texts:
I need to have a 12v battery attached to the arduino for constant running of arduino, but the problem is the charger that will charge the battery.
Yes, there are a million ups systems for that but it will be expensive for just one arduino based system so i was thinking will it work it i connect the arduino to the battery terminal and also connect some automatic 12v battery charger with it too at the same time?
It will charge the battery when it's low and also arduino will start getting the power from the battery (if there is power failure)


texts: Are operations on a MSP430's FRAM Atomic

texts:
In a MSP430 with internal FRAM, I am storing a long variable in FRAM with the following code.
#pragma PERSISTENT(x)
unsigned long x = 0;

    //FRAM write
    SYSCFG0 = DFWP; //unlock fram
    x++;
    SYSCFG0 =  PFWP | DFWP; //lock fram

Given this is a 32 bit value and it is a 16 bit microcontroller, if a power loss were to occur during the write, could data be corrupted?
Do additional mitigations have to be taken such as having 3 variables so that the state of 2 is the correct value?


texts: Mains isolation is mandatory for UL/CE/CSA compliance and other certification?

texts:
I have a design with a non user accesible low voltage section.
Is mandatory to do mains isolation to pass succesfully UL/CE/CSA despite my low voltage section is not accesible for user?


texts: Arduino Uno microcontroller pin broke off

texts:
The lowest left pin in my arduino uno microcontroller (ATMega328p) broke off. That would be pin PB0 (pin 14). I am wondering, would this have any effect on the microcontroller's functionality, or can I continue to use it if I just ignore this broken pin?
Thanks.


texts: MAX5483, 10-bit digital potentiometer controlled via SPI by arduino

texts:
I am desperately trying to get to work an arduino program to control the 10-bit digital potentiometer MAX5483 with SPI, but something is not working. I get some resistance values, but the protocol is wrongly implemented, I fear.. Why is my arduino code below not working?

Here is the arduino code:

#include <SPI.h>

const int csPin = 3;
const int selPin = 2;

void setup() {

 SPI.begin();
 SPI.setBitOrder(MSBFIRST);

 pinMode(csPin,OUTPUT);
 digitalWrite(csPin, LOW);

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

}

void loop()
{

    digitalPotWrite(250);

}

// When working
// 512 = 5070 Ohm
// 0 = 70 Ohm
// 1 = 80
// 1023 = 10070

void digitalPotWrite(int value) {
digitalWrite(csPin, LOW);
byte command=0x0;
SPI.transfer(command);
byte byte0 = (value >> int(value/255));
byte byte1 = ((value & B11) << 6);
SPI.transfer(byte0);
SPI.transfer(byte1);
digitalWrite(csPin, HIGH);
}

Here is the data sheet.
Here is a code for a PIC, which should work:

#include <main.h>

int16 count = 0;
int16 tmp;

void write_pot(int16 data)
{
   output_high(PIN_C2);     //chip select
   output_high(PIN_C3);      //clock
   output_low(PIN_C4);      //Data
   delay_us(1);

   output_low(PIN_C2);     //chip select
   delay_us(1);

   for(tmp=0;tmp<24;tmp++)
   {
      if(tmp<8)
         output_low(PIN_C4);   //Data
      else if (tmp<18)
      {
         if(data&(0x0001<<(9-(tmp-8))))
            output_high(PIN_C4);   //Data
         else
            output_low(PIN_C4);   //Data
      }

      output_low(PIN_C3);      //clock
      delay_us(1);
      output_high(PIN_C3);      //clock

   }
   delay_us(1);
   output_high(PIN_C2);

   output_toggle(PIN_C1);

}

void main()
{
  // spispi_write( )
   while(TRUE)
   {
      if(count<200)
         count++;
      else
         count = 50;

   //   printf("\n\r=%ld",count);

      write_pot(count);
      if(count==50)
         delay_ms(100);
      else
         delay_us(10);

   }

}


texts: How to intentionally overload almost any value resistor with a DC power supply?

texts:
When attaching a resistor to my power supply (which is a Extech 80W 3-in-1 Switching DC Power Supply, capable of 36V 5A) and the amps are set to let’s say 5A at 16V the voltage stays the same but the amps will shoot down to something like .11A, not even close to half an amp. I know this is because of Ohm's law but how can I exceed and force the resistor to take in what the power supply wants to put out? Of course it's the same situation on my weaker power supply as well. Do I have to toggle something on the PSU itself? I've seen at least 5 videos of others frying resistors, but they never show the readings on the PSU's display. I know it's possible with my own PSU, I'm just clueless as to how to configure it. I've tried it on a 4 band 120 ohm and a 5 band 1k resistor.
(I'm not a completely destructive mad man, I just have some useless components that no one wants. I want to stress test them out of curiosity instead of throwing them away.)


texts: Embedded Development - Taking the Next Step

texts:
I'm going to start by telling you what I know. Then I'm going to tell you that I want to get to this magical land of knowing everything about embedded systems development. Then I'm going to ask you what my next steps should be to get there. This answer is rather informative, but I'm trying to get a little more detailed:
What I Know
Let's see, I'm fair with C and C++. Obviously, I want to get better with those languages but I think at this point the best way for me to improve is to just keep using them and continually try to improve my code as I write it. I don't think it would be very beneficial to dedicate any learning exercises to just learning C anymore.
I'm fairly comfortable with designing simple circuits. I see a chip with an open collector output and I know I need a pull up etc. I'm fairly confident that given an IC and its datasheet, I can either figure out how to interface with it or at least ask the right questions to figure out how to interface it.
I'm very good at math and logical thinking. There are few algorithms/design concepts that throw me for a loop. This is definitely my strongest area.
What I've Done
Until now, all of my experience has been with 8-bit microcontrollers. My college course utilized a Motorola HC08, an Intel 8051, and a Zilog EZ8. My professor had built a little dev board for all three of them with a 7-seg display and some other stuff. We programmed them in assembly so I'm somewhat familiar with assembly and I took a basic computer architecture course so I have a decent idea about the hardware. However, we worked on a windows environment and all 3 MCUs had their own IDE and tool chain already setup so I never really learned how my code went from assembly to running on the MCU.
My next step was learning on my own. I got very familiar with the Arduino environment by interfacing with sensors/memories/displays that both had pre-written libraries and some that did not. Next I built my own Arduino board with an ICSP on it and connections to another MCU so that I could flash the bootloader onto bare ATmega328s. Again, however, the IDE and tool-chain was already setup and I never got an understanding of how I went from C/Arduino to code actually running on the MCU.
What I Want to Know
So from the previously linked answer, I think the most interesting/beneficial things for me would be the bullet about learning the tools (compiler and linker), and learning different styles of software architecture (going from interrupt based control loops to schedulers and RTOSes). That is my opinion on what would be most useful... but since I don't know it yet it's hard to say whether that's correct or not so feel free to suggest other bullet points from that answer if you think they would be better and please provide an explanation as to why you think that.

So taking my current knowledge as a starting point and the above description of what I want to know as a goal, I'm looking for very specific suggestions on where to go next. I'm looking for exact project suggestions, websites/blog entries to read, chapters in books, etc.
Also, are there any other holes in my knowledge base that you think I should fill before moving on to the above mentioned topics?


texts: When using an oscilloscope, when is it (in general) better to use DC coupling over AC coupling and vice versa?


texts:
I am now learning about the dark current of PIN photodiode and wonder that if no reversed bias voltage is applied to the photodiode, whether the dark current is 0 or not? If not, how small it would be? nA or pA?

Besides, whether the dark current is DC current or AC current?


texts:
I understand that if load is suddenly ramped up on a power grid:

A sudden increase in current is caused by adding these parallel loads to the circuit.
The current increase thus increases the torque required from spinning generation in order to maintain the speed required for its designed voltage and frequency output. For example a generator designed to output 32 kV at 3600 RPM will see a voltage drop if the speed (and thus Hz) drop.
Since the generator cannot immediately increase its torque there is a brief slow down, which in turn causes a frequency drop and thus a voltage drop.

My question is what some of the dangers of this drop are for the grid? How can this lead to a cascading problem (a blackout)?


texts:
My previous post turned out to contain too many questions, so I'll focus on the main one first, and figure the rest out as needed.

I'm looking at building a DC lab power supply, roughly 1.2-14 volts and up to about 1.5 A, based on the LM317 (and possibly also LM337) voltage regulators. However, I'm a bit torn between two choices when it comes to the basic design: a dual polarity design (+/- 1.2-14 V with LM317/LM337) or a dual rail (2x 1.2-14 V, completely individual rails, 2x LM317).

Example design for the dual polarity:

(Credit: Jason Neal)

The reason I can't decide right now is that I don't understand the following:

If I go with dual polarity (e.g. +9/0/-9 V output), can I power two loads, perhaps with +9/0 for one and 0/-9 for the other? Both should act as if they each had a regular, +/ground supply. My understanding is that the current will go backwards in this case, so that the answer is no?
If I go with the dual separate, 2x positive design, can I wire it up to give the positive/negative output? For example, I've seen people bridge + from one rail and ground on the other, then use the remaining two outputs as +/- and the bridged one as ground.
Will the example design be able to do this, without sacrificing output amperage or cause other problems?

As you can see, the goal is to get both features in a single supply, if possible (without quad rails or such madness).

