texts:
i have finished building my barebone arduino..i want to run the barebone chip with 3V battery i.e double AA 1.5 x 2= 3V..the reason i am persisting using 3V Vcc is because in our project we need to fit in the battery in a given battery slot which is very small..A 9V battery is able to fit in it..currently we are using a 9V battery but the LM7805 regulator is consuming a lot of current..which wont be efficient in future..when we want save battery power and what not..we wont be able to fit in 3X 1.5V i.e 4.5V.

anyways my question is would i able to use 3V directly on my barebone..I will replace my 16Mhz crystal clock with a 8MHz one..because 3V wont work with 16mhz..but how will i source the voltage..some assistance would be really helpful...thanks a lot...


texts: Do automotive relays come with TVS diodes?

texts:
The 500W inductive load question got me thinking.  Cars have large radiator fans that often draw more than 15A and are pretty inductive.  Do automotive relays have any sort of protection from inductive kick back?  Also, in a situation where a physical switch does the switching of power does the switch take the grunt of damaging kick back or does the damaging effect propagate to the source as well?  The physical act of breaking the circuit does generate a spark when a simple switch is used.

Thanks.
Andrey


texts: Would a MOSFET driver be a suitable replacement for this circuitry and would it reduce power dissipation in the FET?

texts:
This is a follow on from a previous question here.
I asked if replacing a MOSFET with a lower RDSon would reduce the heat generated by the MOSFET and the answer I got was that FETs with lower RDSon have higher gate capacitance.
This would increase the time it takes for the FET to fully switch on and could potentially increase the power dissipation.
My follow on question is this:
Would replacing the circuitry before the FET with a dedicated high-side driver provide any benefit?
I would be looking to decrease the switching time if I were to use a FET with lower RDSon (and in turn higher gate capacitance?)
In order to control the MOSFET from a microcontroller pin, there is already a level shifter from 3.3V to 12V which in turn then goes to a push-pull transistor configuration. This seems a fairly solid design to me and I'm not sure if there is any benefit in changing this for a driver. A cost increase would not be an issue in this design. Any direction would be appreciated.
Full circuit details are in the previous question, but here is the schematic as requested:


texts: Why is the air gap in synchronous machines larger than in asynchronous machines?

texts: The length of air gap is inversely proportional to power factor and hence result in poor operating power factor of an electrical machine. Larger air gap length means higher resistance to magnetic flux which causes undesirable increases in magnetizing current and the associated electrical loss. Why would that not mean that air gap length would be minimized in all types of electric machines?


texts: How can I modify this circuit to pickup radio waves better

texts:
I want to build a simple detector for cellphone signals nearby and I implemented the following circuit on breadboard:

Here is my breadboard wiring:

I've checked the wiring 10 times and seems there is no error in wiring.

The only difference with the original circuit is that I used BC547 instead of 2N3904 and 68 Ohm instead of 82 Ohm for the resistor R3. For loop antenna I used a alligator wire.

The circuit doesn't work when even I turn on off a cellphone at  extreme proximity.

It only worked when I cut the loop and inserted a transformer primary winding in series and turn on a drilling machine very near the circuit.

How can I adjust this circuit to make it more sensitive to electromagnetic pick up?


texts: Double sided board w/ d2paks, solder paste?

texts: Can you use paste on a double-sided board w/ d2paks on both sides? There is a small area below the tab but it seems like not really enough room for paste.  If not, then how the heck do you do a double sided dpaks?


texts:
V2 is blocking any current passing diode(1) because of the voltage being higher,however, V3 is equal and opposing V2, therefore canceling out and allowing current flow through the diode?

simulate this circuit – Schematic created using CircuitLab

Assume V2/V3 are induced-EMF's going beyond the PS.


texts:
I'm using an LT1339 switching regulator to create a 24V to 12V 50A power supply and after using the calculation in the datasheet for the LT1339 I think that I need a 60uH Inductor but a 60uH, 50A inductor doesn't exist.

  Lmin = (Vout)(Vin-Vout)/(Δl)(freq)(Vin)
  ((12)(24-12))/((1)(100000)(24))=Lmin
  144/2400000=0.00006H = 60μH

What can I do here and is my calculation even correct? The datasheet is here and my schematic is below.

Also, please feel free to critique the schematic/component values/my life choices/etc.


texts: Output to 3.5mm female jack from microcontroller

texts:
Can anybody point me toward some resources about using a microcontroller to output to a 3.5mm female jack (the kind that you plug headphones into)? I can't seem to find any explanation of what sort of signal is necessary, or just how to make this happen in general.

Thanks in advance!


texts: Find the Impulse response given input and output signals

texts: I would like to know the technique to solve for impulse response given input and output signals.


texts: Capacitor filter optimization for ATmega32U2 board

texts:
I've been working on a project built around a ATmega32U2 with a PMW3360DMâ€T2QU optical sensor and I have some questions on where and when capacitor to ground filters are necessary.
Many of the datasheets for the components I am using recommend capacitor filters at their input and output. I believe some of them may be redundant or just unnecessary, but I'm not completely sure how to determine when they are truly necessary or not.
On my current schematic, I have some capacitor filters that I feel may be unnecessary or redundant, such as the second filter(C8) on the 1.9v line leading to the VDD and LED_P pins on the sensor(U3). The duplicate 1uF capacitor(C5) on the 5v line feeding the 1.9v voltage regulator I also feel may be redundant due to the 5v input from the USB already having a filter on it(C2) between the USB input and the MCU(U1).
How can I tell when a capacitor filter is needed, beyond when a datasheet recommends it and when can and can't I combine duplicate capacitor filters on the same line? Is it mostly a matter of closeness/relative location on the PCB or trace length from input to output? As I understand it currently most datasheets recommend a filter on the input and the output of their device, would this mean that when using multiple devices together that I can skip one of the filters on a line between them because the output of the first device already has a filter on it before going to the input of the second device(Like on the 1.9v line with C8 to the sensor VDD/LED_P pins)? Could I just skip putting a filter on the output of devices and only put a filter on the input that they feed into instead, or does this not work due to trace lengths and noise? Is it possible to combine 2 close filters going to neighboring pins(Like on the 3.3v line with C3,4,7 from the MCU's internal 3.3v regulator to the MCU's VCC+AVCC)? Also, is there a way to determine when a filter is needed, and a proper capacitor rating for it without doing physical testing yourself of prototype boards?
Here is a picture of my current schematic:
I am creating a very lightweight and low profile PCB, so eliminating and optimizing every part possible is beneficial.
Any amount of help would be greatly appreciated.


texts: Hot Swap Controller what could've gone wrong

texts:
Back at it again, now with four hot-swap controller implementations that somehow broke down. I've got four of the circuits pointed out below on a PCB next to each other. All four circuits are powered by a 48V source. These circuits make use of:

CSD19536KTT 100V n-channel MOSFET
TPS2490 hot-swap controller

The circuit is there to provide a slow start to a motor controller (and motor) to prevent a FET breakdown. The enable-pin on the hot-swap controllers are driven by a microcontroller that supplies 5V when 'high'.
During testing the hot-swap on the first of the four loads, the fourth circuit sparked and the MOSFET broke down. Now, this fourth circuit is having 48V on both source, drain and the gate of the FET and this led to a broken hot-swap controller as well. Also, on the first circuit, the gate-ground voltage is now somehow 62?!? volts. In the meanwhile, the 2nd and 3rd will no longer give a voltage other than a couple of milli-volts even while the enable signal is 5V.
To refer to the schematic, the fourth circuit has visible damage between the Vcc and Vsense pins of U1.
On each load's ground, there is a current sensor we use but I'm not feeling this has anything to do with it.
As I've not exactly stated a question, it would be: except for the measurements we've already done (measuring the voltages at points), what might we look into to figure out the cause of this issue we're finding ourselves in? Is there anything we might be missing here and if so, could one explain a bit the details of such a problem?
Datasheets:
MOSFET: https://www.ti.com/lit/ds/symlink/csd19536ktt.pdf?ts=1619099126555
Hot-Swap controller: https://www.ti.com/lit/ds/symlink/tps2490.pdf?ts=1619078176827

Edit:
I added two images of my routing. 1 with the polygons and one without. Note that I wrote (great paint skills) +48V on the top polygon which is the high-current path and one with GND on the bottom. Also note the via's in the bottom polygon connecting to a full GND layer.


texts: Use multimeter to find approximate impedance of miswired speaker array?

texts:
I visit my father's house a few times each year.  When he built the place, he had it wired for sound using in-wall systems, but (it seems) not by professionals.  He blew out a receiver/amp, so I asked him to examine the wiring and he says it has all 8 speakers in parallel, patched together down in the basement!

(See this question for the way it should have been done)

I would like to use my multimeter to find the impedance of his setup next time I visit him.  I don't need to be super-accurate so I would like to avoid sine-wave generators and speaker disassembly.

My plan is to introduce a resistor in series (maybe 200W and 1-4Ω) sufficient to make the system safe against accidental volume knob twists.  Sound quality and max volume are not terribly important in his case.

If I simply hook my multimeter -- a low-end Fluke -- up to the (single) speaker wire coming from the wall, and then use it to test resistance, am I likely to get a reasonable estimate of the total speaker impedance seen by the amplifier?

Edit:
  To be clear, the impedance of each of the individual in-wall speakers is presently unknown and would be tricky to obtain (they are actually mounted in the ceilings).

Outcome:
  Following the advice from Dwayne Reid I purchased a resistor (20W, just to be sure).  I found a free tone-generator program for my laptop, and played a couple different frequencies through the system.  It took quite a bit of wattage and volume to get near 1V (my father went to find his earplugs), but I got close enough that I felt measurements were OK.  Based on that, I obtained 8-9 Ohms of impedance in the system, so the installers apparently had done the job properly!


texts: The voltage of capacitor across battery never reaches battery voltage

texts:
I made some homemade vinegar batteries. The voltage of each cell was measured around 0.45V. I have 18 of them in series and I measured around 6.5V for the whole chain.

Since the vinegar batteries have very low current output, I am using a solar engine to harvest the energy. I used this exact design: http://www.solarbotics.net/library/circuits/se_t1_1381.html

The 1381 that I bought was designed to trip at 4.2V. However, it never seems to produce any output. The output has been steadily staying at around 0.6V. When I measured the voltage across the capacitor, I can see that it was rising when I first connected the circuit. However, it stopped rising at around 2.2V.

Why wouldn't the voltage capacitor get to the same level as the batteries? Does it have something to do with the internal resistance of the battery? In that case, how do I figure out the internal resistance and the trip voltage level that I would need?

Thanks!

Notes on battery internal resistance for an individual cell

The vinegar battery actually behaved quite differently when it was freshly made and after about 3 days.
For a fresh battery cell (when the electrolyte was just put into the vinegar), when I loaded it with a 10K ohm resistaer. the voltage and current kept dropping as I measured them. The voltage and current drawn was really low. The resulte below isn't really that meaningful since the measurements were still changing, but that give you an idea of the magnitude.

