texts: Current limiting ballast for a transformer

texts:
So, guys, I hope you can explain to me how to calculate the necessary parameters for a ballast to limit the current on the primary side of a high voltage transformer.It is for a tesla coil project. To stop excessive current being drawn through the transformer's winding when the secondary is short-circuited.

Transformer specs.
Pri: 230 V/50 Hz, 2.09 A  Resistance: 0.5ohm
Sec: 5 kV, 80 mA

So how much inductance I need to limit the current to 2A?

Solution.
The total resistance Z of a choke coil consists partially of the actual coil resistance R and partially of the inductive resistance XL in a linear relationship of the frequency f and the inductivity L as
XL = 2 πf*L
and
Z = √ R2+XL2
The resistance of the coil R can be measured directly over the coil with an Ohm-meter but usually R hardly plays a role compared to the inductive resistance.
We want to reduce the current flowing through our primary of the HV transformer to 2 A maximally at 230 VAC. This means that the choke coil must have a total resistance Z of 230/2 = 115 Ω.
We measure a resistance R over the coil of 0.5 Ω than the inductive resistance must be √Z2-R2 or √((115Ω2)-(0.5Ω2)) = 114.9 Ω.
The next step is to calculate the inductivity by arranging our formula into
L = XL/(2*π*f)
or L = 114.9/(2*π*50) = 365 mH.

Problem.
So I build a choke of the calculated value and test it out.

But the ballast is not limiting the current of the calculated target Its 2 times higher

I can't figure it out what's going wrong


texts:
Has anyone ever used TDK MLG inductor for impedance matching?

It is very small, how am I gonna connect it to my circuit?

http://product.tdk.com/en/catalog/datasheets/inductor_commercial_high-frequency_mlg1005s_en.pdf


texts:
I have created a 4 bit register in VHDL, within Quartus.  Normally, I connect each of my inputs to one of the dip switch pins or push button pins in the "pin planner" for my particular development board.  Sometimes I have input logic that, for testing purposes, always need to stay high or low.  In the example below, the clearN(active low) input needs to be simply held high without wasting one of my dip pins.  Is there some pin that I can connect it to that will just provide VCC or ground depending on what I want?

LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;

ENTITY REG_4_MAR_SAP_1 IS

    GENERIC(
    size: INTEGER:=3);

    PORT(
    LmN, Clk, clearN: IN STD_LOGIC;
    D: IN STD_LOGIC_VECTOR(size DOWNTO 0);
    Q: OUT STD_LOGIC_VECTOR(size DOWNTO 0));

END REG_4_MAR_SAP_1;

ARCHITECTURE Structural_REG_4_MAR_SAP_1 OF REG_4_MAR_SAP_1 IS

    Signal E: STD_LOGIC;

    COMPONENT D_FF_W_ENABLE_CLEAR PORT(
        D, E, ClearN, Clk: IN STD_LOGIC;
        Q: BUFFER STD_LOGIC);
    END COMPONENT;

    COMPONENT NOT_1 PORT(
        In0: IN STD_LOGIC;
        Out0: OUT STD_LOGIC);
    END COMPONENT;

BEGIN

    Reg4: FOR k IN size DOWNTO 0 GENERATE
        FlipFlop: D_FF_W_ENABLE_CLEAR PORT MAP(D(k), E, ClearN, clk, Q(k));
    END GENERATE Reg4;

    U1: NOT_1 PORT MAP(LmN, E);

END Structural_REG_4_MAR_SAP_1;


texts: Constant Current Load ampere measurement

texts:
I have the following circuit that I am building, a constant current load):

I am using a 9 volt battery and a 1.5 volt battery to power the circuit. My load under test is a AA battery. Based on this video (which is where this schematic is from), I want to know at what point I have to connect the leads of my amp meter to measure the constant current load (as the video does). I want to know where I have to connect those leads, so that when I turn my potentiometer, the constant current changes too (as seen in the video).

I tried to connect the positive lead of the amp meter @ point A as shown in the picture, but my meter reads out 0 amps.

Thank you for your help!


texts: I want to calculate the weights that can be added to the dc motor for loading arrangement. So, how can I calculate this? I am using the motor with 24 volts DC, 6000 rpm No-Load current= 600 mA, Stall current= 30A max. What is the maximum weight that can be added?


texts: Working of the LM-358 - microphone circuit

texts:
I had this task of converting the output of a microphone's voltage (data-sheet link attached) to a range of 0-5V, as this is the range required for the input to an ADC chip.

While I know that op amps generally are used for this task, I couldn't find a comprehensive working mechanism for the circuit - the resistors, the capacitor, etc.

Could someone please explain to me what actually happens in this circuit, and what would the gain of the op amp finally be?

From the datasheet, I calculated the maximum voltage (V max) of the microphone to be 8.9 mV. (10^(-41/20))=8.9mV, where -41 is the sensitivity.

Datasheet of mic: http://docs-europe.electrocomponents.com/webdocs/0f2a/0900766b80f2a57c.pdf


texts: How can I read from an accelerometer through i2c/spi for ~1 second at frequency>2kHz with precise distancing between measures

texts:
Context
goal
My final goal is to perform an fft on acceleration signals with specs at least:

band between ~10 and ~1000 Hz
spectral resolution ~1Hz

on a portable, cheap, low-power device.
hardware
I'd like to do this with cheap portable low power hardware so I opted for an adxl345 as accelerometer connected via i2c (but also spi would be viable) to an esp32-wrover as micro-controller, powered by a 18650 lipo battery. Of course there is no problem, if necessary, to opt for more expensive hardware staying around ~100 euros/dollars.
software
I know and like python more than I know and like C, so I decided to use micropython on the microcontroller to acquire data from the sensor and push it via wifi to a computer that will actually perform the fft.
Question
My question is very focused on how to pass acceleration signals from the accelerometer to the micro-controller via I2C: I have implemented a loop that lasts for the desired acquisition time (say 1 second) and on each iteration tests how much time has passed since the beginning and if it's a multiple of the desired frequency it read a value from the accelerometer via i2c
start = ticks_ns()
while ticks_ns() - start < acquisition_time * 1000000000:
    curr_time = ticks_ns()
    if curr_time - start < (n_act_meas * 999999999. / sampling_rate):
        continue
    buf[n_act_meas * 6:n_act_meas * 6 + 6] = i2c_read_bytes(address, regAddress, length=6)  # 6bytes = 2bytes * 3 signals (xyz)
    T[n_act_meas] = ticks_ns()
    n_act_meas += 1

but this approach is not very precise on the interval between measures (~10% relative error) and has a top frequency of 2kHz in my implementation (below the max frequency of the accelerometer).
I feel like I'm doing something wrong: is it possible to read via i2c the last n measures from the accelerometer (where n~1000 in my case) so that the problem of the timing is relegated to the accelerometer that should have a system that is precise enough to guarantee the nominal max sampling frequency, and a precise distancing between measures?


texts: Vias in Kicad are not connecting to the power plane

texts:
My other vias are connected with the star pattern to them but my 5V and 10V planes are not actually connected to the vias.  They look like they are but after sending out this board to be made they said my power layer is non functioning.

Any help would be appreciated, thank you.


texts: Will any type of solder bond to any non-conductive material?

texts: Are there materials which solder will physically bond to but itself is not electrically conductive?


texts:
I have a simple doubt about the conservation of power in systems that include some filters.

Let's consider this general situation:

The filter is able to attenuate some components (of certain frequencies) of Vin. This means that the power of Vout is lower than that of Vin. I have the following questions:

1) Where does the power Pout - Pin go? If I look for instance at the following example, I'd say that it is dissipated on R, since for all frequencies such that Vout = 0, all Vin drops on R.

Is it correct?

2) Is the previous reasoning true for any type of filters? If it is true, it means that it is not possible to realize filters without resistors (not even ideally): otherwise, where will the power Pout - Pin go?

3) I have noticed that filters that are used in microwave/rf circuits are considered as "reflection attenuators": they (ideally) do not have losses, since power Pout - Pin is reflected by them. But, exactly what does it mean? Which component stores or dissipate that power?


texts: RS-485 over many 1000s ft, ground wire and termination always needed?

texts:
I've only ever used RS-485 over short connections before.  I may have a project coming up where the cables will run several 1000 ft.  My questions are:

Is the gnd wire needed?
Should the shield in the cable be used as the gnd wire?
When must terminator resistors be used?


texts:
Could someone help me to make a clock that has outputs like this

there are 3 clock outputs

I have a reference schematic here, and this clock has 4 output and it made up of 2 flip flops, it uses IC SN74LS74 as shown in the picture, the IC is used to divide the frequency by 4 and then it is possible to use those states using logic gates to give the correct output

So I need the output are just 3 clocks, could someone help me to find a true states for this problem.


texts: We are supposed to find \$R\$ such that \$I_S=0\$ and then find the maximum \$V_{SRC}\$ for operation in the linear region. I tried to use KCL at the nodes but it didn't work out eventually since I got a value of R that is negative. And for the second part of the question how does one determine the maximum possible value in the linear range: I am not sure how to go about this. I would appreciate any help.


texts: Mains LED light bulb flickers when switched off

texts:
We have LED bulbs in our apartment. In the bathroom, the bulb flickers on and off when it's switched off. Same when it was a CFL bulb before I switched to LED cause I hate CFLs. Our mains voltage is 220v. The bulb we have looks like this

If I remember correctly, I should add a capacitor in series to the bulb to fix this. But what kind of capacitor? and what rating?

Update:

The switch is a combined switch and plug in one part. Looks like a normal one line switch.
This apartment and the whole building doesn't have grounding. We don't have this in requirement in our building codes. I'm in Lebanon.
Only this one bulb in the apartment does this. Other bulbs are also LED and two more CFL not changed yet.

Any help appreciated, thanks.

Resolution: I fixed it with an incandescent bulb! I'm too lazy to go electrician detective for now.


texts: Converting Uncertainty in dB to Relative Standard Uncertainty

texts:
Data sheets often give uncertainty in dB.  If uncertainty is specified as a percent, I believe that means it is a relative uncertainty.  Assuming the coverage factor is one, the relative standard uncertainty is the percentage given.  When uncertainty is specified in dB and is converted back to a percentage, the interval is no longer symmetric.  For example, +/-3 dB would be +100%/-50%.  How should I interpret this?

Edit

In The Measurement of Power Spectra by Tukey and Blackman, the interval is given as the spread in dB.  "Spread is the difference between the upper boundary expressed in db, and the lower boundary expressed in db."  And "All intervals are symmetric in the probability sense, half of the non-included probability falling above and half below the interval."

If we think of the interval in terms of total spread, does it make sense to add the positive and negative uncertainties?  For example, +/-3 dB, would be a spread of 6 dB or +/-150%.


texts: USB Full-Speed driver's effect on transfer speed

texts:
I am experiencing problems with USB communications which seems driver related. My setup involves an embedded device set up as a virtual com port (CDC/ACM) with which I communicate over USB. The problem is that the data rates are very slow on a certain computer. I have tested the embedded device on various Linux computers and found the problem to be specific to that pc (the one that matters).