In either case, I would have a single transformer; either a 12-0-12 V center tapped transformer, or a 2x12 V dual secondary transformer.


texts: What's missing in this development board?

texts: I came across an old development board with an ATMEL ATMEGA8A-PU . I am not an expert but I want to use this board. But something is missing in this board as seen in this photo:


texts: Can I replace a 6.3A fuse with an 8A fuse

texts:
I'm shopping for a Universal Travel Adapter and I've found this one which seems to meet all my requirements. I've used a nice one for years and it recently blew out and it doesn't have a replaceable fuse so I wanted to make sure my next purchase would be more durable with a replaceable fuse.

Unfortunately the website that sells this mentions nothing about the fuse specifications, only that it uses a fuse and comes with a spare one.

On another website displaying the same product it does mention that comes with two 6.3A fuse. And on the picture right here:

It mentions that the Fuse Rating is 8A MAX.

This confuses me. Why would they include 6.3A fuses which seem to be less standard than 8A ones if the max rating is 8A.

What does this mean for me? I want to order some extra fuses but I can't find any 6.3A fuses but 8A fuses are plentiful. Since it says the Fuse Rating is 8A max then does that mean I can use those?

I'm also concerned with the picture that shows these tiny looking fuses. If you compare that picture with what a 5mmx20mm fuse looks like, those look smaller. Is this just a flaw in the picture. Do you believe this uses standard 5mmx20mm fuses?


texts:
What is the purpose of this capacitor placement ?
Why is it placed like that near Magnetic Sensor ?


texts: Reflections on a differential transmission line

texts:
I understand why reflections occur when there is an impedance mismatch on a single-wire transmission line.  However, when we introduce a differential line, I am having trouble picturing what would occur in the following cases:

Imagine a transmission line with 100-ohm differential impedance and 50-ohm single-ended impedance.  What would happen in each of these cases?

(1)  There is a discontinuity where the differential impedance remains 100 ohms, but the single-ended impedance changes.

(2)  There is a discontinuity where the differential impedance changes, but the single-ended impedance remains 50 ohms.

The reason this could be unavoidable in real-life design is due to restrictions on stackup and trace width/spacing that may be driven by other mandatory design requirements.  If I have to design in either one of these types of discontinuities, I want to understand which is worse, and why.

Thank you.


texts: What would be an LDOs output if the input is its rated ouput

texts:
I have an LDO TLV733 that output 3.3 volts. I need that the rail would always be 3.3v because anything below that the slaves data pins might get damaged because the host signal is 3.3v. The input voltage can range from 3.3 volts to 5 volts. Anything beyond 3.75volts is guaranteed to output 3.3volts on this regulator but i am not so confident voltages below it.

How do i compute the voltage output of the LDO compared to its input. In the datasheet i could not find a graph of its input output relationship.


texts: I'm having troubles deciphering the datasheet for the DS3231 RTC. The below table shows that 0x02 bit 6 is the flag to operate in 12- or 24-hour mode. But which one correspond to the bit being low or high? I assume the line above the 24 must tell it, but I guess I lack knowledge of the usual conventions.


texts: Is it possible to open two files simultaneously in Multisim?

texts:
It seems that Multisim provides useful feature of
File trees:

And design file tabs:

However, I was never able to find the way to use them. Is it possible to open different files at the same time for multisim. If so, could I ask for some tutorials? I tried to find some on the internet. But with no luck.

Thanks a lot!


texts: Asynchronous single phase Motor do not start

texts:
I have got from my company scrap an old Alcatel Vacuum Pump. After taking apart the  pump and cleaning everything, I tried to make the motor run. Unfortunately apart a noisy 50 Hz the motor don't turn. The bearings are fine, I can make it turn by hand. Then I draw the schematic of the electric connections as I measured it:

The winding has 5 wires (red, white, grey, blue, black). What is beyond my understanding is this Motor start switch circuit which has 3 connections. On this circuit I see two components one big thing that look like a reel relay. I measured 0 Ohm between the yellow and the black connections. The other component is a T220 package.

How does work this start-switch module and how could I test it works?


texts: Can 3 3.7 volt 6000 mah batteries power two 9 watt bulbs

texts: I wanted to know if 3 3.7 volts 6000 mah hour batteries power 2 9 watt bulbs, and a 12-volt pc case fan? If so for how long?


texts: How to make a design more independent of a particular silicon vendor?

texts:
In many hardware projects it would be nice to have the freedom to switch between vendors easily, mainly microprocessors and microcontrollers.

I can see many reasons for wanting to have this freedom, one of them being the ability to easily switch to a cheaper company if one company decided to jack their prices up. Another situation is when a designer decides to change the project in a direction that the old microcontroller just can't handle, I can see this happening within a company that is trying to reuse hardware modules.

Is there any way of designing hardware to be modular enough to easily switch out these core components? What are the issues with designing this way?


texts: DC bias difference between square and sine wave?

texts:
I have a 90V DC voltage, VPP.

I have a 10Vpp (-5V to 5V), 100 kHz square wave that I'd like to re-bias at VPP/2.

Here is the output from LTSpice:

Biased output starts at 45V and then 10V is added, or it seems like it is biased around 50V and swings 45V to 55V.

I expected it to be biased at 45V and swing from 40V to 50V.

When doing a 10Vpp, 100 kHz sine wave:

Output is centered around 45V as expected, swinging from 40V to 50V.

This is probably a really silly question. Maybe I should re-evaluate my life.

What am I misunderstanding about the square wave here?


texts: How do you terminate a CAN Bus that is physically short (i.e. it stays on the same PCB, but has multiple transceivers connected to it). I would think I need one 60 ohms resistor, right?


texts: STM32F107 Clock configuration and USART problem

texts:
My old program (USART section) worked with a 25Mhz external crystal perfectly. I have changed my external crystal to 8 Mhz and multiplied it 8 to have a 64Mhz SYSClock. My timers, PWM and other sections work fine but my USART with 115200 baud rate doesn't work( it sends fault characters). I need to know what my problem is.

void CLOCK(void){
RCC_DeInit();
RCC_HSEConfig(RCC_HSE_ON);
while(RCC_WaitForHSEStartUp()==ERROR);

FLASH_PrefetchBufferCmd(FLASH_PrefetchBuffer_Enable);
FLASH_SetLatency(FLASH_Latency_2);

RCC_PLL2Cmd(DISABLE);

RCC_PLLCmd(DISABLE);
RCC_PREDIV1Config(RCC_PREDIV1_Source_HSE,RCC_PREDIV1_Div1);
RCC_PLLConfig(RCC_PLLSource_PREDIV1,RCC_PLLMul_8);
RCC_PLLCmd(ENABLE);

while(RCC_GetFlagStatus(RCC_FLAG_PLLRDY)!=SET);

RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);

RCC_HCLKConfig(RCC_SYSCLK_Div1);
RCC_PCLK1Config(RCC_HCLK_Div2);
RCC_PCLK2Config(RCC_HCLK_Div1);

while (RCC_GetSYSCLKSource() != 0x08){}

SystemCoreClockUpdate();

}
USART configuration:
USAR.USART_BaudRate=115200;
USAR.USART_StopBits=USART_StopBits_1;
USAR.USART_WordLength=USART_WordLength_8b;
USAR.USART_Parity=USART_Parity_No;
USAR.USART_HardwareFlowControl=USART_HardwareFlowControl_None;
USAR.USART_Mode=USART_Mode_Rx | USART_Mode_Tx;
USART_Init(USART1,&USAR);

NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);

NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);

USART_ITConfig(USART1,USART_IT_RXNE,ENABLE);
USART_Cmd(USART1,ENABLE);


texts: Can electric bike controllers be used with a brushed DC motor taken from an electric lawnmower?

texts:
I am trying to make an electric bike (this is my first electrical project with motors).

To save money, I bought a used electric lawnmower and extracted the motor, as well as two 12V batteries in series (resulting in a 24V battery).

Now, I need to get a controller for this configuration, but I lack knowledge in selecting the correct controller. Someone told me that typical electric bike controllers cannot be used with simple, brushed DC motors like the one I got from a lawnmower machine. Is this true?

This is the controller I had in mind.

Are there different types of controllers that must be used depending on the type of motor you have? Does anyone have a source that describes all the types of controllers?


texts: Use a transistor or MOSFET as a switch to control a solenoid

texts:
I am working on a project to control a solenoid (12 V/DC 12.96 W) with an ESP32. I have attached a circuit design as it is in picture.
I have couple of questions:

Would this circuit work properly?
Do I need to change the transistor (PN2222) to a MOSFET (IRLB8743PBF)?
Solenoid force varies between 30N,59N. How can I control the force of the solenoid via the ESP32?


texts:
I am designing a PCB an need an LED on it. I'm going to direct the light from the LED using a light pipe, so I need it to be as bright as possible. The question is what size I should use? All the other components on the PCB are 0805.

Does the brightness of an LED depend on how large the component is? I.e. can I get brighter LEDs if I choose a 1206 footprint? Or are 0805 and 1206 LEDs the same brightness?


texts:
I want my car's DRL to go off when my turn lights flash.
I'm assuming I need a P-channel MOSFET, Q1 to control the positive voltage.
Then I need resistor R2 as a pull-down so its normally on.
Then if I introduce a smoothed-out 12v from the turn signal, that should turn Q1 off, but it only dims it a bit.
What am I doing wrong?


texts: Pin headers that fit perf board that taper to DIP/SIP leg width

texts:
I'm building some emulator boards to replace some vintage GALs and DRAMs that have failed.  I'm planning to build out my circuit on perf board with the discrete/new components mounted there, using sets of sort-of pin headers extending below the board to fit into the DIP sockets on the original board.

