texts: Best value to overwrite old to tell if memory is not used on eeprom

texts:
I have an EEPROM I want to store CRC32 hashes on between 0x0000 and 0x008C. In this range I need a way that I can erase one of the hashes and overwrite its bytes to a default number. By doing this I can iterate through them later searching for a free space which was initialized to my "free space value" to store a new one at that position.

For instance if the memory looks like:

0A0A0A0A
0B0B0B0B
0C0C0C0C
0D0D0D0D

and I erase the third index by overwriting it with my place holder

0A0A0A0A
0B0B0B0B
????????
0D0D0D0D

I can then iterate 4 bytes at a time searching for a free space denoted by the place holder and then write my new hash to that location marked as free.

With that being said with a CRC32 hash, which value is the safest to use as a free place marker, 00000000, FFFFFFFF, or a specific other value.

Thanks.


texts: What component has the reference designator RY?

texts:
I found a component designated RY8015 which I don't recognize, shown on the photo below on an LCD TV PCB (the bulb-like part next to a green radial varistor).

What is it called? What is its design function?


texts: Protect power supply from regenerative drive

texts:
I am running a 3KW motor on a big 24Vdc power supply (Meanwell RST-5000), through a frequency drive.
When stopping the motor, however, I occasionally get a regenerative backcurrent that trips the internal overvoltage protection in my power supply. The voltage ramps up to about 28.5V. The supply is protected against this, but it does have to be manually reset and breaks the workflow.

What is a good solution to prevent this? Can I just hook up a big (+- 100Ah) Lead-acid battery in parallel to the power supply? Or will this give me other issues?

Please keep in mind that there are huge currents involved (+- 125 A)


texts:
I'm currently learning VHDL and to simulate the code that I write I found out GHDL (open-source), which I haven't tried yet but I think does what it needs to be done.

In order to synthesize the VDHL code into any FPGA, is there any free Synthesis tool or are they all vendor specific (and hence paid)? It would be great to find a general one which allowed to program into any FPGA since I still don't know on which FPGA I'll need to work and since each tool has a steep learning curve - I speak from personal experience with Xilinx's Vivado.


texts: Need help Identifying a resistor like component with orange and black bands

texts: This component was on a telephone that was mistakingly connected to the mains rather than the phone line. Any help would be appreciated!


texts:
This is a basic differential amplifier.

I want to modify it in order to have high input impedance (a few \$M\Omega\$ from DC to at least \$200~kHz\$)

I thought about replacing the CE pair input with a CC-CC cascade pair, or a Darlington pair, but I don't think they have good frequency response.

Any suggestion?

I don't really care about the gain, because I will use another stage for that purpose.


texts: Troubleshooting DTL NOT gate circuit design

texts:
My guide says that the following diagram is a DTL NOT gate. Its output is a LED.

For learning purposes, I tested  it via a simulator. The measured current is not really significant to power on the LED. Opening and closing the switch does not bring enough difference to perform negation as the reading nearly stays at 0.974nA. My understanding of negation is that when I open the switch, the current must be higher. I first thought to have a junction between the switch and resistor connect to ground, but the expected result is that opening the switch will result in 0 A.


texts:
I have one IC for which I can not find any clue for the part number (PN).

It has "BA7P16" and "5810" on it.

What manufacturer has that logo and what chip is it?


texts: What is the difference between these two protection circuits?

texts:
I have seen both protection circuits used in various designs. The first just back to back diodes clamping a line, the other clamping the line to the system voltage rails.

Whats the difference between these to protection circuits? and what are the pros and cons of using each?

simulate this circuit – Schematic created using CircuitLab

simulate this circuit


texts:
I am using STM32VL discovery board(STM32f100rb6)..
I wrote following code for NVIC:

void Interrupt_Init(void)
{
    __enable_irq();
    /*Core Base(NVIC)*/

    //set priority to 0
    //NVIC->IP[6] &= ~((uint32_t)0xff00);

    //Activate Interrupts
    NVIC->ISER[0] |= BIT6;

    //Enable Pending BIT for Interrupt 6
    NVIC->ISPR[0] |= BIT6;
    lcd_writechar('1');
}

and

int main(void)
{
Interrupt_Init();
    while (1)
    {

    }
}
void EXTI0_IRQHandler(void)
{
    //NVIC->ICPR[0] |= BIT6;

    lcd_writechar('2');
}

as you see under Interrupt_Init() I user NVIC->ISPR[0] |= BIT6; phrase to soft-enable exti0-IRQ. so void EXTI0_IRQHandler(void) subroutine must executed and I got '2' on LCD. but  as NVIC->ISPR[0] |= BIT6; execute next line(lcd_writechar('1');) never runs.. but when I commented (NVIC->ISPR[0] |= BIT6;) I got '1' on LCD... whats going on??

  Update:

  I look further into "startup_stm32f10x_md_vl.s" file in my project as
  startup file:

.section  .text.Default_Handler,"ax",%progbits
Default_Handler:
Infinite_Loop:
  b  Infinite_Loop
  .size  Default_Handler, .-Default_Handler

  and:

g_pfnVectors:
  .word  _estack
  .word  Reset_Handler
  .word  NMI_Handler
  .word  HardFault_Handler
  .word  MemManage_Handler
  .word  BusFault_Handler
  .word  UsageFault_Handler
  .word  0
  .word  0
  .word  0
  .word  0
  .word  SVC_Handler
  .word  DebugMon_Handler
  .word  0
  .word  PendSV_Handler
  .word  SysTick_Handler
  .word  WWDG_IRQHandler
  .word  PVD_IRQHandler
  .word  TAMPER_IRQHandler
  .word  RTC_IRQHandler
  .word  FLASH_IRQHandler
  .word  RCC_IRQHandler
  .word  EXTI0_IRQHandler
...

  and:

.weak  EXTI0_IRQHandler
.thumb_set EXTI0_IRQHandler,Default_Handler

  It seems that "EXTI0_IRQHandler" always equal to "Default_Handler" in
  my projects so it cause infinite loop as we define above.

  I think this part:

void EXTI0_IRQHandler(void)
{
  NVIC->ICPR[0] |= BIT6;

  lcd_writechar('2');
}

  never influences the "EXTI0_IRQHandler" definition. why?

Update:

  Is there any way to jump to
  EXTI0_IRQHandler without implementing anything in peripheral?? Like asm("B
  0x58")?  my purpose is to be sure from core configurations then work
  on peripheral configurations ?

Update:

  I nearly found problem but needs help to fix it.. after many
  examination and using debug features I found this piece of code is
  faulty:

    void EXTI0_IRQHandler()
    {
      lcd_writechar('2');
      LED_ON();
      NVIC->ICPR[0] |= BIT6;
    }

  in detail lcd_writechar('2'); cause to issue because inside function
  I am using delay() function.This is that piece of code
  involving delay by SycTick feature:

/*Enable SysTick*/
  //Processor clock (AHB)
  SysTick->CTRL |= BIT2;
  //Counting down to zero to asserts the SysTick exception request.
  SysTick->CTRL |= BIT1;
  SysTick->LOAD = 8000 - 1;
void SysTick_Handler(void)
{
  SysTick_Tick++;
  //lcd_writechar('7');
  SCB->ICSR |= BIT25;
}
void delay(int ms)
{
  SysTick_Tick = 0;
  //Enable Systick Counter
  SysTick->CTRL |= BIT0;
  while (SysTick_Tick < ms) {}
  //Disable Systick Counter
  SysTick->CTRL &= ~BIT0;
  SCB->ICSR |= BIT25;
  return;
}

  as you see I am trying to clear pending bit of SysTick by SCB->ICSR
  |= BIT25; but clearly after running of delay() function
  from inside of EXTI0_IRQHandler() everything hangs..


texts:
What is the program flow to get multiple SPI ports to run at the same time?  I am a linear thinker so it's hard to think of doing more than one task to completion at a time.  I need to read two 24-bit ADCs at the same time (or close to it).  The SPI ports will clock at 40MHz and I need to take 1,000,000 (1M) readings per second.
The processor is a PIC32MZ2048ECH 144-pin.  I can either use just C or C with the Free RTOS.
The ADCs are ADS1675's by Texas Instruments.


texts: Electrically rewiring cells into series or parallel, BMS decision

texts:
I was thinking about making a battery pack that would alow me to select two voltages by electrically switching (via transistors) two parallel 5S battery packs into one 10S battery pack. It offers me a better efficiency than switched regulator.

But I don't know if I should use one 10S BMS or two 5S BMS? What if I would like to connect together three packs of cells? Three separate 5S BMS? I would like to charge the whole battery pack(2x or 3x 5S together) with a 5S charger.

Any suggestions or help is very appreciated. Thanks


texts: How can I balance 2 separate LiFePo4 batteries?

texts:
On my boat I've got devices that run on 24V and others that run on 12V.  Seeing as how the alternator, wind generator and solar panels are all generating 24V, I guess it's fair to say that this is mainly a 24V system.

I have built 3 80AH 24V batteries using LiFePo4 38120 cells, each has its own BMS and these are working just fine.
What do I do about the 12V devices though?

The obvious answer is to use the readily available buck converters, and I am OK with that for most of the 12V requirements (such as instrument displays).
However, I also have a number of bilge pumps that run off 12V and I am not so comfortable with relying on a converter for these.  I would much rather have a 12V battery store running these, to give me a greater safety margin compared with the immediate failure of a broken buck converter.

Before I switched to Li-Ion batteries, I had lead acid batteries.  With 2 batteries in series, I could charge them using the 24V source(s) and then just tap off from one of them to give me the 12V I need for the bilge pumps.  Included in this setup was a battery balancer that kept both batteries balanced, even though I was drawing power from just one of the 12V batteries.
This is an off-the-shelf bit of kit that is widely used in transport applications where additional batteries are used, trucks etc.

Due to the different charge characteristics of Li-Ion vs. lead acid batteries, I don't believe this type of balancer will be suitable to balance Li-Ion batteries since it relies on being able to detect different voltage levels between the 2 batteries in order to do its balancing and Li-Ion maintain full voltage until pretty much empty.

So to my question...

Is there any smart way of performing a similar balancing act between my LiFePo4 batteries?

Thanks.


texts: Wien's oscillator - amplitude stabilization with Zener diodes (loop's gain)

texts:
How come the loop's gain \$\beta A\$ of a Wien's oscillator with Zener diodes is equal to the loop's gain of a Wien's oscillator without Zener diodes?

My professor uses the following expression to determine the frequency of oscillator at steady-state:

Why does he not consider the arm with Zener diodes?


texts: On the use of "BLOCK INTERCLOCKDOMAIN PATHS"

texts:
I based an FPGA design on Lattice reference code that, in the timing constraints .lpf file, specifies:

BLOCK INTERCLOCKDOMAIN PATHS

The design two main clock domains are 100Mhz and 125Mhz so I expect them to drift through phase relationships that violate cross-domain setup and hold times periodically. Each clock domain has appropriately constrained frequencies and the transfer of data between domains looks sound.