From the output of dmesg the only noticeable difference is the driver being loaded on the different computers. The troublesome pc uses uhci-hcd, whereas others use either ehci-hcd or xhci-hcd. With ehci being available on the slow pc, I tried to dictate which driver is loaded but that seems easier said than done on Linux. Others have suggested blacklisting uhci-hcd, but rmmod returns with an error saying the 'module is built-in'.

The OS on the pc was upgraded from a 32-bit Ubuntu 12 to Ubuntu 14.04 64-bit (processor is 64 bit). Wikipedia mentions that uhci only supports 32-bit memory addressing, requiring an expensive bounce buffer to work with a 64-bit OS. Could this be the reason for the slow data rates?

The embedded processor (Infineon XMC4400) supports full speed (12 Mbps) transfers which I understand corresponds to USB 1.0. Am I correct in assuming that certain drivers for USB 1 outperform others?

I am a bit of a hardware noob and would appreciate any advice in aid of a solution or comprehension of the problem. Should I attempt to force certain drivers for the device, and if so, how? Should I revert to a 32-bit OS, or am I maybe limited by the hardware?

The motherboard on the pc is a Versalogic Mamba EBX-37.


texts:
I was reading about the GSM frames used in GSM communication. One thing pretty unusual caught my eye.

  Training Sequence:
  This is used by the receiver’s equalizer as it estimates the transfer characteristic of the physical path between the BTS and the MS. The training sequence is 26 bits long.

  26 bits training sequence:   This training sequence is used as a timing reference and for equalisation. There is a total of eight different bit sequences that may be used, each 26 bits long. The same sequence is used in each GSM slot, but nearby base stations using the same radio frequency channels will use different ones, and this enables the mobile to differentiate between the various cells using the same frequency.

These are the definitions about the Training Sequence from 2 different sources. But, why would someone put the training sequence in the middle of a frame? Wouldn't it be more clever for the training sequence to be in the beginning of the frame so it can train the equalized for what is to come next?


texts: OpAmp: Better to actively attenuate, or drive full range into a divider?

texts:
I want to get a +-15V differential signal (60Vp-p) into an ADC that has a single 3.3V supply.  When I asked a friend to proofread it, he was concerned about the noise performance of R5-R6 vs. using R1-R4 to make U2A output the desired level to start with:

simulate this circuit – Schematic created using CircuitLab

(input protection not shown for clarity)

My understanding is that an opamp's noise level does not depend on signal level, therefore a hotter signal is better.  So I only attenuated U2A enough to match the full input range and left the rest to R5-R6.

(Another benefit is that if something goes wrong and U2A becomes a comparator, then the ADC input is still within the limits.  Probably not likely, but possible.)

My friend thinks I would actually have less noise by putting all the attenuation in R1-R4, deleting R5-R6, and driving C1 directly.  Is this true?


texts: Making a robot go straight using encoder motors and micro-controller (Arduino)

texts:
Now I have a simple chassis with two wheels which are powered by encoder motors. I connected Arduino Uno with the chassis and made a simple program to just count the numbers of signals (in simple terms) from each of the encoder motors.

Now theoretically when the chassis moves straight both readings should be exactly the same (I've checked - They are!). And when one motor is faster that certain reading should be more.

So I made a simple program that keeps a check on these encoder readings and when the difference exceeds a certain value it shuts off one motor until the values don't become equal and then turn on that motor.

Now theoretically the chassis should go in a straight line but it doesn't and performs weird stuff. (Code is attached below).

Now sometimes the code gets stuck in one of the while loops. I've also tinkered with my code a lot. For example instead of while(left_counter != right_counter) I've even done while ((left_counter - right_counter) > Certain_Range

The only problem I can think of is that it takes time for the motors to turn off and in that time the interrupts are wreaking havoc. (I'm new to micro controller programming and stuff although I have quite a lot of experience in C++ etc.)

Please can any one explain why isn't this approach working in keeping the motor straight?

Code (Arduino UNO):

int motor_vcc_left = 12; //LEFT TIRE - BLUE
int pull_up_left = 3; //LEFT TIRE - GREEN

int motor_vcc_right = 11; //RIGHT TIRE - ORANGE
int pull_up_right = 2; //RIGHT TIRE - BLUE

int encoder_vcc_pin = 7;

volatile int left_counter = 0;
volatile int right_counter = 0;

void setup() {
  pinMode(motor_vcc_left, OUTPUT);
  pinMode(motor_vcc_right, OUTPUT);

  pinMode(encoder_vcc_pin, OUTPUT);
  digitalWrite(encoder_vcc_pin, HIGH);

  pinMode(3, INPUT_PULLUP); //LEFT TIRE
  attachInterrupt(1, blinkleft, CHANGE); //LEFT TIRE

  pinMode(2, INPUT_PULLUP); //RIGHT TIRE
  attachInterrupt(0, blinkright, CHANGE); //RIGHT TIRE

  digitalWrite(motor_vcc_left, HIGH);
  digitalWrite(motor_vcc_right, HIGH);
}

void loop() {
  if ((left_counter - right_counter) > 10) {
    while (left_counter != right_counter) {
      digitalWrite(motor_vcc_left, LOW);
    }
    digitalWrite(motor_vcc_left, HIGH);
  } else if ((right_counter - left_counter) > 10) {
    while (right_counter != left_counter) {
      digitalWrite(motor_vcc_right, LOW);
    }
    digitalWrite(motor_vcc_right, HIGH);
  }
}

void blinkleft() {
  left_counter++;
}

void blinkright() {
  right_counter++;
}


texts: PIC18F4580 - PORTD not being read correctly

texts:
I am experiencing a strange problem with reading back the value of PORTD while it is configured as an output. I am writing to LATD to set output on the port. The actual output is as I expect (verified with LEDs), but when I then read the value of PORTD, bits 0:3 always come back as zero...

My first thought was conflict with the ADC, but it is switched off, as are CCP1, ECCP and PSP which also share pins with port D. The code works fine when running in MPLAB SIM but the problem shows up both running normally and debugging with a PICkit3...

Here's the code:

void main (void)
{
   char test;

    ADCON0bits.ADON=0;          //Turn adc off
    ADCON1 = 0x0F;              //Turn individual ADC channels off.
    ECCP1CONbits.ECCP1M = 0;    //Turn off ECCP module
    CCP1CON = 0;                //Disable CCP1
    TRISEbits.PSPMODE = 0;      //Turn off PSP module
    TRISD = 0;                  //PORTD to output
    LATD = 0xFF;                //Set all bits high
    Nop();                      //Wait for output to propagate back to PORTD
    test = PORTD;               //test gets 0xF0???
}

This is really frustrating, all the more so because the hardware actually functions but my self tests keep giving false positives...


texts: Can't get special PIC32 linker section to show up in output file

texts:
I am defining a special section for some data that I want to show up at the beginning of my PIC32 binary image, as follows in the SECTIONS part of my elf32pic32mx.ld file:

  .headerdata ORIGIN(kseg0_program_mem)  :
  {
    *(.headerdata)
  } >kseg0_program_mem

and then in my code, I am initializing a structure like so:

const MODULEINFO SER_05_ModuleInfo __attribute__((section (".headerdata"))) =
{
    sizeof(MODULEINFO),         // UINT16 HeaderSize
    MODULE_TYPE,                // UNIT16 ModuleType
    // etc. etc.
};

When I compile and link the program, the structure shows up in the map file:

.headerdata     0x9d000000       0x48
 *(.headerdata)
 .headerdata    0x9d000000       0x48 DriverHeader.o
                0x9d000000                SER_05_ModuleInfo

but the actual data does not show up in the hex output file.

If I leave off the  attribute ((section (".headerdata"))) in the structure, the structure shows up in the .rodata of the map file, and the data does show up in my hex output file.

When defining special sections, is there something else that needs to be done to actually get them to generate output besides the >kseg0_program_mem line?


texts: L200C regulated power supply - maximum current

texts:
Hi
I need to know what is the L200C maximum current. The datasheet says it's internally limited. Am not quite sure what this means.


texts: Which battery should I use to power arduino+motor shield + two motors

texts:
I am using two motors ( from old two drill machines - same kind, these are 3.6v motors ), connected to arduino + arduino motor shield seeed studio v2.

I tried to use 18v/1.2a battery that was laying at home (from old machine ) what I have noticed is that motors are running for 3-5 seconds than stop, one of the red lights start blinking in the motor shield, then it stops for 3-5 seconds then it works again and loop.

Note: the motors are working when I connect them directly to 4.5 or 6v battery. But when I try to assemle everything , it doesn't work.

I tried 14v battery I noticed the same thing ( but slower, and this is something logical ), the battery of 9v don't make any move ( even by powering th arduino alone (using 9v) and the motors alone (9v) ).

What are things that I should consider here, any thoughts.

What did I miss? And what kind if battery should I use ??


texts:
I am going through an OPAMP Voltage follower/Buffer Circuit.

I have 1 question regarding this Voltage follower circuit using OP-AMP and 2 questions in general regarding OP-AMP:

Let's say my Vcc rails of the OP-AMP are +5V and 0V. And I am giving a constant Vin=2V to the Non-inverting terminal of the OP-AMP and the Output terminal of the OP-AMP is fedback to the Inverting terminal without any feedback resistance.

I know, since this is a voltage follower circuit, the Output voltage follows the input voltage until the input voltage hits the saturation voltage (Vcc) of the OP-AMP.

But how does the voltages start initially?

Like, at the start, the voltage at the output terminal is 0V and 0V is at the Inverting terminal as well.
Now, we give the Vcc power to the OP-AMP and the Input voltage to the non-inverting terminal.
Vcc=+5V. And Vin=2V.
Since the voltage at the non-inverting terminal is greater than the voltage at the inverting terminal, in this case, 2V and 0V, the Output should go to the saturation voltage, right? (Assuming this OP-AMP has high enough gain say 10000)
So, the output goes to 5V and then this 5V is fedback to the inverting terminal which then makes the output go to negative saturation and hence output 0V (as -Vcc = 0V)

Where am I going wrong with the Voltage follower operation? In my understanding, the output still swings from +Vcc to -Vcc only.

I can understand the circuit with the Help of Math and the equations of Gain and the resistors of Feedback and so on. But when understanding with the intuitive working, I am misunderstanding.
Please tell me how this voltage follower works at the initial start-up and how the output follows the input without any math or equations.

The Ideal characteristic of OP-AMP is that the differential voltage between the input terminals is 0V.

But in the real world, we give different input voltages to the terminals so as to amplify the difference between them, right?

If an ideal OP-AMP maintains the differential voltage between the input as 0V, then the OP-AMP can't amplify the differential voltage between the terminals, right?

Isn't this contradictory to the actual purpose of the OP-AMP?
What am I missing here?

Last question,

The OP-AMP has high input impedance and Low output impedance. This means that the OP-AMP input terminals does not have any input currents drawn from the source.

And Low output impedance means, that it can produces how much ever current the load requires? Is there a limitation of how much current the OP-AMP can source?

And the output current to the load comes from the +Vcc power terminals of the OP-AMP right? Is there a limitation to the amount of current the OP-AMP can provide?


texts: What is the best number of PWM signals for Full-Bridge driving? (2 vs 4)

texts:
Full-Bridge resonant converter circuit:

Each transistor (Mosfet) has its own driver (ISO5852S).
I assumed that a full bridge could be controlled with two PWMs.
PWM1A, PWM1B, PWM2A, PWM2B.