Question:  I'm having trouble locating (or even figuring out what to search for) for either very thin pin headers (less preferable) or typical pitch headers that have pins on one end but taper down to something that will not do damage to the original sockets.  Sort of chip legs on one end and pin headers on the other.  What are these called?

I know I've seen them on boards, so I know they exist, but I have no idea what to call them to find them at a supply house.


texts:
I'm an experienced analog/power designer that's been asked by a coworker to scrub a digital design.  He's pretty junior, but a good friend, so I am helping. (So now we're BOTH in trouble.  ;-P

We are connecting a LAN9500 and a KSZ8795CLXIC and are hung up on how to wire the MII connection between the two.  I realize that there are two MII types:   PHY MII and MAC MII.  I attached a scrape of our schematic.

I think that this is miswired, with Tx  connecting to Tx and all of the handshaking being wrong, too.

But confusion comes from examples like this KSZ8863 Eval board.  Where TX connects to Tx and Rx connects to Rx!  For this Phy mode example, anyway.  Here's what I'm talking about:

Also, does timing between these two chips need to be scrubbed?  Or does MII mean that these should connect without glue logic?

Any pointers would be totally appreciated.

Dan (& Brett)

datasheets:
http://ww1.microchip.com/downloads/en/DeviceDoc/00002112B.pdf

http://ww1.microchip.com/downloads/en/softwarelibrary/man-lan95xx-dat/lan950x%20databook%20rev.%201.2%20(07-15-11).pdf


texts: Heatsink or IC: how to determine root cause of overtemp?

texts:
I have a manufacturing situation where we perform a functional test on a board and we are getting frequent overtemperature failures from a BGA package with a heatsink on it. I would like to be able to determine if the cause of overtemperature is because of a bad thermal contact with the heatsink OR if the cause is from the IC itself generating more heat than we expect.

Here's the details:

Large BGA package that dissipates A LOT of power. Very sensitive to heat sink seating
BGA package is a part that is picked by our supplier to meet our specified voltage/power requirements.
There is variation in power dissipation across devices. Unkwown if this variation is caused by heat-sink application or differences between individual IC's. Device has characteristics of thermal run-away? Higher temp and higher current consumption go hand-in-hand (voltage rails are steady).
Heat sink is a copper vapour phase chamber with fins. TIM is a high-performance thermal grease. We have a controlled environment in a chassis with fans forcing air at a constant RPM.
I have a way to measure die temperature of the device to a resolution of 1C. And I can heat-up the device "at will" by running an automated test.

What I would like to do is to perform a test that checks the efficacy of the heat-sink to rule out the heat sink (or TIM or seating) as a problem. One way to do this is to re-apply another "known-good" heat sink and retest, but that is dependent on operator skill for repeatability, and has other manufacturing workflow problems.

Here's an idea for measuring the effectiveness of the heat sink, I'd like to get some input on whether it will be a good idea and/or what would be a better way to test this.

The device has a "textbook" heat-up/cool-down curve that fits nicely to RC-time-constant. In the plot below, I have the device starting at "idle" then I make the device "do its job" in a functional test and then turn off the function after 5 minutes.

I am most interested in the cooling curve because when it starts to cool, I know that the core-part of the IC is no longer generating heat. The cooling curve is just the package cooling down through the heatsink and PCB. I assume that the heatsink dominates the heat transfer especially early on. In other words, the cooling curve is a measure of the cooling performance of the heat sink and not much else. Moreover the other variables across tests have less variation than the heatsink (eg cooling through PCB).
When I normalize the curves to range between zero and one, set the time origin to onset of cooling and look only at the first 80 seconds of cooling, I get nice straight lines in a log plot. Time constant in a cool-running device is 36s with standard deviation <5% over a dozen runs. Time constant in a device where the heat sink has been deliberately impaired to run a few degrees hot was 39s with similar standard deviation.

Now the question if I get a hot-running device and I measure time constant that is the same as a cool-running device, can I rule-out the heat sink and its application as a problem?

I should clarify that this is in a manufacturing context, not design (DVT). The focus is to be able to determine the cause of failures.


texts: How to understand Bode plot or Bode diagram

texts:
I am having difficulty understanding the Bode diagram, which I have understood so far: that depending on the angle of the phase, where the system becomes unstable or stable.
I just don't know what the practical applications are when using this system in a closed loop.
I mean a practical example how to change the control, such as a robotic arm, or a mechanism that can be more sensitive (control)?


texts: Non-rechargeable Battery Gauge circuit / Coulomb counter

texts: I'm trying to find a cheap implementation/circuit to monitor the remaining capacity of a non-rechargeable battery to be specific Lithium thionyl chloride LiSOCI2 batteries. I am aware of TI and Maxim's solutions but i feel they are expensive, i found several coulomb counter projects but AFAIK they fully discharge the batteries to finish the test which for LI-ion (rechargeable) this is not a problem. I was thinking if it was possible to do with simple components (Transistors/Mosfets) and software using a microcontroller to do ? I would really appreciate if someone would point to the right direction. For the curious out there, it's going to be inlcuded in an energy/electricity meter. Thanks in advance.


texts: Why losslessness requires voltage and current must be both zero?

texts:
In the textbook (pg. 260 Linear Circuit Analysis, by Artice Davis), losslessness is defined in such way:

Losslessness: If w(\$\infty\$) = 0 for any v(t) and i(t) waveforms supported by the
element and having the property that v(\$ \infty\$) and i(\$ \infty\$)
are both zero, then we say that the element is lossless ... we must
require that both the voltage and current waveforms approach zero at t
= \$ \infty\$ in order to test an element to see if it is lossless.

An element is lossless when there is no energy loss or energy exchanges. And for instance, if I start with the equation for the energy of a capacitor \$ w(t) = {1 \over 2} C v(t)^2 \$. So long if there's a voltage across the capacitor, energy cannot be zero (not lossless). BUT If I start the calculation with power, where \$ P = v(t) \cdot i(t) \$, then as long as either (and not necessarily both) current or voltage is zero, power has to be zero (so will its integration, or energy). Hence my questions are:

Mathematically, if I calculate energy by integrating power through all time, I get zero power and zero energy (lossless) if either voltage or current is zero. So why does the textbook claim that it is required for both current and voltage to be zero for an element to be considered lossless?

Conceptually, as long as a capacitor "holds" its charge eternally, then the capacitor has to be "lossless" because no charge is leaving the capacitor, and nothing disappears in form of energy away from the capacitor. So capacitor, ideally, can hold a voltage and still be lossless.


texts: Set TIMER interrupt int STM32F4 Discovery

texts: How can I know exactly address of TIMER2 in Interrupt Set-Enable Registers (NVIC registers) to set for TIMER2 interrupt. Document " cortex m4 processor manual" just gives address of interrupt set enable registers from 0xE000E100-0xE000E11C not specific address bit for TIMER2.


texts:
I know there is quite few discussions already on this topic, but since English isn't my first language, I though it better to get some more information about this.

I have used oscilloscopes to troubleshoot electronics problems and measure AC engine current spikes at startup, but I have no experience using them to measure high voltage levels and my experience is with old analog scopes.

So now I have this new DSO and the input rating is 400V peak to peak AC, so it can handle about 140V AC RMS? Not that I'm going to input that much there.

Since I live in Europe the mains here are 230 V @ 50 Hz I can't measure them directly.

If I set the attenuation from the scope and probe to 10X, the voltage is 23 RMS and it is safe to measure? And yes the probes are rated for 1kV.

If that is true, it's also safe to measure voltage between two main lines (400V RMS), since the peak-to-peak would be about 112 volts?

SAFETY: When I am measuring AC, I will be using the scope from its internal battery or with a isolating transformer (1:1) so that it is floating, meaning that there is no connection to earth ground. Are there any other safety issues I have not realized?


texts: Headset with microphone effect on smartphone battery life

texts:
I am building a device that will connect to an Android smartphone 3.5mm jack and was wondering if my device would drain the battery. When checking the current on the microphone line on headset connected to the device I notice there's a current of 0.17mA on that circuit, regardless if the mic is in use or not. Should that affect the battery drain of an average smartphone? Meaning, is there a difference to battery life whether a microphone headset is connected or not?

Thanks.


texts:
I'm new to impedance control PCB design, and I got following information from a PCB manufacturer. This is their standard stack, and I'm planing to control the impedance of my design according to their specification, because it's cheaper. Is it possible to do that? When designing impedance control PCBs, should pre-pegs and core both be FR-4?

Pre-preg thickness - 1080 = 3.04 mil - 2116 = 4.67 mil - 7628 = 7.68 mil

Four-layer top layer - 18 µm copper foil (plated to 35 µm+) pre-preg - 1 x 1080 + 1 x 7628 Layer 2 & 3 - 1.0 mm FR-4 core with 35 µm/35 µm copper pre-preg - 1 x 1080 + 1 x 7628 bottom layer - 18 µm copper foil (plated to 35 µm+) 1.6 mm +/- 10%

How do I calculate εr between the top layer and the second layer using the above information?


texts:
I need to make a dc dc converter and have some ferrite toroids but I don't have the datasheet of the cores so I need to know how much energy are capable do store the core and what current can they handle. I need an average current of about 6A at the output so the inductor current will be at least 6A probably 7 or 8A because of the efficiency and the conversion ratio.