V_oc = 0.46V
R_load = 9.8k ohm
I_load = 32.7 uA
V_load = 0.336V

This gives a internal resistance of more than 5.75k ohm!

After a few day (I did not touch it or have it powering anything), the open circuit voltage actually dropped to 0.192V. I loaded it again with 10K ohm. This time, the current drawan was really stable and the voltage dropped was stable as well.

V_oc = 0.192V
V_load = 0.183V
I_load = 17.0 uA
R_load = 9.8k Ohm

This gives a internal resistance of 529ohm.

Not sure why that's happening. Am I doing the internal resistance test correctly?
Note that the 6.5V overall voltage I mentioned above is the voltage right now (I just made it). Perhaps it will drop tomorrow.


texts: A question about superposition and zeroing condition

texts:
Calculate the voltage \$U_x\$ in the circuit below. Specify zeroing condition of the \$U_x\$ indicated in the figure.

I know I can solve this with the superposition theorem but I'm confused about the \$U_x\$ place and direction. In addition I'm not really sure about zeroing condition.


texts: Which type of components required to achieve pre-determined output sequence?

texts:
Just getting back into electronics. I would like to create a circuit that can be programmed to control the state of a light bulb / relay - e.g., on for 2 seconds, off for 12 seconds, on for 5 seconds, off for 1 second, etc.

Don't really know where to start with this particular project, so not even sure what to search for.

Hoping someone might be able to push me in the right direction.


texts:
I'm working on interfacing 2 development boards. I have control over the 1st development board. The 2nd development board is from a third party vendor.
My board (board 1) has a pull up of 3.9K and the third party vendor's board (2nd board) has a pullup of 1K.

The issue I'm facing, is that when both these boards are powered up separately, they boot up and behave correctly but board 2 doesn't boot when the bus is connected. I have access to a I2C protocol analyzer. Both board 1 and board 2 have accompanying daughter boards. With board x <=> daughter x , the I2C messages and voltage levels are fine.

When I tried to connect board 1 <=> board 2, board 2 doesn't boot. I have made sure that slave clocking is disabled on board 1. The requirement is that board 1 needs to be slave, and board 2 needs to be master.

What I have tried so far :
With the I2C unplugged, I powered on board 1 and checked the SDA, SCL levels. They are at 3.3V. As soon as I plug the I2C connector to board 2 (it's still powered off), SCL and SDA get pulled low.

Now I powered on board 2 using the same power supply to ensure common ground.  The SDA line goes high immediately, but SCL remains low and there is no activity. Board 2 doesn't boot at all.

I have to stick to this order of power up, since the board 2 sends an I2C message only once a few seconds after power up (confirmed this using board 2 <=> daughter 2 with protocol analyzer).

I'm not sure how to proceed here.

Any help is much appreciated. Thank you!


texts: Hi guys, I am looking for some clarification regarding how to create a DC offset for an AC signal. Attached to this post is a quick schematic that I have drawn. Am I correct in saying that by connecting the red/pink lead to the middle of my voltage divider and the ground of the signal to the ground of the voltage divider, that my AC signal (say 1Vpp) will reach a maximum of 2.15V and a minimum of 1.15V?


texts:
I'm just a bit confused about this current transducer/sensor
https://uk.rs-online.com/web/p/current-transducers/1383472/

Datasheet: https://docs-emea.rs-online.com/webdocs/15c5/0900766b815c5532.pdf

I can't seem to figure out the reason for the reference voltage.
Is the output voltage = to -2V when -250A is being pushed and = to +2V when +250A is being pushed?
And is it linearly scaled? I.e would +1V mean +125A?

How exactly is the output working here?


texts: Capacitor charging not working according to t = rc

texts:
I have researched about capacitor charging time, with its charge being at 63% after 1 time constant, being t = RC. I am trying to repeat this by myself, using a 16V 1000µF capacitor, a 1KΩ resistor, and a constant power supply (~7.3 volts, ~1.9 milliamps) from a solar panel, which, as I understand capacitor charging (I may be totally wrong about this, if so please correct me) one time constant should be equal to t = RC = (1KΩ)(1000µF)= 1 second.

Theoretically, after 1 second, the capacitor should be at 63% of its capacity. For it to be at 99% of its capacity, 5 time constants must pass by. I tried this, and I waited for 5 seconds, disconnected the capacitor from the solar panel and resistor, and using a multimeter measured the capacitor's voltage, which didn't even reach 1.5 volts at any of the many times I tried.

I don't understand it, is it that the way I am trying to find the charging time is wrong, as a consequence of informing myself totally wrongly, or that the capacitor that I am using is defective?


texts:
I am looking for effective voltage values for calculating power in a AC sine wave supplied circuit with a resistor under 2 conditions : full wave rectification; half wave rectification.
I have searched the internet for the effective value of a half wave rectified voltage and have found nothing. I think, I have figured it out, but find puzzling the lack of this information.

Effective voltage of a rectified full wave sine is Vpeak/square root of 2
Effective and RMS are the same, average voltage has no use.

Effective voltage of half wave rectified sine wave is not RMS, but rather a
RMS of the original sine wave /2.
Or Vpeak/ 2 x square root of 2
RMS and average voltage have no use.
RMS of a half wave rectified voltage is Vpeak/2 and this is not an effective voltage.
What did I get right or wrong?
thank you


texts: Scaling DC Voltage [0V-6.5V] to [0V to 10V]

texts:
I have an input DC signal voltage 0V to 6.5V that need to be scale up to DC voltage 0V to 10V.
Any advise what type of circuit that I should use?.


texts: how do I connect a BN59-01006A samsung rc to an Arduino Uno IR receiver module

texts:
I have this remote control (BN59-01006A):

and this IR receiver brick(Keyes IR receiver):

I managed to connect the IR brick to my Arduino Uno. I downloaded this library and used a basic Arduino code:

#include <IRremote.h>

int RECV_PIN = 11;
IRrecv irrecv(RECV_PIN);
decode_results results;

void setup()
{
  Serial.begin(9600);
  irrecv.enableIRIn(); // Start the receiver
}

void loop() {
  if (irrecv.decode(&results)) {

    Serial.println(results.value, HEX);
    irrecv.resume(); // Receive the next value
  }
}

I'd like to be able to capture some HEX. values and display them through the serial monitor. The IR module works (the internal LED blinks every time I use the remote control towards it), but it's not displaying anything. What Am I missing? Do remote controls have to be calibrated to connect to a standard IR module?

Thank you much for your help.


texts: What happens to resistor when it "breaks" due to over-current or over voltage?

texts:
What happens to resistor when it "breaks" due to over-voltage or over-current?

Does it short or Open? or it merely ends up outside of specification?


texts:
Normally I think of LEDs being polar and having a definite current direction, the "D" in LED standing for "diode".

However, in working with with a computer case recently, the front part of the case has several LEDs, like the power-on indicator, and these connect via a Dupont two-way housing to a pin header on the motherboard. These connectors are non-polar--I can plug them in either way and it works.

So, how is it that these computer case LEDs appear to be non-polar?


texts: Can unpowered radio work without ground connection?

texts:
One feature of the Crystal radio is that it needs no other power source but that received solely from the power of radio waves received by a wire antenna.

But it also requires good ground connection to work. This is not easily available for mobile use (except on seafaring ships ).

I wonder if there exists some (possibly more complex, possibly heavier, etc) counterpart that could be used without ground connection, and still work off radio wave power alone - say, on a blimp?

(please excuse the misnomer in the title but radio powered solely from the power of radio waves received by its antenna is a little too long for a title)


texts: Scrolling text with PIC16F688 on a 16x2 LCD

texts:
I am trying to scroll a text on first row of a 16x2 LCD using PIC16F688 (Using MikroC compiler). At the moment I want to make a function that inputs a text and scroll it from right to left, like the first character appears at the right and when the next character comes in, last one moves one column left. Is it possible to make this as a general function(method) which automaticly calculate number of characters? If it was C# or something else I would know it is possible to do so with STRLEN function. But what about doing this on PIC:

void leftScroll(char text[])
{
int chars = strlen(text); //get number of characters in given text
char number[] = chars; // store number of charcters
Lcd_Out(1,1, chars); //show number of characters (DEBUG)
}

Any suggestion would be nice!

Here is my program so far. This scrolls the text from right to left. But I want my message start from left and character by character.

// LCD module connections
sbit LCD_RS at RC4_bit;
sbit LCD_EN at RC5_bit;
sbit LCD_D4 at RC0_bit;
sbit LCD_D5 at RC1_bit;
sbit LCD_D6 at RC2_bit;
sbit LCD_D7 at RC3_bit;
sbit LCD_RS_Direction at TRISC4_bit;
sbit LCD_EN_Direction at TRISC5_bit;
sbit LCD_D4_Direction at TRISC0_bit;
sbit LCD_D5_Direction at TRISC1_bit;
sbit LCD_D6_Direction at TRISC2_bit;
sbit LCD_D7_Direction at TRISC3_bit;
// End LCD module connections

char Message1[] = "Sean Walter"; //Top line message
char Message2[] = "Welcome to my LCD project!";
char i;
void main()
{
  ANSEL = 0b00000100; // RA2/AN2 is analog input
  ADCON0 = 0b00001000; // Analog channel select @ AN2
  ADCON1 = 0x00;
  CMCON0 = 0x07 ; // Disbale comparators
  TRISC = 0b00000000; // PORTC All Outputs
  TRISA = 0b00001100; // PORTA All Outputs, Except RA3 and RA2
  Lcd_Init();        // Initialize LCD
  Lcd_Cmd(_LCD_CLEAR);             // CLEAR display
  Lcd_Cmd(_LCD_CURSOR_OFF);        // Cursor off
  Lcd_Out(1,1,Message1);
     Lcd_Out(2,1, Message2);

  do
  {
   delay_ms(50);
     for(i=0; i<2; i++) {               // Move text to the right 4 times
    Lcd_Cmd(_LCD_SHIFT_RIGHT);
  }
   delay_ms(50);
  }
  while(1);

}


texts:
I am designing a signal conditioning circuit to remove all frequency under 20Hz for some EMG measurement. I have several questions about the circuit design:

For the instrumentation amplifier, should I go with higher gain (i.e. around X100) or lower gain (i.e. around x10)? I read several papers and they have competing designs (some said the lower gain is advantageous because the filter will not be saturated by the DC offset, whereas others said that the higher gain has better CMRR) (Note: I am planning to use INA128)
When making a higher order low pass filter, should I cascade multiple filters with gradual cutoff frequency or can I just cascade filters with the same cutoff frequencies over and over? (i.e. I want to remove all frequency under20Hz using a fourth order filter, then should I use filters with cutoff frequencies 30, 27, 23, 20Hz or just 20Hz x4)
When using op-amps with multiple channels, is the gain specified by the datasheet the overall gain of the op-amp or the gain of a single op-amp?
How to calculate the total gain of multiple cascaded filters in a circuit?