Lattice themselves post advice that seems to discourage the use of BLOCK INTERCLOCKDOMAIN PATHS in their FAQ:

  Question How can I block clock domain transfers where I have synchronizer circuits?

  Answer ... trace analyzes all clock
  domain transfers in which it can relate the source and destination
  clock domains. This may not always be desired. You may utilize your
  own synchronizer to handle the transfer between the clock domains. In
  this case trace should not analyze the clock domain transfer. This can
  be done in three ways:

  BLOCK INTERCLOCKDOMAIN PATHS This preference will block all clock
  domain transfers in the design. If all of the clock domain transfers
  in the design are handled by the logic within the design then this can
  be used. Be careful with this preference since it will stop trace from
  analyzing all clock domain transfers.

  BLOCK PATH FROM CLKNET "src_clk" TO CLKNET "dst_clk"
  This preference will block all clock domain
  transfers from src_clk to dst_clk. This covers all of the transfers
  between these two domains. All other clock domain transfers will be
  reported and timed by trace.

  BLOCK FROM CELL "myff1*" TO CELL "myff2*"
  This preference will block the clock domain transfer from myff1* to
  myff2*. This is a very specific path and is useful if you have several
  different types of clock domain transfers between two domains. For
  example, a design may contain an asynchronous FIFO and a FF-to-FF
  domain transfer between the same domains. The asynchronous FIFO
  transfer can be safely blocked, but the FF-to-FF transfer needs to be
  timed.

And:

  Question What is the "BLOCK INTERCLOCKDOMAIN PATH" preference used for?

  Answer  This constraint is used to block paths that involve data transfer between registers that are clocked by different clock nets.
  If used without understanding, it will block all clocks domains from
  each other, even if they are supposed to be related. This can cause
  your tools to not calculate the necessary routing delay between
  related clock and data paths and can lead to intermittent setup and
  hold errors in your design.

  It's best to use a BLOCK CLKNET for each path that is unrelated in
  case you have related clocks.

I feel obliged to remove the catch-all constraint given this advice and explicitly determine the relevant cells in my synchroniser (and their path in the hierarchy) that cross the domains, then block analysis of each known crossing explicitly at the cell level. I know where these should be after all - I designed them in, but the exact hierarchy names will take a while to find from the timing report violations I expect when remove this constraint. This will probably take a day and a few P&R cycles to get them all.

The net effect will probably end up being the exact same design I have at the moment, with a longer constraint file and the same near-critical paths.

So - would you bit the bullet and take out the catch-all BLOCK INTERCLOCKDOMAIN PATHS, and sub in BLOCK .. CELL constraints for every crossing? Or is it not worth the effort and keep the catch-all?


texts:
In this schematic for an induction heater, there are two inductors used for current sources. My question is what happens if I increase/decrease the inductance? For example, what would happen if I replaced the two 100uH coils with 1mH coils?

Source: https://markobakula.wordpress.com/power-electronics/500w-royer-induction-heater/


texts: How to run an electric motor at constant current?

texts:
How can an electric motor, specifically a Brushless DC motor, with constant current rather than constant voltage? With the aim of having a constant torque rather than a constant voltage.

Edit: The motor will have a, more or less, constantly dynamic loading.


texts:
When I need a general purpose NPN transistor I automatically think of the BC847. Other types that always come back are 2N3904/2N2222. (Is BCxxx more European, and 2Nxxxx more American?)
For N-channel MOSFETs it doesn't look so clear, everybody seems to be using a different type. Can we compile a list of common MOSFETs with low \$R_{DS(ON)}\$, say less than 1\$\Omega\$? I think this could be useful for many people.

Possible shopping list:
- N-channel enhancement,
- PTH (TO-92) or SMD (SOT-23),
- \$R_{DS(ON)} < 1\Omega\$,
- logic level (\$V_{GS} < 3V\$)


texts: Recently I have come across Energy Meter IC "CS5463". I read the datasheet and it says that the internal registers of the IC stores the Power information as a percentage. My understanding is that I have to multiply the percentage with a number to get the absolute power rather than normalized power. My question is what that number should be?


texts:
I have a food van with a stock alternator on the engine, and a 3000w inverter setup. The inverter setup uses 2 Trojan leisure batteries. Somehow the inverter setup is also linked to the alternator (I’m sure of this). I have only ever used this for small items like a travel kettle or phone charging. Today I purchased a Slush machine which is rated at 920w. I tried it on the inverter and it ran for a few mins, however as soon as the compressor kicked in the inverter switched off.

The inverter is rated at 3100w continuous power, and 6200w peak power for 1 second.

When the compressor kicks in and inverter switches off, the watt meter on the inverter displays 1920watts.

Now obviously it’s clear that the inverter cannot run the slush machine, so I was wondering what possible solution there are out there.

I should also add that the inverter and batteries were not used for around 18 month prior to fitting the slush machine. What would be the best way to test their batteries? Voltmeter?

I was thinking of adding a second alternator in the engine, would this work to provide enough power to the inverter and it’s batteries to power the slush machine.


texts:
I made a boost converter, and now I want to calculate the efficiency of my circuit. I know the formula to calculate the efficiency which is given by

\$ Eff = \frac{P_{Output}}{ P_{input}} \cdot 100\%\$

where \$ P_{Output} \$ is the Power at the output and \$ P_{input} \$ is the Power at the input.
But, I am confused at the output stage.
At the output stage, the Load is connected, and power depends on the connected load. Which means that there will be different efficiencies for different load. Is this right? Can I just use a normal resistor as a load?

Also, when you make a circuit, what are the major tests you need to perform and check? I mean like efficiency test, thermal test, Emc test, etc.


texts: avr/io.h don't include the appropriate avr/ioXXX.h file

texts:
I'm facing a problem on Eclipse IDE that when compiling my project (which has #include <avr/io.h>), the compiler includes avr/iom16.h (for ATmega16) instead of avr/iom32.h (for my ATmega32). It appears when I press ctrl + click on any constant like DDR in my program, It opens the avr/iom16.h file which means it was included.

I've checked the compiler options of the project and found that the control switch option -mmcu=atmega32 is fine, the same is for assembler options and linker options.

I've tried to make a new project, chosen target hardware as Atmega 32 -as I usually do-, copied my source files into the new project, compiled the project, but the problem persists.

A strange thing also need to be mentioned is when I open the file avr/io.h after compiling, it is showing all the controller constants in gray background (which means they are not defined) except for this one __AVR_ATmega32__ in white background (which means it is defined). The following is the two lines of code that appears with a white background:

#elif defined (__AVR_ATmega32__)
#  include <avr/iom32.h>

So, what is making the trouble then? is it could be something in the earlier preprocessing stages?

Any help would be appreciated.
Thanks in advance!


texts: What is Cut-Off Current in BJT transistors?

texts:
I'm reading a datasheet for a small NPN BJT transistor (UTC S8050).

In the datasheet there are two entries regarding Cut-Off Currents.

Here's a table screenshot

I've tried Googling and YouTubing about this parameters and ended up confused.

Let's take for example collector cut-off. If, say, when there's 20 volts across collector and base there's no current flow, but when the voltage increases to 30 (according to the datasheet) some cut-off happens. Cut-off of what current?


texts: Reading Voltage NTC Sensor, Unexpected Behaviour

texts:
Below pictured is the basic circuit im working with, NCT is apparently pretty much a variable pot resistor.

The measuring point ive added. According to the manual for my car, the sensor is provided with 5v by the ECU and it reads the return voltage.

The Sensor decreases resistance with increasing temperature.

However when I measure the voltage at illustrated point, I get lower voltage at higher temp, and higher voltage at lower temp, the inverse of what expected...

What am I missing here about the behavior of this circuit ?


texts: Subtract two voltages using two instrumentation amplifiers

texts: I'm building a PI controller with inputs read using instrumentation amplifiers (for sensing resistors and floating grounds), rather than subtracting the two input signals with a third chip, is it possible to use the reference pin (as shown in the circuit) in series to accomplish this?


texts:
I'm making a USB HID device using PIC18F2550 using 20 MHz crystal input and using the MikroC PRO C compiler for PIC.

These are my configuration settings:

unsigned char readbuff[64] absolute 0x500;
unsigned char writebuff[64] absolute 0x540;
char cnt;
char kk;

void interrupt() {
    USB_Interrupt_Proc();
}

void main()
{
    TRISA = 0;
    ADCON1  |= 0x0f;
    CMCON   |= 7;
    HID_Enable(&readbuff, &writebuff);
    while(1)
    {
        /*
            LATA=0;
            delay_ms(200);
            LATA=0xFF;
            delay_ms(200);
        */

        while(!HID_Read())
            ;

        for(cnt=0; cnt<64; cnt++)
            writebuff[cnt] = readbuff[cnt];

        while(!HID_Write(&writebuff, 64))
            ;
    }
}

Also included in the project is the file USBdesc.c which can be generated inside the HID terminal of MikroC. But the device is not detected at all...

[UPDATE]

I've tried the older version on MikroC, that is, version 8.2, and I got it working (the HID device gets detected.). But I still can't make it work with the MikroC PRO.

PS.: To make sure the microcontroller is working fine, I loaded a sample hex file for a USB HID mouse onto the microcontroller, and it was working. I just can't figure out what's wrong with my code...


texts: Is it worth it to go full stack as an embedded engineer?

texts:
In big companies, they tend to separate embedded engineers by disciplines such as firmware, hardware, interface software, and PCB layout. Still, I think it's more fun to work 'full stack' and build all aspects of the design when possible.  Obviously some projects are too large for this approach.  All of my experience is with a company that has people separated out.  I would like to transition to a full stack role at some point, but I'm not sure if there is a large demand for embedded systems engineers with broad skill sets.

Is there truly a need for engineers that have exposure to all these skill sets?


texts:
So I've been doing some reseach on DTL ( Diode Transistor Logic ) and started doing some problems, but the problem i stumbled onto gives me some headache.

The actual problem given is

  Given a DTL circuit on the image, determine the logic function of the
  circuit and the minimal value of resistance  \$R_{Cmax}\$  in the
  collector area of transistor so that the output transistor is
  saturated. Known parameters : \$\beta_{min}=50\$,\$\beta=100\$,
  \$V_{CC}=5V\$, \$V_{BET}=0.5V\$, \$V_{BES}=0.7V\$,
  \$V_{BE}=V_D=0.6V\$, \$V_{CES}=0.2V\$

The data given is vague , so i assume

\$V_{BES}\$ - base-emitter voltage of the transistors in saturation mode
\$V_{BE}\$ - base-emitter voltage of the transistors
\$V_D\$ - voltage drop across the diodes
\$ V_{CES} \$ - collector emitter voltage in saturation

As for the logic circuit, i cant make any sensible logic function out it. I also can't see the purpose of the  diode between the two transistors.
As for the calculations themselves, i remove the input diodes and try to solve the circuit. The circuit itself doesn't seem too difficult, but I'm not sure what is the required resistance. Also, what is the purpose of \$\beta_{min}\$ here?


texts:
I have a custom PCB based on imx28 (primary board). It receives external power via a cable. There is another PCB (secondary board) connected via GPIO to the primary board. The secondary board doesn't have power on its own but is powered through the first board.