Edit.

What would be a good test to know if the cores I have can handle a current of 8A with a switching frequency of 10KHz?


texts: Heating a brass blade with soldering iron element

texts:
I am trying to build a ribbon cutter like this. I have completed the rest of the machine with the use of an arduino and a couple of DC motors.

I'm stuck with the hot blade.I am not well versed with heating.Initially I tried to use a nichrome ribbon (5mm width 8cm long) with a transformer. But I got stuck as I could not figure out the resistance of it( cannot measure with multimeter) to identify a suitable transformer.

I am thinking of using a soldering iron filament (40W) and fixing a brass blade to the tip. this is how I have done the calculations;

c=375 J/Kg C for brass
weight of blade 10g (0.01Kg)
I need the blade to heat upto 300 degrees Celsius to cut through the polyester.

to heat the blade to 300 degrees Celsius the energy required is 1125J.

Energy = Watts * seconds
1125J / 40W = 28.125 s

accordingly the blade should reach 300 degrees Celsius in less than 30 seconds. is this correct? my instinct tells me it will not happen.


texts: How can this circuit become more robust?

texts:
I have been working with LED lately and I encountered the following circuit.

simulate this circuit – Schematic created using CircuitLab

The bridge is DB107S 1A  1000V.
The LED work at 60mA, 3-3,4 Vf.
The board is connected to mains power with 230rms @ 50Hz.

The problem is that sometimes the LED's are getting cooked.
I believe that this is caused by voltage spikes that pass in the system since it does not have a low pass filter (RC) in the input.

Any thoughts or suggestions on how to identify the problem?

EDIT: The LEDs are 54 in total and not 27 as my first schematic shown.


texts: How can I read in M-bus metering data with an Arduino Uno?

texts:
I am trying to send data from a Kamstrup Multical 601 to an Arduino Uno using the M-bus protocol.

I am considering trying to use the libmbus c libraries to do this. However, I do not have a lot of experience in c programming so was wondering if:

you think this is a realistic/achievable approach?
anyone could suggest an alternative/easier approach?

The main chip on the Arduino Uno is the Atmel Atmega382P-PU.

After getting the data to the Arduino I aim to perform some calculations and send data to an LCD (this I think I can do).


texts: Enabling/Disabling 24V using sensor and relays

texts:
It is about enabling or disabling a 24V input to a device by using some number of sensors and relay(s).
I am thinking to use three relays in order to achieve my requirements stated below;
Occurrence of the states are in the desired order.
State#1:
I need 24V is interrupted when
Sensor1   HIGH
Sensor2   LOW
State#2:
I need 24V is enabled when
Sensor1   HIGH
Sensor2   HIGH
and tricky part,
State#3:
I need 24V is stay enabled after
Sensor1   LOW
Sensor2   HIGH
or
Sensor1   LOW
Sensor2   LOW
up until the State#1 is satisfied again.
So far, I have thought using 2 standard SPDT-NC relays in order to achieve an AND gate logic and using a latching relay as third one to satisfy State#3.
This is just straight forward thinking of mine and before spending money on those, I like to here your opinions.
I am not much into electrical engineering but more embedded software and digital electronics. Any input highly appreciated.
EDIT:

Normally, the device is fed/energized under 24V. The states are only for enabling and disabling the 24V rail now and then.
If I elaborate State#3 a bit more; If the Sensor2 goes LOW before Sensor1, it shouldn't interrupt the 24V. Only when Sensor1 is HIGH, the feed will be interrupted.

EDIT:
A bit more about my project:
Sensor#1 is just photoelectric sensor and it gives HIGH signal when a box passes by in front of it on the conveyor belt. And the Sensor#2 comes from somewhere else as HIGH or LOW signal. Ultimate goal to start or stop the conveyor belt by enabling or disabling 24V rail as per the sensors as I explained above.


texts: 3+ 3v and 1x 4.5v circuits with one or two batteries?

texts:
This is my first post as I have been searching google for way to long for an answer.

I am building a Proton Pack for my grand kids.  Not trying to build something as a replica or anything just something for them to have fun with.

Currently I went to the dollar store and bought a few LED light kits that run off of 2x AA 1.5V batteries.

Also the gun portion runs off of 3x AAA 1.5v batteries.

I want to put about 3-4 LED kits in each pack and power the gun as well.

What I am trying to figure out is, "How do I power all of the different LED Kits and the Gun with the least amount of battery packs/batteries"?


texts: What does "mod 2" mean in these multi-level inverter switching equations?

texts:
I am working through a paper that discusses the design of a multi-level inverter to connect photovoltaic arrays to the grid. It uses 4 PV modules (only two are shown in the design image below, but it is expandable) along with an H-bridge to produce 31 voltage levels. These are used to produce a modified sine wave with low THD:

The scheme for switching Q1 - Q4 uses a reference voltage:
V_ref(t) = V_max*sin(wt + delta_ref)

The authors given equations for calculating the switch signals, which include "mod 2":

I am aware of the usual meaning of "m mod n" as "the remainder left over when m is divided by n". This doesn't seem to work here at all!

Can anybody tell me how the given equations are able to generate the switching signals?:


texts:
If the open circuit voltage of a 3V CR2450 Battery is at 2.95 Volts: is it at end of life?

I have a CR2032 3V that could fit in the device and I could use a nickel to compensate to fill the gap in the device: is there any foreseeable problem in doing this?

Update: installed a CR2032 as a temporary measure until  a CR2450 can be shipped.  Seems to work well.  CR2032 are 2 for $1 at the dollar store vs $7 for a CR2450 at CVS


texts: Average output voltage of a fully controlled full wave rectifier

texts:
What is the average voltage for a fully controlled bridge rectifier with firing angle \$\alpha\$ ?

In a lot of web resources it is said to be:

$$\frac{V_{max}}{\pi} (1+ cos(\alpha))$$

For example here and here.

But in my lecture notes it says it is:

$$\frac{2\sqrt{2}V_{rms}}{\pi}cos(\alpha)$$

which is equivalent to:

$$\frac{2V_{max}}{\pi}cos(\alpha)$$

Why have I been taught a different formula to what is online? Which is correct, and if they are both correct when should I use each formula?

Extra Detail

In the first link, the formula is derived from:

$$\frac{1}{\pi}\int_\alpha^\pi V_{max} sin(\omega t)\;d(\omega t)$$

which is \$\frac{1}{\pi}\$ multiplied by the area under the input voltage between alpha (the angle at which the output voltage will appear), and the zero crossing point. In the diagram below this is the area under the first "bump" in the \$V_{out}\$ curve.

In my lecture notes the formula for average output voltage is derived from:

$$\frac{1}{\pi}\int_\alpha^{\pi+\alpha}\sqrt2V_{rms}sin(\omega t)\;d(\omega t)$$

The explanation for this is that two of the thyristors conduct until \$\pi+\alpha\$, as shown in the picture below:

So the output waveform looks something like this:

Which is correct?

Thanks!


texts: Low power strategy for dealing with spontainious bit flips durring sleep on AVR 8-bit?

texts:
I am designing a ATTINY-based circuit that is intended to run unattended for very long periods of time on a very small battery.  The device spends almost all of its time in deep sleep, and only wakes briefly in response to a rare pin change interrupt.

I am programming defensively to ensure that the program will always return to a known state even in the face of spontaneous bit flips in almost any register (although I can't get a read on how likely these actually are).

There is one case that I can not figure out how to mitigate: a bit flip to an interrupt control registers that happens while sleeping.

The relevant bits seem to be...

PCMSKn - Pin Change Enable Mask. Must have a 1 for the corresponding pin to generate an interrupt.

PCIEn - Pin Change Interrupt Enable. Must have a 1 for any of the enabled pin to generate an interrupt.

GIE. Global Interrupt Enable. Must have a 1 for any interrupt to occur.

If any of these bits get flipped to a 0 while I am asleep, then the next pin change seemingly will not wake the processor and I am dead in the water with no way to recover.

One way to deal with this would be to set up a safety level 2 WatchDog to periodically reset the processor while I am sleeping, and write 1's to all the interrupt control bits on each reset. This would work great in theory and would seem to be bullet proof, except in practice enabling the WatchDog raises the sleep power consumption several orders of magnitude (from ~0.01uA to ~5uA @ 3V @25C) and thus would cut the projected lifetime of my device from decades to months.

What are some power efficient strategies for robustly dealing with this problem?


texts:
I recently picked up a small DC analog kilovolt meter. The scale went up to roughly 25kv.

I have some microwave oven transformers I would like to test the voltage.

I hooked a microwave diode in series with the kilovolt meter, as an attempt to measure the voltage.

All of the lights dimmed, and the meter essentially acted as a dead short. I thought "I couldn't have burned out a 25kv meter with roughly 2kv" but some more testing provided the same results.

Is there something wrong with the setup? I don't have any info on the meter at the moment other than its a small 1.5 inch diameter analog meter that reads "DC kilovolts" and has a connection on the back for + and -. Yes, I am sure the diode was pointing
The right way.