Thank you so much. Happy New Year!


texts: Why is this Verilog RAM modification better in terms of resource usage?

texts:
I'm using the open-source toolchain Yosys > NextPnr > IcePack for synthesising code for the Lattice HX8K FPGA. Here's a common version of a 1Kb RAM (that I'm using as Video RAM for a VGA module):

module text_ram #(
    parameter A = 10,
    parameter D = 8
  ) (
    input  clk,
    input  we,
    input  [A-1:0] addr,
    input  [D-1:0] din,
    output reg [D-1:0] dout
  );

  reg [D-1:0] vram [0:(1<<A)-1];   // 2^A memory spaces of D bits

  initial
    $readmemh("lib/video.hex", vram, 0, 1024);

  always @(posedge clk) begin
      if (we) vram[addr] <= din;
      dout <= vram[addr];
  end
endmodule

Analysing the resources with icebox_stat (alongside with all the other logic I have; sorry, but I don't know how to isolate the stats for a single component), it reports:

DFFs:     21
LUTs:    204
CARRYs:   26
BRAMs:     3
IOBs:      4
PLLs:      0
GLBs:      3

Now, with this simple modification (which, granted, makes dout different, but ok for my intended purpose):

  always @(posedge clk)
      if (we) vram[addr] <= din;

  always @(*)
      dout <= vram[addr];

It reports:

DFFs:     21
LUTs:    151
CARRYs:   26
BRAMs:     0
IOBs:      4
PLLs:      0
GLBs:      1

Not only it's 53 less LUTs, but what really surprises me is that the BRAM usage seems gone! Can someone please explain me why? Also, how can I inspect such cases to make sure I understand the underlying decisions of Yosys and NextPnr?


texts: Effect on LED driven at a higher Voltage than maximum forward Voltage

texts:
My current PCB configurations are
(10 series 4 parallel)x3 in parallel making 10 series and 12 parallel I am using
Meanwell ELG-75-42 driver giving a voltage of 42V at 1800mA, and a power of 75W. It is a constant current + constant voltage driver.

While each LED is driven at 150mA dropping a voltage of 3.0V so a total of 1800mA and 30V,

LED specs
typical current-150mA
typical voltage-3.0v
maximum voltage-3.6v
As the voltage is going higher than maximum will it affect my LED's?


texts: How do I calculate this inverse Laplace Transform

texts:
I have this transfer function and input, and I have to manually calculate what the systems response will be.
The transfer function is:

and the input is:

I multiplied the two functions and used fraction decomposition by partial fraction expansion and calculated the inverse laplace transform and this is what I got:

But the response I get from that function does not correspond to the one I get using matlab. This is the matlab code I used:

t=0:0.1:100;
FT6=tf(0.1,[1 1 0.1])
r=4*sin(10*t);
V=lsim(FT6,r,t);
plot(t,V,'-')

How do I calculate it properly by hand?


texts:
I have this dual pmosfet that we were going to use one element of to implement a low-voltage cutoff for a battery input (battery comes in from the left), yanking on the base of the darlington to cut the current off.

For various reasons we've decided to implement this differently, still need the other transistor, and don't want to spin a new board design yet. So we're going to DNP the resistors and darlington.

What I'm wondering is if there is any problem I should be aware of in connecting the mosfet's gate directly to ground to keep keep it always turned on?


texts: Maximal power dissipation of the resistances in this circuit

texts:
Assuming I have this circuit below with :
Ic = 200mA , β = 100 , UCE = 15 V

So with some calculations : Ib = 2mA , R1 = 4k7 Ohm , R2 = 75 Ohm
If I want to calculate the power dissipation of both URV1 and URV2 then :
$$P1 = U_{R1} . I_{b}$$
and
$$P2 = U_{R2} . I_{c}$$
But the question here was to calculate the maximal power dissipation of the resistances R1 and R2.
Does this mean that I have to check the minimum value of the amplification factor β arccording to the transistor that I have . In other words, If I want to have the maximum value of IB I would need the minimum value of β to use since the formula is  $$ I_{B} * β = I_{C} $$   Is this how should I consider it or is there another way to calculate the maximal power dissipation of both resistances .


texts: PSU using -15V and +15V in order to get 30V?

texts:
I've been a couple of days looking for an answer, but without much success. I was wondering if I can connect a 30V audio device to the +15V and -15V of a PSU (+15V / GND / -15V)? Or is it preferred to have a PSU (+30V / GND / -30V) and only using +30V and GND? I've read online that I should use the second option but couldn't find why this is better.
The audio device in question is a TSA8498 rated for 14V to 39V.
The PSU is a switching power supply with +15 / GND / -15V (10A).
I want to run it on ~30V.


texts: What can cause a very low frequency sound from a laptop?

texts:
I have a Clevo M57RU laptop here. Whenever it goes to stand-by, sleep or is shut down I hear a VLF sound (presumably close to the ~20 kHz maximum of the human ear) that's even better to hear if the battery led blinks because the sound is intermittent then. When I disconnect power and such the LEDs go off, the sound goes off, as well. When it is operating the sound is probably there, as well, but I can't hear it since the fans are terribly noisy.

I tried to use this Sound Analyzer App on my tablet to give you more information but I can't even calibrate it since:

  Failure: Unstable sound source, ΔL = [5.5–10.5 at different tries]dB

What's causing this sound and is there a possibility to get rid of it?

(I'm absolutely able to master advanced tools like screwdrivers, soldering guns, etc.  I had it open dozens of times for fan cleaning and thermal compound renewing.)

UPDATE

I read the suggested Buzzing power supply. The instructions how to possibly get rid of it, however, are a bit too vague for me (I'm a high-power electrical not an electronics engineer):

  add a load at the output (a resistor)

Of which size?

  put some insulating viscoelastic caulk on the noisy components

What about heat if I put that around a DC/DC converter? 20 V (external power supply) converted to a voltage suitable for LEDs can produce quite an amount of heat, IIRC (crafted 12 V car to 5 V CMOS once), can't it?


texts:
I want to communicate with a microcontroller over a CAN bus which needs (ideally) 120 ohm terminal resistors at the end of each bus. I want to integrate this resistor into the circuit and activate it only if it is needed (depending on which software is being flashed on the controller). Is it possible to switch a resistor using software?

Basically what I have in mind is something like this:
What's the automatic equivalent of a variable resistor?. With only two states (120 ohm and 0 ohm open circuit) switched by a digital signal from the microcontroller.


texts: Bulk Capacitor Ripple Current as a Function of Capacitance

texts:
When you have a bulk capacitor on a time varying load, what is the relationship between the capacitance of the bulk capacitor, the ESR of the bulk capacitor and the ripple current through the bulk capacitor?

CAPACITANCE

It is my understanding that as you increase the capacitance, the voltage ripple will decrease, but the ripple current in the capacitor will increase (assuming a constant load and constant ESR).  The voltage ripple is caused by the voltage drop of I_source flowing through R_source (neglecting source inductance for this explanation).  Therefore, if the voltage ripple decreases (like when you increase the bulk capacitance), then the ripple on I_source has also decreases, because of ohms law. And if I_load is constant, then I_cap must increase because I_load = I_source + I_cap.  Therefore, it would seem, that increasing the bulk capacitance would actually increase the the ripple current in the capacitor.

Is this correct?  I am working on project where we need to decrease the ripple current in the capacitor, and everyone is talking about increasing the value of the capacitor.  Either I'm an idiot and missing something very fundamental, or everyone is gaslighting me.

I guess another way to think about it would be if you decreased the capacitor value to a tiny number, like 10pF, the ripple current wouldn't skyrocket, it would get tiny also.

ESR

Based on datasheets I've seen, ESR decreases as capacitance increase, within a given series or electrolytic capacitors.  Is ripple current through the capacitor proportional to ESR or inversely proportional to ESR?  I would think that capacitor ripple current would decrease as ESR increased because you can think of the capacitor as a parallel voltage source and the ESR as the source impedance.  As you increase ESR, more of the load current will come from the actual voltage source, and less from the capacitor.


texts: Use of Heaviside operator versus Laplace transform in electrical engineering

texts:
Is there a significant difference between Heaviside Operator p and Laplace transform operator s?

I'm wondering why Laplace transform is more commonly used to solve electrical circuits than using Heaviside operator?

Most books do not tell even about Heaviside but mostly Laplace transform. Is one method superior to the other one?


texts: Is there any possibility to override dimension text in Altium?

texts:
I need to place a dimension on a assembly drawing. One of the element I need to be measured shown with a cut (see the arrow place):

So the wire need to be 200 mm, but the dimension text is only 18 (exactly the size on the drawing). I need to replace this text manually.

However the text in the textbox "Sample" is not editable. I can not hide wrong text either.

Any ideas how to make this possible?

UPDATE

Just found one way to go: in the format section choose "None" and the text gone:

However I'd like to keep the question for any case there is any better solution.


texts: Why would you attach a Diode to the base of a BJT?

texts:
I was looking at a DC BJT setup for sourcing current and came accross this

I have never seen a diode attached to the base of BJTs before and was wondering what it might be used for? I believe it might be used for compensation due to effects in temperature, but I haven't seen much info on this or why you wouldn't bridge the voltage at the base of Q1 with a resistor instead. Does anyone have any suggestions to why you might do something like this?


texts: Samsung Powerbot vr9000 reverse engineer PCB connections

texts:
I've been reading along for quite some time and now I would like to ask a question of my own.

Samsung has a vacuum robot series, with a variety of models that mostly only differ in the software. PCB's etc are the same, besides the new model having an additional WiFi module and some vacuum motors needing an additional motorcontroller.

I myself have the VR20H9050UW, or also called the VR9000, superseded by the 9250, which is actually also the 9350, that only features an additional WiFi-module and a different firmware version.

Since the robots run on open source software (as per http://opensource.samsung.com/opensource/vr9000h/seq/0 ), it should be possible to access the filesystem and for example add the Wireless tools needed for the WiFi module to function, right? We could maybe even build a database with the different software versions (that are somewhat improved in cleaning algorithms overtime) and update our robots ourselves.

Here comes my question: I opened the robot to find out what connection possibilities there are on the PCB, and I found a 4-pin connector (accessible even without opening the robot, by a rubber clip in the housing: leading me to think this is the connection needed to communicate with the software) and an 8-pin connector. I figured the 4-pin would be an UART connection, it says bluetooth on top of the connector, so I took my HC-06 and hooked up the 5V (pin 1) and GND (pin 4) connection. With a multimeter I learned that pin 2 features a constant ±3.3V signal, and pin 3 hovers around 0.1V, thus matching the criteria for RX and TX. However both my HC-06 bluetooth module and my TTL cable don't provide me any data in the terminal with screen/picocom/minicom. I ran a python-script brute forcing the possible baudrates etc, however I got no response there either. Could it be possible that I need to enter a specific mode, before I could connect. Or, since libusb is used, could it be a plain USB-connector or maybe even another protocol/connection?