Each PWM, at its own time step, drives two transistors.
The driver has both inverted and non-inverted inputs, so we can protect the system from through-current in the event of a PWM failure.
I have also seen circuits where 4 separate PWMs are used to control the FULL-Bridge. (PWM1, PWM2, PWM3, PWM4), with A, B outputs for each.
It turns out that in the case of 2 PWMs, only two groups of transistors can be controlled separately.
And in the case of 4 PWMs - each transistor separately.
Question:

Why are 4 PWMs used instead of 2 to control Full-Bridge?
What does the separate control of each transistor give?


texts:
I am designing a system which turns on at 45 degC. I want to place a device in series with my circuit that ideally has infinite resistance below 45 degC and then 0 resistance above 45 degC.

I guess the closest I can get to this ideal is using an NTC thermistor but I am struggling to get my head around how to select a B number.

As, to my knowledge, my ideal device doesn't exist I have worked out that an NTC thermistor with a resistance above 10K Ohm at room temp at 10 Ohm at 45 degC would work but, if my calculations are correct, this gives me a B number of 37,000 ish which seems ludicrously high.

I plotted a graph of ln(R) vs 1/T, added my two points and then worked out B as the gradient - is this the correct method? (inferred from this wikipedia article)

Does anyone have any suggestions for an alternative method or where I maybe going wrong in my calculations?


texts: SMPS design problem, low available current

texts:
I'm having an issue with this SMPS design where the voltage is correct at approx. 19.45V but I'm getting nowhere near the target of 3000mA

The zener voltage on D3 is 18V. R3 is a 1K resistor.

When I hook up a 650mA load the voltage drops to around ~ 3V.
When I hook up a 300mA load the voltage sits at about ~12.5V.
Without a load it is at the target voltage of 19.45V.

I would really like to figure out where I've gone wrong with this one :(

NCP1200D60 Sheet: https://www.onsemi.com/pub/Collateral/NCP1200-D.PDF

FQP6N60 Sheet: https://www.mouser.com/datasheet/2/149/FQP6N60-189115.pdf

Wurth 750343068 Sheet: https://www.mouser.ca/datasheet/2/445/750343068-1483750.pdf

Update: I replaced the full bridge rectifier with a MUR460 diode as per The Photon's suggestion and it has improved the current issue considerably. I can reliably power a 700mA load, but I still cannot power a 2200mA load. It seems to spike every 3-5 seconds, powering the load and then dropping immediately. The MOSFET's heatsink get's pretty warm.

Update: I've designed a new PCB and done some more testing. Thank-you for everyone who responded, you all had helpful feedback.

I went on to run with this:

I then made a few more modifications, including upgrading the 47uF caps to 100uF caps.

At the end I'm still stuck with ~600mA but it is working perfectly, no MOFSET heating up, no issues at all.

Andy made a point that I disagreed with at first

  Finally, the driver chip is not “man” enough to control a MOSFET that is capable of delivering anything like 60 watts to the output. You need to rethink this in my opinion.

But I now know he's right. The chip isn't, not without some help. I managed to dig up examples where the chip is used for 40-80W power supplies and seen that they almost always make use of the AUX winding on the transformer (I have one on mine that I'm not using)

See this random example (No idea where it came from):

I have some more work to do at the drawing board to get my current levels, but I'm marking this question as answered, as all the major design issues have been addressed.


texts: Is Multiplexing ever superior to Charlieplexing?

texts:
I've reviewed the two methods, and multiplexing really only appears to have one advantage, that it would be easier to track down a failed LED than in a Charlieplex array.

Can someone more knowledgeable explain any other trade-offs?


texts: Can I use a 600VAC PTC resettable fuse in a 700VDC application?

texts:
I've inherited an old design, and a part used has gone out of production. This part is a PTC resettable fuse, used in a bootstrap circuit, so it's one-shot. When the PTC opens, it has ~700VDC across it, and stays that way indefinitely. Most PTCs I see are rated in terms of AC voltage. My first thought would be that if something can withstand (for example) 600VAC, it should also be able to withstand 850VDC. But I've seen some vague references to this possibly not being true.

So if I have a resettable fuse rated for 600VAC, can I use that in my application? For example, this one:
http://datasheet.octopart.com/TR600-150F-EX-2-TE-Connectivity---Raychem-datasheet-11088140.pdf


texts: How would I detect if a POTS telephone is on hook?

texts:
I've hooked up a plain old telephone directly to a 3W amplifier which happily plays music over the phone. It's the simplest thing on earth -- the 2 wire POTS connection is wired to the speaker output of a miniature "4-8ohm" amplifier.

The phone is not connected to the phone system. It will not have any ringing. It's just supposed to be like a hotline-when you pick it up, it plays MP3 files.

(The amp is really an Arduino with a music shield playing MP3 files.)

When the phone is on hook, it opens the circuit. How can I detect this with an input pin on the Arduino, without interfering with the audio while it is playing? I suspect that there is something I can do here with an optocoupler but it's a bit beyond my understanding.

simulate this circuit – Schematic created using CircuitLab


texts:
When finding parameters of a transformer, can you perform the OC test and the SC test on the same side?
Or is it necessary to perform them on separate sides?

I am aware that by convention in the real world we perform the open circuit test on low voltage side and short circuit test on high voltage side. But can we do them both on the same side?


texts: Esp-01 and 3V3 relay module: unexpected resets (cause 4)

texts:
I am working on a simple circuit (for debugging purpose) which switches a 3V3 relay every second through the Esp-01 GPIO2 pin. The power supply comes from the USB to ESP-01 adapter (but the same happens with another power supply)
This circuit is the following:
**ESP8266-01:**
VCC <--> 3V3 power supply
GND <--> GND (power supply)
CH_PD <--> 3V3 power supply
GPIO2 <--> IN (relay)

**3V relay:**
VCC <--> 3V3 power supply
GND <--> GND (power supply)
IN <--> GPIO2 (ESP-01)

The relay is mounted on a power extension cord, on which I can connect various devices.
Here is my circuit diagram (the breadboard is not represented):
My sketch is the following:
#include <ESP8266WiFi.h>

const int switch_pin = 2;
int state = 0;

void setup() {
  Serial.begin(115200);

  WiFi.forceSleepBegin();

  pinMode(switch_pin, OUTPUT);
}

void loop() {

  if (state == 0){
    digitalWrite(switch_pin, HIGH);
    state = 1;
    Serial.println("1");
  }

  else{
    digitalWrite(switch_pin, LOW);
    state = 0;
    Serial.println("0");
  }
  delay(1000);
}

which produces, on the serial:
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1

 ets Jan  8 2013,rst cause:4, boot mode:(3,7)

wdt reset
load 0x4010f000, len 3584, room 16
tail 0
chksum 0xb0
csum 0xb0
v2843a5ac
~ld
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1

 ets Jan  8 2013,rst cause:4, boot mode:(3,7)

wdt reset
load 0x4010f000, len 3584, room 16
tail 0
chksum 0xb0
csum 0xb0
v2843a5ac
~ld

Thus, sometimes, the Esp-01 resets and, sometimes it cannot "recover" from such resets.
However, when I disconnect the extension cord (from the electrical outlet in the wall), the relay switches indefinitely as expected (I do not know if it's a clue to solve my problem).
I tried with 2 relays and 2 Esp-01 and always got the same behaviour.
Would you have any idea about the origin of such a problem?


texts: Battery management system for my battery packs

texts:
I'm working on battery management system for my battery cells.
the topology is based on inductor energy transfert from the higher charged cell to the lower one in order to balance and equalize the charge between the cells.
two main blocks are necessary in my circuit are first the monitor of voltage and driving mosfets.
i tried first to work with the BQ76PL536 from Texas Instruments but the problem is that his CBn output to drive the mosfet are Digital Output while i want to provide a PWM signal at 100Khz frequency so i dropped the solution and i'm trying to make my own discrete solution.

Gate driving is not a problem but i have some problems with voltage measurement to the microcontroller.
my cells voltage range are from 0V to 1.6V max.
i'm thinking on using voltage comparator for each cell and the output go to the microcontroller.

the other problem is that i'm going to measure this voltage while i'm charging the battery with 17A current.


texts: Are BJTs used in modern integrated circuits to the same extent as MOSFETs?

texts: On modern integrated circuits, are there as much BJT's on the chip as MOSFET transistor? If not, why?


texts: Pinout of iPhone 4/4S rear camera connector?

texts: Has anyone come across the pinout of an iPhone 4/4S rear camera module connector?


texts:
I want to make sure im understanding something correctly. Im learning the MSP430G2 (specifically G2553 is the actual chip im using).

Im def. a newb to computer architecture so keep that in mind.

So from the datasheet/books im reading, the data/address bus is 16 bits wide (2 bytes). And a Word size is 16 bits (2 bytes) (although im still not sure what word means in this context).

However the memory addresses are only 8 bits in size (1 byte). So everytime we send a word? or Opcode, are we storing it in 2 memory addresses? (I read that the MSP430 only looks at the lowest significant BYTE and that it has to be even)

So if were storing a word or instruction (Im not sure if they mean the same thing in this context). Were storing the LSB in the lower memory location (like 0x0200) and the MSB(byte) in 0x0201 for example. But the CPU is only actually reading the LSB? Is this correct?


texts: Should I replace these resistors on my vintage radio?

texts:
The one in the image isn't the 250k one exactly, but it's one I had a picture of. The 250k just has a different colour but is the same kind of resistor.

EDIT, the big red one is a capacitor, the resistors are above and to the right of it

I have a sheet telling me to use 250k resistors however they are measuring out to be 338k instead. I've done this with a couple other resistors and found them to all be slightly over what the data sheet calls for.

Is there a reason for this? Should I replace them or are they fine as they are? Also why are they so big? First time working with vintage components. Looking for any knowledge you guys have on this!


texts:
I've set up a gravity based drip system, but it's clear that the manual adjustment for each plant is impossible. I'd like to have a Raspberry Pi make the adjustments for me based on the assumption that an exact amount of drops will always deliver the same quantity of water.

My idea is to put a low cost sensor under a motorized dripper to count the drops. My question is, can anyone recommend a sensor which only needs to send a pulse to the Pi each time a drop falls? A second question would be a recommended motor to squeeze the tube to slow the drip?


texts:
I am not finding any datasheets that provide clear information about the power dissipation of some gates of the 74LS series:
08, 02, 04, 00, 32 and 86.
Can someone help?


texts:
LDOs, or low-dropout linear regulators, come in various types, but it can be difficult to distinguish them, and to the novice engineer, this regulator is often made to seem deceptively simple.

Some LDOs didn't care about the ESR of the output capacitor (used with film capacitors). Later they were common with electrolytic output capacitors with some ESR and did not work well with ceramic capacitors (MLCC). And now it seems to be common for them to be perfectly stable with MLCCs but have a maximum ESR requirement of a few Ohms.