The meter is very similar to this one on eBay.
Simpson 50280 MOD 27 panel meter 3" 0-500 2 kV


texts: Which board is the best fit for my project?

texts:
I am designing a device that will have an accelerometer and temperature sensors. This device is intended to record patterns in activity of individuals throughout the day. The device will need to operate throughout the day, and should be able to withstand a lot of movement, possibly small weights and generally rough usage. It also needs to be small enough to be carried on a person, possibly latch onto backpacks and fit into pockets or latch onto the belt loops (not sure of the term?).

Which device would best suit my requirements ?

Looking around a bit, it seems the Lilypad is the only Arduino that is small enough. Are there other choices ?


texts: Method for Sending Multiple (16) Channels of Duty Cycle Modulated Signal over Medium-Long Distance

texts:
Problem

What is the best method or industry standard solution for transmitting multiple channels (13 signal, 3 ground) of duty cycled modulated signals up to 25 feet. The data will be transmitted by a computer (BeagleBone Black) and received by an LED Panel at 5V and 800kHz and the signals are duty-cycle modulated, with a 0 measuring 250 ns long and a 1 being 600 ns long, and 1250 ns between bits. The communication is one way - BeagleBone Black to LED panel - and there will be 4 lengths of ~25 feet. The proposed solution should read the 16 channel signal from the BeagleBone Black ribbon cable,  transmit the signal ~25 feet, and convert the signal back into the 16 channel ribbon cable for consumption by the LED board.

Background

I am building an LED display using a BeagleBone Black running the Open Source LEDScape software for a local school to use for educational purposes. The LED panels use 800kHz Duty Cycle Modulated signals. Currently, during development, the BeagleBone Black communicates to the LED panels (16 panels) over 6-inch 16 channel ribbon cables. This works great for development, but I need to mount the LED displays in 4 different locations around a room at a maximum of 25 feet away from the BeagleBone Black. The ribbon cable solution is unable to scale to the 25 feet required. (In each of the 4 locations, there will be chains of 4 panels - the chains are close enough to use the 6-inch ribbon cables.)

The image below is the current state, but the 4 sets of 4 panels need to be spread into separate corners of a room.

Leads

In my research, I've uncovered a number of helpful leads from the community. These include:

Using CAT5e/6 cables: In certain implementations of the LEDScape software (with fewer channels of data), multiple ethernet cables are used. I like this idea, but they use the MAX3040 chip. Using this chip, the number of chips and twisted pairs will add up quickly to transmit all 16 channels.
Bus Buffers: This hackaday article (if I interpret correctly) suggests using a chip like the P82B96 to enable higher capacitance and a boosted voltage. This is at the top of my list, but I'd like to ask the community if there are popular chips that have more than 1 channel to reduce complexity and price. (I only need to transmit data, not receive, from the LED panels)
Differential Bus Buffers: The same hackaday article suggests using a chip like the PCA9615 to encode the data into differential pairs. The reason I have not (yet) selected this solution is the level of effort (and cost) that will be required to install 4 transceiver-receiver chip pairs each with 16 differential pairs (32 wires).

Restrictions

Due to the LED panel specifications, the data must transmit at 800kHz.
Due to the hobbyist project, I would like to use chips that are available in DIP format so that I can use them with a breadboard.
Because this is a volunteer effort and may be reproduced when I release the build instructions, I'd like the solution to prioritize affordability (~$100-$200). Less is better.

I will do my best to answer any questions, but please note that my background is in software and some EE questions may go over my head. Thank you in advance for any help.


texts: I want to use this automotive relay to switch 60VAC, the current max. is 10A. But all its parameters are for DC usage. Can I use it safely to switch AC? It states its "Max. switching voltage" is 50VDC, then what about AC? How can I infer the AC parameters?


texts: Rectifying diode for boost converter in nixie clock

texts: I've been working on this schematic to create a nixie clock. But I don't understand the need for recifying diode D5 in the schematic. Wouldn't a standard diode work? Does it have to do with the "back emf" produced by the inductor?


texts: digital controller design and mapping analog signal to digital integer values

texts:
I have a specific situation i am trying to wrap my head around but i think it should have a general formalism to address the problem.

I have designed a BiQuad controller for a buck converter and i am trying to implement this controller using a uC routine. the design of the BiQuad is done in the S-domain and converting this controller to the discrete form is a well known procedure and no mystery there.

My concern is about the form of the error signal. the error signal  is a simple difference between 2 analog signals (V_reference - V_out).
 i am using ADC converter to sample V_Out that maps it to an integer value in the range [0 - 65536] which correspond to (0 -> Vcc) [vcc here is related to the ADC converter].

now the floating point coefficients of my discrete BiQuad controller need to be a adjusted to accommodate the fact that the error signal i am feeding it is not a real value but an integer mapped value, right ?

while i can covert the ADC reading to a floating point real representation of the error signal , but i would rather do the computation with integer value to make the controller code run faster.

let's assume this simple :

PWM_Duty = a0 * error + a1 * previous_error + b0 * previous_PWM_Duty.

error, previous_error: 32-bit integer value mapped from floating point value by the ADC converter.

a0,a1,b0: floating point coefficients obtained by the controller design.

PWM_Duty,previous_PWM_Duty: the control signal that change the duty cycle of the PWM, it is an integer value between 0 and 100.

my question is how to convert b0, a1 ,a2 to make the control equation do the right controlling it did in the analog world ?

hopefully i am asking the right question here. i would love some reference or books that talk about coding controllers and address this kind of problem.

sorry for the long post :)


texts:
I'm new to PIC's and PIC programming but I'm working on a little project to try get a PIC24F32KA301 to communicate with a Raspberry Pi using I2C. The Raspberry Pi is the master and the PIC is the slave. I have created a little Python program on the Raspberry Pi and tested that it works by successfully communicating with an Arduino, what I want to do now is replace the Arduino with a PIC.

Just for completeness I've included the python program below:

import smbus
import time

bus = smbus.SMBus(1)
address = 0x22

def writeNumber(value):
    bus.write_byte(address, value)
    return -1

def readNumber():
    number = bus.read_byte(address)
    return number

while True:
    var = input("Enter 1 - 9: ")
    if not var:
        continue
    writeNumber(var)
    print "RPI: Hi Arduino, I sent you ", var

    time.sleep(1)
    number = readNumber()
    print "Arduino: Hey RPI, I received a digit ", number
    print

I'm pretty sure I've connected the PIC and Raspberry Pi correctly:

GND <---> Vss (pin 19)
SCL <---> SCL1 (pin 12)
SDA <---> SDA1 (pin 13)

The Raspberry Pi is powered over USB (I think it's 5V, but it might be 3V) and the PIC is powered separately using a 3V battery. The Arduino didn't have any pull up resistors so I assume it's ok to not have any on the PIC (maybe this is wrong?).

I'm using C with the XC16 compiler and the i2c.h library to program the PIC but I'm not really sure what I'm doing, I've tried my best to piece things together from I2C examples and little bits I've read on various forums etc:

#define USE_AND_OR    // not sure what this is!
#include <p24Fxxxx.h>
#include <i2c.h>

unsigned char I2C_RECV[1]

void main(void) {
    unsigned int temp, i;
    for(i=0; i<1; i++)
        I2C_RECV[i]=0;

    TRISA = 0b0000000000000000;
    PORTA = 0b0000000000000001;

    /* INITIALISE I2C MODULE  */
    CloseI2C1();                            // close i2c if it was operating earlier

    while(1) {
        OpenI2C1((I2C_ON | I2C_7BIT_ADD | I2C_CLK_REL | I2C_STR_EN), 0);
        I2C1ADD = 0x22;                     // initialze slave address to 1E

        // receive data from master
        while(DataRdyI2C1() == 0);          // wait until data is transmitted from master
        temp = SlaveReadI2C1();             // read address to empty buffer

        SlavegetsI2C1(I2C_RECV, 1);         // receive data

        if(I2C_RECV[0] == 9) {
            PORTA = 0b0000000000000011;
        }

        CloseI2C1();
    }
}

The code is quite simple (but probably wrong!). Basically I initialise the I2C module and turn on an LED, then I enter a loop, open the I2C connection using address 0x22 and wait for the master to send some data. When data is received I check it's value, if it's 9 I turn on another LED.

On the Raspberry Pi I can confirm that the PIC is accessible by running i2cdetect -y 1. I can see the PIC at address 0x22, which gives me some confidence that I'm at least heading in the right direction! However, when I run the python program I receive an IO error, the error number is 5. I've looked around to find out what that means, but it's a very vague error, basically anything could have gone wrong!

I'm not sure if it's my circuit that's incorrect (i.e. do I need pull up resistors, if so how do I calculate what resistance they need to be?) or my PIC program. If anyone can check the program makes sense or has any advice I'd be very grateful.

Thanks.


texts: What part of a mobile phone charger makes it safe to be charged with opposites polarity?

texts: A mobile phone charger works regardless of whether the charger is the right side up or upside down. As I know, batteries should not be charged with wrong polarity. How do those chargers accomplish that?


texts: STM32 ADC & HAL - EOC selection for polling continiously

texts:
I will ask my question via linking some other question asked by someone. S/he got his/her answer on how to solve, but I am more interested on WHY? Thanks in advance.

