_NVIC_SetPriority(LPTIM1_IRQn, 1, 0);
  HAL_NVIC_EnableIRQ(LPTIM1_IRQn);

  /* 65535 is the value loaded into LPTIM1's ARR register */
  HAL_LPTIM_Counter_Start_IT(&hlptim1, 65535);
}

The interrupt handler currently looks like this:
static uint32_t counter = 0;

/**
  * @brief  Autoreload match callback in non blocking mode
  * @param  hlptim : LPTIM handle
  * @retval None
  */
void HAL_LPTIM_AutoReloadMatchCallback(LPTIM_HandleTypeDef *hlptim)
{
    /* Blink onboard LED */
    if(counter >= 2)
    {
        /* TODO: Do some task here */
        DoRandomStuffHere();

        counter = 0;
    }

    counter++;
}

The code above does not produce an interrupt every 1 second, but the function DoRandomStuffHere() does get executed almost every second. I measured the timing with a stopwatch and the function seems to execute periodically at slightly higher than 1Hz (maybe at around 0.9 seconds between each execution).
I am wondering what the equation looks like for the LPTIMx peripherals. I thought it was similar to TIMx timer peripherals where:
TIMx_Frequency = SYSCLK/((Period + 1) * (Prescaler + 1))
and the Period = value that goes into ARR. If I were to use this formula for the LPTIM1, it does not come close to the 1Hz I am expecting.
What sort of parameters would I need to generate an LPTIM1 interrupt every second? Thanks!
For comparison, I have also included code where the TIM2 generates an interrupt every second:
/**
  * @brief TIM2 Initialization Function
  * @param None
  * @retval None
  */
static void MX_TIM2_Init(void)
{
  TIM_ClockConfigTypeDef sClockSourceConfig = {0};
  TIM_MasterConfigTypeDef sMasterConfig = {0};

  htim2.Instance = TIM2;
  htim2.Init.Prescaler = 15999;
  htim2.Init.CounterMode = TIM_COUNTERMODE_UP;
  htim2.Init.Period = 999;
  htim2.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
  htim2.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_DISABLE;
  if (HAL_TIM_Base_Init(&htim2) != HAL_OK)
  {
    Error_Handler();
  }
  sClockSourceConfig.ClockSource = TIM_CLOCKSOURCE_INTERNAL;
  if (HAL_TIM_ConfigClockSource(&htim2, &sClockSourceConfig) != HAL_OK)
  {
    Error_Handler();
  }
  sMasterConfig.MasterOutputTrigger = TIM_TRGO_RESET;
  sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
  if (HAL_TIMEx_MasterConfigSynchronization(&htim2, &sMasterConfig) != HAL_OK)
  {
    Error_Handler();
  }

  HAL_NVIC_SetPriority(TIM2_IRQn, 0, 0);
  HAL_NVIC_EnableIRQ(TIM2_IRQn);

  /* Start TIM2 Interrupt - 1sec interrupt */
  HAL_TIM_Base_Start_IT(&htim2);
}

void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef *htim)
{
    if(htim->Instance == TIM2)
    {
      /* TODO: Do some task here */
      DoRandomStuffHere();
    }
}


texts:
I want to use a motor to generate musical tones by spinning a disk. The disk will have optically printed sound waves on it.

I would like to know how fast the motor will be able to change speed from one note to another.

The motor will be driven by 3 phase variable frequency drive.

So for example how fast will it be able to double its rpm from 100 to 200 if I instantaneously double the drive frequency?

We can ignore the inertia of the disk for now because I don't know it yet. It would be good to just know a general way to solve this problem, then I calculate for a different inertia.

The motor I am thinking of using is 3 phase brushless slotless type

From the data sheet

Speed/torque gradient 5.21 rpm/mNm

Nominal torque (max. continuous torque) 94.6 mNm

Nominal voltage 24v

Nominal current (Max continuous current) 7.58A
Stall torque 3220 mNm

Rotor inertia 33.3 gcm²

Torque constant 13.6 mNm/A

Speed constant 700 rpm/V

Mechanical time constant 1.82 ms


texts: What are the implications of a ROMLESS device?

texts:
I was looking through the microcontrollers area of Digikey and I noticed a device that i'm interested in although there is the description of "ROMLESS" in the program memory type.
http://www.digikey.com/product-search/en/integrated-circuits-ics/embedded-microcontrollers/2556109?k=LPC4330

What I take away from that is that there is no flash memory internal to the chip but since it is Read-Only memory, I question that.  Maybe this mean that it needs an external EEPROM to boot the program from?

