texts:
I need to power a large 180W LED lamp that runs on DC so I got this transformer that is 12v × 15amp. But I don't understand the labeling on the terminals.

There are 2 +V terminals but no -V terminal, why?
What is the 'com' terminal for and why 2 of them?
What is that terminal between 'com' and 'N'? I'm guessing ground.
What grade/gauge/type of wiring must I use for safe and efficient
operation?
Any additional equipment devices needed for safe operations?
What is the purpose of 'output adjuster' knob? There is a knob in
the corner but it doesn't look like it can be adjusted by hand. What
kind of tool is needed here? See image below.

My aim is to use AC from the wall and turn it into DC to supply the LED. Please show me the correct path lest I get electrocuted. Somebody told me the 'com' terminals are -V output and said there are 2 of each -V/+V so you don't have to jam a thick wire in and instead use two smaller wires. This is a bit confusing. Please elaborate and whether this step is even necessary.

If 2x -V/+V terminals present, is total current/voltage split
between the two? Can I use just one set of terminals to get full
voltage & current, or must I use both? What happens if I use just
one set?

Please help. I don't want to hire an electrician for a job that may be very easy. Neither the LED nor the power supply came with any manuals or supporting documents. LED manufacturer said to use the above power supply.

Additional info on power supply,

Link to actual product page

Item description is found at this link


texts: Amplifiers: Periodic and non-periodic signals

texts:
All the signal amplifiers (op amps) I've dealt with thus far use periodic signals. The idea of bandwidth is natural when dealing with these periodic signals because it is just a description of the range of signal frequencies.

What about when you have a non-periodic signal? Does amplification work in the same way? I'm currently dealing with signals that are very sharp peaks, with small peak widths (i.e. less than a microsecond - nanosecond). This signal is non-periodic and describes single photon detection. Would I approach amplification for this signal in the same way? If so, what is the bandwidth in such a situation? Would it just be 1/(time width of signal)?


texts:
I'm trying to build an electronic lock that takes a 4 digit password and if the password is inserted wrong three times in a row, a logic display is activated.
Below is the lock, it works fine, but I can't figure out how to activate the counter that counts the number of times the password is incorrect.


texts:
I am looking for a battery charger for AA batteries, without taking out the batteries from the board.

The board which is powered by AA batteries is : http://www.tagsense.com/images/stories/products/activetags/ZT-500-datasheet-short-form.pdf

I dont have any idea if I can charge the batteries just by employing the Vcc and Gnd pins I have on the board.

When the batteries are plugged into the board the total voltage at Vcc and Gnd pins is : 3V.

Could any one suggest for a battery charger which can charge the batteries without removing them from the board ..?? I am ready to build the circuit and if I can find already available charger it will be good.

Thanks,


texts: perceived loudness of noise vs. sine wave

texts:
I am trying to understand what gains I need to use each for a white noise generator and a pink noise generator for a human ear to perceive the loudness to be the same as it is for a 440 Hz sine wave at 1 VRMS.

See the two diagrams below for more details:

The noise generator is set up as a linear-feedback shift register (LFSR), running at 500 kHz with a depth of 31 bits. For simplicity, assume a flat response in the frequency domain in the human's hearing range. Though most people don't hear up to 20 kHz, let's still assume a range from 20 Hz to 20 kHz.
To convert the digital noise to audible white noise, a 3-pole low-pass Butterworth filter with a cut-off frequency at 40 kHz and a gain of 1 is used. For simplicity, you may want to assume a perfect low-pass filter with a cut-off at 40 kHz.
For pink noise, a 3 dB/oct. filter is used with a gain of 1 at 100 Hz.

What would be x and y below?


texts:
Preface:

I have done multiple searches trying to determine the directivity of a phased array antenna. I do realize that a single number for directivity is not applicable to all phased arrays since you can have different scan angles and use an arbitrary amount of elements in an array. In light of this, I won't ask for an empirical, single, numerical answer, but rather I'd like to determine a general intuition for phased array antenna directivity .

Question:

Assume one has chosen correct phasing weights for each element in a phased antenna array to achieve maximum directivity at some angular coordinate $$(\theta,\phi)$$ Also, the total radiated power of each element is given by $$P/n$$ where

P: Sum of power radiated by all elements and

n: number of elements

Is said array's directivity better or worse, at that same angular coordinate, than using a single element with $$P$$ as the total radiated power?
$$\ $$

NOTE(1): If it is simpler, assume each element is a perfect isotropic radiator.

A different question that I could ask which would also satisfy my post is the following:

Do phased array antennas offer the advantage of creating a very selective, narrow, main lob that can be steered alone or do they also allow for a greater directivity compared to an isotropic radiator with equal total radiated power?


texts:
Following up this question I need a transistor to switch the necessary current through the coil. I have some spare BC817 lying. My digital output pins can switch 5V@20mA.
Do I need a base resistor to limit the current? I am unable to find the limiting value in the datasheet.

In my current setup (No base resistor) the transistor does not switch. Adding 1kOhm allows me to use it as a switch, but I cant figure out why


texts: measuring a bad motor and large current spikes in a brush motor

texts:
I am new to this forum, I am an EIT and I have been tasked to implement a fixture to measure high current spikes on brush motors when loaded and unloaded.

I am at a loss here as I have never assembled such a project, as I said I am an EIT. I have an idea that will measure the spikes in the 5v motor and result of the data collected will display a LED: red for faulty motor (high I); green fo non-faulty (good I).

I have software support, just need to figure out how I can create the schematic model.

Please if someone can point me in a direction that would be awesome. Thanks in advance!


texts: Reversing P-channel mosfet for polarity protection component selection

texts:
Situation: I'm trying to implement a reverse polarity circuit using a p-channel mosfet and a voltage divider using a resistor + schottsky diode. More information here if you need a refresher.

The key point here is that the MOSFET is reversed. The current flows from Drain to Source, first through the internal diode but after turning on through the normal MOSFET path.

I've been reading various datasheets of various MOSFET's and they all seem to indicate that the maximum Vdrain-source voltage is negative. If I took this at face value it means that a MOSFET can't conduct in both directions, which I know to be false. Example.

Can I ignore this negative number and assume it's a maximum rating both ways or is there more at play here?

Edit: the actual circuit taken from Hackaday


texts:
Screen shot of the question  is given below.

My thoughts

Since the B field  into the page  is decreasing, and induced current is induced in such a way to oppose that condition. So here I can find the induced E.M.F.Becasue induced E.M.F equals to the rate of change of magnetic flux .Then by that argument I find the induced E.M.F, you can find the math part I have done to find it,

$$E.M.F= B*A$$
$$E.M.F= 150*(0.1)^2$$
$$Induced E.M.F= 1.5 V$$

Therefore I can find induced current ,
$$induced current =1.5V/10= 0.015A$$

And the current drawn form the cell is equals to o.20A.

So my question is do I need to get the sum of these two values or subtract them?
Once I use the right-hand rule to detect the direction of induced current , I found it as the direction opposite to the current draws from the cell. You can see clearly see what I am talking about by looking the below image,

Let I0 be the current draws from the cell.

So what I need to do here ?


texts:
I am trying to fully understand the danger of AC voltage but still I have some questions...

I understand that human body has a capacitance that facilitates AC current penetration. I also understand that with an increasing voltage, body resistance is reduced. That's why even if with my multimeter I measure a 1 mega-ohm resistance from left hand to right hand, I just can't use Ohm law and assume that I can put myself in series with a 230V live wire...

But what I am confused about is for a one hand touch on an exposed live wire.

I know I will be shock because electricity will pass through my body to go to earth. But if even my kitchen concrete floor act as a grounding, if I put a live wire on the floor, current should go to earth and my 50 mA differential should switch off.

I have never tried it, but I am pretty sure if I put a live wire on my floor, nothing will happen, right? So why when touching my body the electricity find the earth?

I can understand the shock if I touch a live wire and a grounded object (sink, pipe,  etc.) at the same time.


texts: How can I find Thevenin Equivalent Voltage in the given circuit?

texts: How can I find Thevenin Equivalent Voltage across a & b in the following circuit?


texts: Counter synchronization across two clock-domains

texts:
I would like to understand different approaches to implement a cross clock-domain counter. In all of the following possibilities I have:

clk_a : in std_logic;
clk_b : in std_logic;
reset : in std_logic;

-- cross-domain counter
signal frm_cnt : standard_logic_vector(7 downto 0);
-- control signal: increment counter (synced to clk_a)
signal frm_cnt_inc : std_logic;
-- control signal: decrement counter (synced to clk_b)
signal frm_cnt_dec : std_logic;
-- control signal, perform action on the counter
signal frm_cnt_modif : std_logic;

The approaches I consider are:

Non-clocked counter similar to the answer in How is this simple counter implemented on an FPGA without a clock?

frm_cnt_modif <= frm_cnt_inc or frm_cnt_dec; -- can also be xored

frame_counter : process(frm_cnt_modif, reset)
begin
  if reset = RST_ACTIVE then
    frm_cnt <= (others => '0');
  elsif rising_edge(frm_cnt_modif) then
    if frm_cnt_inc = '1' then
      frm_cnt <= incr_vec(frm_cnt);
    elsif frm_cnt_dec = '1' then
      frm_cnt <= decr_vec(frm_cnt);
    end if;
  end if;
end process;

This simulates fine, and Vivado is able to synthesize it, however it complains about using frm_cnt_modif as clock, which causes timing problems. Additionally the control signals have a chance of overlapping.

Another approach I have tried is to have separate counters in their respective clock domains and perform logic based on their difference. Here, I am concerned with counter overflow, so resetting them when no action on both sides is performed and they are equal seemed like a good solution, however I think that the signal controlling the reset will be subject to similar synchronization problems.

What I am experimenting right now is the 'synchronization to the faster clock'. I have a:

control_synchronizer : process(clk_b, reset)
begin
  if reset = RST_ACTIVE then
    frm_cnt_inc_sync <= '0';
  elsif rising_edge(clk_b) then
    if frm_cnt_inc_sync = '1' then
      frm_cnt_inc_sync <= '0';
    elsif frm_cnt_inc = '1' then
      frm_cnt_inc_sync <= '1';
    else
      frm_cnt_inc_sync <= '0';
    end if;
  end if;
end process;

And the actual counter increment and decrement are performed in a process synchronized with clk_b. This seems to work fine as long as clk_b > clk_a and clk_b < 2 * clk_a.

Any other possible solutions and/or best practices? (I am aware that I should probably use grey-codes for the counter itself).