The primary board is running a custom Linux distribution.
Normally, the setup was to power the secondary board using one of the regulators the SoC provides. When that setup is on, I can't modify the pin because it's consumed by the regulator driver. However, now I need to be able to control the power for the secondary board programmatically. Because of that, I've removed the regulator part and am just using the pin as a generic GPIO which I export to sysfs and just turn the value to 1. That seems to power on the secondary device.

Should I be worried about the stability and power that a GPIO pin can supply (as opposed to the capabilities of a SoC regulator)?


texts: How does Windows know it's on battery power?

texts:
Laptop DC-DC regulator boards are somehow able to communicate with Windows to see how much battery power is left, but my research finds nothing.

Is there a data connection from the proprietary motherboards found in laptops which communicates this? If so, what kind of data connection is it and where does it actually connect? Is it just a PCI-E port with a ribbon cable?


texts: Is it possible to measure frequency upto 500Mhz with 50Mhz oscilloscope?

texts:
Is there a way to measure higher frequency measurements with a 50 MHz oscilloscope (eg rigol ds1054z)? Perhaps some post processing of captured waveforms? Or with the help of some adapters?

I have a Rigol DSO1504z digital oscilloscope.
Link. http://www.scientechworld.com/test-and-measurement-solutions/digital-oscilloscopes/50mhz-digital-oscilloscope-ds1054z


texts: Could the software cause permanent damage to microSD?

texts:
We are using microSDs as a main memory in our devices (raw mode, SPI interface, STM32 MCU), and in these years we had many problems with them.

We have upgraded our drivers many times, and we added many hardware protections to boards too. until now we have solved many problems but there are some remaining problems too. We know that our microSDs have a poor quality and sometimes they find permanent damage (bad sectors, write protected , ...).

My question is that theoretically is it possible to do permanent damage to microSD by software (low level driver)?


texts:
My question isn't really too complex, I've built a few h bridges using 4 n channel mosfets on a bread board. It works pretty well except for it not being able to handle much in the way of power. The design that I use looks something a bit like this.
http://puu.sh/uzedL/e02497c6b9.png

I've made the addition of suppression didoes and a capacitor to deal with inductive spikes. The mosfets are driven using ardunio pins with high value resistors pull the gates to ground. I don't have any fet drivers at the moment but I am not sure if I need them. From the very best of my knowledge and testing there are no real issues with this circuit.

The plan is pretty simple I want to drive a transformers some ferrite others iron.

I know this can be built onto a veroboard, but I am not very good at soldering. So is there a prebuilt solution that can do the following.

1.Have all 4 fets controlled by an ardunio
2.Handle a decent amount of power
3.Support heat sinking


texts: Why is my circuit in parallel with a voltage regulator overheating?

texts:
simulate this circuit – Schematic created using CircuitLab

I'm currently working on a project where we use a Raspberry Pi to print receipts via a receipt printer. I would like to use the same power supply for the Pi and receipt printer so we don't need to worry about staff at the restaurants that will be using this accidentally unplugging one component and not knowing about it. I tried to solder two wires onto the power supply input (from an AC to DC converter 24V, 2.5A out) and then step down the voltage through a voltage regulator. With this method I ended up burning the microcontroller in the receipt printer seemingly when I connected it to the Pi's USB ports. I have a few ideas why this might have happened but I'm not sure, could someone point me in the right direction?

Possible Problems
-The voltage regulator is drawing more then 24V which would force the receipt printer to the same voltage
-The voltage regular draws too many amps and few are left for the receipt printer
-An issue with shared grounds between the pi and printer

More info on the printer (I don't think the datasheet has been released)
http://hoinprinter.com/en/download
LM2596 datasheet https://www.ebay.com/itm/NEW-LM2596-DC-DC-adjustable-power-step-down-module-NEW-GOOD-QUALITY-M13-/351493700220?_trksid=p2385738.m2548.l4275
LM2596 implementation board https://www.ebay.com/itm/NEW-LM2596-DC-DC-adjustable-power-step-down-module-NEW-GOOD-QUALITY-M13-/351493700220?_trksid=p2385738.m2548.l4275

This is an image of where I soldered the voltage regulator leads to the board. (These wires go to IN the the above schematic)

Printer Boards


texts: Charge capacitor with static electricity

texts:
Can i charge a capacitor fully with only static electricity?
I already took a look at: Electrostatically charging a capacitor and How to charge a capacitor with static electricity? but i'm not sure this answers my question fully.
Can you explain to me if it is possible to charge a capacitor from for example a wimshurst machine? What needs to be taken care when the capacity of the cap changes (i.e. if one time i have 100nF and a different one has 1000uF)? Im trying to charge a homemade foil capacitor and before building a bigger one I would like to know if doing this is feasible and what specifications i should aim for. By that approach I want to avoid building a voltage multiplier or other high voltage supplies.


texts:
I'm trying to build a 2 bit counter using JK flip flops. In the simulation it counts up just fine, but when I switch it to count down, it starts at 3 and then goes to zero and counts up again. The clock is connected to a 555 timer, just didnt show it.

Design equation:

Y = M'Q + MQ'

Where Y is the output, those AND and OR gates. M is the control input (switch), it counts down if M = 1 (closed switch) and up if M = 0 (open switch)


texts:
I am going to build a lab bench power supply using smps and LTC3780 step up and down regulator. Like a youtuber great scott built in a video which i will link below. Can such a bench power supply be used in laptop and mobile repair ?

What will be the effect of switching noise if I use that kind of supply in repair work ?

Video link https://youtu.be/wI-KYRdmx-E


texts: Electric shock with isolated material in the circuit

texts:
I never understand why electric shock happens if I'm connecting to ground by isolated material.

Let's consider an example with  monophase 220V electrical system electrical shock while I'm wearing rubber shoes and touching a stripped wire.

With this circuit an electrical shock happens: electrical system-  stripped cable - hand/body - rubber shoes - ground- electrical system- ...

However if I swap the order touching the wire with a shoe in my hand there will be no current through this circuit: electrical system-  stripped cable - rubber shoes - hand/body - ground- electrical system- ...

The same considering the ceramic tile on the floor. This isolate me if I put it between the wire and my hand, but not if it is between my foot and the ground.


texts: Is power balance a relevant factor in the consumption of a house?

texts:
Where I live, houses receive up to three phases from the electricity provider.

There is a company advertising a power balancing service. They claim that if one of the three phase cables is overloaded, this will increase its temperature and thus its resistivity. So, they say, balancing your system will lower your electricity bill.

Is this correct? Is balancing the power load relevant for a domestic electrical bill?

I've heard this might become more relevant in very hot places where cables get hot naturally, is this true?


texts:
I am currently working on an application which will use both a Lipo and an external power source (DC). The external power source will charge the lipo as well as power the system load at the same time (during Lipo charging).

Initially I have based my design on the frequently referenced microcip AN1149 design document. See below

The offered solution suggests a P-channel MOSFET (Q1) and a Schottky diode (D1). My only concern is reverse current flow across the MOSFET body diode.

I understand that Lipo's have a very specific method of charging and I cant figure out if using a MIC94052 type p-channel MOSFET would interfere with the constant current/constant voltage charging process, due to reverse current through the body diode. Now, I have had a look at the datasheet (https://datasheet.lcsc.com/szlcsc/1806131131_Microchip-Tech-MIC94052YC6-TR_C87380.pdf ), and it seems like the Idss is about 1 to 5uA.

Since i have not tested this circuit with a Lipo yet, I wanted to eliminate the possibility of any damage to it. I could potentially just use  a relay instead of the MOSFET (Q1).
Other than the size increase with the relay i dont see any disadvantages. Switching would only occur once or twice a day so im not expecting a short relay life span.

My question is, is it safer to use a relay instead of the MOSFET, or is it unnecessary? Keep in mind my application will have to be running almost all the time (either from the battery or the external supply). So heat generation is a factor (MOSFET).


texts: How to determine position from gyroscope and accelerometer input?

texts: I have a 3-axis accelerometer and a 2-axis gyroscope. I intend to measure something that only moves in the X and Z axis. I've heard of using Kalman filters to smooth out the acceleration vectors, but I can't find a good tutorial for a complete beginner to the topic. Also, I know I can double integrate acceleration to get position, but how do I do this with a finite number of sampled acceleration vectors? I would appreciate links to good tutorials for beginners on both these topics.


texts:
I am using STM32 HAL VCP firmware generated by CubeMX on STM32F4 discovery board. The Virtual COM Port works, I can transmit from the microcontroller to the PC as many messages I want. But in the other direction, from PC to microcontroller I can send only one message. If I try to send a second one, the static int8_t CDC_Receive_FS (char* Buf, uint32_t *Len) callback won't be called, and on the PC RealTerm hangs. My client program hangs too, when it tries to write in the COM port second time.

On microntroller side I removed all of my code in CDC_Receive_FS(), it returns currently only USBD_OK. In the main function there is only a HAL_Delay() periodically called, I tried to remove this too, but it had no effect.

Any ideas, what could be the problem?


texts: Best MOSFET to control small 12v load with NodeMCU?

texts: I am pretty familiar with Arduino, and I will be using a NodeMCU for an upcoming project I'm doing. I have never used a NodeMCU before. I am using it along with a few sensors to turn on and off some 12v DC Solenoid valves to water my garden. Anyways, I was trying to figure out how to control the solenoid valves with the NodeMCU, as I am more familiar with 5v than the 3.3v from the NodeMCU. I was planning on using a MOSFET, but I can't find any other NodeMCU projects that use MOSFETs. They seem to all use those relay boards. What is a good MOSFET for this purpose? The solenoid only draws less than an amp, but im planning on using this mosfet for a go to for other projects in the future, so maybe somewhere in the 3-6A range. The most important thing is working with the 3.3v from the NodeMCU. And can I just connect the base of the MOSFET directly to the NodeMCU pin or do I need a resistor?


texts:
I have used Keil uVision and Microchip MPLABX IDE's a lot for various MCUs. Now starting to use Atollic TrueSTUDIO for STM32 MCUs.

But even after spending many weeks on trueSTUDIO and building many small example codes in it.. i still do not feel comfortable as it was in the other 2 IDEs mentioned above. It was more easy to see the code and focus on it in those IDE's while the trueSTUDIO has so many views on the window that keeps you distracting and its difficult to keep focus on the code..