Link to the question:
STM32 ADC conversion using HAL

Almost the same issue ( eoc selection thing ) confused me for a considerable time too. I still don't know why? Its explanation just says that set the EOC flag at the end of each channel conversion, so yes this also should work. Convert channel 1 (only one channel, nothing interesting, one measurement only) for example and then just set the EOC flag and reset the measurement cycle. What is the reason why this does not work with single conv eoc choice?


texts: How can I design an isolated, wide-range digital logic input compatible with AC and DC voltages from (say) 5V-300V?

texts:
There are some excellent suggestions on how to create a wide-voltage range digital logic input on this question.

The question is very similar to my needs. I'd like to be able to detect the presence of a voltage (either AC or DC of either polarity, from, say, 5V-300V or thereabouts) and have the input go to a digital input pin of a microcontroller. I particularly like the second solution that suggests current-limiting resistor -> zener diode clamping... but...

In my understanding, an input that can take such high voltages should really be isolated (by a transformer / optoisolator) from a normal low-voltage circuit. How could I create an isolated input like this? Is the limited current and voltage of an input circuit like this enough to drive the input of an optoisolator?

And furthermore, how can I cope with DC voltages of either polarity and AC voltages on that input? I assume that I can put a bridge rectifier straight after the input, but that will cause a decent voltage drop before anything else has happened. Then I know there will be a capacitor in there somewhere to smooth out the input for AC, but I don't understand where it should go, how big it should be and how it will affect switch-on and switch-off times when it's just a plain DC voltage input?

Bonus points if the solution can go down to 3V (or even lower) instead of just 5V. Further bonus points for use of only cheap, standard 'jellybean' parts.


texts:
I'm trying to build an Arduino controlled LED panel, used for videography and a general worklight. Planning to use the PWM signal from Arduino and through a Mosfet in order to dim the 12V LED. However I'm afraid that the PWM signal may cause flickers on video, therefore not suitable for videography.

Initially I've thought of using a low pass filter in between the Arduino PWM Output and the MOSFET, which I then realize it wouldn't work as MOSFET can't be used that way. Is there a way I can smooth the PWM coming out of the MOSFET into the LEDs? The LEDs would most probably be 50W.


texts:
I Have the following Schematic:

The book i am using ask for \$V_{BC}\$ which I found by \$V(B) - V(C) = 0V - 9V = -9V\$

The book gives the answer as 9V, is it safe to assume that since voltage is similar to pressure, we cant have negative pressure so I can take the modulus of my result and it would be equal to the 9V would this be allowed ?


texts: How can I connect the KT3170 (The DTMF reciever) to USB (4bit data)?

texts:
This will be my first try at USB intefacing !

May I know how to transfer the data from pins : 11-15 of KT3170 IC to USB ? Data sheet : http://www.datasheetcatalog.org/datasheet/SamsungElectronic/mXuusvq.pdf I guess I will need to configure a Microprocessor for making the OS uderstand what profile of device is this , In that Case what will be my device profile ? Mine is an RF remote control receiver using DTMF which I want to connect to the PC.

I also have a doubt on fast can The KT3170 can interpret the DTMF tone. That is if I press a button (say 1) and immediately within the same second if I press key 2 Will it be able to recieve and decode the DTMF correctly with proper time synchronization ? What will be the latency if I transmit this signal through Frequency Modulation (FM) ?


texts: How to improve torque and RPM of a DC motor?

texts:
I have an FA-130 motor (DC) with permanent magnet, my power source is a 2 AA batteries (rechargeable) so a total of 2.4v.

Assume that all cases will start from the same specification, theoretically, what would happen if I do the following?

Case 1: Increase/Decrease strength of permanent magnets. What would happen to torque and RPM? Why?

Case 2: Increase/Decrease size of magnet wires. What would happen to torque, power consumption and RPM? Why?

Case 3: Increase/Decrease the size of armature. What would happen to torque, power consumption and RPM? Why?

Case 4: Increase/Decrease the number of turns (coil). What would happen to torque, power consumption and RPM? Why?

In general, how can I increase the torque and RPM of this motor given a constant voltage?

Please, explain it as if you're talking to a 6-year old kid, I'm not knowledgeable in this field but I want to know the concept.


texts:
For a class project, I am required to design a Moore Machine based on a problem that we were given. I have already done this with a Mealy Machine, but I am encountering errors with the Moore Machine. Specifically, my design won't "stick" to a state when it's supposed to. For example, when the input is 1,0 and it is in State1, and I toggle the clock but keep the input the same, it does not stay in State1. Referring to the state diagram may help you better understand what I am talking about.

As you can see, my design needs to have 2 inputs. The input 0,1 is not valid for my design. The number in parentheses is the output for each state.

Here is my state transition table and karnaugh maps. The inputs are in the form (P,N), I forgot to add. Also, the input 0,1 is meaningless in my design.

Based on those, I got the equations

D2 = (N' * q2' * q1' * q0) + (P * N * q2 * q0') + (P * q2' * q1' * q0)

D1 = (P * N * q2'  * q0') + (N' * q2 * q0')

D0 = P * N' * q0'

I'm afraid that my equations may be incorrect, I actually have no idea how to solve 5 variable K Maps (and we're not expected to for this class), so I used a program to solve them instead.

Using these equations, I tried to simulate it using LogicWorks. This is where I encountered the problem above. In certain situations it works, but it really doesn't work when I am trying to make it stay in a state. Any help?


texts:
Oldest versions of this post can be viewed through this link.

This is my re-designed layout. What is your view again?

10-32V to 5V 1.2A SMPS Buck Regulator Design.
The IC is IFX91041 from infineon.

Here are the schematics and layouts:
http://www.mediafire.com/?69e66eje7vda1

(I was given 45 cm² (~6.98 inch²) area for both 5v 1.2A and 35V 4A.)


texts: How to make Op Amp Gain Switch Solid state. (vs jumper)

texts:
How do I create a low-cost solid-state op-amp gain switch to replace a header and jumper? Header pins and jumpers are expensive parts to place, take up a lot of room and the jumper is a headache to manage in assembly. Also, this is part of a product and a user-selectable jumper represents a UI inconsistency; all the other circuit parameters are set in software.

About the circuit: This is a digitally controlled voltage signal generator used in part of an analog feedback control system. Bandwidth requirements are low (<20kHz).  The basic circuit tests well. Currently a jumper selects the gain of the second-stage amp. The circuit range is normally +/-10V with no jumper and +/-5v when the jumper brings R7 in parallel with R5.

The jumper goes where U14 is currently shown. How do I replace that Jumper with something solid-state?

Back-to-back small discrete signal MOSFETs? Don’t all the below
implement some kind of back-to-back switch tpology for low-resistance
bi-directional control? Why can't I build one from discrete components?
(Because I don't know how. This is where my design ability/experience breaks
down.)
At first glance an inexpensive 1 channel analog switch (FSA4157)
seemed like a good fit (U14) until I realized the switched voltage
range of the inexpensive chips are limited to Vss-Vcc
(0-5v).
A digital potentiometer would add variable gain control and eliminate
R5, R6, R7. Again, it turns out the tiny, inexpensive chips
(MCP4013) also have similar voltage range limitations.
A quick search of analog switches and digital potentiometers with
expanded ranges yields impractical prices.
Solid state “relays” I’ve found are surprisingly bulky and/or
expensive (CPC1017N). It appears these typically have an opto-isolators
(which I don't need).

This question has been edited from the original post which was flagged as "off-topic" -- probably because I discuss at length the cost reasons why some design options are already ruled out. I contend there is a very specific design question (which was adequately answered) and that cost considerations are not always the same thing as "shopping recommendations" (which are considered off-topic). In the real world, cost is almost always a principle consideration for making design decisions -- especially with numerous otherwise feasible design options.


texts:
I bought today a very old second hand oscilloscope (Philips PM 3253), see picture below.

I put the probe into a +5v circuit before a LED inside an Arduino breadboard (and checked with a multimeter +5v was on that circuit).

However, whatever knobs I turn or switches on the oscilloscope I set, the horizontal line always stays in the middle (except when I change the position knob on the bottom left).

It's my first-ever oscilloscope ... what switch/knob should I set to get a reading of +5v ... or is the oscilloscope broken?

@Update: It works now (sort of). I noticed there was a multiplication of 10 switch on the probe itself (so the difference between 0 and +5v was not visible), and had to change the main amplitude knob and the inner knob (whatever it means) and also the 0 X B Bal knob ...

But the most important is, that it works, now I have to learn what all knobs mean :-)

I made a new question, since I got some major problems using it:
Oscilloscope makes my mains (fuse box) group go down (maybe problem solved)


texts: How to measure load detection for ballast output 18W

texts:
I have a high performance ballast of only 18W and 36W. I would like to do a detection circuit whenever the UV light tube does not have any light out, an alarm/signal can be triggered to replace the light tube to connect to the ballast.

The one i could think of is current sensing using hall effect sensor ACS712-5A. By theory, whenever the tube is not working, i think there shall be no current flow.
However, the current is too small and the signal is in AC and it is very hard to get a read on the sensor.

simulate this circuit – Schematic created using CircuitLab

Is there any way for detect such application ?
Either we need to measure current or using any other solution ?


texts: 3 to 8 line Decoder not switching off LEDs

texts:
I'm currently working with a SN74AHCT138N 3-8 line decoder and the whole point of this circuit is to switch on and switch off a series of LEDs. I connected buttons to the inputs of the IC and LEDs to the outputs and the SN74AHCT138N is hooked up to 5VDC from a Raspberry Pi (I also have a bench power supply). When I switch the power on, all the LEDs switch on and when I click the buttons, they go dim and they go normal.