EDIT1:

After reply from Dave and reading http://fpgacenter.com/examples/basic/edge_detector.php I ended up with the following:

control_a : process(clk_a, reset)
begin
  if reset = RST_ACTIVE then
    frm_cnt_inc_d <= '0';
  elsif rising_edge(clk_a) then
    if frm_cnt_inc = '1' then
      frm_cnt_inc_d <= '1';
    else
      frm_cnt_inc_d <= '0';
    end if;
  end if;
end process;

control_b : process(clk_b, reset)
begin
  if reset = RST_ACTIVE then
    frm_cnt_inc_sync <= '0';
    frm_cnt_inc_sync_d <= '0';
  elsif rising_edge(clk_b) then
    frm_cnt_inc_sync_d <= frm_cnt_inc_sync;
    -- this check was ensuring 1 to 1 pulse translation before rising edge detection
    --if frm_cnt_inc_sync = '1' then
      --frm_cnt_inc_sync <= '0';
    if frm_cnt_inc = '1' then
      frm_cnt_inc_sync <= '1';
    else
      frm_cnt_inc_sync <= '0';
    end if;
  end if;
end process;

frm_cnt_inc_result <= not(frm_cnt_inc_sync_d) and frm_cnt_inc_sync;

This seems safe for any clock values. What I do not understand however, is the purpose of the frm_cnt_inc_d FF (code simulates perfectly fine without it). Anyone able to explain if it is indeed necessary?


texts: Reading oil pressure switch from motorcycle with Teensy (Arduino)

texts:
I'm trying to read a oil pressure switch (I'm actually not sure about the sensor type) from my motorcycle (ZX6R) with a Teensy 4 board (Arduino like).
Here is a picture from the electrical schematic:

Measuring BL/R to ground with a multimeter it looks like it's a closed circuit when the switch is open while it opens once the bike starts up and therefore there is oil pressure.
Hooked it up on a digital pin with pullup and of course I fried the board.
Then I hooked up again the multimeter and (with the bike running) I see an AC voltage with freq and amplitude that changes with RPM.
Then I measured it with an oscilloscope as differential voltage BL/R to ground and I see a voltage that oscillates symmetrically around zero with a varying amplitude between a few mV and 1.5V (I bet if rev up the engine more the amplitude and frequency will continue to rise almost linearly).
The BL/R wire goes straight to the dash that powers an LED. The stock dash will be removed.
2 questions:

any idea of what kind of sensor it is?
how do I safely measure it with a Teensy board? (digital is 3.3V tollerant)

As you can see I don't have much clue of what I'm doing but I have tools and willing to figure this out :)
Thank you
UPDATE:
Adding pressure switch "insights"


texts: 12 V to 5 V with highest current possible

texts:
I have a 12 V, 14 A DC power source and I would like to step it down to 5 V DC with the least amount of loss of current.  Theoretically, by stepping down to 5 V is should be able to get as much as 33 A.

Is there a switching regulator out there that will do this or what components would be necessary to do this?


texts:
I am working on a Qi Transmitter project and I have found that the Qi transmitter that I am using is not able to charge Iphones and Samsung phones at the 7.5 W that it should be able to. I am using the Qi 15W capable P9242-R which is a transmitter type of MP-A2, all the 7.5W capable iphone/samsung transmitter designs are MP-A11 or MP-11a according to the Qi product search page. the P9242-R seems to charge the Iphone at a 5W rate.
I have read the Qi Spec but there doesn't seem that much of a difference between the MP-A2 and the MP-A11 transmitter design.

What is the difference between the MP-A2 and the MP-A11?
Are the MP-A11 and MP-11a the only transmitter types capable of transmitting 7.5W to iphones/samsung phones?
Are there different RX designs that only work with a certain TX designs extended power profiles(EPP)? or will all (EPP) RX work with most EPP TX designs?


texts: Deciding base resistor for transistor switch circuit

texts:
I'm building a transistor switch circuit and below is the schematic.

simulate this circuit – Schematic created using CircuitLab

I calculated R2 resistor (base resistor) value from this formula:

$$R_{R2}=\frac{V_{BAT2}-V_{be}}{(V_{BAT1}-V_{ce})/R_{R1}/h_{fe}*2}.$$

Is this enough for this circuit to operate normally in most situation?


texts:
I would like to ask some questions about inferring the priority and normal encoder using Verilog on the FPGA.

I've used the example codes from the book "advanced chip design practical examples in Verilog"

Code for pri_encoder

module pri_encoder
(D0, D1, D2, D3, D4, D5, D6, D7,
Q2Q1Q0);

input D0, D1, D2, D3, D4, D5, D6, D7;
output [2:0] Q2Q1Q0;
reg    [2:0] Q2Q1Q0;

always @*
  begin
    Q2Q1Q0 = 3'b000;
      if(D0) Q2Q1Q0 = 3'b000;
      else if(D1) Q2Q1Q0 = 3'b001;
      else if(D2) Q2Q1Q0 = 3'b010;
      else if(D3) Q2Q1Q0 = 3'b011;
      else if(D4) Q2Q1Q0 = 3'b100;
      else if(D5) Q2Q1Q0 = 3'b101;
      else if(D6) Q2Q1Q0 = 3'b110;
      else if(D7) Q2Q1Q0 = 3'b111;
  end
endmodule

Code for normal encoder

module encoder
(D0, D1, D2, D3, D4, D5, D6, D7,
Q2Q1Q0);

input D0, D1, D2, D3, D4, D5, D6, D7;
output [2:0] Q2Q1Q0;
reg    [2:0] Q2Q1Q0;

always @*
  begin
    Q2Q1Q0 = 3'b000;
    case (1'b1)
      D0: Q2Q1Q0 = 3'b000;
      D1: Q2Q1Q0 = 3'b001;
      D2: Q2Q1Q0 = 3'b010;
      D3: Q2Q1Q0 = 3'b011;
      D4: Q2Q1Q0 = 3'b100;
      D5: Q2Q1Q0 = 3'b101;
      D6: Q2Q1Q0 = 3'b110;
      D7: Q2Q1Q0 = 3'b111;
    endcase
  end
endmodule

The first question is about the constant expression in the switch case. It seems that constant expression can be located inside the switch (exp) and the element that has 1'b1 can be picked. Does it infer the priority encoder or just normal encoder?

At the first glance, it seems like the case with constant expression will work like a priority encoder, but when I synthesize the above code on the Vivado platform, the synthesized schematic seems like below.

The second question is how can we know if the synthesized design is priority encoder or normal encoder if they are constructed using the LUTs? When I look at the Q2Q1Q02 and Q2Q1Q0[1] it seems that all the data D0 ~ D7 are connected to LUTs only one time. However, for the Q2Q1Q0[0] two LUT6 are connected to generate an output and some data inputs are connected to two LUTs.


texts: Why does coaxial cable cause this effect?

texts:
This is a follow-up question related to my non-contact voltage detection circuit (here). I wanted to be able to detect voltage in a wire a few feet away from the Arduino, so I added a length of RG174 coaxial cable (with the shield grounded) between the 4-inch pickup antenna and the circuit.

I was expecting the coaxial cable to prevent pickup of any other signals, but otherwise no further effects.

The actual results were that the cable did act as a shield, but it substantially reduced the effect of the pickup antenna. To be able to detect the AC field, I had to length it by a few inches and wrap the antenna several times around the 120v wire.

Why did this happen, and is there some way to be able to calculate these variations and be able to determine them before-hand?

Diagram (excuse the MS Paint coaxial cable):


texts: I declare pin 12 as input mode in Arduino UNO. I didn't connect to that pin 12 but if I read state of that pin, the result is always HIGH. I want to avoid that. I made several googling but I don't get cool answer.


texts:
How can i setup a usb host device with pic32MX795 with a pendrive as a device .
I have been able to detect the pendrive and enumerate it partially , but cannot create a file on the pendrive .
I am unable to read the no of sector through CBW .


texts: What measures should I take to protect the USB ports of my PC during development of a USB device?

texts:
I'm going to start developing a USB 1.1 device using a PIC microcontroller. I'm going to keep one of the USB ports of my PC connected to a bread board during this process. I don't want to destroy my PC's USB port by a short circuit or connecting \$\pm\$Data lines to each other or a power line accidentally.

How can I protect the USB ports? Does a standard USB port has built-in short circuit protection? Should I connect diodes, resistors, fuses on/through/across some pins?


texts:
Could anyone let me know how can I calculate the current rating required for a ferrite bead on speaker path?

The speaker impedance is 32 ohms.


texts:
I'm looking at this product, contacts for a connector.

The text says:

  Molex 19420 Series PCB Connector Contact, 2.55 x 2.8 mm, 16 → 14 AWG Tin Plated

What does the last part mean?

  16 → 14 AWG


texts: UART in my code transmits a character, yet on the oscilloscope I find it gave me another signal

texts:
I using MSP430FR6989 microcontroller (development board MSP-EXP430FR6989) to try and send a UART signal via it's TX pin
The configuration of the MSP430:

Clock System 32.768 Khz
Baud Rate 9600
8 bits, No Parity, LSB first, One Stop bit
Using eUSCI_A0 module (Enhanced Universal Serial Communication Interface A0 module), and using P4.2 UCA0TXD pin

The premise of the mini-project is, when I press a button, a digital input isr is serviced, and an 'A' is transmitted via the UART module.
'A' = 0x41 = 0b 0100 0001
so if LSB bit is sent first it will be 1000 0010
following the character format of the UART Start D0 D1 D2 D3 D4 D5 D6 D7 Stop 0 1000 0010 1

Section 30.3.2 of the MSP430 user guide
I expected the signal to look like this in the oscilloscope

However, when I debugged the UART TX pin using an oscilloscope, this is the signal that I got:

the char that I received is (from MSB to LSB): 0b 1010 0001 = 0xA1
I changed the code so that when I press a button a 0 would be written on the Transmit Buffer, but this is the signal I got from the oscilloscope:

I sent a 0 yet I received a 1000 0000
Note: I am not sure if this is relevant or not, but I pressumed time in the oscilloscope goes from left to right, however, the time cursor E is at 0.00 us and S is at -105us, which suggest that time goes from right to left.

That is part of my code that I think is relevant to the post FYI
Clock_Initialization.h
#ifndef CLOCK_INITIALIZATION_H_
#define CLOCK_INITIALIZATION_H_

void clock_initialization (void);

#endif /* UART_CLOCK_INITIALIZATION_H_ */

Clock_Initialization.c
#include <msp430.h>
#include "Clock_Initialization.h"

void clock_initialization (void)
{
    //smclk and mclk = 8Mhz DCO
    //is it possible to disable ACLK

    CSCTL0 = CSKEY;//password in order to modify clock signal
    CSCTL2 = SELA__LFXTCLK | SELS__DCOCLK | SELM__DCOCLK;
    //ACLK -> LFXTCLK (32.768KHz) SMCLK & MCLK -> DCOCLK

    //enable the LFXIN and LFXOUT pins PJ.4 and PJ.5 P84 and P85
    PJSEL0 |= BIT4;//PJSEL0.4 = 1
    PJSEL1 &= ~BIT4;//PJSEL1.4 = 0
}

Baud_Rate.h
#ifndef BAUD_RATE_H_
#define BAUD_RATE_H_

void baud_rate_setup (void);

#endif /* UART_BAUD_RATE_H_ */

Baud_Rate.c
#include <msp430.h>
#include "Baud_Rate.h"

void baud_rate_setup (void)
{
    //baud rate 9600 clock signal 32.768 KHz
    UCA0CTLW0 |= UCSWRST;
    UCA0BRW = 3;
    UCA0MCTLW = 0x9200;
}

UART.h
#ifndef UART_H_
#define UART_H_

#define UART_TX_BUF UCA0TXBUF

#include "Digital_Input_Output/Debounce.h"
//includes the enum Button datatype
/*
   enum Button
   {
        Button0 = 0,
        Button1 = 1,
        Button2 = 2
   }
 */
void init_UART (void);

void sendChar (enum Button x);