As to the 8-pin connector: it features 3.3V VCC at pin 1, GND at pin 8 and al the rest in between is 3.3V as well, except for pin 6, which is a steady 3.0V. Could this possibly be a JTAG connector and how could I verify that?

I provided a photograph of the PCB.  If it would be of any help, I can also measure the resistance between pins.

If you need any more information, please let me know.

PS: I am just getting to know the different StackExchanges. It's already on the regular Stack Overflow, but I figured it would better fit here. My apologies!

Edit: I have removed the serial-sticker from the chip, which reveals the PCB houses an NXP LPC2926 FBD144.
The PCB connected by the black wires at the top of the photograph, which is responsible for giving the power-up/boot command and switching between the different cleaning programs via three touch-responsive buttons, houses an ATMEGA32A.


texts: Confusion with PIC32MX1XX/2xx datasheet information (clock source for USB)

texts:
Maybe there are some experienced "wolves", who could help out to clear out confusion about internal/external clock sources. Particularly, I got lost while reading PIC32 family reference manual, "Section 6. Oscillators".

As for the fact, I know that using external oscillators are recommended for stability, accuracy and flexibility. However, I was trying to figure out if I would be fine using only internal oscillator of PIC32MX250F128D, I do have requirement to establish communication with PC using internal USB hardware.

At initial impression it seemed, that I'd be just fine, then I started reading in greater detail and notice that:

It states that internal oscillator isn't used for normal USB operation:

  6.3.4 USB Clock (USBCLK) Generation
  The USBCLK can be derived from the 8 MHz internal FRC Oscillator, 48 MHz POSC, or the
  96 MHz PLL from the POSC. For normal operation, the USB module requires exact 48 MHz
  clock. When using 96 MHz PLL, the output is internally divided to obtain 48 MHz clock. The
  FRC clock source is used to detect USB activity and bring USB module out of Suspend mode.
  Once USB module is out of Suspend mode, it must use a 48 MHz clock to perform the USB
  transactions. The internal FRC Oscillator is not used for normal USB module operation.

Another paragraph states that it can be used, even not very clearly:

  The internal 8 MHz FRC Oscillator is available as a clock source to detect any USB activity during USB Suspend mode and bring the module out of the Suspend mode. To enable FRC for USB usage, the UFRCEN bit (OSCCON<2>) must be set to ‘1’ before putting the USB module in Suspend mode.

Then from block diagram, we can see that for the USB we need clock signal of 48MHz, however internal clock is only 8MHz, and it doesn't go throughout any multipliers to USB block:

Actually, once I written this post it became more clearly. I still have questions such as, if my goal is to use this MCU as USB device (CDC class(to act as virtual serial port)) I may not need full speed of USB, therefore it may be enough just to use internal clock source of 8MHz? Otherwise, could we conclude that there is no other way out except using external oscillator based on my requirements.


texts: Replacing NPN Transistors that failed with similar/better?

texts:
I have done some research about this before hand(https://www.electronics-notes.com/articles/electronic_components/transistor/choosing-replacements-transistors.php). I have a switching 12v dc power supply that had been running perfectly fine for several months until it failed during a rather hot day. The power supply is passively cooled(although it will be actively cooled after I reassemble everything). Once the failure occurred, I tested the components, no bad shorted or bulged capacitors. Only failure was two e13007-2 npn transistors  on the input side of the circuit(most likely heat related, as through my research that is their most common cause of failure). Replacing is not physically difficult, and with active cooling I probably could replace them with the same transistor but I am having a hard time finding it available for delivery anytime in the near future.

Since I am not too familiar with npn and pnp transistors, I am asking; would the similar, more available, 13009 npn transistor be an acceptable replacement for the e13007-2 transistor?


texts:
I'm a beginner, I'm working on a new project to light up LED with my phone (through WIFI). I'm using Arduino Uno, nRF24L01, LED, breadboard and jumpers.
I don't understand how can I program the Arduino to only turn on and off the light when I press a button in my application, and also I don't know which application supports nRF24L01 since every guide I'm looking at shows that I need TWO board - Tx and Rx. I thought nRF24L01 could enable me to control the Arduino board through WIFI, why can't I only use it as a Transmitter?
Which application can help me control the nRF24L01 (like Blynk for ESP8266)?
Can I use only the code for Tx to operate the board?
Thank you


texts:
Hello I will use this circuit to put lights in a model car:

Now the question is if you can see is required one ATMEL AVR ATmega168P with CPU clock frequency to 8 mhz and I can´t find in any place something with 8 mhz. For example:

http://www.mouser.com/ProductDetail/Atmel/ATMEGA168P-20PU/?qs=sQl1Qs3BAuUB3FY8Qd8AOQ%3D%3D

http://www.amazon.com/ATMEL-ATMEGA168P-20PU-ATMEGA-20MHZ-DIP-28/dp/B00MMYP0AM/

I heard about the ATmega168P-PU like the link at top but in specifications they say 20mhz. In resume any place I found 168P I can´t see something that say 8Mhz. Can I use for example that chip amazon sells and does not affect in the function?

I bought this programmer also:

Atmel AVR AVRISP mkII AVR ISP mk2 USB XPII Debugger Programmer for Studio 4/5/6
eBay item:251058218265

I hope you can help I have everything I just miss the 168P 8Mhz or if someone know where can I buy.

update:

Then in conclusion I can buy

http://www.amazon.com/ATMEL-ATMEGA168P-20PU-ATMEGA-20MHZ-DIP-28/dp/B00MMYP0AM/

And I will be safe ok?


texts: Right settings for the voltage ripple measurement?

texts:
Background:
I have been assigned to monitor the signals related to TPS61091 boost regulator section. I am particularly keen with respect measuring the ripple on the 3.3 V output voltage. I have Lecroy 20Gs/s oscilloscope.

Until now my search on the internet has yielded the below information.

To use the shortest possible probe length. I have the small ground spring with my probe, so i can use it
Measure voltage right across the source: for this, I am planning to probe the voltage directly across the output capacitor.
Probe settings to 1x: this I picked up from a TI application note. I cannot do this  probe settings to 10x, because the probes are fixed 10x ones.

My questions:.

Is point number 3 above still has any work around?
Are there any better practices I have missed out to measure the ripple accurately?


texts: Multimeter XL830L: How to know if it is AC or DC?

texts:
I have a wired heater controller attached on the wall. I lifted the controller and saw two power lines connected to it on the back. I was not sure how to measure the voltage. This Quora answer says:

IN ac mode, if it reads as zero then the output is either DC or Zero. If it is not zero then anyways the output has ac

But when I measured it with a cheap multimeter XL830L. When the knob at V~ 600 or 200, it read "20.0". Then I turned the knob to V- 200 or 20, it read 10.0 (but periodically dropped a little bit).
After measuring that, I completely detached the controller, and saw the back panel. There were + and - etched near where the cables were connected on the back. Then why did it read "20" when I the knob was at V~ 200.


texts: Single PWM input signal to H-Bridge DC/AC inverter

texts:
Im attempting to follow some of the multitude of h-bridge designs out there to create an inverter using power mosfets. While I can get the circuit to invert the polarity using the design in the first answer here: H-bridge - concern about mosfets, I'm only seeing .2v coming from a 24v supply. (I'm using IRF1405PbF n-channel and SUP53P06 p-channel fets) - from what I've read I'm not saturating them properly so they get hot and don't fully switch.

The outcome I'm after is to convert a DC voltage to AC at a higher than 50hz frequency in order to drive some Christmas light strings that have half the leds in each polarity without flicker.

Could anyone point me to a bridge schematic that would allow for a single PWM input (to control freq and most likely provided by a rasp pi). Or, anther way to generate a greater than 50hz AC supply from DC at around 24-30v/5A?


texts: Is this circuit one or two-port network?

texts:
Below is a two-port network representation:

And what I understand so far according to the definition of a two-port network, there must be two independent variables and two dependent variables as in the above figure. And a port's input and output current should be same to call it a port.

But how about the following circuit from this text?:

Is the above circuit a "passive two-port network" as the text claims? Or is it a one-port passive network?

There is only one independent source in that network above which is Vin. Vout is dependent on Vin; so it is not independent for me at least.

So is this type of passive networks are two-port or one port network?

Is there a practical example for a two-port passive network ?


texts: Will a resistor fixed just in front of an op amp change its gain?

texts:
We have a circuit as shown in the image. Now if we didn't have the resistor Rp, the circuit is a simple negative feedback circuit with gain given by -(R2 / R1).
But the presence of Rp changes the circuit. However, what I think is that since no current flows via an ideal op amp, hence no current flows via Rp, therefore its presence changes nothing. So the circuit is the same without Rp, hence the gain of the circuit in the image it's still -(R2 / R1).


texts: Can I plug 4 Ohm speakers to 16 Output directly?

texts: I have Samsung YP-U3 player with Earphone Output 20mW (16Ω) and I want to connect it with speakers taken out from my old laptop that are two 4Ω (1.5W). Can I do it directly or speaker will break down shortly and If I cant't how could I match input to output. Adding 15Ω resistors in series will match them?


texts: Why is the upper part of a Leyden jar terminated with a small sphere?

texts: I often see pictures of Leyden jars that have a small ball attached to the end of the upper connector, was it just a question of aesthetic ?


texts: How do I determine the range of wire wound adjustable resistor?

texts:
I'm looking at buying a 300W tubular adjustable resistor. Like this:
https://www.digikey.com/product-detail/en/vishay-dale/RBEA03001R000KFB00/541-10193-ND/9765057

Digikey has four part numbers in that RBEA series, 1Ω 25Ω, 50Ω, 100Ω. All of them are 300W, For any of these, how do I know the adjustable range for a given part number?

UPDATE:
For background, I want to build a dump load and I  would like it to be a little bit flexible, if I can. I'll end up wanting somewhere around 0.5Ω to about 2.0Ω per resistor (I'll probably have four of these in a 2S2P array). It doesn't need to be quick to adjust, and the resistance doesn't have to be dead on. I'll be dumping a max of about 600W and have a plan for a fan and nothing flammable around.


texts:
I am designing a PCB which has a micro and some chips that work with I2C.

I have used pull-ups (4.7 kOhm) to VCC (3.3V in my case) on the lines. Just like the picture below. I added 150 Ohm resistors myself...I have no idea if they are necessary or not but I have heard a low value series resistance can help with reducing noise??

Regarding termination, I have read official documentation Every I2C bus must be terminated. The problem is, there are no schematic/photo on that page and I can not understand what they mean in that page.