Can anyone suggest how to make the look and feel of trueSTUDIO simple?
Someone told me that it's possible to use some other editor like Notepad++ for code writing and the compiler, linker etc toolchain from the trueSTUDIO. Is it advisable and how can that be done?


texts:
Background
I have a device with a NiMH battery. This is a portable device, so I need to know how much battery I have left at all times.
To achieve this, I want to map the battery voltage to a percentage between 0% and 100%.
Characteristics
The battery I am dealing with gives me the following information (printed in the device):

NiMH Battery 7.2V, 400mAh

Manual Information:

Battery voltage V: 6 ~ 10
Nominal capacity (mAh): >=400
Power(Wh): 2.4-4
Charging temperature (Celcius): 0 - 45

Research
I have read some articles indicating that this is possible, but unfortunately I have not found the mathematical formula they used ( page 6 of 14 ):
http://data.energizer.com/pdfs/nickelmetalhydride_appman.pdf
Problem
What is the algorithm that, given the current voltage of the battery, can tell me how much % I have left?


texts:
For the measurement of the resistance of another PCB I am using a current source seen in the figure below. Now I can measure the voltage with an ADC. With the measured voltage and the set current I can calculate the resistance. After I calculated the resistance I am going to power up the PCB. Now I want to measure the voltage across the PCB. But before I power up the PCB under testing I need to "disconnect" the current source. This way I can measure the voltage and the resistance with the same ADC pin.

Picture from https://cdn-reichelt.de/documents/datenblatt/A200/DS_LM_334.pdf, page 6.

I am going to feed it with 5V, and I need to measure something up to 500k. To achieve this I need a current <= 10uA (5V/10uA = 500kOhm), Let's go for a 5uA max and the circuit can go as low as 1uA. So after the current source I need some kind of switch that's doesn't change the current higher than 5uA.

I am also open for other options like another current-source which can be "disconnected". I just think this is a stable current-source and hope to work with it.


texts:
I'm relatively new to electronics - most of my experience is just tinkering with Arduino projects in a more limited sense. I've been working on a project for a week now and have a bit of a (probably basic) quandry..
So I'm trying to convert an SNES controller to be wireless. I've got the SNES Controller side finished - its an ATMega328 + nRF24L01; I'm using the SNESPad library to get input from the controller - I put the state into an int and send it off to the receiver - another ATMega328 and nRF24L01; from there I can bitshift to get the state of each button.
That all works perfectly.

What I'm struggling with his how to take the current state and output that back to the SNES. I've looked at the NES/SNES serial protocol, and understand what I need to be doing there, but the only part I can't figure out is how to wire the sucker. The SNES has its 5v vcc line and its ground. I would imagine I would tie its ground to the ATMega's (it's powered by its own source), and not take the 5v. At that point, I should be able to read high/low off of the Clck, latch, and data lines coming from the snes? Or is that not the case?

To sum up the root of the question, I have a powered circuit that I want to interface with another circuit - is sharing ground all I need?


texts:
I need to manage backlight on a 7 inches touch screen from Chalkboard Electronics that has a HDMI connector and a power jack only. I only need to power backlighting on and off. Can it be done through HDMI?

EDIT: I found back the real reference from Chalkboard Electronics. The display is based on this model.


texts: Identify 40-pin PDIP device with top marking: TEZ C18071S 133807

texts:
I'm trying to find a data sheet for C18071S but can't find any references to this component anywhere. It's a 40pin PDIP. Any help most welcome!
Edit: Added schematic. I hope this will help identification.


texts: How to know the maximum pull up/down resistor of a specific logic pin of an IC?

texts:
I am designing a circuit and needs to place some pull downs on the address pins of PCA9546 and usually my go to resistor values for these kind of situations is either 10k ohms or 100k ohms. These values work almost all the time.

Having said that, I thought that if I were designing this circuit where power consumption is critical surely the datasheet must have some information that tells me the maximum pull - up / down. But I could not find such information on the datasheet.

What section of the datasheet does information belong? If the IC that I have given does not have this information (considering its not meant for low-power applications) can you give an example datasheet that has this information?


texts: USB-C Battery pack - charging and powering other devices using the same USB-C plug

texts:
I'm designing an ultra-small LiPo 1C battery pack using the TopPower TP5400 charging control and boost output regulator IC. Design is working fine, but currently I'm using a microUSB socket for charging and a USB-C plug to plug the battery pack into the device to be powered.
But I want to use the USB-C plug for powering a device, as well as plugging it into a charger's USB-C socket to recharge. There are two design issues:

My USB-C plug is always powering 5V at the VBUS pins - this is wrong due to the spec (unless it is sufficient to advertise it being a DFP by the included 56kΩ pull-up) - and
I have to sense if the battery pack is plugged into the charger or into the device it is supposed to power.

Any hint for a clever (and small) design to switch power and sense the CC pins?


texts: Transistor switch with 2N2222A and cooling fan as load

texts:
I am building a temperature sensor monitoring system with microcontroller.

The input node changes the value if the sensor detects a temperature higher than 70 degrees. I have checked the voltage at the input node, its 3.28V, when its supposed to be high, the fan needs 0.18A to turn on. the voltage at the output node (collector) is 2.2V, but is supposed to be 3.3V with enough current to turn on the fan.

Could someone suggest a solution to amplify the voltage at the collector and its current.

Thank you


texts: Use internal pull-ups for row/column key scanning with diodes

texts:
I'm writing some microcontroller software to read a mechanical keyboard, which has diodes to prevent keys from interfering with each other.

The keyboard has the keys set up with row outputs and column inputs that can be scanned; basically the boxed area in this schematic, but with many more keys:

simulate this circuit – Schematic created using CircuitLab

Rows R0, R1, and columns C0, C1 are GPIO pins on my microcontroller, AT90USB1286 (8-bit AVR).

I have limited understanding of actual electronics and don't really know how to use diodes effectively. I believe I could scan the keys using the following (naive) process:

Set R0 to output high, all others low
Read all Cn pins to find out which R0 keys are pressed
Repeat for R1, R2, etc.

For that to work, my understanding is that each column would need to have a pull-down resistor to prevent floating signals when no column keys are pressed. My microcontroller has optional internal pull-ups on every GPIO pin but no pull-downs, so I would need to add them myself. I don't believe I could use the pull-ups and change the scanning row output to low because the diodes will prevent the low signal from reaching the column input.

However, I am wondering if I could swap the row and column roles:

Enable internal pull-ups on all Rn
Set C0 to output low, all others high (or hi-z?)
Read all Rn pins to find out which C0 keys are pressed
Repeat from 2 for C1, C2, etc.

This would mean that my schematic would use R0 and R1 as inputs with pullups enabled, and C0/C1 as outputs; each one would output low when scanning it.

My primary concern is that the diodes will somehow prevent the low output from overriding the pull-ups, or something like that.

Does this approach work?  Should I output high on the column pins that I'm not scanning, or is it okay (or better) to make them hi-z/inputs?


texts: MATLAB multi-player planar coil geometries Fasthenry, Fastcap

texts:
I'm looking for some software to calculate inductance and capacitance for planar coils:
I have tried Layout editor - doesn't calculate inductance for imported gerber files from Kicad and I am not sure if its capacitance calculation is right
I have been searching for MATLAB scripts or any other program that implements fast henry and fast cap and ran across many references scripts using MATLAB it is possible that anyone here has a reference where I can find them?
I found a user on here https://electronics.stackexchange.com/users/15805/samuel
but I can't find a way to message directly as a new member, that seems to have something very closely related.
This is his quote from a year ago
"Very nice. I wrote some Matlab scripts this summer that generate multi-layer planar spiral coil geometries and automatically generate input files for and invoke fasthenry/fastcap to extract inductance and capacitance. Also the script generates scripts for Eagle and Cadence PCB (Allegro) for automatic layout of said coils on PCBs. The simulated inductance matched with fabricated coils within 1.5% for 26 coils from 5µH-130µH. I was very impressed with the accuracy of those softwares, and their scriptibilities. Glad they'll work for you too. – Samuel Nov 9 '12 at 3:46"


texts:
This is for a Raspberry Pi AVR ISP interface board. Most of the functionality is around level shifting the logic to the target board's voltage. This is achieved with a 74ABT125 chip. It's powered by an AP2331 that is fed from a switch which feeds either 3.3v, 5v or nothing (in which case the buffer chip is expected to be powered by the target.

Of concern is one small portion of the circuit:

simulate this circuit – Schematic created using CircuitLab

VCCIO is the output of the AP2331. It's fed into the Vcc line of the '125 and a couple of other 4.7k pull-up resistors that have diode-resistor level shifters for the MOSI and SCK lines from the Raspberry Pi. !BUFFEN is the output enable line on the '125. !PI_RST is the GPIO pin on the Raspberry Pi that initiates programming. It normally floats, but is asserted to 0 (ground) to reset the target.

Note that the actual programming functionality of this circuit works perfectly. It's just the LED - which is supposed to indicate programming is active - that isn't working.

What's going on is that when the system is idle and the power switch is set for 5 volts, the LED is out, as you'd expect. When the power switch is set for 3.3 volts, the LED glows at something like 1/3 brightness. When the power switch is set for no power, the LED turns on.

Clearly some sort of current path exists through the transistor when the switch isn't set for 5 volts.

I've tried cranking the base resistor up to 200k, but that didn't change anything. What I do notice from doing that is that the LED sort of fades in - probably because the bypass cap across the power supply pin for the '125 is charging up.

I can try cranking up the resistance of the VCCIO pullup resistor - that particular signal doesn't need to be particularly fast.

Anybody have any other ideas how to make this LED act as intended - turning on only when the !PI_RST line is grounded?


texts: How can I understand that at t<0 the DC source is disconnected?

texts:
Fundamental of electric circuits by Sadiku at page 264 in the example 7.5 how come the DC voltage source is disconnected when the circuit is in t<0 position ?????

please help this is bugging me out :(


texts:
I'm wondering if it's possible to drive 50W via PoE (cat 6e or cat 7) single cable? I want to power up a quite hungry ARM board, which has power rating of 5V 3A (15W) and a camera, which needs 12V 2.5A (~36W), so it will be a total of 50W power. I was thinking of driving 48V 1.1A via the cable and use two DC-DC step down converters, one for camera and the second one for the board. Cable length shouldn't be more than 10m, so power loss is neglectable. Am I overthinking this too much and standalone power cable will be an easier/safer solution?

Thanks!

Thanks everyone. I was unaware of special PoE equipment for network and power on the same rail, and since I'm going to use gigabit ethernet, it really seems that standalone 48V cable would be a better solution.


texts: Proteus thermal exposed copper (opening) for the pcb layout

texts:
I am using Proteus 8.7 and I am so confused about how to make a power plane (copper pour) exposed .
I mean I want that area free from green mask so that It can make its use as thermal dissipation area. Which layer should I use to make this opening ? The layers I can use for the top side is "top paste" and "top resist" for this purpose . But I don't know which one would help me to achieve what I want .


texts: Propagation delay in case of synchronous counters

texts:
Consider 4 bit counter as shown below:-

Here suppose we consider propagation delay of each flip flop =2ns and propagation delay of each AND gate is 3ns, then what will be the total propagation delay?