#endif /* UART_UART_H_ */

UART.c
#include <msp430.h>
#include "UART.h"
#include "Digital_Input_Output/Debounce.h"
//includes the enum Button datatype

void init_UART (void)
{
    UCA0CTLW0 &= ~ (UCPEN | UCMSB | UC7BIT | UCSPB | UCSYNC);
    //No Parity, LSB first, 8 bits, One Stop Bit, Ascyc.
    UCA0CTLW0 |= UCSSEL__ACLK;//CS 32.768 KHz
    UCA0CTLW0 &= ~UCSWRST;

    P4SEL0 |= (BIT2 | BIT3);
    P4SEL1 &= ~(BIT2 | BIT3);
}

void sendChar (enum Button x)
{
    switch(x)
    {
    case Button0:
        UART_TX_BUF = 'A';//0;//'A';
        break;
    //...rest of the code
}

in main.c
#include <msp430.h>
#include "Digital_Input_Output/Debounce.h"//have enum Button datatype
#include "UART/Clock_Initialization.h"
#include "UART/Baud_Rate.h"
#include "UART/UART.h"

//code

int main(void)
{
    //code

    clock_initialization ();
    baud_rate_setup ();
    init_UART ();

    _BIS_SR (GIE);//enable global interrupt

    while(1);

    return 0;
}

#pragma vector = PORT1_VECTOR
__interrupt void Port1_ISR (void)
{
    switch(P1IV)
    {
         //code
         sendChar(Button0);
         //rest of the code
}

Kindly help me with my issue.


texts: How to write a program to create multilevel waveform using arduino

texts: I need to make a 5-level multilevel(staircase) waveform for my major project from an arduino.  How can I get 24 V supply form. I tried to change pulse width by PWM using analogWrite(),but it can produce either 5V max or 3.3V max.please kindly help me!


texts: Fault-current circuit breaker breaking on grounding neutral conductor?

texts:
I just put some lamps on and got the fault-current circuit breaker triggered. While skinning the earth conductor the knife touched the neutral.

I was a bit puzzled: I thought that happens only under the following conditions:

Live goes to ground and
Live is actually live (the light switch was turned off).

Apparently those assumptions were wrong. So my questions:

What kind of fault current can there be from neutral to ground?
If neutral has tension relative to ground, just out of curiosity, how much tension is it usually?

I'm in Germany in case this matters.


texts:
I have this code below for a Amp Op Tutorial from this youtube video: https://www.youtube.com/watch?v=3qE3gL7XbT4.  I get the error below for missing value but unsure what is the problem.  I'm new to pspice, so how do I get the simulation to operate correctly?

(ExpressProject "OpAmpInv"
  (ProjectVersion "19981106")
  (ProjectType "Analog or A/D Mixed Mode")
  (Folder "Design Resources"
    (Folder "Library")
    (NoModify)
    (BuildFileAddedOrDeleted "x")
    (CompileFileAddedOrDeleted "x")
    (File ".\opampinv.dsn"
      (Type "Schematic Design")))
  (Folder "Outputs")
  (Folder "Referenced Projects")
  (PartMRUSelector
    (0
      (LibraryName
         "C:\PROGRAM FILES\CADENCE\SPB_17.2\TOOLS\CAPTURE\LIBRARY\CAPSYM.OLB")
      (DeviceIndex "0"))
    (VCC
      (LibraryName
         "C:\PROGRAM FILES\CADENCE\SPB_17.2\TOOLS\CAPTURE\LIBRARY\CAPSYM.OLB")
      (DeviceIndex "0"))
    (GND
      (LibraryName
         "C:\PROGRAM FILES\CADENCE\SPB_17.2\TOOLS\CAPTURE\LIBRARY\CAPSYM.OLB")
      (DeviceIndex "0"))
    (VDC
      (FullPartName "VDC.Normal")
      (LibraryName
         "C:\PROGRAM FILES\CADENCE\SPB_17.2\TOOLS\CAPTURE\LIBRARY\PSPICE\SOURCE.OLB")
      (DeviceIndex "0"))
    (VSIN
      (FullPartName "VSIN.Normal")
      (LibraryName
         "C:\PROGRAM FILES\CADENCE\SPB_17.2\TOOLS\CAPTURE\LIBRARY\PSPICE\SOURCE.OLB")
      (DeviceIndex "0"))
    (SOURCE VOLTAGE
      (FullPartName "SOURCE VOLTAGE.Normal")
      (LibraryName
         "C:\PROGRAM FILES\CADENCE\SPB_17.2\TOOLS\CAPTURE\LIBRARY\DISCRETE.OLB")
      (DeviceIndex "0"))
    (R
      (FullPartName "R.Normal")
      (LibraryName
         "C:\PROGRAM FILES\CADENCE\SPB_17.2\TOOLS\CAPTURE\LIBRARY\DISCRETE.OLB")
      (DeviceIndex "0"))
    (RESISTOR
      (FullPartName "RESISTOR.Normal")
      (LibraryName
         "C:\PROGRAM FILES\CADENCE\SPB_17.2\TOOLS\CAPTURE\LIBRARY\DISCRETE.OLB")
      (DeviceIndex "0"))
    (LM741
      (FullPartName "LM741.Normal")
      (LibraryName
         "C:\PROGRAM FILES\CADENCE\SPB_17.2\TOOLS\CAPTURE\LIBRARY\OPAMP.OLB")
      (DeviceIndex "0")))
  (LastUsedLibraryBrowseDirectory
     "C:\Program Files\Cadence\SPB_17.2\tools\capture\library\pspice")
  (MPSSessionName "Ryan W")
  (GlobalState
    (FileView
      (Path "Design Resources")
      (Select "Design Resources"))
    (HierarchyView)
    (Doc
      (Type "COrCapturePMDoc")
      (Frame
        (Placement "44 0 1 -1 -1 -8 -31 0 200 0 150"))
      (Tab 0))
    (Doc
      (Type "COrSchematicDoc")
      (Frame
        (Placement "44 2 3 -1 -1 -8 -31 52 579 52 239")
        (Scroll "339 315")
        (Zoom "200")
        (Occurrence "/"))
      (Path
         "C:\USERS\RYAN W\DOCUMENTS\EDUCATION\COMPUTER PROGRAMMING\PSPICE\TUTORIALS\OPAMPINVTUT\OPAMPINV.DSN")
      (Schematic "SCHEMATIC1")
      (Page "PAGE1"))))

**** INCLUDING SCHEMATIC1.net ****
* source OPAMPINV
R_R3         VO 0 1k
V_V1         VI 0  AC <AC>
-----------------------$
ERROR(ORPSIM-16492): Missing value
+SIN 0 500m 1k 0 0 0
V_V2         V+ 0 12Vdc
V_V3         0 V- 12Vdc
R_R4         N00303 VO 10k
R_R5         VI N00303 1k

**** RESUMING demo1.cir ****
.END


texts: Constant current source math - Using AD8276 differential Op-Amp

texts:
So I'm trying to implement a constant current source to conduct a specific measurement using a
AD8276 differential amplifier. I'm trying got derive the equations my self for sanity check, and to give a little me weight when I present my idea. This is what I have work out but my math doesn't checkout, here is a [circuit diagram][2] for my calculations

simulate this circuit – Schematic created using CircuitLab

things to know Rf1=Rf2=Rg1=Rg2 and R1=R2

The equivalent resistance of the parallel circuit consisting of the load resistance and the negative feedback lines
$$R_{eq} = {({R_L}^{-1}+(R_1+R_2+R_{f1}+R_{g1})^{-1}})^{-1} $$

The voltage at the positive terminal, using the voltage divider. This is mainly where I thin I have gone wrong.
$$V_1 = V_{ref} * ({R_{f2}+R_{eq}})/({R_{g2}+R_{f2}+R_{eq}}) $$

Next it is understood that the negative terminal of the op amp will have the same voltage as the positive terminal, 0 potential diffrence
$$V_1 = V_2$$

V2 will be propped completely across Vg1 and therefore the current through R1,R2 and Rf1 can be calculated by calculating the current through Rg1
$$I_{Rg1} = V_2 /R_{g1} $$

The total current supplied by Vref is
$$I_{total} = (V_{ref} - V_1)/R_{g2}  $$

And therefore the current through the load is
$$I_L =I_{total} - I_{g1} $$

This does not give me the same results as the equation provided from the sources of
www.analog.com/library/analogDialogue/archives/43-09/current_source.html figure 5 without the transitor.
$$I_o = I_L = V_{ref}((1/40K)+(1/R_2) $$

Any thoughts?

EDIT: I fixed my diagram error


texts: Ultrasonic generator - a couple of questions

texts:
Here is the ultrasonic generator circuit I'm trying to understand:

It is powered by USB and it produces 100V at 100kHz on the piezoelectric speaker BQ1.

Two mutually inverted PWM signals go from the micro-controller to the transformer T1.

Questions:

1) Is this the simplest, cheapest circuit of the ultrasonic generator with similar output?

2) Why do we need C1-C2 capacitors?

3) Center tapped transformer T1 is used here, but is it ok to replace T1 with a transformer without center tap and to use single PWM signal as input?

Edit:

4) Why C1?

5) If I'm powering the circuit from a separate power supply which is able to deliver several amps do I need R1, C1, C2?


texts: Effect of Positive and Negative voltage supply in LM741 opamp

texts:
At first,i created a simple schematic of non-inverting amplifier using LM741 having a gain of 2. The supplied a.c voltage at non-inverting input is 1V having frequency of 50 Hz. And i get the result what i had expected, the output voltage of 2 v peak and 50 Hz.

In the second scenario, i kept all the parameter same expect i grounded the negative voltage supply and i get unexpected result. Peak voltage at the output is 800 mv and lower voltage is -200mv. And the screenshot of the simulated waveform is presented below.

Tx in advance.


texts: Replacing Decoder/Driver IC (30V, 300mA)

texts:
I'm looking to replace an FP2800a decoder/driver IC for a flipdot display.

This chip decodes to 28 outputs, which it can drive towards a Vcc of 30V or GND with a maximum of 300mA.

A search on distributor websites gave nothing comparable, all modern display driver ICs with internal decoder can supply a maximum of a few mA only, while switching to a design with an external decoder would give me an insane component count (and way too much current capacity).

The smallest design I can come up with at the moment would be one decoder IC driving a set of FETs that connect a half-bridge to the output -- so 30 FETs, and one readymade half-bridge driver that integrates the "high/low" and "enable" signals.

Is there a better way to do this?


texts:
after watching few videos on YouTube with exploding capacitors i decided to learn few things about the polarity and the voltage rates by trying to make a capacitor explode.

I made few test to try on then. First was the overvoltage test. I took a capacitor rated at 6.3V and i gave him 12V directly from a wall adapter. Nothing* happened however when i pulled it out from the protective box it was verry hot!
So i straped a digital thermometer on the capacitorto monitor the temperatures and i put it on with the cables reversed. That was part of the second experiment with the reverse polarity. Quicly the capacitor jumped from the 25C (my room temperature) to 83C and then back down to 27C however no explosion! But after mesuring the capacitance with a multimeter the capacitor was completely dead. I couldn't mesure anything.

After this experiment i have the following questions.