My understanding, and correct me if I'm wrong, is that this difference must be due to differences in their control functions, that instability is caused by insufficient phase margin, and that this instability should be countered by introducing one or more zeros to the control function (adding ESR to Cout and/or feed-forward capacitance across R1 in the control loop).

But I'm missing the bigger picture as to what the differences are with regards to their build and regulation schemes, how to spot the different types, other than look for the ESR requirements, and what other factors, related to build and regulation scheme, might be prudent to consider when choosing an LDO.

Can someone provide me with a good overview?


texts:
I have a Dold Safety relay OA5621OA5621 data sheet on page 2 of the data sheet it lists standard variants:

I have a 24 volt relay, OA5621.52 with 2NO/2NC contacts. I can't figure out what Rsp means, is it the contact resistance or coil resistance?

I need to find the coil resistance, is it 3753 ohms or 960 ohms?


texts: Conductivity and high speed transmission using aluminium slip rings

texts:
So I came across a Persistence of Vision globe based video where a YouTuber he makes DIY slip rings to power and control some LEDs as seen in this picture:

My question is, given the high rate of data transfer needed to turn on and off the right leds at the right time, would this set up have an effect of the project? If an LED has 400Hz refresh rate, will this set up manage to get that happening?


texts: Combining CPU and RAM on stacked silicon

texts:
Xilinx developed a way to combine multiple dies in a single package by using a silicon interposer (I don't know whether they're actually are the first ones to do this). This way, they achieve huge bandwidths between the individual dies, much more than would be possible if the signals had to go through IO pins (for more details, see here or refer to the whitepaper).

Now why doesn't Intel, for example, use a similar technique to combine the CPU and the RAM in one package? This would allow for a much higher memory bandwidth, among other benefits (slightly lower latency, lower power dissipation, fewer package IO pins, fewer signal routes on the mainboard).

Sure, there are some drawbacks (the DRAM chips would have to be stacked, the amount of RAM is fixed, an additional interposer die is needed (though this can be manufactured in an older, cheaper process node)), but considering that the memory bandwidth bottleneck is an increasing problem for a growing number of cores, this should be worth it. What am I missing?


texts:
I am dealing with PICs for some time and now I want to learn how to use an AVR. I have 2 MCUs in here, the AT32UC3C2512C-A2UT and the ATXMEGA32A4U-AU but I still dont have any programming tools.

In the PIC, things are pretty simple: You just buy PIC Kit 3 and you can program and debug all PICs for a cheap price. But in AVR I can see so many options in Atmel's website, and not just in products but in technologies (PDI, JTAG etc..).

Since I am pretty noob in this subject, I wanted a quick comparison of the options out there and not just the programmers and debuggers but also about the technologies inside them. The DIY options will be most welcome.

In the internet there are some quick reference guides, like this one, but they are years old and they do not compare the technologies inside them (in that link they don't say for example the difference between TPI and PDI or JTAG and the benefits of each one of them), just what they do, so it's hard to choose one.

Please bear in mind I need a programming board for the MCUs I mentioned. I appreciate all the help!

EDIT: I think this link might help.


texts:
This is probably a stupid question but I am new to IO link sensors.
When using IO link technology with a PLC (siemens s7-1200) can you connect devices that are not IO link sensors?
For example say I wanted to connect an existing normal push button to a IO link master, is it possible to cut the plug of the IO link cable and connect the button with the 3 required cores( positive, negative and the signal wire)?


texts: How to free up memory in a CircuitPython board?

texts:
I'm using a Feather M0 Express from Adafruit with a DS3231 Precision RTC FeatherWing for a custom clock project that displays time with LEDs.
The clock works as follows:

When the clock gets plugged to a power source, the MCU program gets the time from the RTC shield;
it saves it on the board, and uses from that point onwards the internal clock of the MCU.

The time gets displayed correctly, but after a few hours, the LEDs stop working. I've run tests with the garbage collector and found out the board runs out of memory space. I have to hit the reset button to make it work again.

I've tried to use the garbage collector with gc.mem_free() but it doesn't seem to free up any of the allocated memory.

Any tips on how to cleanly free up memory space on those boards?

Thanks in advance!


texts: Can I use a MPPT Solar Controller to charge my auxillary 12V AGM Battery from the car battery/alternator?

texts:
I have a RedArc solenoid and a Victron 75/15 Smart Solar Controller.  Can I use the combination of these two units to charge an 12V AGM Deep Cycle auxiliary battery from the car battery/alternator when the car is running ?

The RedArc solenoid is no longer battery sensing and only works via the override lead being pulled to 12V.  I'd connect this override lead to the car's ACC or running output of the vehicle.

Second, the Victron unit provides multi-stage charging and is configurable for multiple different batteries and provides some nice feedback via the Victron App.

Third, if this combination does not work, can I add a RCNUN BuckBooster ( Input 8-32V DC, Output 13.8V 8A - Constant Current output from 8-13.8V) between the solenoid and the MPPT Controller to regulate the output?

I have been pondering this for some time.  I have the piece hence the interest.  Thank you.


texts: How can extend the cable distance from a condenser microphone to the ADC without loosing fidelity?

texts:
I am new here so please forgive me for a vey basic question. I have a TASCAM iM2 in my possession. This is a stereo condenser microphone coupled to an ADC that connects to the the latest iPhone models via the dock connector.

http://tascam.com/product/im2/

I am in the process of dismantling it so that I can extend the physical distance between individual microphones. As you can see from the photo, there are 3 wires connected to each mic. I'm guessing that the black ones connected to the dock casing are ground, the yellow leads are probably a DC voltage to charge the plates and the red and white wires are probably for the actual audio signals.

I only want to extend the distance of each mic by 8 inches or so from the circuit board. I was planning on extending the wires using a cannibalised stereo audio extension cable (the ones with the 3-pin 3.5mm jack on each end). However, I want to extend the wires in a way that will not introduce much additional noise. One of the great things about this unit is that the ADC is so close to the microphones, so there is not much chance to pick up noise on the way. What would be the best way to shield this, or would the short distance I'm talking about not be a problem anyway?


texts: Is that any best way to measure High side mosfet drain current?

texts:
To be specific, I am using 6 MosFETs (for ex. PSMN030-60YS) to drive an inductive load. I want to measure drain current of High-Side MosFETs. The way I am doing right now is by lifting the MosFET mounting base (drain pad) and attaching a small loop as possible (I know it does add some extra inductance and have small voltage drop) across the mounting base of MosFET itself and drain landing of PCB (a crude image is attached below).

I don't know any best way to measure drain current of high side MosFET apart from this.

Is there any proper way to do so without adding extra L or R component by adding a wire like I displayed?


texts:
I want to build a sound detector circuit for my project. I am free to use any amplifier but not much complex circuitry. I googled and found this circuit using LM 386.

Is this good enough or is there any better and more efficient circuit and/or amplifier ?
I have to use MSP430 instead of arduino.


texts: My first AVR C program- LED not blinking

texts:
I created a simple program to be put onto a ATMega328P chip (Datasheet). I wrote my first program in ATMEL studio that I wanted to use to Blink an LED at a rate of 0.5Hz with extremely low power usage. Here's my code:

/*
 * GccApplication1.c
 *
 * Created: 11/12/2017 8:56:49 PM
 * Author : Brice
 */

#include <avr/io.h>
#include <util/delay.h>
#include <avr/power.h>

int main(void)
{
    clock_prescale_set(clock_div_128); //set the clock to use the 8MHz internal clock divided by 128 for an internal frequency of 250KHz, consumes 0.4mA while not sleeping.

    while (1)
    {
        PORTD4 == 1;//Set pin 13 of the micro to high.
        _delay_ms(1000);
        PORTD4 == 0;//Set pin 13 of the micro to low;
        _delay_ms(1000);
    }
}

What I expect this code to do to this micro-controller is to turn PORTD register 4 on for 1 second, then turn it off for a second.

currently, The PortD4 will not have any voltage changes to it, and remains grounded while the device is powered.

Any explanation of this would be appreciated!

For this instance, I'm using the Arduino Pro mini board for prototyping..

pin 4 of the Pro mini is connected to the common Anode of an RGB led, and the G pin of the LED is connected from a 510 Ohm resistor to GND. I've tested the wiring with a working arduino, and the led even lights at 3.3 Volts pretty brightly.


texts: How to use coordinate strip electrically?

texts:
I want to build simple CNC machine, via reusing printer head, connected to arduino.
As per motion its all right: I use L298N dual driver, and can control movement direction and speed via PWM, setting appropriate voltages on the pins.

Question is that I need a coordinate system, and printer head had some plastic PET strip with transparent and black stripes. And I guess, an "opto isolator"? (correct me if i am wrong)

My question is how does it work and how to operate this strip "electronically"?

Should I set or read voltages? What voltage and at what rate? (arduino is a discrete machine, kind of fixed-timestep "adc sampler")
Should I control current, for instance, limit it?
Does that operates like led, or a resistor, or a transistor?

PS: Strip is on the photo below:


texts: DDR3, Data Mask Pin-swap within a given byte lane

texts:
Is it possible to swap "Data Mask" or "Data Strobe" pins with DQx pins within the same byte lane.
In Freescale's "Hardware and Layout Design Considerations for DDR3 SDRAM Memory Interfaces" app note, it is stated as "Pin-swap within a given byte lane to optimize the data bus routes further."
A byte lane comprises of 8 Data Bits, 1 Data Mask Bit, and 2 Data Strobe Bits.
As I understood for example, I can swap DQ2 pin with data mask bit or data strobe bits within the same byte lane...
I am confused because in all the examples on the internet, the data pins(DQx pins) have been swapped only in themselves.


texts: Will these heatsinks be sufficient for my mosfets?

texts:
I need to control 10 12VDC motors at ~25Amps, so I decided to make my own mosfet H bridges to control it ( with 2 n chan et 2 p chan ).
I will need 10 H-Bridge, so 40 Mosfets. ( 20 n chan and 20 p chan )
The mosfets which I'd like to buy:

N-chan https://www.sparkfun.com/products/10213
The p chan is FQP27P06 (I can't send more than 2 links under 10
reputations )

These mosfets have 62.5 degrees per watt thermal resistance to ambient, and the N-channel one has 0.045 ohm maximum resistance drain to source. The p-channel has 0.07 ohm

So I will have 0.045*25*25 = ~28 watts for N-channel and 0.07*25*25 = ~43 watts for p-channel

43 * 62.5 is a very big value so I was asking myself if a heatsink would be enough to absorb this heat ?

I've found these heatsinks: http://www.ebay.com/itm/10pcs-IC-Aluminum-Heat-Sink-With-Needle-fit-for-TO-220-Mosfet-Transistors-HM-/181411561757

I'm gonna have 40 of these, knowing that I will use 8 mosfets maximum at the same time ( 2 motors max at the same time ) if I put all of the 40 heatsinks in contact the 8 mosfets would be able to dissipate on the 40 heatsinks. ( which makes one very big heatsink )

I could also put 1 or 2 cooler fans.

would this be possible ?


texts:
The major steps of physical design that I learnt from a VLSI lecture are: 1)Partitioning 2)Floorplanning 3)Placement 4)Routing. The question of mine is about the steps 2 and 3.