My naive understanding of termination is that the bus should be end-up with some resistors, something like:

So, what should I do?

Keep the series resistors?
Add termination resistors at the end? if so to ground or VCC and what values?


texts: Use Teensy 3.2 in breadboard without soldering

texts:
I bought a Teensy 3.2 board, and the package included some headers:

I want to use the Teensy in a breadboard, and so I plugged in the headers and put the entire thing in my breadboard:

The little holes in the Teensy and the header pins don't make a good connection, so I have to apply some sideways pressure to make it work. I guess the intention is that I solder those pins to the Teensy, right?

I don't have a soldering iron right now though and I would like to keep the Teensy in its current state, so is there another way to connect it to a breadboard? Thanks for the help!


texts:
I at the moment using the LTC2364-16 ADC. I notice some linearity issues in my application for specific ranges of the ADC conversion.
I have a sine wave as my ADC input.
The linearity issues can be seen in the attached images (the results are converted to decimal, meaning 2.5V=65536)

The input window of the ADC is  0 -2.5 V. I am using the LTC6655-2.5V voltage reference to supply the two reference pins of the LTC2364. For the VDD power supply I am using an NCP512-2.5V voltage regulator and the 0VDD is supplied with 3.3V, coming from another board in the system. I have used the stated (in the LTC2364 Datasheet) capacitors to bypass the two reference pins and the supply pins to ground.

In the past I have supplied the reference pins with 3.3V giving an ADC input window 0-3.3V, but the result was exactly the same and I was missing codes in the exact same spots (i.e.: 49300-50000 codes).

I have also connect directly a function generator to the ADC input and the result remain the same. So the problem is not caused by the input circuit.

At the beginning I assumed that it was due to noise in the reference pins. That was the reason I put the LTC6655-2.5V, but no difference.

The fact also that the conversion does not stuck to a specific code, but there is a fluctuation as can be seen in the second  attached image, is not helping me to draw any conclusion of what causing the problem.

I am not sure if you have come across that kind of  problems in the past,
or if you can suggest me what else I can check.


texts: Differences between parallel resistor-capacitor filters and series resistor-capacitor filters

texts: I've only worked with series resistor-capacitor filters before, so I'm not very clear about the operation of parallel resistor-capacitors filters. Can somebody explain to me what are the differences between them and series resistor-capacitor circuits in terms of operation? Any help will be much appreciated.


texts: Effect of radiation detectors on electronic components

texts:
After the Fukushima nuclear disaster that took place in Japan in 2011, any imports from there are checked for nuclear radiations using radiation detectors.

I recently ordered components from Digikey but it will be tested for radiations because at the customs they suspect that one of the ICs is made in japan! Since I don't know much about how these radiation detectors work, Can they cause any type of harm to the ICs (Processors, FPGAs, memories, optocouplers, opamps, ...etc) ?


texts: Is it legal to create your own stm 32 board

texts:
Is it legal to create your own board containing STM 32 controller and advertise it commercially?

I have made a custom board and want to advertise it - is it OK? Any legal/copyright issues? If yes how do I address them so that I can advertise safely?


texts:
I have a USB C powerbank and require it to power a "dumb" circuit, i.e. just a USB C connector with, for example some LEDs on it. There is no microcontroller.
I used a voltmeter and a USB C breakout board, connected to my power bank,  to see if there is any voltage on any of the pins. I got 2.3V on CC1.
Do I need to set up any PD options, e.g. just with pull up resistors to get 5V by default, e.g. on V BUS?


texts: What happens if you overcharge a 3V supercapacitor to 5V?

texts:
Is there any physical risk of damage, such as fire or explosion, with overchargering such a low rated capacitor to 5V?

Assume the Capacitance of the supercapacitor is 5F. You can further assume it's this supercapacitor.


texts:
I just want to use a BJT transistor to act as a interface between a microcontroller and a MOSFET. I need to turn on and off an N-Channel MOSFET for controlling a much higher current on high voltage. A power N-channel mosfet, as far as I know, requires at least 10V Gate to Source voltage to achieve the minimum On resistance. I have 12V on my board so I decided to use that 12V for turning the MOSFET on.
The schematic is shown below.It seems that this BJT won't switch on that way?

How can I use NPN Transistor to turn on and off the MOSFET without inverting the signal?

Thanks!


texts: AV Receiver playing music using RCA Analog input (AUX) from Mobile 3.5 mm stereo source

texts:
I have a pioneer AV Receiver VSX-832-K with RCA AUX INPUT "input (Sensitive/Impendency  ) 200mv/47K ohm"
issue :
when i am trying to play music from mobile using 3.5 mm headphone jack using RCA cable connected to AVR, music is coming with low volume with distorted audio like imbalance of base/treble/loudness/voice
if i use source from Blu-ray RCA out put, sound quality is perfectly fine
2.0vms (1khz,0DB),600Ohm  RCA Jack L/R
Query : what circuit can be used to convert mobile 3.5 jack out put compatible with AVR RCA input to have better sound quality, i observed that cheap audio system is playing audio without much noticeable distorted audio but it is really bad if i hook it to my AVR VSX-832-K
https://source.android.com/devices/accessories/headset/jack-headset-spec
Mobile 3.5 mm head phone jack specification
Maximum output voltage drive    150mV   >= 150mV on 32 ohm
Headset Speaker Impedance Level Device Support  Notes
Low Threshold Detection : Headphone (low) < 1 Kohm
High Threshold Detection :Line In (high) > 5 Kohm


texts: There are different ways to wait on a signal change in VHDL. In my testbench I need to wait on a signal but if it does not change in say 100us, then I must continue the test. How to do this?


texts: Is this differential RC filter needed on a reference voltage?

texts:
What is the use of the differential RC filter at the end of this op amp (at least I'm seeing R100+R98+C28 as that)?
P3_3V_REF is a reference voltage for the 4 ADCs in the TMS320F28377D-EP MCU. An article from LT explains to me the reason for using the buffer after the reference voltage IC when providing a reference voltage to multiple ADCs from a single source. I could understand why you might want an LPF on your reference voltage to cut out any high frequency noise, but I dont see the need for it to be differential. So is there any reason for R98?
Thanks


texts:
When calculating the active power in the 3 phase Star, and Delta formations, there are two different currents used depending on the layout. I have shown my working below, with what I have been taught.

However, I am wondering why when calculating the Active power for the star connected formation we use \$I_{phase}\$ for the calculation. Whereas in the Delta connected formation we use \$I_{line}\$. What is the reason for this?


texts: Is it possible to achieve 0% to 100% PWM duty cycle with AT90PWM3B?

texts:
I want to implement fast PWM generator using AT90PWM3B.

The chip itself has three 'Power Stage Controllers' (pwm generators). Each PSC controls two outputs (A and B). For each output there is a SET comparator value and RESET comparator value. On counter value with SET the pin goes high, on match with RESET goes low.

Since I want to use only three channels, I am going to use Channel A of each PSC, and use channel B to set frequency (counter resets on match with RESET B).

Because of that, I selected the 'one ramp' operation mode, which is defined as:

I am going to set:

OCRnRB (RESET B) to value defining frequency. The PSC frequency (counter frequency) is 64MHz, I need output at 100kHz, so I'm going to set it to 640.

OCRnSB (SET B) to same value as RESET B, I'm not going to use this value

OCRnSA (SET A) to 0

OCRnRA (RESET B) to 'Duty Cycle (0.0 - 1.0) * 640'

Now I want to know what is going to happen on border values:

When SET A == RESET A - Is the On-Time going to be 1-cycle or 0-cycle?
When SET A == 0 and RESET A == 640 - Is the On-Time going to be 100% or 100% - 1 cycle?
How can I get zero 'Dead-Time 0'? According to image from datasheet it cannot be less than single pwm period.
Is there any way to get full range from 0% to 100% (inclusive)? I don't want to completly disable PSC, because I still want to use turn-off-on-compare feature. However, if possible, I can disable PSC at 0% if it's possible to keep it at 100%.


texts: Understanding why an OPA27 is unsuitable for a window comparator and a MC1458DR is better

texts:
I'm a junior electronics engineer and have a question about a window comparator circuit I've built:

Circuit Explanation:
The op amps have a tight reference voltage on their non-inverting terminals. U1A pin 3 is set to 5.025V with precision resistors and U1B pin 5 is set to 5V.
The inverting pins of both op-amps are tied to a 0-10V input signal that varies depending on an external system.
The outputs of both op amps are tied to the LED of an opto isolator (U1A output = Anode of the opto-isolator, U1B output = Cathode of the opto-isolator). When the input of the external system providing the 0-10V signal is in the window of 5V - 5.025V, the opto-isolator will be active as U1A pin 1 will be high and U1B pin 7 will be low therefore pulling the opto-isolator to ground.
The Problem:
I originally tried using 2 x OPA27 op amps instead of a dual package MC1458. When I initially tested the circuit, the opto-isolator would not switch and the voltage on the inverting terminals of the OPA27 devices started to "follow" the 0-10V signal (by this I mean as the voltage on the inverting terminals swung linearly between 0-10V, the non-inverting terminals no longer remained at their fixed precision voltages as defined by the resistor ladder).
My question is why did the OPA27 not work in a window comparator configuration while the MC1458 has no problem? The MC1458 is not a comparator. It is, much like the OPA27, a general purpose op-amp. They both have similar Common Mode Rejection but I can't seem to understand why the MC1458 is better for the job (and ultimately, why the MC1458 worked but the OPA27 did not).
Any help would be greatly appreciated - Apologies in advance if anything similar has been asked or if this is a really rookie question.


texts: Side effects of using a motor with a greater current on a battery with a lower rated current

texts:
I'm looking to power a 33A brushless DC 2000w 48v motor.

Ok so I have a lithium ion battery, and it's manufacturer states this:

Specs:

48v
1000w
13s3p
28Ah
Rated discharge current: greater than or equal to 10A
Maximum instantaneous current: 40A
Maximum operating current: 13A

Now if the max operating current is 13A, then why would it say it comes with a 25A BMS?

Either way, my question is: with these specs, will my motor fry the battery? If not how long could it run on a charge?

Here is the manufacturer's description:

  48V 28Ah 1000watt 13S3P 18650 Battery Pack MH1 54.6v E-bike Electric bicycle battery Scooter with 25A discharge BMS with charger

high capacity 48v 28Ah 1000w 13S3P Lithium ion Battery Pack For 54.6v E-bike Electric bicycle Scooter with discharge BMS
Product Parameters
Battery brand:okoman
Battery Type: 18650
Single cell voltage: 3.7V
Combination: 13 Series 3 and
Nominal voltage: 48V Input voltage: 48V Output voltage: 48V
After the combined capacity: 28000mAh (28Ah)
Battery Dimensions: 238 * 66 *60mm (There may be a 10 mm error) 3 * 13
Outside packaging: Blue PVC
Inside with protective circuit: overcharge, over discharge, over current, short circuit protection!
For other needs can contact the owner, thank you new and old customers.