What are the perfect conditions for a capacitor to explode?
What killed my capacitors? The extreme temperature, the voltage or the polarity?
Should i be worried about the polarity of the power on my projects? (Except from ICs)

Few things for the capacitor:

100uF
6.3V
-40 to +105 temperature
Chinese el' cheapo


texts: Weird overflow behavior of character type variable

texts:
I am trying to design an ON-OFF Keying decoder for an RFID reader project I've been working on. Below is the code that runs on a PIC16F887 @20MHZ. The compiler is Mikroelektronika mikroC PRO for PIC.

What I was trying to do is to toggle PORTC.1 every 200uS. The code runs as wished, but only for about 5.8 msec, as I measured with the oscilloscope. After that, PORTC.1 do not toggle.

I am guessing that somehow it is related to the overflow of  the fiftymicrosand data_time variables. If we increase fiftymicrosvariable every 50 usec - actually this is what progam do, it will overflow after 255*50 microseconds which is equal to 12.75 msec.

Whenever I change the type of the variables fiftymicrosand data_time to integer, the problem diminishes.

Could you help me understand what is the reason behind this behavior?

volatile unsigned char fiftymicros=0;
volatile unsigned char fiftymicroscounter=0;
volatile unsigned char data_time=0;
volatile unsigned int milis=0;
volatile unsigned int milis_ctr=0;

void calculate_data_time()
{
     static volatile unsigned char ctr=0;
     static volatile unsigned char ind=0;
     if(fiftymicros-data_time>3)
     {
       data_time=fiftymicros;
       PORTC.F1=~PORTC.F1;
     }
}

void interrupt()
{
     if(INTCON.T0IF)
     {
      TMR0=198;
      INTCON.T0IF=0;
      fiftymicros++;
      if(++fiftymicroscounter==20) { fiftymicroscounter=0; milis++; }
     }
    if(INTCON.RBIF)
     {
      //data_time=fiftymicros;
      INTCON.RBIF=0;
     }
}

void main()
{
     ANSEL =0;
     ANSELH=0;
     TRISA=0; PORTA=0;
     TRISB=0x01; PORTB=0;
     TRISC=0; PORTC=0;
     TRISD=0; PORTD=0;
     TRISE=0; PORTE=0;
     OPTION_REG.INTEDG=1;
     OPTION_REG.T0CS=0;
     OPTION_REG.PSA=0;
     OPTION_REG.PS0=1;
     OPTION_REG.PS1=0;
     OPTION_REG.PS2=0;
     INTCON.TMR0IE=1;
     INTCON.RBIE=1;
     INTCON.GIE=1;
     UART1_Init(9600);
     Delay_ms(100);
     milis_ctr=milis;
     while(1)
     {
      calculate_data_time();
     }
}


texts: What's all this "rails" nonsense on a computer power supply?

texts: This is in danger of becoming a computer question, but I've always wondered why do computer power supplies have so many 12V "rails". I have a 800W dead supply with four 12V 16A "rails", but internally, they are all connected to the same transformer, use the same diodes and the same capacitors - in fact, they are all electrically connected to each other. So why call them separate rails (given they are in fact the same rail), is it just marketing or is there some proper reason?


texts: Determine a suitable replacement battery cell for an obsolete product?

texts:
A friend of a friend of mine has a prosthetic knee that was developed in 2010 which requires battery packs that are being phased out.  He has asked me if there is a way to replace the internal batteries for these units, so I cracked one open and they seem to be an array of about 12 x 3.7v lithium ion batteries arranged in two parallel "strings", each of 6 cells in series (6S2P) (approx nominally 22V per cluster) of the following type
link .  These cells individually are not available for anything less than 10,000 unit purchases, which obviously is not really an option for this one off repair.  I am a computer engineer with some experience in power systems but I have never worked with a lithium ion source before and am trying to be cautious about choosing an appropriate replacement battery.

I have been looking at these two batteries as replacements.  Each vary a little bit from the source battery, either in size, capacity, or discharge rate.  What I am curious as to is whether these variances from the original pose any significant risk?  I suspect the power characteristics are close enough to provide at least ... some functionality, however the charging circuit and battery packs are pretty elaborate and I would hate to drop $150 in battery cells just to find out that they didn't work or worse... caused a safety issue.

List item
List item

If it's of any interest, here is the link to the product that this comes from
Power Knee

If there are resources as to answers for these questions, or links to other battery suppliers who may be able to meet my requirements, I would accept any and all feedback.  Thank you in advance.


texts: Voice and data through TDMA in VHF systems

texts:
In a VHF radio system using TDMA can a time slot be used to carry both voice and data bits together or is it necessary that both be transmitted in two different time slots.
Also while reading an article on channel size, I read channel size=12.5Khz and also the channel spacing. Should it be correct? Shouldn't be the channel spacing less than channel size?


texts: I've been asked this question a couple of times in screening tests.  Options are VCVS VCCS CCVS CCCS, Which one of the four options is best fit ?And would the answer depend whether we talk about the Ideal op-amp or the non-ideal op-amp ?


texts: Consistency of the mains frequency throughout the UK

texts:
I'm working with a number of frequency meters which are reading the mains frequency in the UK from different locations. The problem is that I haven't been able to find information on whether there are local fluctuations in the grid frequency due to the geographical location, the local grid or the environment in which the meter is placed. While I expect that there is some level of local fluctuation I have no idea of how significant it is (i.e. is it in the mHz, uHz or nHz range).

I'm aware of the discrepancies I would expect to see due to the varying accuracy and precision of the individual meters. The tolerance of the meters I'm using is +/- 1mHz so if the local fluctuation was in the uHz or nHz range I’d consider it to be negligible.

My overall goal is to determine if I have a reading on one meter how close will the other meters be reading.

Edit: Just to be explicit my question boils down to: When measuring the mains frequency in the UK from multiple locations what, if any, variance exists between measurements if we were to disregard measruement error? And what is the cause of said variance?


texts: Seeing NVIDIA's Massive RTX3090 leaks got me thinking. Would it be possible to almost seamlessly stack PCBs? Like have the small parts on the bottom and bigger parts on the top and put a liquid cooling type system in between them? That would almost completely negate the whole space issue NVIDIA has so they could stick with a smaller GPU but still pack power. I have like no electrical experience so I don’t know if it’s a thing that’s been done before. Love to hear your input.


texts: Help with decoupling capacitors not working

texts:
I am powering a SIM800 module which looks like this:

This module is rated between 3.6v and 4.4v and can draw upto 2A.
I have this hooked up to a single 18650 LiON battery. According to the datasheet these are designed to run from this kind of battery. The problem I am having is that when it powers up, the moment it joins the GPRS network, the module will reset. This I presume is because of the extra power requirement as it joins the network. Reading the datasheet it suggests a decoupling network. At the moment I have it like this with the SIM800 next to the battery and the decoupling network off to the side.

This doesnt seem to make any difference and the SIM800 just resets as soon as it joins the GPRS network. I am wondering if it should be like this with the network at the end of the decoupling capacitors or doesnt it make any difference? I have soldered this part so it's not easy to try this configuration so wanted to ask the question first. If it doesnt make any difference what am I doing wrong??

If I have it hooked up to a bench power supply I get the same problem but if I push the voltage up to 4.3v it seems stable so I am sure my problem is with the decoupling somewhere.


texts: Use MOSFET series resistor instead of shunt for current measurement

texts:
If I have a setup where a N MOSFET drives a heavy inductive load (say, 25A peak), can I use the MOSFET's internal resistance to measure said current the same way I would use a shunt resistor?

The value of the equivalent series resistance when the MOSFET is active (i.e. Rds-on) is usually very low and easy to find in the MOSFET's datasheet. I know it is not ideal, and will strongly depend on the FET's temperature a well as the current (so I have a loop there). Still, is there any serious impediment to this approach?

The reason I want to do this is because I have a system where I need to minimize component count as well as avoid any extra losses (i.e. shunts) when driving the inductive load, but can compute some corrections/linearization on a temperature-sensing micro-controller if needed.

I am almost 100% I saw a LiPo battery manager that appeared to do something similar, but I am unable to find it. As I recall, this IC estimated the charging current using something similar to what I just described. But maybe I am just mistaken.


texts: Why a capacitor is connected between two ground terminals and what difference does it make?

texts:
I was referring to a datasheet where I found a capacitor is connected between two ground terminals. Are these really ground terminals or am I reading the datasheet in the wrong way? Can someone help me to understand what this part means is datasheet and why is this type of connection is used.

See the "Page 27" of the below datasheet

Reference datasheet: http://www.ti.com/lit/ds/symlink/lm3450.pdf?ts=1591116185629


texts: Effects of changing the frequency of a transformer

texts: If the frequency of a transformer is decreased by keeping voltage same, then what will be the new KVA rating, magnetizing current and inductance, the induced voltage and loss of the transformer?


texts: Purpose of resistors from phase to phase on 480V motor

texts:
I have inherited a project with a motor circuit that I cannot figure out the purpose of some resistors.

It was initially designed for operation in Europe at 400V 50Hz. Since it is operating here in the US now it is operating at 480 60Hz. The motor is running 20% faster, but for this application it does not matter. The motor is controlled by a solid state device up stream that will swap the phases to open or close the motor. The motor is very small, FLA of 0.62 and will open and close about every 6 seconds.

If someone can give me a clue as the the purpose of the resistors, or a thread to start pulling as to why they are there, I would appreciate it

Thanks!

Here is the circuit:


texts:
I need to connect this kind of button to my Arduino for a project :

http://www.ebay.com/itm/NC-N-C-Emergency-Stop-Switch-Push-Button-Mushroom-Push-Button-4Screw-Terminal-KG-/172356802290?hash=item28214416f2

This one is 600V, so I guess I cant connect it to the 5V of my arduino.
I don't know if if fits....
Do I need an external battery? How to wire it?

The other option is to self-build a button with one of these connectors : http://www.automation24.fr/commande-et-signalisation/element-de-contact-etroit-eaton-180792-m22-fk10-i132-3060-0.htm

What do you think?

Thanks ;)


texts: FR-4 RF attenuation (when used as an enclosure)

texts:
I want to use a blank PCB (no copper) as a panel of an enclosure because it seems to be the cheapest way (Seeedstudio et al.) to have custom holes and cutouts.

I wonder if antennas placed behind such a material can work (ordinary FR-4, just without copper) and what the attenuation is? I am thinking of 2.4 and 1.5 GHz.

The only resources I could find deal with frequency limits when the FR-4 PCB is actually carrying the signals.


texts: Calculate residual energy in rpl.mhrof.c code in cooja

texts: I'm working in develop of rpl protocol I want to calculate residual energy in rpl.mhrof.c code in cooja, some one here know the c code of residual energy of the nodes please?


texts:
I would like to design a tactile switch footprint, where there are clearly two pads and two pins on each side of the switch, but let eagle cad's router know that it can route to either pair of pins. I don't think is possible, but just incase. As an example, in this data sheet, pins A and A prime are at the same electrical potential, but are referring to two different pads. Is there a way to let Eagle, and specifically Eagles router to know that these two pins and two pads are connected internally?

Maybe this is a bad idea. I just don't know.

Thank you!


texts:
I was just wondering how complex numbers can be applied in electrical engineering and why we use complex numbers over regular, real numbers for this application (e.g what capabilities does the complex number have that real numbers do not in electrical engineering)?