It seems like the steps floorplanning and placement are somehow overlapping. We decide the places of the sub-blocks in floorplanning. But in placement step, we also decide the places of the sub-blocks and this time we take the interconnections into account too.

Placement step seems to be the expanded version of floorplanning. Then why do we have these two as seperate steps to be done one after another? Or should we think of them as a single step that are done interchangeably?


texts:
I have four motors attached to each of the wheels of my car. Two of these motors are servo motors and the remaining two are 12V DC motors. Since I could not get a rack and pinion type steering mounted on my car, I decided I would save myself the trouble and use Dc motors along with the servos to facilitate steering. But I have a couple of question as to whether I am on the right track:

Is the above idea a good one. (I don't want to use four servos since I would have to open it and modify it to allow continuous rotation.)
I was thinking of using something like the 8051(may just buy an Arduino to ease the process) to generate the PWM and then feed it into the two servos and use a H-bridge for the back wheels to reverse polarity, start and stop.

Is what I am doing right?


texts: How and in what chronological order did different transistor biasing circuits arise?

texts:
On the wikipedia page for BJT biasing, there are about 4 different biasing methods discussed. I can analyze and understand each one of them, however I want to know how and in what order people came up with them - what problems they had and how they tried to solve them. From what I know, most of the time you would use a voltage divider with emitter degeneration, however that doesn't look like it was the first thing people thought of when they wanted to do biasing. For example, I would assume that someone first just tried a fixed bias, but then realized that it doesn't account for beta variations and is unstable, etc.

I'm happy with either a comprehensive answer or some kind of reference to a book, article, paper or anything really. I'm asking this because I want to go through the same process myself in order to better understand things.


texts: I need 5v@500mA to 12v@5A for 2.5 seconds every 5 minutes

texts:
I've run into quite the problem. I have a load that requires 12v@5A for under 2.5 seconds. However, my supply is a USB 5v@500mA. This is not an immediate load. The load will only need to be activated once per 5 minutes, so I have some time for charging of possibly capacitors or a lipo.

What would be the best way to go about this? I've could not find any boost converter for that much of a power increase, so I know I'm going to have to store that charge somehow.

I've researched adding a lipo and a charger circuit, however, I cannot seem to find a 3S lipo charger that is in a package with exposed leads. In previous exchange forums the BQ24115 was recommended, however I don't have the capability to solder that small of a device currently with my time restraints. Also, I don't see how that chip monitors 3 cells, as all the applications provided in the datasheet seem to be for only a 1 or 2 cell LiPo, which I still can't figure out how the chip balances the cells as I see no hookup for "cell 1 sense" or "cell 2 sense". There has to be an input somewhere for it to read the individual cell voltages, assuming that chip can do balance charge.

Capacitors. I don't know very much about them, however I do know it is a potential route. A colleague recommended I charge capacitors individually, then use a transistor to arrange them in series for the load dump. (because I need 12v out from the caps, with an input of 5v).

Any help would be much appreciated! Thank you.


texts: Transient buildup of capacitively coupled transistor amplifier

texts:
I'm trying to understand the following section from "Communication Circuits: Analysis and Design" by Donald T. Hess:

Here \$W(t)\$ is defined by $$W(t) = e^{\frac{q(v_i(t) - v_{imax})}{kT}}$$
How the equation 5.3-12 and $$e^{\frac{- q v_{imax}}{kT}} = \frac{I_{dc}}{I_{ES}}$$follows from equation 5.3-11? Initial condition for capacitor implies \$V_{dc}(0^+) = V_{dc}(0^-)\$ but it doesn't seem to have applied here. So what's the reason for that? How can we apply \$v_i(t) = 0\$ for \$t\lt 0\$ to the equation 5.3-11?


texts: Should I use Counter1 to record time series data?

texts:
My Atmega328 will record data from an external sensor at around 100Hz over several minutes. Communication is done through I2C requests to the sensor. I need to store the time of measurement (relative to the first measurement) together with the sensor data. Precision of at least 1ms is required.

My plan is:

Start Counter1 (16 bit) at an appropriate scaling
Whenever Counter1 wraps, increment some register
When sensor data is requested, also store the values of Counter1 and the wrap-count register

Is this a good plan? Are there better solutions?


texts: How would I protect my hardware from unwanted magnetic induction?

texts:
To my understanding, magnetic induction is the process of varying magnetic fields producing a potential difference in a conductor, resulting in current.

How would I protect my hardware from strong, moving magnetic fields that could potentially produce a high voltage and damage my hardware? Do hardware manufacturers do anything to protect against the occurrence of unwanted magnetic induction?

What's to stop me from putting a large amount of magnet wire in my bag and connecting it to an alternating current supply (such as a car battery with a DC to AC inverter circuit), and then taking a trip down to the hardware store, causing damage to any hardware I walk past? (that's just an evil example - I doubt I would be able to produce a magnetic field strong enough to cause any damage, but my point still stands)


texts: I’m thinking of buying a brushless DC motor to power a watchmakers lathe, but I am hesitant because of the complicated looking, very expensive controllers and drivers that go between the motor and the wall outlet. I don’t need a variable speed controller, so it seems the only requirement is to reduce 120 V to 48 V and imagine there are simpler, much less costly, ways to do that. Can this be done?


texts: How to DIY a anti static bracelet or ground oneself?

texts: My laptop battery inflates and no longer works. I buy a new one and plan to install it myself, but I don't have an anti-static bracelet. I don't want to shock my laptop with statics. Is it possible to DIY one or DIY ground myself? Like maybe use a wire to connect my skin and a nail on wall, or just don't wear shoes and touch ground with feet? I was even once told that if we wash hands because water connects to water tap, which connects to wall, we eliminate our statics for a short time. Then we do our work as soon as possible. Is it true? Or even maybe I connect wall socket ground pin to me and laptop? But there is a 1M Ohm resistance in the adaptor, so it is me directly connecting to ground, and has a 1M Ohm between me and the laptop.


texts:
Peak Factor of an AC signal
How to determine the Peak Factor of a multiple frequency sine wave of different amplitudes?
Like in the given question:


texts: Test transformer with signal generator and oscilliscope

texts:
I would like to see how well a sine wave would pass thru a transformer. (from primary side to secondary)

Is it possible/practical to test small transformers which you might find in small low powered consumer devices with a signal generator and an oscilliscope?

sample transformer:

https://www.hawkusa.com/manufacturers/hammond-mfg/power-products/pc-mount-transformers/161d120

if so, is it really just connecting the signal generator (sine wave) to the primary,
 and the oscilloscope to the secondary?

(assuming the windings ratio would not blow up anything)


texts: What does 1 and 0 mean on this power supply?

texts: I have a Shaw Scientific power supply. On the front there is a switch to set the voltage from 0 to 12 volts. There is an on/off switch. There are connections for ac and also for dc. Then there is a switch with two options, 1 and 0. What could this function be ?


texts: How do I setup entity for a 1 to 2^n output demux with n select lines using VHDL?

texts:
I am working on a assignment do make a demux with 2^n outputs with n select lines. I have a my input (x bit wide, in this case x is 32bits) and my enable pins taken care of. But I don't know how to go about setting up entity so that my output is 2^n with n select lines. So far my entity declaration looks like:

-- Entity declaration
entity DEMUX is
-- Get the size of an integer
generic(Len :integer);
-- Map input, output, selection and enable signal ports
port(
   Inp : in std_logic_vector(Len-1 downto 0); -- Input pin
   Ena : in std_logic; -- Enable pin
   Sel : --How to set select lines?
   Oup : --How to set outputs?
);
end MUX;


texts:
I have a opto coupler to detect 12v and use this on a micro controller at 3.3v
Used the 4N25 before and they worked fine but i switched to the FOD053LR2 wich has 2 opto inside for better space usage.

i am not sure how to calculate the right resistors since the CTR is nog clear to me from the datasheet.

Below the schematic.

it also seems to me that PIN 3 and 4 are switched in the schematic and datasheet?

input voltage VIN is 12v ~ 18v

PDF of the opto coupler:
http://www.mouser.com/ds/2/149/FOD053L-190687.pdf


texts: For an engineer who solely knows C/C++ for programming microcontrollers, and has no idea about developing fancy GUI application for communication with his embedded systems, Which book and IDE might be a good start for embedded systems engineer for developing GUIs in Windows?


texts: How does a signal travel down a telephone wire?

texts:
Supposing a computer gets data over telephone wire, it has to send/recieve signals, but how do things work?

Does it use analog signal or a digital bits?
How does it send/recieve "1"s and "0"s?


texts: What is the gauge of wire used in a typical commercial 40 pin IDE cable?


texts: Mutex in RTOSes in this specific situation

texts:
Consider the following codes:

/*----------------------------------------------------------------------------
 First Thread
 *---------------------------------------------------------------------------*/
void Thread1 (void const *argument)
{
    for (;;)
    {
        osMutexWait(mutex, osWaitForever);
                Thread1_Functions;
        osMutexRelease(mutex);
    }
}

/*----------------------------------------------------------------------------
  Second Thread
 *---------------------------------------------------------------------------*/
void Thread2 (void const *argument)
{
    for(;;)
    {
        osMutexWait(mutex, osWaitForever);
                Thread2_Functions;
        osMutexRelease(mutex);
    }
}

As far as I've noticed from RTOS's scheduling ,RTOS assign a specific time to each task and after this time is over,it switches to the other task.
Then in this specific time,inside task's infinite loop ,maybe loop is repeated several times until task's specific time finished.
Assume task is finished in less than of it's time's half,then it has a time to fully run this task once again :
in last line after releasing mutex , then it will achieve mutex before than task2 for second time,Am I true ?
assume timer tick occur when MCU run Thread1_Functions for second time,then task2 cant run because mutex owned by task1, RTOS run task 1 again and if timer tick occur every time in the Thread1_Functions, then task2 has no chance to running,Am I true ?


texts: What is the purpose of a reset button on power strips?

texts: I'm just curious why would someone put a reset button on power strips in which don't usually implement any digital circuitry. I'm sure it's not for discharging any capacitors, since power strips don't have any.


texts:
I have 4 12V DC motors each draws 0.65 A max. And a Raspberry Pi which works at 5V and 1A max. I want to do a moving platfrom which at least will hold 5kg of mass.

I have 2x L298N motor driver modules each can support 2 motors and can give 5V output for Raspberry Pi.

So what battery source should I use with 2 or 4 motor connected to this platform?


texts:
I'm reproducing an existing design that has a number of copies of a circuit which is large enough that I want to use the multi-channel in Altium.  I want to preserve the existing designators, but they look like this:

Sheet 1:
R100, R102, R103, Q100, CN100, U100, U101, etc.

Sheet 2:
R200, R202, R203, Q200, CN200, U200, U201, etc.

and so on for all sheets (identical aside from the designators).  R100, R200, R300, etc. are all the same component type, as are Q100, Q200, Q300, etc.

Altium gives some flexibility for defining the component naming convention, but I don't see a way to accomplish the above.  Is there a way to do this?