So I'm not entirely sure so here I am asking:

1) What does this exactly mean

and

2) How would this change a design?


texts:
How do I do (ac XOR bd) + a
I came up with the solution:
a’c’bd + acb’d’ + a
I am not sure if this is correct


texts:
I've built a simple circuit to test a combo of a MOSFET (SUP70030E) and a gate driver (TC4452):

The MOSFET should be compatible with the gate driver (if I'm not reading the datasheets wrong) and the circuit works fine - I'm switching the LED on and off in 10 second intervals.

However, the gate driver starts running very hot very soon, and I'm measuring 150 mA at the gate driver VDD all the time. That's more than 3 orders of magnitude higher that what the datasheet says, and the current stays the same with both 0 and 1 at the input.

Any idea what could be causing this?

EDIT: The MOSFET is fine (keeps cold and easily switches when connecting directly to 12V), and the driver draws 150mA even with the output disconnected.


texts: Which boards with ARM(like stm32, etc.) can have GPIO pins which can give 3.8V or higher as an output?

texts:
I am trying to get pulses from my board. Right now, I am using stm32f103 board.
The problem is that output voltage values of pulses are 3.3V but I need at least 3.8V or higher.
As I understand ,I cannot have it with my stm32f103 board. So I am looking for the ARM-based boards whose GPIO pins can give 3.8V or higher voltage values as an output.
Thanks...


texts:
I’m having some serious issues finding the point at which the root loci cross the imaginary axis for the following Open Loop Transfer Function (OLTF) ;

We have been taught to substitute s = jw and multiply by the complex conjugate in order to have Real and Imaginary segments separately. Using 1 + u + jv = 0 where u = -1 and v = 0 to solve for w and k.

Below is an image of my working up until the complex conjugate, after this point the mathematics gives me the impression I have either made a mistake or there is a simpler method to solve this problem.

It may be useful to know the location at which the loci cross the Imaginary axis is 1.799 (from MatLab).

Any help is greatly welcome and thank you for any time you spend on this!

Have a Good Christmas!

Appended :

k has been introduced into the OLTF in order to find its maximum value for stability. Using u = - 1 and subbing the value for w (found from the Imaginary segment) into the Real segment.

Below is my working for find an OLTF with Real and Imaginary segments separated ;


texts: Can several Ethernet PHYs cause damage to one another if they transmit on MDIO bus simultaneously?

texts: I have 4 ethernet devices (1 PHY - AR8035; and 3 Dual PHYs - DP83849IFVS) on my custom PCB board. ICs are controlled by SoC AM335x via MDIO bus. Previous revisions of the board worked fine. New revision on the other hand doesn't work. The only differense is that now MDIO bus connected to Dual PHYs (there was no such thing in the previous revisions), so 4 devices on the bus now. So the problem is that now Dual PHYs behave unstable - heavy packet loss, strange registers values etc... While debugging I've noticed that at first accidentally AR8035 PHY has the same PHY address as DP83849IFVS device, so the devices may have started to transmit simultaneously. Can that fact damage the devices? As far as I understand if the outputs are open-drain (which is my case) nothing can happen, the current will be just devided between two transistrs. Something bad can happen only if the outputs are push-pull. Am I right?


texts: Why a pure resistive AC circuit absorbs power at all times according to this equation

texts:
Here is the equation of average power in a pure resistive AC circuit:

"Fundamentals of electric circuits - Alexander Sadiku"

How this equation imply that the circuit absorbs power all times, I understand that resistor only absorb power and there is no reactive elements in the circuit like capacitors and inductors, but I want to know how it was concluded from the equation above.


texts: Can a PCB circuit have through hole components on both sides of the board

texts:
I'm making a temperature sensor ciruit on a 1×1 inch PCB and needed to put some components on the other side to fit everything. All the components are through ole.

Is this feasible, I was able to order the boards and it said there wasn't an error, but I wanted to make sure I didn't do anything incorrectly.


texts: The SERDES/transceiver design inside the Ethernet MAC controller

texts:
I'm a little confused about the "SERDES" interface between MAC and PHY chip, and I drew some figures to illustrate the connections which confuse me as shown below. The MAC controllers in 3 figures are the same, but the transceivers inside the MAC are not so straight forward to me. The 1st and 2nd figures are normal application which transmits the data through copper media with coded information (through PCS/PMD/PMA inside the PHY chip). The interface between the MAC and PHY is SGMII or XAUI for 1G and 10G base-T Ethernet.
However, the 3rd figure confuses me. There are applications where the MAC is connected to the optical-electrical conversion element, and transmit the data with lasers and fiber cable.