I have done some research concerning impedances and understand how they are written in complex form, however I am still confused why complex numbers are necessary in this field over regular numbers.


texts: Digital Logic Design - Sequential Circuits

texts: The circuit diagram below is in a stable state because of the two inverters. Why and how did it reach a stable state?


texts:
My colleagues and I are having a discussion about the circuit below, specifically: Is the op-amp being used as a comparator, or as an amplifier, or something else entirely?

The circuit is a negative voltage regulator that tracks a variable positive DC regulator. The LM337 (REG3) output is equal and opposite to the positive supply (connected to the top end of R5). The op-amp + input is referenced to GND. When the DC outputs are equal and opposite, the voltage divider R3-R5 produces 0V at the - input. The output of the op-amp produces the DC voltage required to put the LM337 regulator output at the desired voltage, exactly 1.25V more positive than the output (e.g. if desired output is -10V, ADJ is -8.75 because of the 1.25V reference voltage of the LM337).

Comparator? It's comparing the output to the reference. Amplifier? The LM337 is in the feedback loop and the op-amp is amplifying the error between the desired voltage and the reference. In other words, comparators are usually open loop, with rail-to-rail outputs, but this is definitely a linear circuit.


texts:
I learned an algorithm for winding a BLDC motor. This algoithm has the windings crossing several stator teeth similar to this image:

When I google BLDC stator, I see way more images like this :

In this image, the windings mostly go around a single tooth. They do not span multiple teeth awkwardly. This second version looks much easier to wind... So my question is, the second version... Does winding a motor like that make it lose efficiency? If so, how much efficiency? I am building just a practice motor, so I don't really care if its 100% efficient if it would be easier to wind!

Also, can anyone recommend some good modeling software to model the magnetic fields? I saw this program "motorsolve" but it  looks expensive!


texts:
I have a LCD Display with white LED backlight. I want to connect it to a MOSFET which will be controlled by my ESP-12E Microcontroller.

I'm wondering which resistor to use. The data sheet says:

Absolute Maximum Ratings:
Back Light Forward Current ILED -- 25 mA For each LED

Electrical Characteristics:
Forward Current IF -- 20 -- mA
Forward Voltage VF -- 3.2 -- V

(4 LEDs parallel)

Question 1:

Is the value per LED?

My power supply will either be 5V or 12V

The other data sheet page says:

LED Backlight Power Supply: max. 3.2V (by 3.3V Power Supply 2-5 Ohm Resistance, or by 5V 20-25 Ohm Resistance)

But if I calculate for 5V power supply I get:

25 Ohms * 0.02 Amps = 0.5 V

Question 2:
So does that mean a voltage drop of the resistor of only 0.5 which would result in a voltage of 4.5 V for the LED which seems to be too much?

Or do I have to calculate with 0.08 Amps because of the 4 LEDs?

25 Ohms * 0.08 Amps = 2 V

Question 3:

Would this mean the overall voltage drop is 2 V but every LED still gets 4.5 V?

For 12 V that would mean a 150 Ohms resistor?

I'm not that good at physics, I just want to make sure everything is correct so I don't damage anything.


texts: Source voltage in discharging capacitor equation

texts:
The voltage across a discharging capacitor in an RC network is

$$V_c = V_s (e^{-\frac{t}{RC}})$$

Rearranging this equation for t gives

$$t = -RC \ln \left( \frac{V_c}{V_s} \right)$$

Say I have a capacitor charged such that the voltage across it is 3.6V and I want to find the time it takes to reach 0.9V. I remove the voltage source and the capacitor begins to discharge. Since I have removed the source, what is the value of \$V_s\$ in this equation, and how do I use it to find the time it takes the capacitor voltage to reach 0.9V?


texts: MOSFET - what is ohmic region in transconductance curve?

texts:
For mosfet transconductance curve, I'm used to seeing ohmic/linear region in output charactersitics(drain curves), and for the transconductance a regular parabola going on forever.
But recently I encountered below curve  which is flattening after some \$V_{GS}\$ and the author was calling it ohmic region. Does this mean the drain current doesn't increase even if we increase \$V_{GS}\$? Really appreciate if someone please explain why this happens...

Figure 12-9b shows a typical transconductance curve. There is no drain
current until VGS = VGS(th). The drain current then increases rapidly until it reaches
the saturation current ID(sat). Beyond this point, the device is biased in the ohmic
region. Therefore, ID cannot increase, even though VGS increases. To ensure hard saturation,
a gate voltage of VGS(on) well above VGS(th) is used, as shown in Fig. 12-9b.


texts: What factors do I need to consider when selecting an inductor to use in a circuit with the MT3608?

texts:
I am trying to use the MT3608 chip to boost the power output of a 3.7V lipo battery from 3.7V to 5V, which will ultimately power an ATMEGA32U4 chip. Below is a picture of my circuit where I have already selected resistors and capacitors to output a voltage of 5.01V.

The MT3608 datasheet states:

  The recommended values of inductor are 4.7 to 22μH. Small size and better efficiency are the major concerns for portable device, such as MT3608 used for mobile phone. The inductor should have low core loss at 1.2MHz and low DCR for better efficiency. To avoid inductor saturation current rating should be considered

My questions are/what I need help with is:

How (and where) do I calculate the current of my circuit so that I can determine the appropriate current rating of inductor L1?
What inductance should be used for inductor L1 between 4.7 and 22μH and why?
How do I calculate the best ratio of inductance to DCR to minimize power core loss?


texts: DALI Signal Voltage Range and Power Supply connection confusion with WAGO

texts:
In an attempt to solve this problem, I was cross-checking my connections several times. During this, I thought it will be interesting to see the DALI signal coming out of WAGO DALI Module as opposed to the signal coming out of my board. I was surprised to see that, the DALI signal voltage range from WAGO DALI module is very low compared to what is given in the standard. I was expecting a signal range like (18V HIGH - 0V LOW [with appropriate tolerance]) but I got something around 1.7V.

Now, I am wondering if my power supply connection and understanding is correct at all! and I want to understand the basic DALI signal flow between DALI PHY and DALI Slave. Here with the WAGO Module, I am using 18Vdc, 1.1A 787-1007 module as the power supply.

Q1.I could not exactly understand how and why is this voltage level stepping down from 18V to the range of ~1.5V.

This is how the Wago DALI Multi-Master Module block diagram looks like

Q2. How is the current limiting to 250mA carried out in the above circuit?


texts: What factors does the set-up time and Hold-time for an interface IC depend on?

texts:
I am working with EEPROM and QSPI Flash ICs. They have this electrical parameter called as Setup time and Hold time. I know we must not violate this in order for proper communication.

But my question is : different ICs have different values of setup and hold times.

Why is it so? On what basis is the setup and hold time value determined? Like, is it a standard for I2C Interface, SPI interface and so on? Or is it determined by someother value?

Please help me understand and provide clarity.


texts: DC-DC step down 12V to 5V source versus straight 5V source

texts:
Here is the scenario: I have a project needing 3 supply powers:

3.3V to run the microcontroller (max 100mA)
5V to run a bunch of adressable LEDs (max 8A, the most current intensive)
12V to supply op amps (max 15mA x 6 = 90mA for all opamps supplies)

The question is: if I want to use only one power adapter brick to power this thing, is it more logic to use a 12V power supply and step down to 5V and 3.3V? Or is it better to use a 5V power supply since most of the current is used on this voltage and simply step-up to 12V for my opamp needs?

Note: All opamps are signal level, the 12V is to have maximized headroom to preprocess my analog signals.


texts:
I have a PCB board with the stackup shown below. I want to calculate what would be the impedance (and capacitance too?) of a 5" PCB trace on the L1 layer.

How to calculate it?

For example, I am trying to use this calculator (https://www.eeweb.com/toolbox/microstrip-impedance/), what should be the value of the fields?


texts: Do you know the name of this item for crimping two cables?


texts: Looking for data sheet of the following Modbus Sensors #updated

texts:
I'm a noob in this area, please ignore any stupidity and lack of info and any help is appreciated and I'm ready to provide all clarification on the post if by chance any info is missing.

So i have been working with the following sensors and I have searched a lot for the data sheet of these sensors to talk with them and I was unable to find them. So the problem I'm having now is that I'm not sure which registers are to be read on the temperature/ humidity sensors to get the reading from the sensors. The sensors are given below.

Among the sensors below i have successfully communicated with the 4th sensor (setpoint display) and has an data sheet for an older revision of rev6, but if you guys happen to have the datasheet for rev17 or closer i appreciate it very much.
So communicating with that sensor was through Modbus request of 0x0103007700013410 and i got a response of 0x0103020019CFC7 (format). here I'm reading the data from 119 (0x77) register. But I'm unable to communicate with the other sensors as the register to read is unknown. Any help is appreciated thanks in advance.
This is a reference I used for understanding and using modbus commands:
http://www.like2do.com/learn?s=Modbus

This is the link for the datasheet of the 4th sensor:
https://temcocontrols.com/wp-content/uploads/sites/4/2018/07/AQ-N.pdf

Update: I was able to find some info on the second sensor I'll leave it here if somebody in the future may need it
sensor 2: https://techsparx.com/energy-system/modbus/simple-modbus-rtu-temperature-sensor.html
but I'm still looking for a valid datasheet.

Sensor 1.

Sensor 2.

Sensor 3.

Sensor 4.


texts: Working principle of the AD8232 high pass filter

texts:
This is the datasheet of the AD8232.

On page 22 in the section  "Additional High-Pass Filtering Options" is this diagram:

It is said that the cut off frequency is located at

I tried to find out where this formula came from.

I tried to make the equivalent circuit of this filter in hopes I could find the transfer function of this circuit.

What I get is not in accordance with the high pass filter circuit and looks like a low pass filter:

I would be happy if someone could explain to me how to get the cut off frequency and equivalent circuit of this high-pass filter.

EDIT: Thanks Andy Aka, so if there is a low-pass filter in the negative feedback of an amplifier the circuit performs as a high-pass?
And I still don't know how to get the cut-off frequency formula.

As far as I know the formula for the cut off frequency is
$$
fc=1/2\pi\sqrt(R1C1R2C2)
$$


texts: I have a Samsung PS43E450 TV (pic here). I lost the power cord. Can I just use the power cable from my PC (since it fits in the slot), or will it blow up?


texts: How to select a good optocoupler for uart to 20 mA current loop converter?

texts:
I'm trying to make a circuit that converts UART signals to 20 mA current loop signals.
I tried this circuit to switch the signals.

I am not much experienced in optocouplers I had just two types to test, TLP251 and 4N25. The below pictures show voltage of Node1 on oscilloscope. The input signal on TXD is a 20 KHz sqaure wave.

What is a good choice for optocoupler which is capable of transferring signals up to the 1M Baudrate of the uart?

This is what I got with 6N137.