I could live with just doing a copy and paste of the circuit and updating the designators to match the existing design, but then I would lose the advantage of using the Copy Room Formats tool in layout, which is the main reason I want to make this a multi-channel design.


texts: Why does voltage of pirmary circuit in potentiometer increase as we take more length of the potentiometer wire?

texts:
In this video by Khan academy, Mahesh Shenoy (The narrator) says around 7:14 of the video that if increase the length of the red wire we take, then the potential supplied by the battery increases (By increase length, means to move that contact of wire connected to galvanometer further to the right)

I couldn't understand why he said this, so I try to figure out on my own by labelling potentials on the circuit, assuming the negative terminal as 0V , we gain 9V when we pass through battery from negative to positive

In this diagram it seems left end of the red wire (The blue dot) has highest potential and the PD should drop as we move to the right. However, this is inconsistent with the Mahesh's result, where have I made the mistake?


texts:
I have a firmware from a long discontinued product that I would like to improve on. The firmware is in a .mot file format (SREC from my research) and is uploaded using a tool called M16C asynchronous serial flash loader. From what I can tell the M16C specifies the type of micro controller. I attached the first three lines of the code below to show what the file looks like.

How would I start to go about extracting any useful information from this firmware so it could be modified? I assume it's not possible to go back to the source code that was originally compiled, but what can be accomplished from reverse engineering this? and what tools and software would point me in the right direction?

S0030000FC
S2240C0000FEFF0F00FEEF0F00FEDF0F00FEBF0F00FE9F0F00FE7F0F00FEFF0E00FEFF0D00C2
S21C0C0020FEFF0C00FEFF0B00FEFF0A00FEFF0900FEFF0800FEFF000097

Here is a dropbox link to the whole file if needed:
https://www.dropbox.com/s/7tues99wdllkzc8/ThrottleControl.mot?dl=0


texts: How Does One Do Block RAM Inference on Altera Cyclone 10 LP FPGA Boards in Verilog

texts: I have tried to google for this a lot but I can't seem to find anything.


texts: differential amplifier measuring current below supply rail

texts:
I am measuring the current from a battery (12v) using a shunt resistor. But if i can i want to use the normal rail  as supply for the op-amp:

Now my thinking is that because of the two voltage-dividers (r311/r314 and r312/r315), my non-inverting input will be closer to 1.8v than to 0, and my inverting input will 'start off' at 0v and then be pulled to ~1.8v by the op-amp.

Is this possible, or am i forgetting something? I didn't find any reading on this anywhere.


texts: What is the physical significance of the group delay of a system/filter?. Why is the slope of the phase response critical in a communication system.


texts: can SOT883B package BJT transistor switch a relay with 21.1mA coil current?

texts:
I am planning to use miniature BJT in a circuit , but I haven't used them before, The specs of NXP  BC847BMB  TRANS, NPN, 45V, 0.1A, SOT883B shows 100mA as collector current, I am worried if it can switch a G6K-2G-Y-DC5 relay.

The relay mentions 21.1mA as col current. I would be using a 3.8V value for VCC. Please help in understanding how to do the calculations and determine if this will work or not.


texts:
In the schematic builder that calculates voltages/currents/transient analysis that we have been provided for the electrical engineering course, MOSFETs have the parameter "W/L Ratio".

I figured that it was probably Width:Length, but how does that affect the constant K, and the voltage threshold? I realise that there is not enough information for absolute values, but really I'm looking for a formula that relates the variables.

So my question is, what is the relationship between W/L, K, and the threshold voltage of the MOSFET?


texts:
I have implemented a function f which takes as input 4 digits vector, how could I draw that correctly?
I know how to draw a function with 4 inputs but not one with vector on inputs.
An image could be really useful. Thanks


texts: Don't understand the current direction in a flyback diode circuit

texts:
I'm aware of that, in a circuit, inductive loads need to be protected with a flyback diode because if the circuit gets open the magnetic field will collapse forcing a current flow in the opposite direction.
What I don't understand is that last part: opposite direction, let me explain:
Let's take the following flyback diode example at normal operation (circuit closed):

Suppose now that the circuit opens. My understanding of what a current in the opposite direction should be is the blue line, and the actual current flow that must happen (otherwise the flyback diode needs to be inverted) is shown in red:

So, why is the actual current flow (red) described as in the opposite direction while it is going in the same direction as before?


texts: Simulating a linear voltage regulator with ngspice

texts:
I am trying to simulate a simple linear regulator using gschem and ngspice. However, my output voltage varies by over a volt as my input voltage goes from 10V to 20V. Can I reduce this swing in the output voltage by changing circuit parameters or is this a characteristic of linear regulators?

My circuit looks like this:

And the netlist that gets generated (witl the comments and models stripped out) is this:

V1 Vin 0 16.8
C2 0 Vout .1uF
C1 2 0 1000uF
D1 2 0 1N4004
R5 q1base 0 1k
R4 q1base 3 5k
R3 Vout 3 1k
R1 q2base Vin 2k
Q1 q2base q1base 2 2N4401
Q2 Vin q2base 1 2N4401
Q3 Vin 1 Vout TIP29
.end

When I perform a dc sweep on v1 by doing dc v1 5 25 .1 my output is as follows:


texts: Why aren't SRAM modules laid out in a matrix?

texts:
I'm currently reading about RAM modules. Bigger DRAM module are laid out in a matrix. When retrieving data you first retrieve the row  and then the column. One of the benefits of the matrix lay-out is that the row and column addresses are multiplexed on the same pins, so you only need 2^(n/2) pins for the addresses.
By using a matrix the pin count can be reduced quite easily, so why isn't this done with SRAM modules?


texts: Is Code Sourcery G++ Lite still a viable project?

texts:
When I tried to download a newer version of Code Sourcery G++ Lite for ARM,
I noticed that I was redirected to another company and it is really hard to find anything on that site about Sourcery G++ Lite for ARM.

Does anybody know the status on the Sourcery G++ Lite for ARM project?
Is it still alive, does people still work with it? Will it be available in the future?

Update: They seem to have renamed the project into Sourcery CodeBench Lite, so maybe the question is not relevant?

Update: Mentor Graphics is closing the project, it is no longer a viable alternative.

Notes: The current viable place to get gcc for ARM seems to be from Linaro

https://www.linaro.org/about/
https://www.linaro.org/downloads/
https://launchpad.net/gcc-arm-embedded


texts: What's the best way to implement a MFB low-pass filter?

texts:
I'd like to design a second-order Multiple feedback low-pass filter. I am using the design in TI’s Op Amps for Everyone pdf.

There are 3 resistors and 2 capacitors that need to be selected. I'm looking for a voltage gain of 2.

What's the best method for calculating the other component values?


texts: Difference amplifier using Op-amp in LT-SPICE

texts:
I am simulating differnce amplifier in LTSPICE as shown below, i have used 400V DC source with 10V sin wave and then i am dividing it by factor of 80 and them taking differece with 5V source.

Below are the output waveforms, the left one is at the output of opamp and the right one is the voltage between 79k and 1kohm resistors.
I have no clue why is the opamp output voltage is oscillating between ~1V to ~9Vs. Please help me is solving this problem.


texts: Will microcontrollers use more current on lower voltage?

texts:
A project I just read gave their consumption data in µW. The main component was a microcontroller, which has stated in its datasheet what different current consumptions it has in different modes (nRF51422).

Since P = U*I, should I have any reason to believe that the datasheets current numbers are actually larger when the voltage goes below its nominal voltage? The micro can run from 1.8V-3.3V I think.


texts: Switched or linear charger IC for lead-acid battery - which one to pick?

texts:
What is the difference/practical consequence of using switched vs. linear charger controlling ICs and which one should I choose?

I understand that the switched regulators/chargers use a PWM while the linear ones use an adjustable voltage divider.

But how does that map on the practice? I need to charge a lead-acid (Yuasa 6V 1.2Ah) battery from the solar battery and I choose between TI's linear UC2906 and a switched UC2909.


texts: Modeling a photomultiplier in LTspice with basic components

texts:
I am working with the SensL MicroFJ-60035-TSV photomultiplier. A link to the product can be found below:

http://sensl.com/products/j-series/

I'm trying to develop models with it using LTspice in order to model a first-stage amplifier circuit with it, but I'm not sure how to best model it with basic components. Right now, I'm using the following circuit as a model; I tried to roughly model it around one for a diode, since this essentially functions similar to one.

simulate this circuit – Schematic created using CircuitLab

The thing is, I never worked with photomultipliers before, so I don't really understand what the deal is with dark current, breakdown voltage, etc. Is this the best way to roughly model a photomultiplier? What can I do to make the model more accurate given the specifications?

UPDATE: I did some research, and I found a proposed SPICE model for silicon photomultipliers. The model can be found in the link below:

http://www.sciencedirect.com/science/article/pii/S0168900213007389

This seems like a useful model with which I can roughly model my designs, but I don't know how to model the various components from the datasheet alone. Components such as the quenching resistor and capacitor, the junction capacitance and the internal resistance, how can we extrapolate these values from the datasheet?


texts:
Currently, I am designing a Power Amplifier to driver an acousto-optic modulator which will be used in an optical experiment.

I want to get a 4W Sinusodial Wave, So I Choose the MA-COM's MRF136 as the last stage Power Amplifier. I refer to the datasheets of MRF136.

I found that the figure 1 in MRF136's datasheet provides us with the 150MHz test circuit, but with no accurate Capacitor or Inductor Values. For example, the  figure 1 in MRF136's datasheet  puts that L1 -- 2Turns, 0.29" ID, #18 AWG, 0.10" LONG.

[1]How can I calculate the exact value of the Inductor provided in the official test circuit in the datasheet, and purchase the proper RF inductor in the CoilCraft Corporation?

[2]Or Should I just put the official test circuit aside, and JUST simulate the S-parements in the Keysight's ADS software to get the proper Inductor's values?

[3]I thought that if I could reproduce the curves of the MRF136's official test circuit in the Keysight's ADS software, I can get an better understanding of the Power Amplifier Design.


texts:
I'm learning a bit about general purpose timers on my STM32F4Discovery board, and would like to know how I can configure the timer to invoke a timer interrupt each second, or at least have the auto-reload value reset to 0 every 1 second.

I know the MCU runs at 168MHz, and I'm using the internal clock as the TIM2 clock source. I would like to understand better how I can calculate the appropriate prescale value, period and clock division to achieve 1 sec.

TIM_HandleTypeDef timeBase;
timeBase.Instance = TIM2;
timeBase.Init.Prescaler = 0;
timeBase.Init.CounterMode = TIM_COUNTERMODE_UP;
timeBase.Init.Period = 168000000; // Hypothetical value (Period cannot be greater than 65535)
timeBase.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
HAL_TIM_Base_Init(&timeBase);

Am I correct in saying that the above, with a prescaler of 0, period of 168000000 and clock division of 1 will cause a the timer auto-reload value to reset to 0 each 1 second?

Now, the Period has a max value of 0xFFFF (65535), so to me that means I need to manipulate the prescaler value, and period to achieve a 1 second auto-reload value reset.

Is there a formula for doing this?


texts: Calculating the value of bypass capacitors for an amplifier

texts:
I want to know if there is a rough any ready way of calculating the capacitance required to decouple the power supply used in an amplifier. (Rough and ready because I'll be adding 30% to the value anyway!)