The battery charging requirements: please in the shop to buy another charger!
1: the need for a dedicated lithium battery charger;
2: Charging voltage: 48V
3: Charge current: greater than or equal to 5A

The battery discharge requirements:

1: Output 18 lines, length 200mm, red and black each one
2: Enter the outlet line leads to a 2.1 length 200mm
3: Rated discharge current: greater than or equal to10A
4: maximum instantaneous current: 40A
5: Maximum operating current: 13A


texts: How to measure voltage in a PS/2 keyboard cable?

texts:
I have an old PS/2 keyboard, I doing a future project with it, but for now I just want to measure the voltage in the cable. However I don't know how to do it, so let me explain.

It's a PS/2 keyboard, and I have a P2/2 adaptor that transforms it into a micro USB cable that get's connected to the PC.

It has 4 wires:

Red: VCC power
Black: Ground
White: Clock
Green: Data

The circuit looks basically like this (apology for my drawing)

The mini USB is connected to the computer, then it's transformed into a PS/2 cable via an adaptor. The adaptor acts as some kind of resistance. Then the wires are connected to the keyboard via a PS/2 port.

I have basically drawn the 4 wires as they are there, I have removed the external insulator cable on that segment in the drawing so that I can measure the voltage.

I have measured the voltages at the points illustrated on the picture.

A1->A2 =   0.6 mV DC

B1->B2 =  0.6 mV DC

C1->C2 =  2.2 V DC

D1->D2 =  5.22 V DC

I have also measured the voltages between the wires, after the adaptor:

A2->B2 = 5.24 V DC

C2->B2 = 5.24 V DC

D2->B2 = 5.24 V DC

So I guess the (black) ground cable is like the return path of the circuit since A2,C2 and D2 have 0 Volts between them, they are only connected with B2 separately.

Meanwhile I have also measured the voltages before the adaptor:

D1 had 0 Volts between all other points

A1->B1 = 5.25 V DC

C1->B1 = 3.05 V DC

A1->C1 = 2.2 V DC

Question

The question is what is the voltage in the "Yellow Area", meaning in the wires that go out of the adaptor and go into the keyboard.

So my goal is to determine how much watts of power the keyboard uses, so I would need to multiply the voltage in each cable "going out" with the amperes going through each wire and add them together.

How to measure exactly the voltage in the yellow area?

So which measurement is the correct measurement from above, in order to determine how many volts there are in the wires in the yellow area. And use that volt to multiply with with the amperes flowing through each cable to determine the watts of current that the keyboard uses.


texts: I know that ratio R1 to R2 determine the output voltage of LM317. E.g. R1 = 200, R2=330 ohms will produce about 3.3V. My question is, what if I use 2K and 3.3K for R1 and R2? What is the impact of increasing the resistors values but keeping the ratio the same?


texts: How do I use T-Flip Flops to derive circuits - given the clock signal speed?

texts:
I've been trying to do my EE homework for several hours and cannot figure out how to do this stuff.. I've read through the chapter multiple times, searched YouTube and Google, and nothing seems to help at all. So I thought I'd give this a shot.

I'm given a problem that tells me the starting clock = 100MHz. I'm asked to derive a circuit using T-Flip Flops to generate 50MHz and 25MHz signals.. and to make a timing diagram for all 3 signals.

I can't stand EE, but it's a requirement for my major unfortunately :/

If anyone can help me out, I'd greatly appreciate it. Thanks!


texts: Circuit help. I want a Voltage gain from 5 volts to 10 volts.

texts:
I need some circuit help.. I am trying to boost my voltage from a 5v source to a 10v output so I want a Gain of 2. I Ran the simulation and built the circuit exactly how it is shown in the figure below. I am using an op-amp 471CN and when I test the circuits output (Vout) I still only get a 5 volt output. I'm fairly new at this so can anyone help me with trying to figure out why i'm not getting 10 volt output. I'm sure it's simple but I just don't see it now. Thank you for your time.

simulate this circuit – Schematic created using CircuitLab


texts: "IF" statements in a process do not work properly

texts:
My VHDL code doesn't do what I need it to do.
I have an incoming 8-bit code that I need to grab by the "button" "reset", then I need to return the number of rhe first "1" there is in this code. for this I am copying it into sub sequence and pushing it until there is a "1" in the end.

but "q" doesn't stop incrementing some how...
What is wrong?

library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;

entity count is
    port
    (
        clk : in std_logic;
        reset   : in std_logic;
        start   : in std_logic;
        q       : out integer range 0 to 7;
        sequence : in bit_vector (0 to 7)
    );
end entity;

architecture rtl of count is

signal sub_seq : bit_vector (0 to 7);

begin
    process (clk)
        variable   cnt  : integer range 0 to 7 := 0;
    begin
        if (rising_edge(clk)) then
            if reset = '1' then
                sub_seq <= sequence;
            end if;
        end if;

        if reset = '1' then
                cnt := 0;
                sub_seq <= sequence;
        end if;

        if ((reset = '0') and (sub_seq(0) = '0')) then
                cnt := cnt + 1;
                sub_seq <= sub_seq sra 1;
        end if;

        if (start = '0') then
                cnt := cnt + 1;
                sub_seq <= sub_seq sra 1;
        end if;
    q <= cnt;
    end process;

end rtl;


texts: Current Transformer flux and back emf with only one turn

texts:
Having looked for a number of days on the internet and studied to the best of my ability I am a little stumped on the current transformer flux linkage.

From my basic understanding of a voltage transformer, as a CT can be viewed as a step up VT.

A current in a coil of wire lags the voltage by 90 degrees due to inductive reactance.
This has a flux linkage in an iron core which induces a back emf to a secondary coil of wire which corrects this phase displacement (+90 degrees). and produces a current in phase with the primary voltage.

My difficulty in understanding the CT is that they usually in my industry have only one turn on the primary which is therefore not an "inductor" so how is the secondary of a CT in phase with the primary when there is no initial 90 degree displacement?

Thanks

Hope this makes sense

Ben


texts:
I'm exploring an old device that detects RF frequency. It has a generator of bipolar spike pulses +-1V interleaved by 0V sections, diodes and antennae (L1).

simulate this circuit – Schematic created using CircuitLab

I have some basic issues understanding the principle of this simple circuit. I'm therefore seeking an advice or correction to my reasoning.

I think by design it was not set to the resonating frequency that matches the RF signal of 20khz. All values are actual, but I'm a little bit unsure of L1, it was measured with an ad-hoc arduino circuit.

Looks like positive V1 pulse is getting to the ground via diodes.
The negative pulse charges capacitor C1.
The resistor is here to make some little current flow just to catch up the RF.
C1 starts discharging when V1 rises from -1V to 0, this should make the negative spike smoother.
The C2-L1 catches some part of the RF wave, inducing some potential (positive or negative).

I'm having difficulties to understand how C2-L1 affects the current in the circuit.

The circuit also drives a transistor Q1 (always open) that controls the LED. The transmitter is another device, its frequency can be adjusted and when it matches the V1 frequency, the LED goes almost off.


texts: Ideal operationnal amplifier with source

texts:
I was wondering... I have read about ideal op amp, that we could change this circuit :

Into this one (with the ideal model), where the input resistance Ri is infinite, and the output resistance negligible (so Ro = 0 Ohm) :

simulate this circuit – Schematic created using CircuitLab

We then told me that, since the Ri is infinite, the voltage at node A is zero (since Vi = 0), so Va = 0 (node voltage).

But what happens if we have that?

simulate this circuit

Will the voltage at A still be zero? Does it changes absolutely nothing to have Vs2 there? I'm confused on this one. I've seen only problems with the + gate of the op amp at ground.

Thanks!


texts: How to "push buttons" on voltage ladder?

texts:
I have a quite simple task I can't wrap my head around. I have an old home 5.1 sound system with optical input that plays sounds from my media center. Its remote broke, and while I tried to fix it, I understood how much I hate having one more remote on my desk.

I'd like an microcontroller to "push" the required sequence of buttons to wake sound system up and make it switch to desired AV2 audio input.

I found service manual with schematic in PDF, it appears that buttons are just a "voltage ladder":

The device guesses which button was pressed by measuring the resistance (ranging from 200 Ohm to 1K). In theory I can easily solder 2 wires and apply the required resistance between them myself.

The problem is that I don't really know how to do that.

Do I need to make an array of transistors with similar resistors and close the circuit through required resistor one at a time? But won't the voltage drop on a transistor make this approach impossible?

Or should I use some form of analog output (PWM + "low pass filter")? But won't the voltage of my microcontroller fry the circuit of the audio system?

I can fit a relay board inside, after all, but it is stupid.

Please point me in the right direction.

(as far as I can understand, the circuit operates on 4.8V)


texts:
I am new to Arduino, so I purchased a starter kit with a 800 pins (or something like that) breadboard.
I would like to know if it is possible to cut it (or saw it) in half on the long side in order to have 2 still working, squared breadboards.

Thanks!


texts: As stated in the title, Can I produce small signal gate-source voltage by applying small signal source-drain current? There is no doubt that I can produce Ids by applying vgs, what about the other way around?


texts: Need help with circuit to sense model train direction

texts:
I'm fairly new to digital circuits, so please be patient.
I'm designing a circuit intended to sense the direction of a model train. The intent is to use 4 reed switches (SW1 to SW4) to feed 4 SR NAND latches. SW1 and SW4 are used to reset the latches.
The logic I used is:
When the train is going from left to right, SW1 will reset the QLR and QRL latches. Then, SW2 gets activated, and QLR is set to high. When the train hits SW3, QRL remains in its current state (0) and LR latch is set to 1. Finally, when SW4 is activated QLR is reset.
The problem I'm having is that, when SW3 is activated, the LR latch does not get the logical 0 out of the inverter.
The moment I connect the Q output of the QLR latch to the inverter (7404) my QRL gets set to high.