As all flip flops get the same clock, we add the propagation delay of flip flop only once but my doubt is whether to add the propagation delay of AND gate only once or twice ?

So will the propagation delay be 2+3 =5ns or 2+3+3=8ns ?


texts: Circuit analysis- boost controller IC frequency change

texts: can anyone explain how this circuit works. A little background, this is a circuit which is used to change the switching frequency  of a boost controller IC , so that it doesn't operate at a single frequency and the operation is over a range of frequencies. V2 can be thought of as a pulse coming from the microcontroller.


texts:
I am new to digital design, and have recently purchased a Bemicro MAX10 FPGA development board to help get my feet wet. I am trying to learn VHDL, and have downloaded a few PDFs to get me started. The circuit I am trying to create is a simple LED circuit. There are two buttons that are inputs, and two LEDs that are the outputs. The idea is that, when either button_0 or button_1 is pressed on the board, LED_1 lights up. When both buttons are pressed, both LEDs light up. Here is the code I have written to accomplish this:

library IEEE;
use IEEE.std_logic_1164.ALL;

entity Button_LEDs is
    Port ( button_0 : in std_logic;
           button_1 : in std_logic;
           LED_0 : out std_logic;
           LED_1 : out std_logic);
end Button_LEDs;

architecture Behavorial of Button_LEDs is

begin
    LED_0 <= (button_0 AND button_1);
    LED_1 <= (button_0 OR button_1);
end Behavorial;

The issue is that when either button_0 or button_1 is pressed, LED_0 lights up instead of LED_1. The line

LED_0 <= (button_0 AND button_1);

is behaving like an OR gate rather than and AND gate.
Both LEDs light up when both buttons are pressed, which is expected. I have double checked pin assignments, and I am positive that they have been assigned correctly, so I am very confused by this logic.


texts:
I'm designing a front end bike light just for the fun of it, and I've hit a problem. So far my design will have an input voltage of 3V, but all the white LEDs I find have a forward voltage of 3.2V or greater. I am curious if there are any white LEDs that I can run off of 3V.

My goal of this light is more of a "be seen" light than a "light up the entire area" light. I plan on blinking the LED with a 555 timer. I will power my circuit with 2 AAA batteries, or maybe a watch battery.


texts: How do you reduce an 8 output ALU to a 4 or 3 output ALU?

texts: I can implement the functions in the picture below, but then if I implement them independently, I would have 8 outputs to the mux. Our professors wants us to reduce the ALU to only 3 or 4 outputs, I have tried but am not getting anywhere?


texts: Is it possible for a VHDL component to have multiple architectures?

texts: Just a thought I had: is it possible for a VHDL component to have multiple architectures if outputs are not modified by both? If so how can we select the one to use at synthesis time (like the C preprocessor)? What happens if multiple architectures can coexist and outputs conflict?


texts:
I would like to create a SPICE model for a constant power load. I'm guessing that would involve using an equation to dynamically adjust the model's resistance based on the applied voltage. How do you do this in SPICE?

(I'm currently using Eagle but any SPICE2 or SPICE3 answer will work)


texts: What is the Fritzing part for the connector block on the Arduino UNO?

texts: The Arduino UNO has a number of connector blocks, e.g. the A0-A5 block. I want to design a PCB using Fritzing that has the same type of connector block. What is the part name for this type of connector, and is there a part with the ability to have a variable number of connectors, like what can be done with the Fritzing generic IC part?


texts: Waveform issues with inverting amplifier

texts:
I'm trying to achieve a gain of exactly -1, however the output of this circuit isn't the expected waveform (correct gain, just wrong wave).

Is there an issue with the circuit?


texts: Why would you need an op amp for reference voltage when the voltage divider does the trick?

texts: Is there a reason this schematic uses an op amp (AD8031) for the reference voltage of the op amp (AD8544) filter when the voltage divider already brings down the voltage anyways? Can the AD8031 op amp be removed? Also, to save power, can the voltage divider be replaced with a buck converter?


texts: Earth Loop Impedance Meters; Difference between 3 lead (L-N-E) and 2 lead (L-N/E)?

texts:
In our company we use various different brands / models of ELI meters. Some have three leads, live, neutral and earth, and some have only two leads, one live and one neutral/earth combined.

Can anyone tell me the difference between the two types of meter (if any) and how they differ?


texts: Nature of conventional current flow in a p-n junction

texts:
More specifically, I'm confused about the concept of hole diffusion. I can understand that electrons diffuse towards the p-type material. However, the concept of holes diffusing is a little bit strange.
When I think about the diffusion current that occurs in the depletion region, I imagine moving the electron from a donor atom in the n-type material, leaving behind a positively charged ion, to an acceptor atom, filling the hole associated with it and creating a negatively charged ion. The result is that the total charges in the diode are conserved, but a conduction electron and hole are annihilated. Wouldn't it be more accurate to say that the electrons "fill" the holes in the p-type material?
I suppose another way to ask this question is the following. Would it be accurate to say that positive current in a p-n junction involves hole movement in the p-side, but when it comes to the n-side, involves "movement" of positive charge by positive ions? I'm not sure that the absence of the extra electron at a donor atom is considered to be a "hole", but it seems like from this level of analysis it could be viewed as one.


texts:
I have assembled AN7149N-based power amplifier according to the datasheet, but it shows no signs of life. The only changes I made were 2,7 ohm resistor instead on 2,2 ohm one, and 1000uF capacitor instead possibly (misprint in the datasheet) 100uF one at pin 3. Also, routed Vcc differently from the suggested PCB layout (I have no idea why designers are trying to route Vcc under capacitor). I assumed pin 1 to be on the left when looking at the front side of AN7149, where the dot is.

I have checked the PCB for continuity (and isolation of neigboring tracks) and all connections two times, but neither channel seems to work with 8 ohm load, no signs of signal. Excitation is seen nowhere else except on the input pin. Vcc is approximately 12v and power supply is capable to deliver 4A.

Combined screenshot and photo of the board follows:

What else can be done to debug this circuit?

Update: caps polarities are according to the datasheet; without input: no midrange voltage on any pins, except pin 1 has 1.4 V and some other pins something like 0,4 V (except Vcc pin, of course).

Test input Vdc is at 0 (can this be a problem?), Vrms of nearly sine-wave approximately at 2,8 V.

Update 2: I have another AN7149N, which I connected on the protoboard to GND (pins 4 and 9), Vcc (pin 10) and also input pins decoupled from 6V voltage divider. Current is almost 0.5 A, and the device is getting hot quickly. Old device never got warm. And, most important, I am getting signal to the loudspeaker.

Solved: Seems like I had bad luck with a particular chip. Amplifier works great after replacing the IC on PCB. As in one of the answers, I've added capacitor and resistors to the ground. I've added heatsink to make sure it stays cool.


texts: Stopping Vehicle Mounted Units from stopping abruptly

texts:
I have installed a touchscreen computer in my old car. The computer runs on 12V DC power supply. I have installed a standard 24V DC to 12V DC converter to power the computer. The 24V DC input to the DC-DC converter is from the car's battery.

Now, my car is having some starting problems, the battery voltage gets low and at times I have to jump start the car. Or in some cases when I start the engine the voltage across the input to my DC-DC converter abruptly falls to 0V, and rises to 24V DC within a fraction of a second.

Due to this sudden fluctuation my computer restarts. Is there a way to ensure that the voltage doesnt fall to prevent this sudden restart ?

I am new to EE-SE please let me know if the tags I have used are appropriate or not. Thanks.
I know one of the obvious solution is to get a good battery and get some work done on the alternator and all. But is there any circuitry that can be designed (using easy to find objects at electrical store) at home to achieve this ?


texts: Automatically switch charging lead to highest available connection in a variable series of batteries

texts:
I have a circuit which I use to charge LiPo batteries with a balanced charger. The idea was that I want to charge up to three 2S batteries as one 6S battery without the problems related to simple parallel charging.

To do this I put all cells in series and connect each of them to the balance port of the charger. Then I use a bridge to manually connect "+" to the highest available cell for the main leads. The charger detects the number of cells and adjust the charging voltage automatically. The cells usually charge with 0,3A - 0,6A. Still the charger requires an additional connection between GND and the positive pole of the last cell in series, which is what the bridge is for.

Letting the single cell aspect aside it boils down to GND, S1, S2, S3 and I want to switch automatically to the highest of them based on what is available. So when I plug in the first LiPo the main charging lead needs to be between GND and S1, with two LiPos between GND and S2 and with three between GND and S3.

I think it should be possible to use some MOSFETs to make this automatically. But I have no idea on how to make this dependent on the number of LiPos connected. It would be cool if this would also work for two 3S LiPos or one 2S and one 4S. So basically having automatically the connection to the highest available cell from a maximum of 6 in series.

Any ideas on how to solve this without manual switching?


texts: Why did the 74xx family never have a hexadecimal to 7-segment-display chip?

texts:
The 74xx family of TTL ICs has several BCD to 7-segment-display chips, such as the 7446-7449, which could display digits 0-9.  However, there does not seem to have been a hexadecimal to 7-segment driver in the 74xx family, which would also display the digits A-F.  Why was no such chip made?

This is a historical question about the 74xx family (including variants such as 74LSxx and 74HCxx).  It is not about alternative solutions, which are already discussed here and here.


texts: Retrieving energy data from dali2 D4i memory bank (202) of a luminare

texts:
I'm trying to read the memory bank202 from a DALI-2 supported led luminary for energy consumption.
it returns a value of zero. when i gone through the Dali part 252 energy reporting Doc. It asked me to latch the lock byte.
Latching involves in series of steps as per docs,

selection of memory bank DTR0, DTR1
(0xC3, 202)  (0xA3, 0x02)

Enabling write to memory bank for which i used
(255, 0x81)

writing to memory registry 0X02
(0xC7, 0x55)

But i receive no response from control gear also. I am not sure if my second and third statements are correct.
Please correct me if I am missing something or suggest me with a better solution.
Bare If my question is silly. As I am new to DALI.


texts: How does a capacitor function in a 120V AC motor circuit?

texts:
I don't understand the direction of current flow when a capacitor is wired in series with the start windings in, say, a fridge or other AC motor  running at/under 120V AC.
Wiring diagrams seem to suggest that voltage energizes the hot leg of the circuit and current flows through the run windings and then returns via the neutral leg. Without a capacitor, the same thing would happen to the start windings. Problem there I guess is that both windings would be in phase and thus no spin created for the rotor.
So, a capacitor is wired in series with the start windings which I kind of understand. But I don't know how the voltage and current behave.
Does voltage energize the hot leg, flow through the start windings and then charge the capacitor?
When voltage on the hot leg oscillates down to zero, does the capacitor discharge back toward the starter windings, or does current flow through the capacitor to the neutral leg?
Basically I don't understand where the capacitor's charge goes when the hot leg is hot and when it is not.
Lastly, is the capacitor placed between (downstream from) the start windings and neutral, or could it be wired between incoming voltage and the windings?


texts: Can optical fiber communication be used to transmit analog signals?

texts: I am confused because I read the LEDs/LASERS used in optical fiber have finite levels.  If for instance ASK is used to transmit digital baseband data then will the LED or LASER be able follow the ASK continuously and will detection be possible?


texts: How many low-power batteries to power up 12V LEDs?

texts:
I bought some strips of 12V LEDs and it comes with a pack of 10 x 1.5V batteries. The whole pack gives ±14.88V, which I thought to be quite high. Is this normal? Does this reduce the life of the LED strip?