I tried adding pull-down resistors to get rid of a possible float, but that still didn't work. (It was pointless as well, as the LEDs are 5V LEDs). The setup is shown below:

Something else to add: On the datasheet, the required amount of input current (Icc) is 1.5mA and I did the calculations and it said a 3.3k resistor should be put in place where Vcc is. I just want to know how I get this working, so if I press input A (first input), it activates Y0 (output 1) and so on.


texts:
For most common/casual 3 phase induction motor, If we connect proper capacitors in series or parallel, can we get resonance like LC circuit ?
thank a lot. star or delta . doesnt matter.


texts: LC circuit VS CL circuit low pass filter

texts:
Are these two topologies for LC low pass filter equivalent?

simulate this circuit – Schematic created using CircuitLab

simulate this circuit

I mean, if I got a switching source, is it the same using an LC compared to a CL series connection to smooth out the voltage? I am referring to long run behaviour after the very first duty cycles; of course I can expect that the configurations will show phase difference as voltage step response.

Do the very same LC equations work for the CL configuration? Is cutoff frequency calculated the same way?
Moreover, are there any specific EMI considerations? In the first circuit, the load without GND reference could surely be a risk for EMI, compared to the second circuit. What about adding a decoupling capacitor between the low side of the load and GND?

simulate this circuit


texts: avr microcontrollers and how to get started coding init or main loop or timers or interrupts

texts:
I have been modifying AVR and PIC microcontroller code for a few years now for work but have never written anything from scratch, I understand it pretty well.

I am starting to write my own code now and am having trouble getting started. I was wondering how other people start writing code and if there is a book or tutorial people would recommend on this.

Do you start with coding your initialization function then interrupts then timers then the main while(1) loop... I am wondering what the best way to get started is.

Thank you


texts:
I'm new to embedded systems. I have MPLAB Xpress Evaluation Board.

I see that the board has MikroBUS connectors. Going through the internet, I couldn't understand what is the purpose of the MikroBUS? Which functionality does it allow? What is the way to connect to it?


texts: usbOTG can I invert the D+ and D- diff pair?

texts: Can I invert the D+ and  D- in a USB OTG connection?, would it work? I know that in some protocols like PCIe you can do it, but Im not sure about usbOTG.


texts: Why is my program stored in flash memory instead of EEPROM in ATmega328?

texts:
As I was going through the differences (basically they are same, but they still have some differences) between flash memory and EEPROM here, I figured out that the flash memory can handle lesser amount of write cycles than the EEPROM.

But, the program I upload to my ATmega328 is written in flash memory. This means I write the flash memory every time I upload a program into the microcontroller. But I think I have never written on the EEPROM.

So I wonder why flash instead of EEPROM?

Going through the datasheet, I figured out that the flash memory has the storage of 32 KB while EEPROM has 1 KB. If this was the reason why my programs are uploaded to flash, why didn't the designers make 32 KB of EEPROM and 1 KB of flash?

The only reason I found to program on flash was the speed. Is this the only reason?


texts: When does P Channel mosfet have 12v on drain as output?

texts:
Ok, so I have an engine control module for an RTV, and I know that based on a neutral safety switch, it will only allow you to start the engine if it is on park or neutral. So, basically what I have found out is that when DRAIN is 12v, the starter is allowed to crank based on this output, however I noticed that I have only got 12v on DRAIN once while trying to change different gears. Meaning that it is an intermittent issue. I have checked that GATE has about 12v and SOURCE has 12v at all times when changing gears to park or drive, but when I saw that DRAIN had 12v, I did not check what SOURCE and GATE have. So, my question is, how does DRAIN turn into 12v? Is it when GATE becomes ground, if so the problem is going to be whatever drives the GATE? I am still trying to figure out if this is a computer fault or not. The mosfet part number is J530, and I do see another IC chip, I do not know if it drives the gate or not, but here is the part number, MH3292F16. NOTE: J2 and AB on schematic, I am not sure exactly what these transistors are, no part number either.

simulate this circuit – Schematic created using CircuitLab


texts: Need help to find correct values for dummy load resistor

texts:
I am working on converting an old ATX PSU to a DIY lab bench power supply. Everything is going well, but I can't seem to find out the correct dummy resistor load values.

The 3.3v rail has 22A and the 5v rail has 21A, and usually the dummy load should be on the rail with most power. However, I read that it's very rarely it's put on the 3.3v rail, so I will put it on the 5v rail.

But I need some help to find the correct value to put on the dummy load. And should the resistance be in parallel or series?


texts: Is it possible to replace a DIAC circuit with an SCR circuit to drive a TRIAC

texts: I have a triac DIAC cirtcuit. I don't have any DIACs on hand, but I do have plenty of TN1215s. Is it possible to generate the required pulses using an SCR to drive the TRIAC's gate?


texts:
Is it possible to have a wireless SWD interface with a simple Data and clock line like the cheap STM32 ST-Link clones.

My initial, and flawed, idea was that I would have an ST-link plugged into the USB port of my computer and on the Data and clock lines that would normally go to the target MCU i would build something that just monitors the state of the data and clock pin and send its over wireless to a receiver which in turn is plugged into the MCU and changed the data and clock lines  accordingly.

This idea may have many flaws but the main one I see is that if I am just relaying to the target the pin changes I have no idea if the Host is asking the target something and the target has to take over and relay information, at which point I need to check the state of target pins and relay that back to the host. So in other words i need to have in depth knowledge of the protocol and not simply relay pin changes back and forth??

Unless there is a simple way of figuring out which way the data should be going, like an extended clock signal or something... I do not know the protocol well enough.

This idea stemmed from wireless transmitting serial data which is easy, but anything else gets a bit more complex. Also stems from a product that I just saw that does the same but uses a Wifi connection to debug and program.

So the question boil down to is it possible the way I am describing of just checking pin states and transmitting that and having it mimicked on the other end or not?


texts: Are 7nm or 10nm transistors reality or is it just a marketing strategy by processor manufacturers?

texts: Now a days chip manufacturers, like Qualcomm, claim that they have built a 7nm chip. Is 7nm really the size of transistor or is it just a marketing strategy? If 7nm is just for marketing and not the size of transistor, then what exactly 7nm is?


texts: PIC CCP in compare mode not changing CCP2 pin

texts:
I'm learning PIC C programming from Gooligum Enhanced C lessons. In lesson 14 CCP module there is example 4a which flashes LED every 500ms, see below:
Using 16F1824 PIC

I can compile in MPLAB X and when I run it in simulation mode CCP2 which is shared with RC3 doesn't change state when TMR1 reaches CCPR2 value.
I also loaded this in Proteus but LED doesn't flash also.
Can anyone perhaps quickly compile this and see if it works?
Or explain to me what is going on?

#include <xc.h>

#include <stdint.h>

/***** CONFIGURATION *****/ //  ext reset, internal oscillator (no clock out), 4xPLL off
#pragma config MCLRE = ON, FOSC = INTOSC, CLKOUTEN = OFF, PLLEN = OFF //  no watchdog timer, brownout resets enabled, low brownout voltage
#pragma config WDTE = OFF, BOREN = ON, BORV = LO //  no power-up timer, no failsafe clock monitor, two-speed start-up disabled
#pragma config PWRTE = OFF, FCMEN = OFF, IESO = OFF //  no code or data protect, no write protection
#pragma config CP = OFF, CPD = OFF, WRT = OFF //  stack resets on, high-voltage programming
#pragma config STVREN = ON, LVP = OFF

/***** MAIN PROGRAM *****/
void main()
{

/*** Initialisation ***/

// configure ports
TRISC = ~(1<<3);                // configure PORTC as all inputs
                                //   except RC3 (CCP2 output)

// configure oscillator
OSCCONbits.SCS1 = 1;            // select internal clock
OSCCONbits.IRCF = 0b0111;       // internal oscillator = 500 kHz
                                //  -> 8 us / instruction cycle

// initialise Timer1
TMR1 = 0;                       // clear timer
T1CONbits.TMR1CS = 0b00;        // use instruction clock
T1CONbits.T1CKPS = 0b00;        // no prescaler
T1CONbits.TMR1ON = 1;           // enable timer
                                //  -> increment TMR1 every 8 us

// configure ECCP2 module
CCPR2 = 500000/8;               // initial compare time = 0.5 s /8 us/count
CCP2CONbits.CCP2M = 0b0010;     // compare mode, toggle CCP2 on match
                                // (CCP2 initially low)

/*** Main loop ***/
for (;;)
{
    // Toggle CCP2 output every 0.5 sec

    // wait for CCP match
    PIR2bits.CCP2IF = 0;        // clear CCP2 interrupt flag
    while (!PIR2bits.CCP2IF)    // wait for flag to go high
        ;

    // add 0.5 sec to last compare time
    CCPR2 += 500000/8;          // add 0.5 sec / 8 us/count
}
}


texts: Why does the Karnaugh map use gray code and not binary?

texts: The row and column headers for a Karnaugh map are written in gray code and not binary. I am wondering why. Is it because that the Karnaugh map needs to wrap around, and gray code is symmetrical?


texts: Why is there a capacitor in parallel with this fan? What is the benefit?

texts:
(source: electronicdesign.com)
I understand that capacitors store charge, however this circuit is supposed to be a proportional controller. I just dont see why the capacitor is needed. Perhaps to reduce oscillation?


texts:
I would like manufacture a very simple one layer board to learn how a PCB is manufactured. I prepared the layout of the circuit on Eagle Cad, and am planning to use acid etching method: use iron to transfer the toner to the copper board. I already bought the following items:

Acid: sodium persulfate
Etching paper: Film paper (http://www.farnell.com/datasheets/1640461.pdf)
Board material:  FR4 Epoxy Fibreglass (http://www.farnell.com/datasheets/52206.pdf)

I bought these items some months ago, I also prefer to buy stuff from Farnell or ELFA as they are convenient for me for some matters and I don't have local stores that I can shop such equipments.