Any help reviewing fundamental issues with my design will be highly appreciated


texts:
I have a Teensy I2C bus driving a PCA9306, which happily talks to multiple ATMEGA32PBs on separate cards connected to a backplane.
Some of the cards require isolation and work on a lower voltage. For this reason, I have an isolated DC-DC converter and an ISO1540DR doing the I2C level translation from the 5V side of the PCA9306 back down to 3.3V and providing isolation. So the order of devices looks like:
Teensy <3.3V> PCA9306 <5V> ISO1540DR <3.3V> ATMEGA328P
The PCA9306 doesn't seem to like driving the ISO1540DR - is there some way around this or a more suitable replacement I could use in place of the ISO1540DR?
Edit:
What I have just realized is that I think that side 2 of the ISO1540DR may be better suited to the backplane side, and side 1 to the microcontroller since side 2 can sink/source 100mA and side 1 just 20mA.
Teensy side PCA9306:

ATMEGA side I2C:

PCA9306 datasheet
ISO1540DR datasheet


texts:
I have a CD4026BE Connected as follows. (leds is actually a 7 segment display) When i toggle the clock from pos to neg nothing happens.  IF i keep clock on pos and toggle clock inhabit, it will start counting.  Why does the clock input not work?  I was hoping to use the clock inhabit to stop the counting of the clock input.

simulate this circuit – Schematic created using CircuitLab

simulate this circuit

Cleaned-up schematic.


texts: inQuiescent Current with Downsteam Devices

texts:
I have a circuit with a regulator (TI TPS61098 datasheet) with 300nA
Ultra-Low Iq in "low power mode". What is the total current draw if I have other downstream devices with leakage current when the system is in "low power mode"? Let's say my input voltage is 1V and output is 3.3V.
Will the TI regulator only draw 300nA from the input rail or I_input  = 300nA + (Downstream Leakage Current x Efficiency x 3.3/1) ?
Thanks!


texts: Does potential difference exist between Earth ground in geographically diverse locations?

texts:
Earth ground is used as a reference from which all voltages are measured in systems which are earth grounded. Because the earth absorbs or dissipates nearly unlimited electric charge, it should always be at an ideal zero or ground potential. (Barring such problems as corrosion or improper grounding.)

I understand that high voltage transmission lines do not simply have a ground at each end of the system; that multiple ground connections are utilized throughout the length of the line to keep things consistent. This is because conductors are imperfect, etc.

My question is, if you could measure the potential difference between two distant points, both earth grounded, using an ideal superconductor, would there exist any difference (if so, why)? Is the "zero reference" on one continent the same as another? Common sense tells me it should be, it's the same earth. Someone asked me whether there would ever be a reason that they differ, and I couldn't say definitively.


texts: Best practices for using subcircuits and hierarchical blocks in LTspice

texts:
I'm designing a series of circuits in LTspice and wanted to get some feedback on the accepted way to use subcircuits and hierarchical blocks. The LTspice manual is somewhat vague on these topics. In the screenshot below, I've copied one section of my circuit to help illustrate the point.

The highest-level circuit contains a "V/F Converter" block which references a schematic with an LM331 chip. The "LM331" block in turn references the functional circuit for this IC. (LTspice doesn't include this component, so I found it elsewhere online.) I'm also using parameters that are passed down from the top-level block to the bottom-level LM331 circuit which set the logic and source voltage levels (note the "Vcc=12" and "Vlogic=5" parameters in the "V/F Converter" block). The entire circuit works fine and simulates the way I expect.

From a layout/organizational standpoint, are hierarchical blocks the right way to set this up in LTspice? Since the LM331 is an actual component, I'm thinking it might be better to convert it into a subcircuit using a netlist file instead of a schematic. As a subcircuit, I'd have access to the Components Attribute Editor and a few more fields for setting up parameters as opposed to the single PARAMS line that the hierarchical block uses. However, with the component as a subcircuit, I think the underlying schematic would go away since it'd be driven by a netlist. This would make the component a bit harder to debug since it would no longer be laid out visually.

At the end of the day, I suppose the functionality is the same regardless if I'm using hierarchical blocks or subcircuits (at least in this example), but I'm curious what the best practices are. Are there any advantages one way or the other?

Here are some screenshots of the two approaches. Note the difference in the editor dialog boxes and the Open Symbol/Schematic buttons.


texts: Why asynchronous counters can not work at high clock frequencies?

texts:
Asynchronous counters can not work at high clock frequencies and cause problems with decoding circuits. What does this mean in terms of timing and operation of the circuit?

Why a “re-synchronizing” output flip-flop may be required for these counters?


texts:
I am currently playing around with this Thermoelectric Peltier Cooler Setup:

I have read that it's possible to cool these elements down to more than -20°.
However, I got the elements for cooling an aluminum pipe, so I glued both onto the pipe to cool it down.

Its already cooling them down, but clearly not that much as I expected (Just around 0°).

My question is: how can I get more cooling\heating performance from the peliters?


texts: Op amp problem - unexpected simulation results

texts:
I am referring to the accepted answer in this question

The answer has 25 votes, and is picked as the best answer but after carefully reviewing it, I could only come to a conclusion that it is not accurate or that I am missing something.

Here is the original Circuit:

A, What is the point of this so-called super-diode, where the last stage has already been off-set to vcc/2? (meaning the signal from last stage are all positive)

Here is my simulation. Clearly it's different than the simulation from the original answer.

B, That is a just differential amplifier however, it seems to be stretching the signal. It seems to me that in first stage, he adds (off-set) vcc/2 to the signal, and the last stage, he subtracts vcc/2 from the signal.

I am wondering whether I am missing something. Otherwise, I am wondering what the correct answer to the original question is.

Update: Here is a complete simulation.

Update 2:
I think I got it now. The circuit requires a real sound wave as input.


texts: Short sound when toggling a light indicator

texts:
What is that “click” sound we hear when a light indicator turns on or off on some very simple devices, like the lights that tell us when some flatirons or ovens are heating up?

I can’t open the circuitry of my oven just to find out what controls the light. What electric or electronic device which makes a little “click” when toggling its output could be used to control a light? And why would this device be better than a LED/transistor pair? (I’m speaking of recent devices, built in this decade, not my great grandmother’s charcoal flatiron!)


texts: Control Engineering: Model parameter estimation for a motor which will be under various loads

texts:
I am creating a closed loop controller for a motor which is part of a robotic arm. I give it a required angle, the controller calculates a control input, the motor moves, a pot feedbacks the angle, repeat, and the arm ends up at the required angle.

I am using state variable feedback, with integral action, and in order to calculate the control gains required for stability and speed I need a mathematical model of my system.

To get this model I am using statistical model identification techniques. I am inputting a random control signal into the motor, and recording this and the angle of the arm at each sample time. I'll then have sample input and output data of my system, and I can use a mathematical optimization technique to find the model parameters that best fit this data.

My Question

When under actual operation, the robot arm will be lifting a variety of weights. Does this mean the model I found with no load (intrinsic load) is invalid?

How do I get a mathematical model of this system when the load on the motor can change?


texts: Are there darlingtons more powerful than the ULN2803A?

texts:
I made a card controlling 24 electromagnets with an Arduino board via 3 darlington ULN2803A

My power supply for the electromagnets was 20 V and 300 mA for each electromagnet.

Due to the physical power of the electromagnets being too weak, I replaced my supply of 20 V by one of 36 V (the electromagnets support 40 V).

When I tried the new 36 V supply, it worked for a minute and then my ULN2803A burned!

However, the ULN2803A documentation indicates that they support 500 mA at 50 V!

Is there a Darlington that supports 36 V and 400 mA per channel, that I could use in place of the ULN2803A?

Or is there another way to control my electromagnets under 36 V?

Thanks for your help.
Did I understand right ?

Sunnyskyguy EE75, You warn me that the Solenoids will dissipate Pd=V²/DCR=36²/67=19W.

Half of my solenoid are under tension about Half a second every 2 seconds.
Do you think it will be OK ?

I wonder if to double the SLA5085 is a solution ?


texts:
I am trying to use this equation for difference amplifier to sense a max current of 75 mA.
However in my circuit I have no R4 so which equation should I use?


texts: How to interface with the Apple Watch for the purpose of accessing its internal memory?

texts:
Unlike other apple products which can be directly connected to a PC via USB, the Apple Watch is completely wireless from the point it exits the factory, as far as I am aware.

Aside from a 6-pin diagnostic port under the watches strap I am unaware of any method of connecting the device to a PC physically.

I need to be able to connect the device to a Windows PC such that I am able to make a forensically sound copy of the devices internal storage, in image format. By internal storage I mean any part of the device which stores data.

I am currently in the field of digital forensics however I have only ever worked with Windows and Linux, therefore my experience with Apple is limited.

What hardware could I use to extract the data I need from the device and/or where could I find more information on the matter?

Thank you for any input on the matter.

Although I have not received any information back from apple in regards to the hardware, through checking the device drivers that are available for the watch I have discovered further information on the types of storage that the watch uses.


texts: What current rating should I be looking for on a Battery Management System?

texts: I'm designing a power hungry robot and this is my first time constructing a battery pack. Specifically, I am going to use a 3(series) x4(parallel) 18650 battery pack using these Samsung 35E cells. The calculated max current draw on this battery pack would come out to be 32 amps. When finding a Battery Management System, should I be looking for one with a max current rating above or below(like this one) the calculated 32 amps of the battery pack?


texts: How does my 802.11 a/b/g/n wireless card determine the modulation to use?

texts: I was thinking yesterday about how the 802.11 a/b/g/n standards all use different modulation schemes, but my wireless card manages to detect frames from networks that may use any of those modulations. So, when my card detects a signal containing a frame from my neighbor's 802.11b network, how does it know to demodulate it with, for example, DSSS and not OFDM? Does it just attempt all modulations? Does it use some kind of signal sensing?


texts: Can I determine three circuit elements from an impedance curve?

texts:
I have impedance data (\$|Z|\$ and \$\phi\$) of a diode, measured at a fixed frequency but depending on the applied bias. The diode can be modeled as a series resistance \$R_s\$ and a parallel circuit a capacitance \$C_j\$ and \$R_j\$ (related to the junction).

simulate this circuit – Schematic created using CircuitLab

It's a bit long but it's possible to write down the analytical expression for \$|Z|\$ and \$\phi\$ of this circuit, so that only \$R_s\$, \$C_j\$, \$R_j\$ and \$f\$ (frequency) appear in it.
It seems to me there are three unknowns but only two parameters (\$|Z|\$ and \$\phi\$). Am I missing something or is it anyway possible to calculate all three elements from the data?


texts: How to prevent voltage droop when discharging a battery?

texts:
This is quite an open question, so apologies in advance if you would rather schematics and the like, if you really think this would help I can provide them

My problem: boosting from 2x AA Li batteries to 27V to supply an AC piezoelectric pump which resonates at 22kHz and draws around 1.2W.

On a stable PSU the system works great, I have a gate drive and H-bridge (which I design with help from this community so thank you to anyone who contributed to that part already!) and I get a good efficiency (as high as 92%) BUT when I swap out the PSU from batteries I see the following issue

The battery voltage drops significantly which therefore ruins my boost conversion.

I started at pumping for 1.5s then off for 40s. I shortened the pump cycle durations (this is to create pressure inside a steel canister btw) with the hope that I wouldn't be triggering the PTC fuse and increasing the battery's internal resistance - however this seems to still happen with shorter pulses

Is this inrush current? if so how do I make the current drawn more constant?

I've added 1000uF to the battery terminals so that some of the pulse comes out of their rather than the battery, which certainly helps but doesn't solve the issue

I'm using a load switch to turn on the boost converter (MT3608), should I stick to just using the enable pin? maybe the booster is still getting settled when I then use it (50ms later, maybe not enough?)