Also, if I'm using rechargeable Ni-MH (1.2V) batteries instead of the pack that comes with the LED stip, how many do I need?

Thank you.


texts: usb 3 SS cable type to IP64 panel connector

texts:
I am designing an industrial equipment on which a USB 3.0 connection is required (for speed reasons).
The electronics being in an IP64 box, I am forced to transfer the USB-C/3.0 connector to a panel connector.
So I wonder what type of cable to use to make the link between the main card and the mini USB-C panel connector card (ffc/fpc, ribbon, custom & twisted, connectorless...).

I don't have a PC on hand to look at how the USB 3 connector on the front panel is made.

Any opinions or recommendations?

Thanks !


texts:
How to generate signal who have value less then one clk in vhdl?

Signal req is generate base on input signal dat1 and dat2. If they are equals, signal req have value of 1 less then one clk.

On diagram down is shown how signal need to looks.

Thank you for the help in advance.


texts: Modify an AM/FM radio to an airband receiver: What, if any, changes to the demodulation circuit?

texts:
It seems to be possible to modify a cheap AM/FM radio to receive air traffic control (ATC) communication just above the regular FM band. One range used for ATC is at 108...137 MHz.

Some quick projects seem to de-tune the local oscillator that mixes the incoming signal down to the intermediate frequency (IF). To make the frequency of the local oscillator higher, an air coil is widened (reduced inductance) and a variable capacitor is turned such that its value becomes lower.

Examples can be watched here or here.

So far, I get everything. However, when looking at the data sheet of one of the ICs commonly used in such radios, and turn to page 6 for the typical application circuit, it seems that it should be a good idea to modify the demodulator as well, because the ATC signal is not broadcast in FM, but in AM.

Do the little hobby projects still work just because they use a very strong signal close to an airport and somehow, something will get through the demodulator anyway, or does it really not matter if the circuit is not optimized for AM instead of FM in the VFR range?

Edit:

I just read on a German forum that the trick has to do with using the ratio detector in a way it was not designed for. Seems like this way, a device designed for FM-demodulation will work for AM. I would be grateful if someone could explain how this works.


texts: Are the anodes and cathodes in a vacuum tube truly charged? Can I treat them like any other charged object? also how can I calculate the charge? How would I calculate the alternating charge if it's ac?


texts: It has always been a puzzle for me how a certain type of information can be discarded from a system when it is unused. Say, for example, the Internet Protocol (IP) specification states that packets whose version is neither 4 nor 6 are 'discarded'. Since the packets' representation is a signal of some sort, how is this information 'discarded'? Where does it go? Is it dissipated as heat or something else? (I don't know how to tag this, or whether it's in the right section so excuse me if I'm wrong here)


texts: hall effect potentiometer,linear output voltage .6 - 3.3v. How to reduce output to 1/2 the speed

texts:
What I have is a accelerator pedal that is putting out a voltage that the for whatever reason the Subaru ECU is interpreting at 2x the speed and this is normal. So 1/2 pedal movement is WOT at the throttle body.
The pedal is internally hall effect potentiometer and supplied with 5v.
So I only have control between .6v - 1.95v, from 1.95v - 3.3v the ECu ignores.
Being hall effect means I cannot simply reduce the 5v supply. I have to reduce the output but without having any arduino knowledge, i'm at a loss in my research. Voltage dividers wont work on a varying voltage ? How can I take total output 3.3v and cut it in half?


texts: Saw the term "expert in SoC bringup" on a job description for an embedded software developer: SoC here refers to System-on-Chip, but I was wondering what the term "SoC bringup" meant.


texts:
I am attempting to use an Arduino Duemilanove as a tool to program an ATtiny85 from the Arduino IDE.

I was using the instructions at ForkRobotics which are ...

Upload ArduinoISP sketch to Arduino
Connect Arduino pins 7, 8 & 9 to LEDS (heartbeat, error, programming)
Connect Arduino Pins 10,11,12,13 to ATtiny85 pins 1,5,6,7 (plus 5V & GND)
Download Arduino Tiny code from http://code.google.com/p/arduino-tiny/downloads/list
Select Tools -> Board -> ATtiny85 (w/Arduino as ISP)
Select Tools -> Programmer -> Arduino as ISP
Load the example basic blink sketch (s/pin 13/pin 4/) to the ATtiny85

I can see the ArduinoISP heartbeat LED pulsing but at the last step I get the following errors

Blink.ino:10:21: error: Arduino.h: No such file or directory
Blink.ino: In function 'void setup()':
Blink:15: error: 'OUTPUT' was not declared in this scope
Blink:15: error: 'pinMode' was not declared in this scope

Arduino.h does exist in   ...\Arduino\hardware\arduino\cores\arduino
but not in (for example) ...\Arduino\hardware\attiny45_85\cores\attiny45_85

I made the following exceptions to the process described above ...

I already had an old 2009 Arduino IDE installed so I started by downloading the latest stable Arduino IDE and installed it in a new directory. I opted not to install USB drivers.
I wasn't sure which download to pick from the code.google URL so used attiny45_85.zip from hlt.media.mit.edu instead.

Should there be a ATtiny85-specific Arduino.h in ...\Arduino\hardware\attiny45_85\cores\attiny45_85?
What have I done wrong?


texts: Is mbed RTOS suitable for commercial motion control solutions

texts:
Is the mbed RTOS suitable for commercial motion control applications? Is it advisable to separate the actual motion controller from the network handler, etc (i.e. motion controller in separate MCU)?

Does anyone know of any commercial motion controllers which operate on the mbed's RTOS?


texts: Diode Rectifiers Driving Highly Inductive Loads Producing Input Square Wave?

texts:
According to a textbook that I have, when driving an inductive load with a diode rectifier, the input current becomes distorted. The illustration of the circuit below has the input as an AC source, but the text originally had this circuit as being driven from a transformer if that has anything to do with this.

The circuit (where Vx = E in the waveform diagrams):

The Waveforms (middle is distorted input current).

Further, if the load being driven is highly inductive, the text goes on to describe how the load current will remain almost constant with a small amount of ripple, and the input current will be be like a square wave? For one, how can the load current remain constant while the input is distorted? Here is a illustration from the text:

Can someone explain this?


texts:
I have seen a few electrical schematics where there are separate symbols for grounds. "Agnd" and "Gnd"

Can someone help me understand what are the differences between those two and where to use "Agnd" and "Gnd" ?

And it would really help if you could provide an answer relating to the Common Mode Choke component (as I have seen the different grounds in power sections having CMC)

Please help in very basic electrical terms.


texts: Thermal pads under IC, how to place vias without soldermask / Decoupling question

texts:
I'm looking for a good solution on how to design a thermal pad that is good for solderpaste assembly.

PCB fab that I'm using can't place any soldermask on vias like in this example:

And I'm not practic to design this pads. As I read on some documentations this vias, with solder on them, can suck solder creating problem on IC fixing and possible solder short circuits.

I tought about placing vias on the corner and with a solder stencil place solder only on the inside of thermal pad. But I don't know if it's good.

Can someone advice me a good method?

Also, I've an additional question not really related to this. I've read about decoupling (Decoupling caps, PCB layout) that every ground local plane should have only one spot to main ground plane, but in this case we have a lot of them, it can create problems?


texts: FPGA: what is the input of Timing and RTL simulation?

texts:
For FPGA design, compilation of the design produces a bitstream. What is the input of the simulation (Timing and RTL)? Is it the bitstream itself? Another file?
For Altera specifically, what are possible formats for the bitstream and what is the format for the input of the simulation?

Also, what is the synthesis? is it a kind of compilation? what are input and output? is it needed on all FPGA? is it producing input file for simulation or for loading onto FPGA and hardware debugging?


texts: Calculating resistance value for voltage range

texts:
I have been working on a DIY Nixie tube clock.  Looking at the schematic for my specific Nixie tubes, the ignition voltage is 170V. This led me to buy a 12V - 170V boost converter. Using this I can power on the Nixie tubes, but the main issue is that the most efficient voltage to run the tube at once it has been ignited is 145V.
I can't remember where, but someone told me that I should use a resistor. I am not entirely sure why, I am quite new to electrical engineering so it would be helpful if someone could explain why I need a resistor and how to calculate it.


texts: kW Rating of emergency generator for sump pump

texts:
I have a 1/2HP sump pump rated at 11 Amps running and 43 Amps starting. I would like to buy an emergency portable generator to power it. I know that for 11 Amps I'd need at least 11 x 110 = 1210 Watts, and for 43 Amps = 4730 Watt. Generators also have running/starting watt rating.

So what is my minimum required rating running/starting Amps if I need a generator to power ONLY this pump?


texts: Using a microcontroller to make a series of LEDs blink one after the other

texts:
This may seem like a nooby question, but I have a cycle light with 5 LEDs:

*  *  *  *  *

And it has a button, which when pressed hase different modes:

1st press: all LEDs blink together
2nd press: all LEDs stay lit
3rd press: 1st LED goes on, then it goes of and 2nd LED goes on, so
on till 5th, then 4th LED again...
4th press: it turns off.

I was wondering how to make this. I can make a simple circuit so that all are on. I was thinking, that something like an 8-pin microcontroller can be used to make them blink together, but for them to blink independently, I guess I will have to use a microcontroller with enough pins so that each LED has it's own?

But my bike light is pretty small and I don't think it is running an AtMega32 or something. How does it work?


texts: What kind of patterns are used to mark a PCB?

texts: I would like to create a pattern for my PCB. I would like to update the pattern with changes in BOM, external interface, software, changes in pads. I would like some suggestions of patterns used in pcb design.


texts: Creating an Integrated Circuit Component in Altium

texts:
I am new to PCB designing and I am new to Altium. I want to make a schematic, PCB design and simulate a RF circuit involving a GPS receiver front end IC MAX2769. Altium library does not have this IC. I can create the component in library and also its layout for PCB. But for Signal Integrity simulation purposes I need to define what's inside of this IC package. How do I do that? Maxim does not provide a simulation model for this IC. Do I need to define all the individual components inside the IC package or is there any other way?