Questions:

My first question here is, where is the PHY function now (PCS/PMD/PMA) in this situation? Looks like the data is transmitting directly from the "SERDES" of MAC to the other MAC's SERDES, only the media transformed from electrical to optical, without any coding or manipulation as PHY chip does on copper application. Is there any reason why we can do that (or I should say, why we need PHY chip to transmit the data through copper media)?
Is it because the 1000 Base-X follows the physical layer of FC0 (FC-PI, fibre channel physical interface) and not the OSI model? If that’s the case, why we don’t need the PCS/PMA/PMD stuff for fibre channel application? And any special design in the transceivers to achieve such goal?
The second question is, what's the difference between SGMII/XAUI and SERDES? It seems that the MAC chip can support both function on the same high-speed lanes. The SGMII/XAUI are usually used for the connection between MAC and PHY chip, where the “SERDES” is used for MAC direct connection. I used to believe that interface like SGMII or XAUI are all SERDES, but it confuses me now.
The other question is, there's another connection called DAC (Direct Attached Copper), does it have anything to do with MAC to MAC connection? The signals now connect the MAC without PHY, why can we do that? If we can do so, why bother to add external PHY on the RJ45 scenario? Is is about the transmitting distance?
Do we still need DC balance in fiber signaling? If not, why bother to encode the data to 8b/10b or 66b/64b?
So many questions listed since I’m still new to the networking area. Hope someone can help me with this.

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@alex.forencich

So, the reason why we can use the MAC chip to directly connect to the SFP module(without PHY on the module, only optical transceivers) is that the MAC chip is supposed to have a built in PHY, is that correct?

In other words, can I assume that the data encoding, formatting, etc (all the PCS and PMA functions) are all done in the MAC chip now, instead of doing that in the external PHY chip?

If so, looks like 1000basex do need to go through PCS and PMA before the data can be sent to SFP module, is that true?

The key point which confuses me earlier is that I used to think that 1000base X didn’t require PCS and PMA, and can be connected directly to the SFP module to transfer the data from MAC logic.
I grep a figure from Intel and Synopsys website and which may explain that the 1000Base-X still need PCS/PMA functions before going out the chip. If my assumption is correct, the common MAC chip may have built in two kinds of PHYs, and have a switch inside the chip to select which interface it should be running on by detecting the outside modules. For example, if it detects the SFP module with optical devices only, it’ll be configured to be a XFI interface.
Please correct me if anything wrong here.

And, the reason why we need external PHY for RJ45+copper cable is because we need to transform SGMII into MDI interface to meet the requirement of the 1000Base-T requirement, right? In this case, the internal PHY may be configured as a pass-through mode, and use SGMII from MAC module to external PHY chip.
Not sure if that’s correct.


texts:
My Roland Cube 60 Bass went up in smoke the other day. (after about 30 years of reliable service.) No blown fuses. Hmm. Opened it up and found that a 1/2W resistor was burned up. Similar issue here:

Repairing/understanding this guitar amp master stage

And this schematic is the same (except for ref designators)

It's the 330 Ohm on the collector of Q10 (PNP driver).
All parts and continuity are all OK so far. (Q's, R's, C's, D's)
Was thinking that the connector to output Q13 was open. Guess not
but I may have moved something during board removal.
Power Q actually OPEN? BE junction tests OK (diode drop).

Any other ideas? (voltage on that 1/2W 330 Ohm jumps to about 30Vdc with an input! otherwise very low)


texts: Using an iPhone as a cassette recorder for 80's home computer

texts:
I've got an old 80's home computer (a Microbee) that I've just got running again.  It uses cassette to save/load programs and I thought I'd see if I could use my iPhone instead of an actual cassette recorder/player (since I don't have one).

I made up a cable with the 4 pole iPhone style 3.5mm plug and for loading (playing from the iPhone) it works perfectly.  For saving (recording into the iPhone), the iPhone doesn't seem to switch over to the external microphone input and continues to record from the internal mic.