The final Circuit in my mind would be something like below:

I need the logic to be the same not inverted which mean 5V on TXD makes 20 mA on current loop and 0V makes 0 mA.


texts: FPGA - synchronise “very close” clock from signal

texts:
This is more of a learning question, I can solve the problem but it would be good to know how to do it - can a clock be reconstructed from a signal, and is it easier when the frequency of the clock is basically known?
I am using a Terasic DE10 Lite board, mirroring video from a Mac SE/30 (512x342x1bpp) on a VGA display. Mac connections are vsync, hsync and pixel from the analog board, level converted to 3.3V and then connected to FPGA board GPIOs. At 1024x768 it’s a fairly good fit if pixel doubled. Getting VGA out at 60Hz is not hard, an ALTPLL IP block at 65Mhz makes it just a matter of counting front/back porch and sync pulses.
Copying the Mac signal is a little harder. I ended up with one @always on an ALTPLL clock running at 15.67 MHz (and experiemented with mult/div numbers to try to get it as close as possible), the Mac’s pixel output rate. I cannot exactly match the clock rate this way. This counts down the vertical blank period then for each line counts in until pixels begin and samples each pixel. Pixels are written to a slab of dual port RAM made from another IP block and output by the VGA routine.
This works and is perfectly readable. But it is ugly since there are sampling errors due to the slightly mismatched clocks. If instead of the ALTPLL clock I take CPUCLK from the Mac's PDS connector and use that to clock in the pixels, everything is as steady as can be. Using the FPGA clock the pixels are unsteady and randomly change where they should not.
The question is, what do you do if you can’t take the system clock? I think there must be some way to dynamically adjust frequency and phase shift based on input but I don’t know where to look.
(this question got no response at Stack Overflow, is perhaps a better fit here)


texts:
The photo below shows a part  that I am trying to find a specification for. I suspect that it is a microcontroller, and is part of a larger device that is essentially a timer. It clearly bears the National Semiconductor logo.

However, I cannot find this device via searching, and it doesn't seem to fit into the National Semiconductor device naming conventions. Is it plausible that this might be a part custom-made by N.S. for the larger device manufacturer? Is this kind of thing done?


texts:
Fast, high resolution ADCs, especially ones that have parallel output, usually have a separate supply pin (DRVDD, (drive vdd) or OVDD (output vdd)) presumably because they don't want to couple noise to the sensitive analog supply while all the digital output signals toggle.

Most ADC datasheets recommend a single unbroken ground plane right under the device and connect the OGND and GND to this plane with the least possible inductance.

We have a situation where we have several of these ADCs on a single board. I'm wondering whether the "single unbroken ground plane" recommendation still holds even when there are multiple ADCs on the PCB.

In our design we went with two separate ground planes, one for GND (gnd of VDD), the other one for OGND (gnd of OVDD), and we connected these two planes near the edge of the PCB, where power enters through an adapter jack.

Any ideas, real world examples or links to reference documents will be appreciated.


texts:
What is a Node?

  In electrical engineering, a node is any point on a circuit where the terminals of two or more circuit elements meet.

An image from my textbook...

Why is the node rightward of Node 3 (GND) ignored?

It seems to have the same voltage as Node 2, in which case I wouldn't solve for both. It'd be great if someone clarified because I'm not confident in my reasoning.


texts:
This is a home automation/AI project that I am currently figuring out details for, and currently I'm trying to figure out a way that i can detect which direction someone is walking through a door so that if someone is walking into the room the "AI" would play a welcome message, and if they were leaving the room it would play a goodbye message.

The only thing I can think of to be able to do this is to use 2 sensors such as laser break sensors or ultrasonic sensors which will use the information of one being tripped before the other one to determine which direction the person is going, a problem I can see with this though is the actual door tripping one of the sensors


texts:
Can somebody share me your methods measuring the PCB size in CAM Software ?

In PCB house ,we always measure the size according to the centre of outline and get the final size of the unit board or panel. but that can't be matched with the size in panel drawing given by customers. if we deduce the outline width ,then we can get the same data.

Take a project for example, In the panel drawing, the unit size is 79.3*98.4 mm,when we measure the size in Gerber by our way , the final size is 79.42*98.52 mm, the outline width is just 0.12 mm

See the picture below to get clear issues.

How do you define the final size from the engineer view ? Shall we all follow the size in the panel drawing ?


texts: Amplifier with two-pole is unconditionally stable

texts:
This is from a lecture slide:

  Amplifier with a single-pole is unconditionally stable.
  Amplifier with two-pole is also unconditionally stable.

Are these properties considered for closed-loop transfer function of amplifier?
The maximum phase with one pole is 90 degree as frequency approaches infinity.
For negative feedback the maximum phase shift for No.1 is 270 degree and for No. 2 is 360 degree.
In this case, the No.2 is still unconditionally stable because the total phase shift is 360 only when frequency approaches infinity and this doesn't happen.
Am I understanding it right?


texts: precision and accuracy of a measurement system

texts:
I have read the difference between precision and accuracy. As normally (mistakenly) they are considered to be the same, but in actual they are two different things.

My question is regarding the accuracy and precision of a measurement system. Lets say if i am measuring current across a resistor, which has a voltage tolerance of ±0.25%, and it is connected to a micro-controller having an ADC which is 0.5% accurate (including all the offset,gain and INL errors), my total accuracy with which I'm measuring the current is ±0.75%, i.e i will have a total absolute error of ±0.75%.

I have the following question:

1) If my system is ±0.75% accurate, can i say that its 1.50% accurate (i.e without the "±" sign) ?

2) For the above described system, can i say that if i take 20 different readings, and try to observe the precision of my system, will it be ±0.75% (maximum) as well ? For this i made a rough sketch attached herewith, showing the accuracy of ±0.75% by a red circle. Some readings are taken which (should always) lie inside this circle. So by looking at these readings, i think that we can say that our system's maximum precision will be ±0.75% as well. Am i right ?

3) I asked about precision in 2), am i right to say --> ± 0.75% i.e can precision be denoted by ± ? (like for accuracy ± is used.)

4) If precision can be denoted by ±, then just like 1), can i also say that the precision for this system is 1.50% ? (i.e without the "±" sign) ?

NOTE: The reason i asked 1) and 4) , is because normally i see things written like, this thing is x% precise or x% accurate, i.e with no ± sign with it. So without going in its detail, one should think of it as ±x% or ±0.5x% ? I mean what is the norm here ?
I hope i made my self clear.

Please help me clear my doubts. Your helpful suggestions and comments would be appreciated.

Thank you.


texts: How can I isolate voltage dividers so they aren't interfered with by other parts of the circuit?

texts:
I have a small and very basic circuit that PWMs an RGB LED.  It has a potentiometer to allow me to set brightness level for night time and a LDR that allows me to detect night time.

I took some measurements of the LDR under various lighting conditions so that I could select a reasonable resistor to put in series with the LDR as a voltage divider.

In practice, however, the readings were not what I expected.  If I measure the resistance of the LDR with my multimeter, it's about 1/5th what I had measured when it was not in the circuit.

I selected a 51K Ohm resistor for the LDR divider circuit.  My multimeter is also measuring that as 10K Ohm.  The potentiometer I'm using for setting the brightness is 10K Ohm, but in circuit it measures as about 3K Ohm.

I'm assuming that these resistances are reduced because they're in parallel with each other, but I can't figure out how to isolate them so that I can get reliable readings for the micro-controller.

I'll do my best to mock up the circuit . . .

simulate this circuit – Schematic created using CircuitLab

Based on some of the comments, I decided I should isolate parts of the circuit to see if I could reproduce the measurements in the full circuit.  I built this circuit in a breadboard and the measurements are the same as I mentioned above.  That is to say, my expected resistances are reduced by about 66%.

simulate this circuit


texts: Holding torques of a 7W stepper and a 48W stepper

texts:
Does anyone know why a 2.5V 2.8A (=7W) stepper has a holding torque of 1Nm whilst a 24V 4A (=48W) stepper has a holding torque of only 2.7Nm:

Stepper 1:

Stepper 2:

The latter draws 7x the power, but gives just 2x the holding torque. The inductances are roughly the same. The first is 2.8mH and the latter is 2.4mH. What might cause a 48W stepper to draw so much more power but give so little more?


texts: Struggling to understand wire gauge and strands

texts: I have been trying to understand wire gauge for a project, but there are so many different strand types and sizes it's alittle overwhelming. The wire needs to be 30 AWG and stranded, is it common for 30 AWG to have 7 strands or can it have more like 26?


texts: what is the relation of VGS on P and N channel mosfet

texts:
I'm a little bit confused on the Vgs(voltage-gate-source) of a mosfet...from what i understand so far the Vgs is simply the potential difference of the voltage applied from gate to source...

FOR EXAMPLE:
using a p-channel mosfet
assume that Vg=10 volts and my Vs=18 volts
so i get a VGS= -8

using a n-channel mosfet
assume that Vg=10 volts and my
Vs=0 (vs is always 0 since the source is at the ground level)
so i get a VGS= 10

i hope someone will clear this confusion of mine...TIA


texts: Transimpedance amplifier with diode feedback

texts:
Can someone explain the effect of capacitor and diode on the below circuit?

Since  when injecting 0.2uA (instead of photodiode)to the opamp with only a resistor(1Mohm gain)  feedback I am getting a correct output of -0.21 V, but when I add the diode 1N4148 (with resistor)the output becomes positive +0.21V  and when I add the capacitor to resistor and diode the output became -0.15v why this happen.

I know transimpedance opamp use the capacitor to stability but have no clue why the engineer who designed this circuit added a feedback diode.

simulate this circuit – Schematic created using CircuitLab

Note: After while I found out that his bom was wrong and he is using a zener diode 1N821A over there, which change the whole story


texts: Converting files between Altium Designer and Circuit Studio board layout file

texts:
I am using Altium Designer 17 in my institute, but in my laptop I have Circuit Studio 1.4. Schematic file made in Altium Designer can be opened in Circuit Studio.

Is it possible to open layout file in Circuit Studio, generated by Altium Designer? Is there any conversion software available to convert the files between the two?


texts:
I have this piece of code here:

library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
entity first is
port(
a : in STD_LOGIC_VECTOR(3 downto 0);
b : in STD_LOGIC_VECTOR(3 downto 0);
result : out STD_LOGIC_VECTOR(3 downto 0);
clk : in STD_LOGIC
);
end first;

architecture behavioral of first is
begin
process(clk)
begin
result <= a + b;
end process;
end behavioral;

In Quartus II, how can I tell the software that I want 'clk' to be a clock so that I can find out the maximum frequency (Fmax) at which this design can run? Whenever I compile my design I get the warning 'No clocks defined in design'.


texts: Switching pre regulator and linear regulators

texts:
I need to have a 5v supply with around an amp of current draw max, and a 6v supply with around a 4amps current draw max. I was thinking: instead of having two switching regulator circuits, just having one 5amp 9v switching regulator circuit feeding into an Lm7805 and an lm338t (linear regulators) to generate my 5v, and 6v rails, respectively. My Vin is around 18v. Pololu makes some nice switching regs that fit my needs.