I am in real need of support right now. Thank you very much. IC internal circuit is as below.


texts: Pin name confusion with Allwinner A20 and DDR3L/2GB

texts:
I've been trying for the past hour to find the correct definition and the proper way to use the,

DML,
DQSL,
DQUO,
DMU,
DQSU,
DQSU, the part has two DQSU pins.
There are no corresponding pins on the A20 SOC, I've read the data sheet but no useful info, the memory IC is AS4C128M16D3B-12BCN 2GB from Alliance Memory.


texts: What is the purpose of the relay in this circuit?

texts: I have tinkered with relays while building small projects with microcontrollers in the past.  Usually I use them to switch higher amperage circuits off or on. I recently purchased this horn and this wiring kit for it, along with a small 12v battery.  I also had to purchase an automotive relay that was not included in the wiring kit.  However, I have no idea what the purpose of the relay is, since the horn is activated using the push button supplied with the kit.  Could I have just wired the + terminal from the compressor straight to the battery, then wired the - terminal to the switch, then to the - terminal of the battery?


texts: reference source for copper conductivity vs. temperature?

texts:
I am looking for a curve for copper conductivity vs. temperature over the -55°C to +180°C range (covers std. ranges of semiconductors plus NEMA class H insulation in the case of magnetics / motors) but cannot seem to find anything searching on the internet.

I have heard that it depends on the particular copper alloy as well, I'm just looking for "normal" copper found in electrical wire.

Does anyone have a reference that would include this information?

edit: I'm not looking for a linear approximation (the Wikipedia page on conductivity lists copper conductivity and its temperature coefficient at 20°C) but rather a curve.


texts: Replacing a switch matrix with diodes with a Analog Crosspoint 8x8 Switch

texts:
I have an old piece of a equipment (A Casio MT65 keyboard) which uses a matrix of switches with diodes in series with every switch.

Similar to this: http://www.learn-c.com/diodematrix.gif

I wanted to replace this is chip similar to this: ADG2188BCPZ
https://au.mouser.com/ProductDetail/Analog-Devices/ADG2188BCPZ-REEL7?qs=sGAEpiMZZMud93iq7xrBrWoLPJZxA8o1K2kenMlNaz8%3d

My question is: is this possible as the chip doesn't have the equivalent of the diodes on it's cross points?
Is there anyway to do this?

Thanks


texts: What is a good method for wireless transmission of images in a ~2km radius?

texts:
I am working on a project requiring regular image transmission over a 2km range. This needs to be done in an area with no cellular coverage.

Energy efficiency is a factor, however it does not need to be anywhere near as low as Lora for example (and hopefully a higher bitrate than Lora can achieve).

In an ideal scenario there will be approx 10 nodes (cameras + mcu + power supply) each sending images back to a central device approx 50 times per day.

Some additional details/parameters (as requested in comments):

Approx transmission requirements of 50 * 5MP JPEG photographs per device. E.g. ~50*1.5MB = 75MB per device per day.
Power is to be supplied to each camera by a small solar panel. 10W, 12V (ideally - however this can be varied within reason).
The install location is a farm/rural environment, where most of the cameras will have some obstruction to line of site - e.g. from trees. But it is not fully built up.
The budget is modest, sub $50AUD (~30USD) per device for the comms side of things. Obviously the cheaper the better, but for this project there is a bit of flex.
Regarding frequencies- I am not entirely sure, a method that uses unlicensed spectrum would be strongly preferred.

I will greatly appreciate any suggestions! Many thanks for the assistance to commenters in helping me to better define my query.


texts:
I tried to display hello world on a 20x4 LCD using Atmega328. But I failed to display any character on the screen. I'm not sure where the problem is, either the initialization or the timing order. I am using PortB as data port and PortD0 as RS, PortD1 as RW, and PortD2 as EN.

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

#define dataport PORTB
#define commport PORTD

#define rs  PD0
#define wr  PD1
#define en  PD2

int LCD_Init(void);
int LCD_SendData(unsigned char *);
int wrcomm(void);
int wrdata(void);

int main(void)
{
    DDRB = 0xFF;
    DDRD = 0xFF;    //set portD 4,5,6 as output pins
    _delay_ms(500);

    LCD_Init();
    while (1)
    {
        LCD_SendData("hello");
        dataport = 0xC0;
        wrcomm();
        LCD_SendData("world");
    }

    //while(1);

    return 1;
}

int LCD_Init(void)
{

    //Function set
    dataport = 0x38;    //0b00111000, DL = "Low", 8-bit mode; N = "high", 2-line display; F=0, 5x8 display
    wrcomm();
    _delay_us(50);

    //clear LCD screen
    dataport = 0x01;    //clear screen
    wrcomm();
    _delay_ms(2);

    //display on/off control
    dataport = 0x0e;    //0b00001110, D=1, display is turned on; C=1, cursor is turned on; B=0, blink is off
    wrcomm();

    //cursor at line 1
    dataport = 0x80;
    wrcomm();
    _delay_us(50);

    //entry mode set
    dataport = 0x06;
    _delay_us(50);

    //cursor or display shift
    dataport = 0x1C;    //0b00011100, S/C=1, R/L=1, shift all the display to the right, cursor moves according to the display
    wrcomm();
    _delay_us(50);

    return 1;

}

int LCD_SendData(unsigned char *s)
{
    unsigned char *j = s;
    int i;
    for (i = 0; i < strlen(j); i++)
    {
        dataport = j[i];
        wrdata();
    }
    return 1;
}
int wrcomm(void)
{
    commport &= ~(1 << rs);     //selecting command register
    commport &= ~(1 << wr);     //selecting write mode
    _delay_us(200);
    commport |= 1 << en;        //EN = 1
    _delay_ms(1);
    commport &= ~(1 << en);     //EN = 0
    _delay_ms(1);
    return 1;
}
int wrdata(void)
{
    commport |= 1 << rs;        //selecting data register
    commport &= ~(1 << wr);     //selecting write mode
    _delay_us(200);
    commport |= 1 << en;        //EN = 1
    _delay_ms(1);
    commport &= ~(1 << en);     //EN = 0
    _delay_ms(1);
    return 1;
}


texts:
I'm trying to make a footprint for this connector:

But I have a trouble about pinout.

What is the SLEEVE TERMINAL, TIP TERMINAL, SHUNT TERMINAL?

What is my power connection? V+ and GND?


texts: Connecting 4-20mA signal to esp8266 ADC circuit

texts: I'm trying to measure a 4-20mA signal using an ESP8266. I designed this circuit to scale the 4-20mA signal to 200mv-1V signal suitable for ESP8266 ADC. Is this circuit a good practice? Should I add or remove any part?


texts: Learning the Art of Electronics - diode clamp

texts:
Working through Learning the Art of Electronics, Hayes T, I'm stuck trying to build the diode clamp in Figure 3L.7 on page 137, as below:

The text says to, "Drive it with a sinewave from your
function generator... ...and observe the output." So presumably +ve from the function generator connects to "in", +ve from the power supply to "+5 volts", and scope probe to "out".

Having searched the web and studied various clamp schematics, I still can't work out the answer to my question which is, where to put the ground leads from function generator, power supply and oscilloscope?

Thanks

David


texts: What's a good method for filtering out glitches from stepper motor step signal?

texts:
I have a product which contains 2 stepper motors. I've been hardening the system against EMI and ESD.

It used to reset or crash when hit with static. I've been able to mostly eliminate this by grounding everything that's metal, shielding, adding ferrites, etc.

One problem I have not been able to eliminate, is that when the machine is statically shocked, the stepper motors will almost always move one step.

The step signals originate in a MCU on one PCB, travel through a ~12in ribbon, and end at 2 stepper drivers. I believe that EMI is coupling into the long wires and causing an erroneous pulse.

There is currently no termination or filtering on the step line, I would like to add some. What's a good strategy for this?

Here are some ideas I have:

Add a RC low pass filter near the stepper drivers.
Add a small cap ~1nF to ground near the drivers to shunt high frequency noise to ground.
Add a resistor to ground near the drivers such that a few milliamps are required for the step signal to go high.

I'm using a barbecue lighter as a static wand for testing.

Edit: I've added 10nF caps right at the stepper drivers, and that seemed to dramatically reduce the problem. Should I be worried about the capacitive load stressing out the MCU?


texts: Why does this UART Daisy Chain keep frying?

texts:
My team and I are creating a project where a sensor board is controlled by two Arduino Nano's, connected using a UART daisy chain. Whenever the board is turned on using a USB connection, the Arduino's and their sensor function normally. But when the 12v source is added, the programmer (or something else inside of the Arduino) of the Nano breaks. We are powering 16 leds and 16 tcrt5000's with these two Arduino's.
My questions are:

What causes these Arduino Nano's to fry?
If it's a short circuit, how do we keep it from frying again?

I've added a schematic below.

*EDIT:
First of all, I'd like to add something: the two nano's have their own regulators. If I take out one of the two nano's and plug in the source, it runs fine. The LEDs
and the Sensors work normally. If I add the second one, it breaks down.
Second, to clear up, I've added a picture of our setup by adding the design of the PCB.

EDIT 2:
To be specific of the burned down Nano's:
After plugging in both nano's and plugging in the source, the two nano's were not controlling the LEDs. After removing the power, getting burned by the hot regulator and hot pins from the Atmel, and plugging it into my laptop, I couldn't get the code to upload again because of a "Programmer not responding" Error.
It seems like something inside the programmer got fried. I just don't understand how.


texts: Altium Designer - Disable components on the PCB editor

texts: What do I do so that only specified components are selectable, and the rest are non-selectable?


texts: Using 74HC14 to invert a signal for HIN and LIN pin on IR2110

texts:
recently ive been working on a sstc solid state tesla coil project.I am using IR2110 gate driver ic for driving my IRFP450 N-channel mosfets in half-bridge configuration.so the IR2110 ic have two inputs which is the high side input(hin) and the low side input (lin),for the high and low side inputs i cant directly connect my oscillator circuit two both pins which will short the mosfets,so for that ive designed a simple circuit consist of an hex inverter ic
The 74HC14 hex inverter.
The signal from the oscillator circuit and the antenna goes to the pin 1 of the ic (1A) and in pin 2 (1Y)i should get a low output that i can connect to low side of the mosfet driver and pin 2 (1Y) will be connected to pin 3 (2A) thus the pin 4 (2Y) should theoratically output a high signal that i can connect to the high side of the mosfet driver ic
Long story short can i get the desired high and low signal via this circuit?
And finnaly,im running the entire setup with a total of 25v for the half bridge,12v for the gate driver ic and 5v for the logic side
The frequancy is roughly around 450khz with 60% duty cycle

Edit:for some reason i cant post any comments,so im really sorry if not not replying im having some problems
And i will do some research and try every circuits that you guys provide,im really sorry


texts: Why are both a voltage regulator and 2 MOSFETs used for a 3-5V to 3.3V circuit?

texts:
I'm adapting a breakout board for the LMS9DS1 IMU to suit my own needs. This breakout board has an input range of 3-5V and works on 3.3V. However, the circuit, as shown below, seems to have two ways of dropping the voltage. The MIC5225 (bottom left) is a voltage regulator, but don't MOSFETs (BS138, top left) also serve this purpose? What is the purpose of the extra MOSFETs? And can I drop both the regulator and the MOSFETs if I already have 3.3V?