I've wired up the plug as follows (based on this: https://discussions.apple.com/thread/1114891?start=0&tstart=0)

Computer Tape Out -> 3.5mm plugin sleeve (iPhone Microphone In)
Computer Common Ground -> 3.5mm next up from sleeve (iPhone Ground)
Nothing -> 3.5mm next down from tip (iPhone Right Out)
Computer Tape In -> 3.5mm plugin tip tip. (iPhone Left Out)

Would welcome any ideas/suggestions.


texts: Resistor will heat up on what amount of current?

texts:
I tested a 470 ohms resistor with 35mA DC current flowing and my resistor is heating up.

On my final design I have created a voltage divider circuit using

R1=10k ohms
R2=220 ohms
maximum input voltage is 220 Vdc
maximum DC current would be 21.5mA DC

I've only tested a maximum of 20Vdc as an input because I don't have available 220Vdc. I wonder if my R1=10k ohms and R2=220 ohms resistor will heat up on maximum DC current of 21.5mA

Is there a way to calculate whether it will heat up or not?


texts: What are the ways that change in capacitance can be measured?

texts: What are some ways that capacitance change can be measured e.g in a capacitive pressure sensor


texts: What does "ku" or "kU" mean with regards to procuring ICs? (not about RF)

texts:
NB: This is not referring to RF subject matter.
I'm seeing 1ku and 10ku on procurement documentation for purchasing motor driver ICs (TI DRV8811 and some others). Does this mean "one-thousand units"?  Sometimes I also see it written as kU (10kU) in the same context.


texts: Can AC/DC conversion losses from solar panels be avoided with a Tesla Powerwall?

texts:
(background: I'm just playing with numbers, trying to estimate how many solar panels would be needed to fully supply the energy for a home and 2 Tesla cars)

I've been reading up on solar panels and on Tesla car charging. That page mentions that the conversion efficiency from DC (solar panel) to AC (what home appliances need) is 75-80%.

On some Tesla forum somewhere I read that the charging efficiency from the wall plug to the car is around 85% (can anyone confirm this?). Can I conclude from this info that a Tesla car is actually a DC device?

So, if I understand all of this correctly, I lose ~25% to convert solar panel energy from DC to AC (selling to the utility company) and then again ~15% to charge the car battery from the wall plug (buying from the utility company).

Is it possible to avoid both of these conversion steps by charging a Tesla Powerwall from the solar panels during the day, and then charge the car from the Powerwall during the night? (avoiding the energy grid completely, no net metering considerations)


texts: NPN transistor turning on with grounded base

texts:
The NPN transistor in bottom left with grounded base is turning on in circuit simulator for some reason.
Can someone tell me why is this happening?
Circuit Simulation link

I know why the other 3 transistors are turning on. I am not using this circuit instead this one h bridge


texts: How to select and use Strong Magnet together with hall sensor and amplifier?

texts:
With reference hall effect IC sensor (hopefully on topic as normal EE work) used together with these silver color magnet, as this example of 20 by 10 mm from ebay,

Do they have different formulation (chemical composition) with different property, strength of magnetic field and cost?
What are the popular (most used, low cost, widely available) formula?  What is the likley formula as in the photo?
How is 'radiated' (field caused by magnet with 0 to 30mm) magnetic field strength measured? Unit and measurement procedure (distance, orientation).  For antenna and loud speaker, they produce sound or wave over distance. We measure them by signal level and directional property diagram. What is the equivalent for these magnet?   What typical mag field in G or T at distance 1 to 20mm for the 10 by 20mm magnetic as photo? Rough range needed for choosing sensor chip which rated at mv output per G or T.
How is the magnet shape, rectangle, round, etc., affect the
'radiated' field strength?
How is the magnet shaped? Is is like ferrite coil core, that can practically make into any shape and size? Is that by 'mold', pressed or machined?
For photo magnet, can the pole be made, North South at top and
bottom of the 'flat biggest area side' or NS has to be at the two
ends (20mm biggest length in this photo).


texts: Voltage Across NMOS and PMOS Transistors

texts:
So I have the question above concerning an NMOS and PMOS transistor. The goal is to find V1 and V2 in steady state. My understanding is that because the gate voltages of zero and Vdd are there, the transistors are "on" and current flows.

Is the idea here simply that the voltage will get as close to 1.2 as possible for each V1 and V2, until such a voltage would cause VGS to be below the threshold voltage?
So for example here V1 would reach 1.2V as PMOS is on. But V2 would reach only 0.8V because any increase past 0.8 would mean VGS < Vt. Is that right?