Are there any potential drawbacks to this arrangement? I heard it referred to as a switching pre regulator. When answering please bare in mind I'm a hobbiest.


texts: Protect user space critical section from interrupt

texts: I am using Beagle Bone Black with Arch Linux ARM OS to communicate with ltc-6804 chip via SPI port. I have came to a point that the interrupt from the OS in the middle of sending read command and receiving measured values causing a trouble for me to get a valid measurement from the chip. Is there any way to "protect" the part of the code being interrupted on the run? In the other words, let the send and read section complete without any interruption.


texts: What's the smallest footprint dual H-bridge?

texts: I am designing a circuit with 4 small electric motors. The motors I selected are SMT and are driven by 3V power source. It makes sense to drive each pair of motors by a dual H-bridge, but I can't find a part small enough. Another option is to use a number of small simple parts instead of the integrated part, I have calculated that I would need at least 16 resistors, 12 transistors and 8 diodes, but even when using 0402, VMT3 and SOD-923 packages this takes a considerable area of the board. Ideally I need a BGA or QFN part to save space on the board.


texts: Adequate way to connect sensors far away from arduino

texts:
I have a simple setup when I have to read analog values from a light sensor, and I need to put it far away from the arduino (several meters away). I want to know how can I create a wired reliable connection from the arduino to the sensor.

simulate this circuit – Schematic created using CircuitLab

Here is the function that activates the system:

void photoResistorActivation () {
  int photoResistor = 1024 - analogRead(PHOTO_RESISTOR_PIN);
  if (DEBUG) {
    Serial.println (photoResistor, DEC);
  }
  if (photoResistor >= LIGHT_THRESHOLD) {
    personDetected = false;
  }
  else {
    if (personDetected == false) {
      trigger = true;
      personDetected = true;
    }
  }
}

Edit: I have received valuable feedback in the answers about how to avoid noise, but I want to clarify that I'm asking about physical connection (cables, connectors and so on). What kind of cables should I use? Jumper cables?

Thank you


texts:
I'm trying to build the following circuit. The advice on the site I got it from said to try using 1n4001's instead of 1n5817's, because that would get the voltage down to around 15V, which is what I need. Looking at the schematic, though, the 4001's are precisely what are used in the standard doubler design.

What should I do to drop the output to 15V? I'm not much of an electrical engineer. I just follow directions. Thanks for your help.


texts: Why does a pull-up resistor not stop current flowing to the input pin when the switch is open?

texts:
Sorry this is such a silly question, but I can't seem to understand this. In the third diagram here it shows a pull-up resistor.

I understand that when the switch S1 is closed, current is pulled down to ground and assumes a value of 0. This doesn't short because of the resistor limiting the current.

My question is: When the switch is open and the current is flowing into the input pin of the device, how does it pick up that this is a high value and not a low value? Wouldn't the resistor limit it to the extent that it would be .0005 A and so it would barely register with the device?

EDIT: Also, I am just looking at the pull-down resistor case on the same page. Why does the first switch not short when it is directly connected to VCC, there is no resistor, and the switch is open? Isn't this a no-no? I can't really grasp what is going on with the pull-down resistor.


texts: Antenna frequency rating matter? (For home devices)

texts:
If devices transmit and receive at certain frequencies, and if you wanted / had to replace the antenna, do you have to use the same frequency rating?

Example: I have a garage door receiver, and the frequency is 300 mhz and I wanted to add an external antenna for better range. Would I need an antenna rated for 300 mhz, or would a higher rating do?


texts:
I am trying to estimate forces acting between two sandwiched flat coils, with opposite currents sent through them. This is clearly not my field of expertise and High School is quite some years past and this may be a stupid question, so bear with me.

Suppose I have two flat coils (Archimedean spirals) with some inner and some outer radius and number of turns. From that I can calculate the length of the wires. Now I'm calculating the Lorentz Force that one coil exerts to the other with

$$\vec F_1 = I_2 \left( \vec l \times \vec B_1 \right) $$

and vice versa, where \$ \vec F_1 \$ is the Lorentz Force exerted by coil #1 on coil #2, \$ I_2 \$ is the current in coil #2, \$ \vec l \$ is the length of wires, and \$ \vec B_1 \$ is the magnetic field of coil #1. The magnetic field seems to be

$$\left| \vec B \right| = \frac{\mu_0 I}{2\pi r}$$

with magnetic constant \$\mu_0\$ and distance between coils \$r\$.

Now when I think about this, this seems to be true for two parallel wires, but I am not sure if this also holds for non-straigth wires, i.e. coils. It's hard to get my head around this; when I wind up my wires into coils, \$ \vec B \$ must be totally different, as there must be many many more interactions between turns of the wires, right? How would I calculate this?


texts: Connecting RFID reader with RS232 interface to an arduino

texts:
I am attempting to detect 134.2kHz RFID tags using a chip from Priority 1 Design, specifically this one

I am attempting to connect this to an arduino Uno, but I am not really sure where to start. There appear to be some instructions here on how to read and write data to an RS232 interface RS232 interface, however I was wondering if I need to do this? There are tx and rx pins on the board as well, but I don't seem to be able to find any details on what kind of output those pins produce? Do I need to communicate to these additional ports using RS232?


texts: Linear and Switched-Mode Supply Common Shared

texts:
We have a mixed mode PCB system with both digital and analogue systems. Due to high speed they all share the same ground on the PCB, but use logical spatial separation to control noise. SO PCB input of {+5V DIG, 0V GND and +12V ANA}.

We are box building a modular power supply, 12V analogue from linear power supply (8A total) and 5V digital from switched mode supply (5A total).

The cabling to our units from the PSU is 3 wire, as multi-core is not an option in terms of $/m (we are operating in a remote, distributed setup).

My question:

The mains input has a GND green/yellow conductor to be connected to the rack mount chassis (Earth / Protective Ground / 0V). Both the linear and switched mode PSUs have V+ and Common outputs. As I don't need stacked voltages or negative voltages, and that the supplies use the same ground on the PCB, I was planning on connecting both Commons together and out to the PCBs.

1) Is connecting common together a reasonable strategy when cable ohm/m is taken into account? Is switched-mode noise likely to negate the usefulness of the linear supply?

2) To ensure this shared common is 0V, should I also connect the common output to Earth (Chassis Ground)

Also, all supplies are re-regulated and decoupled on the PCB.

Thanks All.


texts:
I want to make some modular mood lighting. The idea is that there is one master in the chain (the one that gets turned on first) and the other lights can plug in to each other. Each light has a rotary encoder to adjust the color. What I want to do is:

Have the first light check for a master on the chain, if there is none, it becomes the master.
If there is a master, request an address from the master (maybe begin with an address of 255, then send a request for a new address to the master)
The master sends the desired color to the slaves, each time it changes.

I'm having trouble trying to make the other devices find the master on the chain. Is there some smart, if any, way to do it? If there isn't, is there another way/protocol with which it could be done?


texts: When does the placement of a resistor matter?

texts:
I've been a programmer for years but am very new to electronic engineering. So far I see people saying it doesn't matter where a resistor goes in your LED circuit as long as it is present, but it sounds like that's the nature of the basic LED circuit.

When does the placement of a resistor start to become important?


texts:
my question simply is to know where is the origin of UART system. Is there any standard covering it.
I can only see similar question here but the only answer is saying Wikipedia !!!
I can see many chip vendors providing UART chips, but based on What? what is the standard describing UART and its framing?


texts: How do you find the equivalent resistance here? (I realized it's a Wheatstone bridge, but it's unbalanced, so that doesn't help.) I tried using Kirchhoff's laws, but there is no cell given.


texts: A lot of questions regarding lithium ion power supplies and power regulation with safeguards

texts:
Per a members request I am making a post compressing multiple possible posts into one and providing additional info.

I am making a 18650 powered portable electronics workstation that will have many features.  I would like the following features:

upgradable at any time for more capacity and still be able to use the same components
have integrated charging capability
be as cheap as possible
automatically switch to charging mode when cable is inserted
display an approximate battery level
be fan cooled while charging and when a power output goes past 50 degrees celsius.
have adjustable voltage and current output , a 24v output port for a ts-100 soldering iron, a 12v soldering fume extractor port, a 20v protected laptop charger port, and a 5.2v protected phone charger port.

Pseudo circuit schematic is below.  I'm sorry it's messy; I was drawing fast.

Can anyone recommend a better system, safer laptop/phone charging, and/or check over my "schematic"?   I will be putting the tp4056's, relays, and cooling fan regulator on one perfboard sheet.

Every battery has its own protection circuit.  I forgot to put the battery meter on the drawing, and the switches.  Every power output will have a switch on the positive wire BEFORE it goes to the regulator.


texts: How would multiple ADC channels be processed?

texts:
Looking at this manual,
http://www.ni.com/pdf/manuals/371235h.pdf

I see the following picture related to a DAQ board's ADC,

Assuming all 4 ADC channels are used,
how would multiple ADC channels be processed?
Which of the following be more likely?

The ADCs collects samples sequentially,
i.e.: ADC 0 collects one sample, then ADC 1, then ADC 2, then ADC 3, then back to ADC 0 again, etc.?
ADC 0 to 3 all collect samples simultaneously?


texts: Any negatives using a Triac to transmit square wave?

texts:
I want to use a TRIAC as a switch to open a gate to transfer a 9600 baud rate square wave (for a uart communication between two avrs).
Currently I'm using dc relay, but I'd like to use the Triac to reduce the power consumption and increase the components durability. But I'm not sure if the Triac will have any side effects.Please advice.Thx


texts: Safety precautions when developing and testing mains voltage devices

texts:
Specifically, I am planning to design and build an energy meter to measure power drawn from mains - 120V 60Hz.
What are the risks associated with developing and testing this device and how to minimize/eliminate them?


texts: What is the relation between the mains frequency and the ideal PWM frequency in this circuit?

texts:
Below is a triac control circuit used in on-off mode:

The mains freq. is 50Hz. The micro-controller PWM frequancy is set to 5Hz in this simulation. Optotriac is triggering the triac. By playing with the duty cycle is the load current through R2 is enveloped between each pulse width on time.

But if I increase the PWM lets say 100Hz or over the triac is always on and there is no on-off control.

Why is that? Is there an optimum PWM frequency in this case?


texts:
I'm starting the wiring for my project and would like to solder two resistors together in series. There is good chance that the wire will be exposed to heat and gentle turbulence.

What is the best way to solder axial-lead resistors?

I have seen that twisting the metal wires from each resistor is a good technique. Is this the same for the electrical wiring? Should the electrical wire be twisted with the resistor wire when soldering?

I was also thinking that if there were to be slight turbulence, would it be a better idea to put an electrical wire between the resistors so that the solder doesn't get damaged by movement?

I will be protecting the resistors and wiring with good quality heat wrap for added protection although the electrical wire is rated for high temp use and is very durable. The resistors are also more resistant to heat than standard ones so they cost a little bit extra (talking pennies though!)


texts: When are Avalanche-Rated MOSFETs Necessary?

texts:
Why do we care about avalanche rating for power MOSFETs in circuits that exhibit inductive kick (flyback converters, motor drives, etc.)?

I understand the basic destructive mechanisms behind avalanche breakdown. As described here, the primary mechanisms are triggering the internal NPN into snapback, and plain old overheating until the semiconductor becomes intrinsic.

I also understand that avalanche breakdown can be avoided entirely by employing freewheeling diodes, active and passive snubbers, or simply placing a Zener diode in parallel with the MOSFET.

Please help me understand: With all of the choices for absorbing the inductive kick energy, why should MOSFETs need to be "avalanche rated?" After all, with proper engineering, shouldn't it be possible simply to avoid pushing the MOSFET into breakdown? Not to mention, many snubbing techniques produce substantially less heat because they return some of the energy back to the power source.

Given that some MOSFETs are 100% tested for their avalanche rating, it seems like some people really care for it. The MOSFET manufacturers wouldn't take on the added responsibility if they didn't have to.