Sorry if this is a silly question.


texts: Error in constant current sink circuit and current regulator

texts:
I have found a circuit online, which is supposed to be a steady current sink:

simulate this circuit – Schematic created using CircuitLab
and every time I simulate in LTSpice, if I change Vc, the current through RL is changed and I don't understand why this is happening. Can anyone help?
I have another circuit (which is my own invention) and it kind of has the same working principle. It is a current regulator without using any feedback, and it is this:

simulate this circuit
R3 is the load and it still shows odd results when run it. Above the zener voltage, it should work like a constant current sink and below the zener voltage of the diode, it should work like a NPN circuit with some base voltage and some collector current for output.


texts: How to use AD 676 Analogue to Digital IC

texts:
I want to  measure degrees using linear potentiometer, so I thought to use the AD 676  analogue to digital converter (ADC) IC.

Is this a good ADC for monitoring a potentiometer?

If so, how can I use it? A schematic of an example implementation would be helpful.


texts: How to find current limit or resistance of current path that is a polygon in PCB?

texts:
I'm trying to understand what is the relevant path of current when I use polygons for PCB design.

Edit: I'm particularly interested in the current limit in that path without destroying it. Please ignore the thermal reliefs. I'll be removing them soon.

So in this example, I would like to know the current limits for the path connecting the two points of node A. I know the height of the copper, I'm assuming the length would be a straight line connecting them. But what is the "width" here?

Also, how different is the answer to above if the shape is not so nice. i.e. :

Examples/explanations using pictures would be appreciated.

I'm using Altium designer. Is there a built-in tool from there to do measure current limit or resistance between two contacts?


texts: How to dynamically pull to ground USB D+/-

texts:
I have two separate electronics parts linked together via USB D+, D- and GND only (no VBUS).
On the second circuitry (part B), I have FAN3989-D (pdf). VBAT=4.2V is on all the time.
On the first circuitry (part A), I want to implement a logic to control D+ and D-.

What should I build so that FLAG1 is high when S1 is on and FLAG1 is low when S1 is open? I guess that I want to short D+ and D- when S1 is on. How could I do that?


texts: This has been floating in my mind for a while, everything has a frequency. Like a dc-dc converter, my scope is 100 MHz(i know that's a bandwidth but it has the unit of frequency). I understand that an Astable 555 has a frequency which is the mark and space time based on the values of the cap and resistors. And then you have the use of band-pass filter which can filter different frequencies so what is this all about? How does a direct current have a frequency? And the relationship between bandwidth and frequency as they have the same units.


texts: DC Circuit Analysis from Sergio Franco Book : Electric Circuit Fundamentals

texts:
If current source is absorbing power then the polarity wise Vb will be +ve.Then i calculated the value of Vb=4 x 2A = 8V
Va= Vb + (20*2) = 48V
and Vs = 164V
Thus for current source to absorb power of 0 W., voltage source has to change from 17V to 164 V. But ansewr is 140V. Even if i take
Change = 164-17V = 147V.
Where am i wrong ?


texts: Bipolar Transistor Inverter Circuit Analysis

texts:
I have been trying to understand this question and I'm just not sure what equation to use for the collector current.

I'm not sure if I need to be using an output voltage function of time?
All I have got is this:

Any input or advice will be much appreciated.
Thank you for taking your time to read through this.


texts:
I am a total newbie at electrical stuff. I have been reading a while about voltage, current and resistance. I have many doubts but I will try to summarize them:

What happens with the current in a circuit that is not consumed by any device? I explain myself: imagine I have an electric circuit with one battery of 1,5V. I put a small light bulb of 1,5V too in the circuit that needs 0,01A to work. Lets assume the current is 0,03A in the circuit(calculated from the Ohm Law). In order the light bulb not to burn with 0,03A, how does it to prevent from burning with these 0,03A when it only needs 0,01A?

Thanks a lot


texts: what is the meaning of the pin out with 3.3V2, 3.3V3, 3.3V4 etc. I understand its 3.3 volts DC

texts: What is the meaning on a circuit board pin out when you see 3.3V2 or 3.3V3 or 3.3v4 etc.


texts: Understanding combinational feedback loops

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Please give me a simple example of a verilog code that results in combo feedback loop.
Why are these feedback loops undesired in your design? How to interpret blocking vs non blocking assignments in Verilog? - StackOverflow question
Why/how are combo-loops present in (some) Finite State Machines and Pipeline stages?


texts: Changing film capacitors to ceramic capacitors in pulsed induction metal detector

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I am looking at building a metal detector similar to the circuit below.
In the instructions, it is stated that 'Capacitors with values less than 1uF are polyester film type (+/-10%)'. I am planning to use SMD ceramic capacitors rather than film capacitors for ease of manufacture. I am aware that the capacitance of ceramic capacitors changes with the DC offset. I think this shouldn't be a problem for bypass capacitors and capacitors that form RC time constants. Are there any film capacitors in the circuit that should definitely NOT be replaced with ceramic capacitors? If so, why?


texts: Parallel LED strings of different colors and Arduino

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I need to use 7 strings of led, each one of a different color. I will control each string using a Arduino and the BC 337 Transistor.
The string will be connected to a 12V power supply.

I have read lots of things about LED's. I think the right way is to use the string in parallel, with each string having it's own resistor, based on the voltage drop of the led in that string.
So, the string blue will have a resistor and the string red will have a different one, because the voltage drop of one LED is different than the other (the colors are different).

Here is the circuit I draw. I only need to calculate each string resistor value, depending of the voltage drop of the led.

Is it right and safe to use? My only doubt is that I read in a lot of places that this kind of thing would require more complex components to regulate the voltage. And then I read a lot people saying this design is good enough.


texts: checking uart overrun and framing error flags in linux

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Checking uart overrun and framing error flags in linux.
In some microcontrollers I can access overrun and framing error flags programmatically. Is it possible to access these flags from command line?


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Working from a data sheet reference design a 47nF/X 250V capacitor is recommended.

What makes a capacitor an X capacitor? From some googling i've found that X capacitors are meant to go across mains. From some vague references they are metalized film capacitors because they are self healing.

Would any metalized film capacitor be an X capacitor as long as the voltage rating is met or exceeded, or is there some other specific rating that officially makes it an X capacitor?

Would a data sheet specifically say "X" capacitor or is there some other subtle way that it would be listed?


texts: Polyphase multivibrator (real vs SPICE simulation)

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i have a following schematic for three-phase multivibrator:

SPICE simulation shows that it should work (11 volts peaks on collector nodes):

However, when i make this circuit on breadboard it does not work, only left and right LEDs are on, and no fluctuations occur. I have tried to google polyphase multivibrator circuits but non of them seem to work (i always use PN2222A). Is it PN2222A transistors fault? Thank you for help.

UPDATE 1 : As pointed out by Andy Aka i did make a wiring mistake (forgot to connect middle transistor's emitter to ground) . Circuit started to oscillate, however only left transistor visibly cuts off, middle is roughly half off, and right transistor only slightly dims. Ring oscillation is present.

Oscilloscope shows additional 600kHz oscillations at the collector of the right transistor.


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I was looking at simple AM radio schematics and came across this one:

As you can see it has an audio transformer. I'm still attempting to grasp the concept of impedance and such, so can someone explain why this is necessary? And how would such a transformer even work to change the impedance? What would be the difference if you didn't use an audio transformer?


texts: How can I improve this circuit to drive a servo with a 555 timer?

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I am trying to use a 555 timer to create the PWM signal for a servo motor.  I found and constructed the circuit in the attached image.  It does work as advertised, and I can adjust the servo's position via the potentiometer (labeled VR1 in the circuit).  However, when outside torque is applied to the servo, it does a poor job holding its position.  I can turn it several degrees at which point it jitters.
I know this is not a power supply problem because using the same setup and a signal generated by a microcontroller, the servo can hold its position perfectly against any torque I can apply.  So I am guessing there is some noise generated by the servo under load that is causing the timer to misfire.  If this might actually be the problem, where that noise would be, and how to suppress it I do not know.  So, my question is: how can I modify this circuit so the servo has more stable performance under load?


texts: How does a Touch Screen Digitizer Tester work?

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I'm currently replacing my screen for my Iphone and having issues with my touch screen dropping. The guy who sold it to me said he used this to test it.

http://www.ebay.com/itm/LCD-Display-Touch-Screen-Digitizer-Tester-for-iPhone-6s-4-7-6s-Plus-5-5-/112000947874

Now, I'd like to believe this guy but I'm curious as to how this box could test the touch screen, what could those little boxes mean?

Thanks


texts: A question on factors affecting the offset removal of an opamp circuit

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I will use a function generator module which outputs 0-1V sine-wave for frequencies of interest from 0.5Hz to 30kHz importance. So my input will be 0-1V sine wave but I want to obtain an AC sine wave with 1V amplitude and 0V offset i.e symmetric swing. I also want to achieve this not by using too complicated circuitry.

Theoretically below circuit works to eliminate such offset:

And here is the output 1V with symmetric swing:

I don't have experience with these but I have couple of questions:

1-) What component in practice should replace Voff for a better accuracy? Voff can be a voltage divider or a reference voltage; but what in practice is better for a reliable offset removal?

2-) The circuit above assumes that the incoming sine is always a 1Vpp with 0.5V offset. What if the Vin's offset varies, is there a solution for that? I mean is there a zero offset Vout solution for a possible varying offset of Vin?

I don't know what is the main issue in such circuits so these are the questions I need to figure out. Maybe some other things like power supply stability, opamp type ect. more important. It would be great to hear if some could share experience.


texts: Do Fixed Bias BJT 's have a cut in voltage?

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I am doing a DC analysis of a Fixed bias BJT and am trying to calculate its collector current. So far I have these following values.

I am using a MMUN2211LT1 bias resistor transistor network.

My Emitter is shorted to GND (so VE = 0V).
My Voltage supply on my Collector is VCC=2.5V with an RC of 22kOhms.
The Voltage supplied to my base is VCB =.785V  with an RB of 7.6kOhms.

So usually when I do DC analysis, I usually calculate my IB using Beta and the cut in voltage (VBEON), and then I am good to go calculating my other values. However, the datasheets I have found for this part do no not mention a cut in voltage or Beta. Should I be using a different set of values to analyze my circuit, or should I be assuming a constant current is going through my BJT. Any advice to deal with these lack of parameters would be greatly appreciated.