Questions:
1) Does this depend on the type of amplifier used (in my case, common emitter stage going into an AB pushpull)?

2) Does this depend on the signal to be amplified, (in my case just a simple sinewave).

3) How is this linked to the power rating of the amplifier (in my case only a few watts.)

4) Does the voltage effect it? (apart from the voltage rating of the cap being high enough for the supply! (in my case 25v))

5) Does the frequency effect this, (in my case 50kHz to 5MHz)

In short, what steps/calculations should I make to calculate the values of the bypass caps needed to decouple the supply and prevent distortion due to supply ripple voltage?


texts: Why does low frequency RFID have a short read range?

texts:
If I want to get the wavelength of a radio wave, I must divide the speed of light by the frequency? So having a 125 kHz RFID means an estimated 2km wavelength?

If its wavelength is 2km long, why does this low frequency RFID have a short read range?


texts:
If we put for standart 3 phase induction motor sinewave voltage input,
will we get sinewave current if we measure motor current with osciloscope.
At least sinewave like current ?


texts:
I have got 8 UV-C lamps connected to a portable battery(AC) through a smartplug. I am using 4 UV Ballast with 2 lamps connected to one ballast. I am controlling the lamps with help of a wireless controller which involves periodic switching on and off.
When everything was new it was working absolutely fine, now the entire unit is 5months old and there is a frequent flickering of UV lamps. when i turn ON the UV light using the controller, it extinguishes automatically now and then But when i turn it ON again after sometime it again extinguishes. I am trying to debug what the problem is but I am not able to figure out the exact reason.
The specification of battery, UV ballast are in the respective links.
Specification of the UV-C Lamps:
Standard voltage AC100 / 200V
Discharge start electricity pressure 94%
Lamp current 0.800 ± 0.050 A
Lamp pressure 92 V
Lamp power 67 W
It would be really helpful if someone can give their insights.
Upon serious research I also came to know that UV ballasts shelf life decreases with more we switch ON/OFF the lamps. Is this maybe the reason?


texts: Bluetooth modules: Bluegiga BLE112 and HM10

texts:
I see that Bluetooth LE modules like the Bluegiga BLE112 sell for around $20, whilst HM-10 sell for just $4.

Beside the FCC certification, what makes the BLE112 a superior product? The both have onboard the CC2541, which is the most critical component. Are there usually pitfalls with cheap modules like the HM-10 though?

Is there a catch somewhere?


texts: If I have two 18650 Li-ion batteries with different capacities, can I charge them using the same circuit?

texts: I have several 18650 Li-Ion batteries, many with different capacities. Can I charge them with the same charging circuit (5 to 3.7 V 1 A buck converter)? Can I put them in parallel and use the same step up circuit to make a 5 V USB bank?


texts:
I am trying to drive a MAX7219 LED controller and 8x8 LED Matrix via SPI from my Arduino MEGA 2560.  I can control the MAX7219 via SPI using my Bus Pirate, but for whatever reason, when I try to control it from Arduino (code below) I get no response.  Furthermore, I connected my Bus Pirate to my Arduino SPI pins and put it in sniffing mode, and it shows no communication, whether or not CS is low.  Does anyone have any idea why this is not working?

Code:

#include "SPI.h"

void setup() {
  pinMode(10, OUTPUT);
  lcd.begin(20,4);
  SPI.begin();
  pinMode(13, INPUT);
}

void spiWrite(byte reg, byte data){
 digitalWrite(10, LOW);
  SPI.transfer(reg);
  SPI.transfer(data);
  digitalWrite(10, HIGH);
}

void resetMAX(){
  spiWrite(0x0f, 1);
  spiWrite(0x0c, 1);
  spiWrite(0x02, 13);
}

void loop() {

  if(digitalRead(13)==HIGH){
    resetMAX();
  } else {
    spiWrite(0x0f, 0);
  }
}

I am using the SPI pins on the ICSP header (Clock = 3, MOSI = 4) and Pin 10 (on the PWM side of the arduino) for the Slave Select.  On Pin 13, I have a switch to enable sending different commands to the MAX7219, though that is currently having no effect, since it seems I am sending no SPI commands at all.  Thoughts?


texts: FM Transmitter Circuit (range 3 km) on Multisim

texts:
I am new to the telecom simulations system specially multisim, which I am having a project that I want to simulate.

My project in (Analog Communications) is consisting to have FM Transmitter (Modulator) that accepts a generated signal (Sin, Cos) and get me the modulated output as a Graph.

I've found this FM transmitter circuit (3 km range):

 ![two muppets][1]

and I am building that circuit on Multisim, and I failed. Because I faced many problems, first of, the variable capacitor symbol is weird here in the multisim, and the regular capacitor doesn't have variable options.
Secondly, when I Use signal generator as (Sin, Cos), the output gets weird after 5 second of the simulation.

I want to show the input signal (before modulation) and the output signal (transmitted or modulated).

I guess my output result where not the as expected, as the signal (Sin with phase 90°) is giving weird result of few seconds of simulating.

Below are screenshots of the simulation results within time.

Any ideas how to edit or fix the above circuit to have this output is similar to what it should be?


texts: Does any RCA connector work for S/PDIF interface?

texts:
I'd like to work with this chip : http://www.cirrus.com/cn/pubs/proDatasheet/WM8804_v4.5.pdf

The S/PDIF Input mentioned in the datasheet states that the input impedance is 75Ohm. So I think that it should be used with 75Ohm coaxial cable, with RCA jacks.

So, my question is simple (and probably stupid too) : does any RCA connector work for S/PDIF interface ?


texts: Implication of switch closure on behaviour of circuit

texts:
I have the following circuit, where: $$v_o(t) = -R(t)v_i(t)$$
$$v_i(t) = 1V$$
$$R(t) = (1 + 0.5cos(20\pi t))\theta (t)$$

And $$\theta(t)$$

is the Heaviside step function.

I'm asked to solve for v0 if the switch closes at t = 0s, which gives me:

$$v_o(t)=-1-0.5cos(20\pi t)$$

Next, I'm asked to solve for v0 if the switch closes at 50 ms. Now, I don't understand what effect this has and how I should mathematically model it.

What "happens" in the circuit between t = 0s and t = 50 ms if the switch is closed during that interval? How is that reflected in the equations that describe the circuit?


texts:
i'm trying to use TMR0 on a PIC18F2420 to time the opening of a device and display the percentage it is opened. the issue i'm having is that it has frozen up pretty much all other operations. i'm not quite sure where i went wrong. if anyone could help i'd greatly appreciate it. i have my internal clock set for 4MHz and Tmr2 is keeping track on an external interrupt.

my main code upon setup sets
    GIE = 1;
    GIEL =1;

and my routine that i'm tracking sets
TMR0ON = 1;

void int (void)

{
RCONbits.IPEN=1;
INTCON2bits.RBPU=0;
INTCONbits.INT0IE=1;
INTCON3bits.INT1IE=1;

INTCON3bits.INT1IP=1;

INTCON2bits.INTEDG0=0; //interrupt at falling edge
INTCON2bits.INTEDG1=0;
GIE=1;   // Global interrupt enable
INTCON2bits.TMR0IP=0;
INTCON2bits.RBIP=0;
INTCONbits.TMR0IE =1;
INTCON2bits.TMR0IP = 0;
}

//========================================================================
void Counter(void)
{

Timer0count=0;
TMR0ON=0;
TMR0=0x00;
//PR2=0xFF;
T0CON=0xD0;
TMR0IF=0;
TMR0IE=1;
TMR0IP=0;
TMR0ON=0;

}
//========================================================================
void Counter1(void)
{

//  Timer0count=0;
TMR0ON=0;
TMR0=0x00;
//  PR2=0xFF;
T0CON=0xD0;
TMR0IF=0;
TMR0IE=1;
TMR0IP=0;
TMR0ON=1;

}
//========================================================================
#pragma interrupt_level 0
void interrupt low_priority lowISR()
{
if(TMR0IE && TMR0IF)
{
    if((Timer0count) >= 16)  //915 is a count for a minute
    {

        TMR0IF=0;
        TMR0IE=0;
        TMR0=0x00;
        Timer0count=0;
        TMR0ON=0;
        percent++;
    }
    else
    {
        TMR0IF=0;
        TMR0IE=1;
        TMR0=0x00;
        Timer0count++;
    }
Counter1();
}
}


texts: At my work we use IDC headers and cable terminators a fair bit, and we've noticed that most headers have a gap on the sides (see image below). It looks like a clip would grab the gap nicely, but have never seen any cable terminators with any such thing. My question is why might the gap be there?


texts:
I have a portable bearing heater which works with 3-phase 230 V power supply.

My power supply is 3-phase 380 V. Is there any way to convert the 3-phase 380 V to 3-phase 230 V? Please note that since the equipment is portable, it is important that the solution be portable too.

I added the picture of wiring diagram of the equipment.
The manual indicates:  The equipment is designed for 3 phase 230V power supply (Between each hot wire, 220 volts can be measured) when 2 phases are connected. it means 2 phases out of 3 phases are connected.

The supply power is 3-phase 380V,which means between each hot wire, 380 volts can be measured and between the neutral and any of hot wires, 220 volts can be measured


texts: Handling DNP parts in ActiveBom in Altium Designer 19

texts:
I have another issue with ActiveBOM in Altium Designer 19, this time related to DNP ("do not populate") parts.  For example, I have a bunch of 1k resistors in my design, some of which are not populated: I have a field in the resistor library part called "Populate" and it's empty for parts to be used and set to "DNP" for parts to not be populated.  So far, so good.

The exported base-view BOM has DNP has "[No Value], DNP" as the values and my vendor needs the DNPs removed from the BOM.  So, I have to manually go through the schematic and find the designators for the DNPs and delete that designator from the BOM.  This process has to be repeated for every BOM export.

This is silly, manual and time consuming.  Is there a better way?

A flat-view BOM export (with Populate column showing) addresses these issues, but is not in a consolidated view.

Another, loosely related SO question about BOMs and DNPs.


texts:
I have a signal that is at 4 kHz. This signal shifts by 40 Hz depending on some user input. I like to detect this change in software as fast as I can. What should be the ADC frequency I should use?

I currently plan to sample at 40 kHz and use a window of 10 ms to do an FFT to find out this shift. But before I build the system, I like to get a second opinion.


texts: Doesn't quartus II support simulate with a verilog file?

texts:
I want to simulate my module StreamLight ,So I create a Simulatefile module:

`timescale 1ns/1ns
module Simulatefile();

reg clk;
reg reset;
wire[5:0] light;
wire counter;

//monitor motor1($light,"counter=%d",counter);
initial
begin
     reset=0;
     clk=0;
     #1 reset =1;

     #1000 $finish;
end

always #4  clk=~clk;

StreamLight StreamLight0(.clk(clk),.reset(reset),.light(light),.counterlook(counter));

endmodule

then, I set this module as Top_Level Entity,and  click Analysis and Synthesis.Then comes the error:

"Error: Can't synthesize current design -- Top partition does not contain any logic"

But I still can't simulate, Doesn't quartus II support simulate with a verilog file ?


texts: Pressure sensor unstable after Arduino power off/on

texts:
I am using my Arduino Uno to read analog sensor values from this pressure sensor.
I have the Arduino powered with a 12V power supply from the wall. I'm using the 5V from the arduino for the LCD and an 8ch relay board as well.