Another way of asking the question is: How much is avalanche rating worth? Is it unavoidably necessary in some circuits, or is it just a convenience? Did avalanche rating ever save you in a design?


texts: Output Impedance of a Wilson Current Mirror

texts:
Is the ideal output impedance of a Wilson Current Mirror 0?

Also, in the formula for the actual output impedance of Wilson Current Formula (i.e. R_out = [B/2]* r_o), what does r_o stand for? Also, what is the order of magnitude of a Wilson Current Mirror?


texts: Datasheet unclear on the dimensions of the 16 pin SMD part

texts:
I am planning on using a quad optocoupler IC named ISQ203XSM (http://www.farnell.com/datasheets/90948.pdf?_ga=1.159355187.80908598.1463646290) and am confused regarding the dimensions of the SMD pckage. The datasheet doesn't seem to mention if this is a generic package like an SOP or TSSOP and the dimensions seem incomplete. Is there something that I am missing here?

I also emailed the company that manufactures these to clarify the matter and I haven't received a reply from them.

Thank you in advance for any help!


texts: Overloading of ESD protection diode on CAN lines through current during Bulk current injection - test

texts:
I have a design checklist question for a typical CAN circuit for an automotive application as below :
The question is related to the ESD suppressor : "Was a capacitor parallel to the diode considered, respectively carefully proofed the max. power losses in case of high-frequency distortion ? (Critical : overloading of diode through current loading during BCI-test)"
My application circuit is something similar to the below circuit, except that there are capacitors on the CAN lines on the other side of the ESD diode(NUP2105L) near the CAN bus, as well.

I understand that the diode is for clamping high voltage surges and the capacitors are to smooth out the noise on the CAN lines, and BCI effect on the CAN lines is high frequency noise- I'm imagining this is what the CAN lines see during BCI test(I have actually asked a question regarding this, but unfortunately couldn't get an answer, Bulk Current Injection on CAN bus )

So, thinking of an answer to the question above, a capacitor parallel to the diode is considered(but is my thinking right ? are they asking about the capacitor on the other side of the diode- nearer to the CAN bus), but I don't know how to proof the maximum power losses in case of high frequency. Also how do I quantitatively calculate the overloading of the ESD diode during BCI.


texts: What does hot and cold mean on an AC outlet?

texts: So I sometimes hear that the outlet has a smaller hole for hot and larger for cold so its harder to stick your finger in hot. But if it is an AC wave, shouldn't they both be the same, because they get 50% of pos. and neg? What exactly does Hot and Cold mean on an AC outlet and does it have something to do with ground? (ex: you touch hot and it goes through your body to ground and gives you a shock)


texts: arduino output pins collapsing voltage - is it dead?

texts:
After a while i came back to my arduino UNO R3, and attempted most simple program, that sets digital output pin high.

I measured voltage over that pin, and got 5 volts, but when I connected an LED, it didnt light.

I measured the voltage again, and found out, when I connect LED and resistor, Voltage just collapses to 1.8 volts !

I used FOR loop and checked, every output pin does the same.

Q: is my arduino uno broken, is there anything i can do?

i have SMD version of atmega328


texts: mAh and Wh ratings not matching with voltage of device

texts:
I was under the impression that
Wh = Ah * V

I have a 20000mAh battery charging device for my phone but am confused about the information provided by it on the side.

It claims to have a 5V output (3.1A max), and a capacity of "20000mAh/74Wh". But following the above equation, 100Wh = 20Ah * 5V. Where does this discrepancy come from?


texts: Why do most RFiD tags use hexadecimal numbers?

texts:
RFID tags store one 24-digit hexadecimal number.

Why use a single 24-digit hexadecimal number?


texts: Which circuit best approximates a zener diode?

texts:
Above on the left side is the original zener diode circuit.

I want to draw an approximation of this circuit, given the zener voltage Vz and zener resistance Rz (Rz is considered constant for simplicity). Vout should match the output of the original circuit.

Which figure (A or B) would be more correct?


texts:
In the circuit below:

I often see capacitors like C4 added in the feedback path of a non-inverting audio amplifier, and often times I heard that it acts like a high-pass filter.

However...

At low frequencies, C4 is open, and at high frequencies, C4 is a short circuit.

But R1 isn't changed. And there is no "DC blocking capacitor" shown by default. So does placing a capacitor in series with the "low-side feedback resistor" (R2 in the circuit) make the amplifier a high pass filter or a high shelf filter?


texts: Rough estimation of power consumption in an electronic design

texts:
I want to get a rough estimation of the power that my design is going to need. Is it sane to calculate the power of every IC component based on values in DC Characteristics in the corresponding datasheet, add them together and get a rough yet reasonable value or will I be totally off?

EDIT:

DC Characteristics have 3 columns minimum, typical and max. I will use various combinations based on the use of every IC in a given state. I thought it was clear in the original question that I will use values (which include min, typ, max) from DC Characteristics table, not the max values per se, but apparently it is not.


texts: Propagation delay in 4 inverter w/l ratio

texts:
hi guys, I was given a task on optimizing propagation delay of four inverters using cadence software. The circuit connection is shown in above figure. I was asked to change the ratio of w/l for pmos and nmos to get minimum delay. The length of pmos and nmos is 160nm. So, I just need to change the width of pmos and nmos. However, what should I put the value of width for pmos and nmos??

I need tphl=tplh (symmetrical cmos).I understood that the  in order for tphl=tplh, the ratio of w/l pmos must greater than 2.5 w/l nmos. or any other suggested value?????????

Increasing the w of pmos: tplh will reduce
Increasing the w of nmos: tphl will reduce

1)What is the suitable width value for each pmos and nmos considering length=160nm ?
2)Can the width of pmos/nmos smaller than length ie >>>> w/l= 48nm/160nm????or the width must be larger than the length of pmos/nmos???
3)Since I am using cadence software to design,do I need to take in consideration of capacitance or other formula?

ps: I am not familiar with VLSI


texts: How much RF power can a microstrip line handle?

texts:
Transmission lines on printed circuit boards must be impedance controlled lines since we want to transmit the full power and avoid the reflections.

Microstrip lines have three parameters that we can change to achieve 50 ohm impedance:

copper thickness (T)
substrate thickness (T)
track width (W)

Due to design constraints, there is only one parameter (track width,) left to achieve 50 ohm.

For example on 0.76mm Rogers4350B substrate at a certain frequency and with 35 micron copper thickness, line width becomes 0.37mm for a 50 ohm transmission line. But this relatively thin line must support transmitting 45dBm RF power.

My question is:

How much RF power can a microstrip line handle with a specified width?
How can we calculate this?
What parameters should we consider on the basis of this problem?


texts: What software was used for these schematic diagrams?

texts: I have several diagrams that I attached to this post. Does anyone know what software was used to make them? I attached the diagrams as PNG files but in PDF files that I have, they are in vector graphics.


texts: Setup Time, Hold Time - What is the underlying principle for having them?

texts:
I'm learning about setup time and hold time of a FF connected to a bus. But the textbook fails to explain exactly why are those needed in an operation. Isn't a FF always powered on and attentive to bus signal changes? How does turning on the clock signal dozens nanoseconds later after the signal went live on the bus help the FF capture it reliably? Does the FF actually sample a continuous segment of signal on the bus, instead of just one instant?(Or is it a difference between theory and reality). If yes, how does that work in reality?

Thanks.


texts: How to solder through-holes for quadcopter boards?

texts:
Its a flight controller for multicopters. Should i stick the wires from the top or bottom, and should i solder the top side or bottom side? I searched on youtube, but there is no definitive way to do it, and no great camera angle for me to see how exactly its done, and many use pin headers isntead.

Should i tin or not? That kind of thing. I know it normally has to be a cone shaped, but not sure if this applies here.

And lastly, how to keep it holding all that as i solder? Its much harder i imagine than soldering onto a pad. Use helping hands on the wires?


texts: BJT, resistor, and diode work but ULN2803 does not

texts:
I am trying to control some 5V relays with a mC.  At first I went with using a BJT, a 470 ohm resistor, and a 1N4004 diode to control each one of the relays.  Each mC output pin is 5V, 40ma.  This setup worked well.

I wanted to see if I could do better so I am trying out the ULN2803an driver chip.  However, this sort of works.  It runs for 5 seconds then the mC freeze or starts controlling the output pins incorrectly.

The yellow wires connect directly to the output pins of the mC.  Pin 9 of ULN2803an goes to ground, pin 10 of ULN2803an goes to +5V.

Do I need resistor between the mC and the ULN2803an chip?  Is the ULN2803 hooked up correctly?  Is there something else I am missing?  Everything works with the BJT, resistor, and diode combo.  I thought the  ULN2803an would be exactly the same.  Any help in figuring it out would be appreciated.


texts: Why do different batteries of the same voltage have different results and which battery would i choose?

texts:
I want a power a homemade robot that uses an arduino and 4 small dc motors and a few sensors. Ive used pp3 energizer 9v batteries to power it in the past and they worked well, i used 9v again after they died but a different brand and learnt that not every 9v is the same as it wasnt strong enough for the bot to make turns. Why do different batteries of the same voltage have different results and some are stronger than others? is it because of internal resistance because 9v use the same chemicals i couldve sworn?

I want to use a nimh rc battery now that will last long and be strong enough for the robot and was wondering if amp hours means capacity and if was to use 2000mah battery, it wouldnt damage the arduino. I have my eyes set on this battery and charger and was wondering if they would work together too?


texts: Why does it take over 4 seconds to eliminate audio popping in this circuit?

texts:
I made a simple audio mixer circuit with its output going to headphones. Right now I'm only testing with a single audio signal at the input, which is music from a smartphone. I hear a pop sound after I apply power (2 x AA) to the circuit, unless power has already been applied for at least approximately five seconds. Even if I leave power applied for a minute, and then I disconnect and reconnect power, there is a pop sound. What about this circuit would take five seconds to stabilize? VCC stabilized nearly instantly when I measured on the scope.

I'm using a dual op amp IC, the LM4808 (http://www.ti.com/lit/ds/symlink/lm4808.pdf).

There are four 470 uF decoupling caps in parallel at the output (for a desired cutoff), and a 1k resistor to Ground that I included as a discharge resistor, but it doesn't seem to have any effect.


texts: Is there any way to noninvasively/invasively measure the current/voltage (Power) to get actual power consumed by load?

texts:
One of the application im working on needs three phase power measurement to be done through micro-controller. The power measurement is in the range of 90kVA.
Is there any way to noninvasively/invasively measure the current/voltage to get actual power consumed by load(compressor in this case).

I want to understand a way to measure a Power consumption with a sensor and update data to server with IoT to remote server. micro-controller aspect here is peripheral and any WiFi module can be used to update data to server.

While referring to some material I did came across some methods as Abraham electrostatic voltmeter or Transformer ratio method and some other for voltage measurement.

High Voltage Engineering - J R Lucas 2001

But need to understand which method is used in commercial measuring instruments.
Also is it practically possible to keep any WiFi or RF node for data collection at its vicinity?

Note:I clearly understand the risk at these Power levels. Im here to understand the technology so that i can concentrate on my part of design.


texts: Interfacing a temperature sensor with PLD without implementing SPI/I2C bus

texts: Are there any temperature sensors which can be interfaced with PLDs without having to implement a SPI/I2C bus at the PLD end. I am looking for something which can be interfaced without having to be involved in the complications of code the receiver part of some protocol.