As you can tell i'm new to power supply design so maybe i'm missing something obvious

I've tried cascading two steps, battery to 5V5 then boosting to 27V but it seems like this doesn't prevent the voltage droop.

Based on consumption of the system and the expected capacity of the batteries I think I should get a lot more out of them, I know that it's not as simple as mAH as stated but i'm miles off

I would like to avoid feedback limiting the H-bridge itself since i'm using a standard MOSFET set-up and really need to keep all 4 FETs in saturation, so feeding back to reduce the gate voltage won't help me unfortunately


texts: Dual mode Bluetooth for transmitting audio and connecting with an App

texts:
Hi my name is Raveen Baloo from Singapore. Currently, I'm working on a project, building a case box which has a MCU and a LCD
screen. A removable bluetooth dongle is connected to the case box which will allow users to connect and display a message on the LCD screen through an mobile app.

Now, on the other end of the dongle, there will be an audio jack. Users can remove the bluetooth dongle from the case box, and connect
it to a radio or a walkman using the audio jack. Now, the user will be able to connect a bluetooth headphone with the bluetooth dongle.
This upgrades the existing radio into a bluetooth enabled radio.

I have done some fair amount of research but I'm still new to bluetooth technology and having a lot of trouble. Here are some of the questions that i have:

1) Since its going to be a removable dongle, do i need a separate MCU with the dongle?

2) Will I be able to use standalone bluetooth audio module (RN-52)?

3) Is there a Bluetooth audio module while will be able to both act as a receiver and transmitter?

4) Will it be better just to have a separate in-built bluetooth in the case box itself or a separate MCU chip in the Bluetooth dongle?

5) Which Bluetooth module out there is the best for this project?

I really hope someone out there will be willing to help me out to clear some of my doubts or to direct me to some good materials out
there on Bluetooth. Really hoping to hear from you guys. Feel free to ask me any question regarding this project.

Thanking in advance.

Best,

Raveen Baloo


texts:
This is a LTSpice model I created for a single electron transistor macro model:

.subckt SET 1 2 3

+pi=3.1415926535897932846
+CF1=40 ; 2CG/e
+CI2=0.2e-9
+CR2=100e+6
+CVp= 0.02
V2 5 3 DC CVp
V3 7 3 DC ‘-CVp’
D4 2 8 DIODE
D5 3 8 DIODE
RR1 1 3 R= ‘CR1+CR2*cos(CF1*pi*V(2,3))’
RR2 1 4 R= ‘CVp/(CI2-2*CVp/(CR1+CR2*cos(CF1*pi*V(2,3))))’
RR3 1 6 R= ‘CVp/(CI2-2*CVp/(CR1+CR2*cos(CF1*pi*V(2,3))))’
D2 4 5 DIODE
D3 7 6 DIODE
.MODEL DIODE D(N=0.01)
.ends

I got error message that symbols RR1, RR2, and RR3 are undefined. What does that error mean and why did I get it?


texts: Dysfunctional onboard LAN controller chip getting very hot, is it safe?

texts:
I have had an Intel LGA775-based motherboard (DG33FB) for about 8 years now, but for an year or so the LAN port was unreliable, sometimes working and sometimes not. No software solution was working, and it was an Integrated controller so there was no obvious hardware solution.

Recently a power surge (suspected) blew the SMPS, so I bought a new one. When I connected the 24-pin ATX power supply to the board (with NOTHING else, not even the CPU power connected), the entire "lower" area of the board (towards the PCI-e slots) near the ports was getting hot. By touch and an IR temperature "gun", I isolated the hotspot down to this 82566DC ethernet LAN controller (see below), which is unfortunately BGA-mounted. The chip and nearby components are apparently reaching nearly 100°C, even on standby! It's extremely likely that this was the case even before the SMPS blew, and obviously connected with the dysfunction of the LAN port. The LINK LED on the LAN port flickers under various manipulations indicating a loose contact. Don't know if the heating and loose contact are connected.

What should I do? I don't think I can just leave it like this, but a nearby repair shop said they don't do BGA (de)soldering.

Also, what is that glass-like "window" on the chip? Quartz window for EPROM erasure using UV?


texts:
I'm developing a battery monitoring circuit. There is a problem. I launch a survey of all ports ADG507. For the test, I connect only two power supplies instead of the first and second batteries. The second power supply is 0 volts, the first 6.5 volts. No problem, I read from the ADC value of 6.508 volts on the first port. I increase the voltage of the second power supply and read from ADC the correct value on the second port. But on the first port the measured value begins to decrease and continues to fall to zero with the increase of the voltage on the second port up to 7.347 volts. The measured voltage value on the second port is correct. On the first port is 0, but I did not change the value on the first port. The voltage value at the first port remained at 6.5 volts from the beginning of the experiment. What kind of miracles? Why is not the voltage at the first port measured correctly when the voltage at the second port rises? What's my mistake?

Measurement log

2018-05-30 10:53:17,702 INFO    tcpm.   MainThread  connected
6.508
0.000
0.000
0.001
0.001
0.001
0.001
0.001

2018-05-30 10:54:39,502 INFO    tcpm.   MainThread  connected
6.391
2.057
0.000
0.001
0.001
0.001
0.001
0.001

2018-05-30 10:56:11,119 INFO    tcpm.   MainThread  connected
4.066
4.067
0.000
0.001
0.001
0.001
0.001
0.001

2018-05-30 10:56:50,075 INFO    tcpm.   MainThread  connected
1.229
6.513
0.000
0.001
0.001
0.001
0.001
0.001

2018-05-30 10:57:42,671 INFO    tcpm.   MainThread  connected
0.333
7.374
0.000
0.001
0.001
0.001
0.001
0.001

The whole scheme with a controller and other kit is big. The problem is in the multiplexer circuit or (and) its interface with ADC. I append  the test  scheme  and a sequence of measurements.

Nothing works. Assembled scheme from the AD7705 datasheet page 41, assembled  my scheme, with resistors at the mux input, without resistors at the mux input, with connection 0 mux and ADC to 0 battery and without, in buffered and unbuffered mode of ADC. The voltage measurement is still incorrect. The ADC measured value at one input of the multiplexer depends on the voltage at the other input.  And when I turn off the power of the multiplexer the  inputs of the multiplexer without input resistors very heavily load the battery. What I doing wrong? MUX inputs scheme? My previous scheme assembled on the relay gives stable results of voltage measurement. In theory, it is possible to develop this scheme on multiplexers, or it is better not to waste time and leave the circuit on the relay?

(the text has been edited)
  I do not plan to power the multiplexer from the top of the battery stack, because the all battery stack is 48 volts but the power supply of the multiplexer is 16.5 volts max. And I dont need it.The entire battery is connected to the charger and I do not need to get power from it. I tried to isolate the power supply circuit using differential inputs and a DC/DC converter. I just need to measure the voltage on each cell of the battery. And now I made the test circuit (added to post) to just  to understand - why voltage behave strangely. If I could to understand this then the entire circuit with 8 batteries can be assembled without problems.

I use a two-channel power supply for testing instead of batteries and DVM Fluke 27II for measurement. Set A0=A1=A2=0V ENA=+5V to use only the first port mux S1A S1B. Now set the supply voltage CH1=6 volts, CH2=0 volts.  On the digital voltmeter we have 0.790 volts. I'm increasing the voltage onCH2. CH1=6V CH2=3V, and on digital voltmeter we have 0.774V. Continue increasing the voltage on CH2. CH1=6V CH2=6V, and on digital voltmeter we have 0.757V Why is this happening? Why the output voltage of the multiplexer decreases with increasing voltage CH2? How to fix?


texts: How do I make a discrete voltage detector?

texts:
I would like to design a circuit which has outputs LOW when the voltage it is connected to is below a threshold, like 3.3V.

There are some ic's you can buy to do this, but I would like to make my own so I can tweak the detection voltage for each specific application. From looking at the datasheets for these chips, it looks like they create a reference voltage and then use a comparator to compare the input to the reference, then that drives a transistor. Does that seem correct? Sorry if this is very simple, I am a noob :)

Thanks

Example IC by microchip: http://ww1.microchip.com/downloads/en/DeviceDoc/20001434K.pdf

Another example by ST: https://docs-emea.rs-online.com/webdocs/135f/0900766b8135f981.pdf

-Edit:

I don't need a very accurate device, the threshold voltage can vary quite a lot for my application. I found a voltage reference which is quite cheap and might be suitable, but I guess the reference voltage needs to be lower than the input voltage will ever be.

https://lcsc.com/product-detail/Voltage-References_TL431_C181103.html


texts: Limiting sensor input voltage without biasing measurement

texts:
I need to measure precise voltage in the range from 0.375 volt to 10.1 volts from a source with 100ohm impedance.  Maximum voltage however, may be well above 10.1V, so I need to be sure I do not exceed the ADC maximum.  The ADC I am using measures from 0V to 4.096V with an absolute input maximum input of 5.3V. Impedance is about 15 Mohm. Target accuracy is on the order of 100uV.

I tried using a resistor voltage divider with a combined resistance of about 1k ohm to reduce the 10.1V input to about 4.0V, and added a 5.1V zener diode as protection against excessive input voltage.  However, at 4V divided voltage, the zener has enough reverse leakage to drop the measured voltage by 10mV.

Is there a better way of using zeners?.  I simply put it in reverse between the divided voltage and ground.   Alternately, I could use an opamp to scale the voltage instead of a resistor divider, but that adds parts and complexity.

Any suggestions?


texts: How to analyze RL circuit with sequential switching?

texts:
I am trying to solve this question:

However, I am having difficulties solving as I only have come across circuits which are initially closed then opened, not vice versa as is the case here. Specifically, I am trying to construct the simplified circuit for t<0. Usually, for the latter case, the inductor is a short circuit for the 20 Ohm resistor if t<0. However, I am unsure how it acts as this circuit starts open and then becomes closed.
So far, all I have been able to do is to a source transformation, making the current source a 150 V voltage source and combining the 10 and 5 Ohm resistors.
Any help would be appreciated, thanks!


texts: Is some protection necessary for a RS232 link between PIC-MAX232-Computer?

texts:
I have a circuit with a dsPIC which communicates to a computer using a MAX232 (there ain't any optical isolation).

The circuit ground is not bounded to the earth. But the equipment case is earthed.
The computer is connected to the equipment through a DB9 connector on the rear panel of he equipment.

It works fine most of the time. But some clients (not much) after receiving the equipment  complain about the RS232 link, which doesn't work. When I get back the equipment I see that the MAX232 is not working, and I have to replace it (but it worked before, I have tested it).

Is there a "good practice" of putting some protection for the RX, TX after the MAX232, like a TVS or something? Or my mistake is to not bound the circuit GND to the earth to prevent voltage differences when the serial cable connects the equipment's GND to the computer GND?

edit: Device in question (from comments)