The sensor is just connected to the 5V, GND and the signal goes to analog input 3. I calibrated the sensor 4 times already, because it keeps giving me unstable values after I pull the power supply out:

The sensor is fixed at the bottom of the water tank, and shielded from water with silicone. Therefore the pressure load is already constant. (e.g. 25 cm h2o).  With calibration procedure I meant that I increased stepwise the waterheight, and measured the output signal and then let excel make a linear fit with an equation, which I implement in the software.

As you can see, the sensor's response is quite linear every time, but for me it seems like a sort of offset problem. When I used an external power supply and measured the voltage of the sensor with a DMM, it seemed stable, going to the same voltage every time.

Has anyone an idea what is going wrong, or what I have to add or something? (Already read something about adding a capacitor but I don't think it's a short-time interval).

I'm new to this site and just started with programming with Arduino.
(I'm trying to make my aquarium refresh water automatically).

-EDIT: Thanks everyone for the suggestions. I didn't solve the problem with the pressure sensor, but I'm pretty sure it was the problem that the differential p2 was blocked and therefore the reference pressure wrong. Since I indeed want to measure continuously for a long time, the hose like in a washing is no solution for me. I decided to do it with an ultrasonic (hc-sr04) sensor. This works fine! Problem solved:)


texts: Strange parameters in datasheet of 74HC4046

texts:
In datahseet of 74HC4046, page. 10.

Why the typical value may bigger than the max. value, or lower than the min. value? I don't think it's a typo, because there are others like this, such as p. 16

Any reason? What "typical" mean?


texts: What's mean these microcontroller pin input/output modes?

texts:
I bought an stm32f103ret6. When I saw the reference manual, I saw that it has several I/O modes.

For input: floating, pull-up, pull-down
For output: analog, open-drain, push-pull

I have already worked with AVR MCUs which have tri-state and pull-up. So I can understand pull-up and pull-down, but, I can't understand the modes floating, analog, open-drain, push-pull. What do these modes mean and when do I use which?


texts: Why is voltage specification irrelevant in tripping a PPTC polyswitch?

texts:
In a circuit, a resettable fuse (or polyswitch or PPTC) is a kind of breaker component that trips when the AMPERAGE exceeds a given treshold to protect against overcurrent faults.  PPTC basically trips because of heat dissipated by high current which makes its inner connection loose and opens the circuit.

The question is: If heat dissipation can be calculated using watts (amperage X volts = watts), then how can this PPTC be rated at exactly 4000mA while being suitable for between 16v and 240v? 4A*16V=64W up to 4A*240V=960W.  That's 15x the power.  Have you ever touched a 40W vs 100W light bulb? It's not the same heat dissipation at all. So how can this be that the same PPTC will trip at 4A no matter if the circuit is under a 16V or 240V tension?


texts: LED intensity issues on Attiny85 with 74HC595 to control 8 LEDs

texts:
I want to light up 8 LEDs where I should be able to control intensities of the LEDs as well. Since I want the circuit to be as small as possible on a printed circuit board (PCB,) I am using an Attiny85 IC for the following problem.
For all the 8 LEDs, I would like to light them up with a very good brightness level. So say, current of each LED is 20mA.
The Attiny85, has two PWM pins (PB0 and PB1)(i.e., pin 5 and pin 6.)
But since the maximum output of each pin on the Attiny85 (or Arduino Uno) is 40mA, if I connect 3 LEDs to a single Attiny85 pin, the current will be   divided and the intensity of LED is lower.
I am planning to use a 74HC595 shift register IC so that I can connect the PWM pins of micro controller as the input to 74HC595 IC and control 8 LEDs with the 8 output pins of 74HC595 without any current dividing factor.
Is this a good idea, or will the low current (low intensity of LED) issue on each output pin of 74H5C95 still exist since we are using only 3 pins of the Attiny85 to control all the LEDs with a 74HC595 IC?
Basically, I want to know how much current output will be getting from each pin of 74HC595.
Any other thoughts would be very helpful.


texts: Impedance line matching and component value matching

texts:
I have the following circuit for the SIM900's antenna connection, using the A10393 antenna from digikey:

In closer look:

First of all my knowledge on RF design is not great. My questions now are what should the trace width be in order to match a 50 Ohm line and how I can calculate the value of L2.
I read the datasheet and I also have a link below, and it gave different values for L1 and I did not quite understand it. The zero frequency (R0) is what the mid value of the resonance range and should I care about the L1 component?. I couldn't avoid placing a through hole via because I should have placed the antenna on the bottom side.

Frequency is 850 - 900MHz, the GSM range.
The board is two layers and its thickness is 1.6mm.
The distance from the source pin to the antenna feed is around 15mm.

No GND plane passes underneath, on both layers, the antenna (it is only the board plastic) or near it at a distance of around 5mm (datasheet recommendation 2.5mm).

Datasheet: http://www.antenovam2m.com/documents/download/62712f84669a7974ad90987d256beb9f503605e766135


texts:
I have a sensor that I am trying to connect to via an ethernet cable. The sensors pinout gives

  "Signal Name:" +TX +RX -TX -RX.

My assumption would be to hook up:

  +TX to +RX (ethernet pin: 3)
  +RX to +TX(pin 1)
  -TX to -RX(pin 6)
  -RX to -TX(pin 2)

I have also tried swapping polarity +TX to -RX... but to no avail.

The sensors manual says everything should be in DHCP mode and should discover within a minute.

If you have any questions don't hesitate to ask.


texts:
I have a push button that by default is in 'ON' state and a LED attached to it. I want the LED to light up when the button is pushed down, instead of being on by default.

As far as I understood I need to use NPN transistor as a switch to accomplish this, but I still don't understand how.

Is there a way to make the transistor work inversely? For it to be in an 'OPEN' state - The LED is not glowing when electricity is applied to the base, and when I push the button, (base receives no electricity, but the gate opens)? Thank you.


texts: Why does my op-amp circuit always give near zero output?

texts:
I have an op-amp design same with the picture seen below with TLC271.I have an analog sensor that goes as Vin. I am giving 3.3V from an arduino to power it. And reading values from an analog pin.

The problem is that the output gives between 0mV-8mV while sensor and resistors are connected.

r2=220 ohm| rf=22k ohm| sensor gives output between 0-200 mV

*Image taken from http://www.electronics-tutorials.ws/opamp/opamp_3.html

*I also have a zigbee module connected to arduino and a 5V 1A powerbank which powers the arduino.


texts:
I'm facing a weird request. I have to build a sort of "encoder", to detect the direction and the rotation speed of a black/white wheel at 150 mm from my PCB.
In the past I did a lot of this things using a couple of IR leds and receivers and worked very well but I was very close to the encoder surface (few mm).

I can draw the wheel as I want. The diameter should be about 200 to 400 mm and I can paint just one half black and one white (or put a more reflective material) to have 2 readings on each complete turn. Better, even if not mandatory to divide it in more sectors to improve accuracy, reading multiple times per turn.

The rotation speed goes from 0 rpm to max 60 rpm, in both directions.
A 7-bit resolution, that is 128 steps, it's enough about the speed estimation.

As said before, my idea was to place two IR led/detector on my PCB separated by some distance (i.e. 20 mm). Then I measure the time needed for the "white" part to activate both sensors.

With such a distance this doesn't work due to the angle of the receivers that detect the incoming white section quite at the same time. I tried to put on a tube to reduce the angle, but with no acceptable results.

Any other idea about how to fix this system or propose a different one?

EDIT

Forgot to say anything about the environment.
It's indoor, no direct sunlight. But there are other lights in the nearby that might change colors or even flash. For this reason I tried to use a carrier (the common 38 kHz) to be able to filter out the noises.

For safety constraints I cannot use laser at all.


texts: All dielectric materials deform under the stress of an electric field, it's called "electrostrictive effect". And some dielectrics exhibit an additional piezoelectric effect, such ceramic capacitors, but the dominant mechanism is piezoelectric effect. I want to know if plastic film capacitors have this phenomenon? And has anyone encountered this?


texts: Wrong result in spice simulation of DC Offset at AC coupled diode

texts:
I'm playing around with a diode as AM demodulator and have stumbled upon a phenomenon that seems logical but I can't reproduce it in LTSpice. My setup is the following:

simulate this circuit – Schematic created using CircuitLab

U_in is a sine wave with amplitude of about 0.5V and a DC-Offset of 2.5V.
$$ U_{in} = 2.5V + 0.5V * sin(wt) $$

Now when I measure the voltage after the decoupling capacitor, which is supposed to strip the DC bias, I get a sine wave with \$ U_{max} = 200 mV \$ and \$ U_{min} = -800 mV \$.

So far, so good. My interpretation of this is that the positive half wave is passed through the diode above the forward voltage of about 200 mV while the negative half wave is blocked by the diode and generates a negative DC offset on the right side of the capacitor.

I know that I can align the signal around 0V by adding a DC return path after the decoupling cap.

The question is why I cannot reproduce this behaviour in LTSpice. Even when using a detailed capacitor model with ESR and parallel resistance, adding the scope input (1Meg, 15p, 10:1) to the simulation and trying different diodes, the result will always be a sine wave that is offset by at most 10 mV. If it wasn't for the measuring utility, I'd say there wasn't any DC bias at all.
Am I missing something? Is there some parasitic parameter I'm not taking into account?

Here is a screenshot of my simulation, the green trace is the (wrong) simulation, the blue trace is what I see on the real world scope:

Any help would be greatly appreciated!

Kind Regards


texts: IC controlled triac dimmer design, zero crossing detection and inductor sizing

texts:
I'm trying to create a dimmer that uses an IC to control the triac firing. My understanding is that I need a random phase optocoupled triac driver. However I need to know when the zero crossing is on the IC. I've seen circuits similar to below for optocouplers

Here's where I'm confused, every depiction of an optocoupler shows the two left pins as an anode and cathode, which brings me to my first questions.

Does the DC side only conduct on the half wave? Or is it actually two parallel diodes in opposite directions? If that's the case,
Could I implement my zero crossing detection by having the far right wire go to an external interrupt on my IC and just switch between positive and negative edge trigger, causing an interrupt when it crosses zero because it switches between VCC and GND going to the pin?
Wouldn't the Vf of the diode cause issues because it wouldn't conduct until slightly past the zero crossing whenever the AC crosses the Vf?

Next, regarding noise, I've seen several ways of minimizing this.

Is it better to turn on at the zero crossing and shut off midwave or turn off at the zero crossing and turn on midwave as far as minimizing noise?
Sometimes I see inductors, sometimes I see RC snubbers in dimming circuits. Most online circuits show the RC snubber, but the ETC Sensor dimmers I've worked with have very large inductors (though I don't know if there's also an RC). Is there a reason to use one over the other/both?

When choosing a size for the inductor,

Do triacs have a rated switching speed? (e.g. to calculate the dI/dt across the inductor, do I assume it's an instantaneous change or is there a rated 'speed' for a triac? The only dv/dt ratings I've seen on a triac have to do with protecting it from false firing.

Thank you so much