As I search more about how to implement the etching method, I notice that the etching paper(film) that I have is for UV etching method. But I still wonder if I can use it on my production (iron toner transfer, acid etching, ... and it is the only etching paper available on Farnell)? If it is not the case, I see many paper suggestion (Glossy, Carbon 20, Bond) that puzzles me what to use, some even suggest to use magazine papers.

The second question, "photo resist" is printed on the board material (above) that I have. One side of the board is copper coated. I wonder if I can still use that board on my production process? If it is not the case, what material do I need to use, I see many materials like FR2, FR4, epoxy resin, FR-3, CEM-1/2/3/4, G-10....?

Would you suggest any other materials/equipment I should have apart from etching tray, sand paper, plastic glove, iron, hand-driller?


texts: SMPS troubleshooting (unable to provide enough current)

texts:
Recently I found one of my SMPSs (a laptop power brick) malfunctioning, what happened is - it provides enough voltage as declared, but it can't sustain at the mentioned current even at short circuit (below the mentioned threshold) it goes up to 1 A and falls and oscillates.
I have checked the output cap (not checked the capacitance yet, as I have to desolder), it's not bulged neither the filter diode at the output is damaged.
The switching FET and diode also seem good (my meter doesn't have enough voltage to make it beep at continuity still it gives some reading).
I am not certain if the optocoupler can cause the error, due to insufficient gain, it is less likely!
Please help me with where should I start looking next.


texts: How to synthesis, fit, and generate assembly bistream without re-launch all proccess in Quartus?

texts:
In Quartus Prime (17.0) it take a looong time to generate bitstream on my computer.
To generate the rbf for cycloneV, with DDR3 controller and serializer/deserializer in design it take about 12 minutes each time I modify a single parameter in design.

Is there a method to speed the process if design has been already generated in the past ?


texts:
I tried connecting the GPIO1_0 pin of LPC1114 to the input pin 1 of the ULN2003a IC. And I connected a 9V supply to the COM pin of ULN2003a. For whatever the logic level at pin1 (i/p) of ULN2003a, its corresponding output is always 0.57V. The logic high of the MCU at the o/p gives around 3.1V. What is wrong here?

EDIT: I am trying to drive a stepper motor using the uln2003a as an interface to MCU. I haven't connected the motor yet. I want to make sure it will not burn the MCU. I figured out the common pin of the motor should be connected to the +ve power rail.

Is it safe to connect the MCU o/p pins to uln2003's input pins without any current limiting resistors between them?
The Motor's rated voltage & current is 24V and 600mA. The ULN2003A can drive only 500mA. Is it safe to drive the motor at 9V with ULN2003a?


texts: Why aren't tethered balloons used instead of Cellphone towers?

texts:
If we use tethered balloons with wireless gateways fitted on them (let's say for Cellular or LPWAN communication), they can provide much more coverage. Why aren't they used then?

While there are many instances of high-altitude balloons (like Google's Project Loon, Space Data SkySite® or this question on this StackExchange), I could find scarce resource on low-altitude tethered balloons.

What I could find was this work done in 2008 (IEEE Conference Paper) by a  research lab. Another recent conference paper (2016) is this from another lab. The first paper also demonstrates that the tethered balloons turn out to be lower cost in the long run.

I wonder how come we don't have tethered-balloon based wireless gateways when they are cheaper and provide more coverage than fixed towers?


texts: How to connect to service pads without soldering

texts:
I am trying to connect to service pads like the these (the golden, round connectors)

my soldering skills are good enough to solder some wire onto these, but I have to check a lot of different pads and most of them just for a few seconds (I am looking for the TX Pin which gives me console access to the embedded device that I am trying to repair), so soldering seems to be a suboptimal solution.
So my question: Is there any kind of standard trick to get around soldering here? Maybe something like a special kind of crocodile clip?
Please excuse that this might be a duplicate. I am not a professional in electrical engineering, but rather a pure mathematician who tries to help his father-in-law with a problem involving an nasty programmed and very bad documented drone.


texts: What are all of the pins of the Beaglebone Black Rev. C serial (debug) header?

texts: The Beaglebone Black Rev. C has a serial debug header with 6 pins. I would like to know what each of these pins is. If numbered 1-6 starting closer to the 5v barrel connector, pin 1 is ground, pin 4 is RX, and pin 5 is TX. What are the other pins? Are they NC (not connected)? do any supply any power? Can they safely have an applied voltage (3.3V, 5V, or other)? Consider that most FTDI cables, which match up to the Tx/Rx/Gnd header pins, have a supply voltage output that would line up with header pin 3 (as I have defined the numbering). Are the other pins functional RTS and CTS, as would match up with the FTDI connections? What are the safe/recommended voltage ranges for pins?


texts: Using LMR62421XMF to boost Li-ion voltage from 3.3V to 7.5V@0.5A but voltage droops

texts:
While designing using the LMR62421 for boosting from 3.6V to 7.5V, I followed the typical circuit from the datasheet (below) and simulated it on WORK bench for 0.5A.

When used practically for a load of 15 ohms, it is getting loaded and the  voltage droops to 6V. I found that it does not support more than 100mA. Is there anything I missed out in the design or do I need to change the circuit from the typical?

R1=10K
R2=51K
C3=470pF
C1=C2=22uF ceramic caps
L1=10uH 56 mohms & 2.5A
D1=SS14

I require help as I am stuck and the design needs to be released ASAP.
Apology for delayed edit:
Found issue in the layout and updated the same. Please find below layout images and inductor details:


texts:
After adding an inductive load at the switching node of the half bridge circuit, the drain current keeps increasing. Why is this so? What have I done wrong in the circuit? I first tried to put L,C,R in the load side by caluclating like in a synchronous buck chopper, but that was not converging for DC Bus 100 V or DC bus 200 V. I am first trying to simulate at frequency = 100kHz or 200kHz. Please suggest a method to calculate the load inductor value to be added here. My objective is to study the active clamping, so for that I need to first simulate a self-turn on like phenomenon, i.e the "glitch" in the VGS waveform.
MOSFET used is SCT3160KL.

Also, in the circuit I had downloaded from TI website had that 10nF capacitance (C9) connected between Gate and Emitter of the IGBT in their circuit, which I replaced with my MOSFET. What is its purpose? I removed it and simulated but I could not figure it out.


texts: What is the meaning of this statement "If any diode has fully recovered before the V across it starts to swing, there is no reverse recovery current"?

texts:
Here is an excerpt from the book 'A-Z Switching power supplies' by Sanjay Maniktla.

"To minimize EMI, ultrafast diodes should be selected on the basis of softer
reverse recovery characteristics. For medium- to high-power converters, RC
snubbers are also often placed across these diodes (at the expense of some
efficiency). In low-voltage applications, Schottky diodes are often used. Though
these diodes have no reverse recovery time in principle, their body capacitance can be relatively high, and can end up resonating with PCB trace inductances. So an RC snubber is also often helpful for Schottkys. Note that if any diode has fully recovered (i.e. zero current) before the voltage across it starts to swing, there is no reverse recovery current. In that case, diodes really don’t have to be ‘super-super-fast.’"


texts: Difference between link-aggregated 10x10GbE and "True" 100GbE

texts:
I'm reading on 100G Ethernet and came across this article by ADVA. On page 2, top paragraph (before "Spectral Efficiency"), it compared link-aggregated 10x10GbE and a "true" 100GbE and says

  A true 100GbE path between two core routers will produce 100Gbit/s of
  throughput, more than twice the real performance of a 10x10GbE
  aggregated link.

But what is the real difference between them? As I understand the "true" 100GbE also put 100G on 10 different wavelengths each carrying 10Gb/s (some cases 4x25G), how is that not link-aggregation? Is the difference not in the physical layer but how you code the packet onto the physical layer? Is there a reference how this is done?


texts: Can you identify a manufacturer logo on a connector? Ellipse with inside crossed by two lines forming an arrow

texts:
Does anyone know this manufacturer logo?

It seems to consist of an ellipse with two lines joining at the border of the ellipse.

The part is a SMD barrel connector. We drew the logo and used google image search but weren't successful. Extensive manual search didn't retrieve anything useful either.

I'm sorry for the image quality but the thing is really tiny (6 by 9 mm) and we took the picture with a phone camera through a scale magnifier and couldn't do it better.

Addendum
A second source is of no secondary use, because we already have some, but they fail a certification test because the spring forces are too weak. This type of connector used by a competitor doesn't fail the test, so we want to know the manufacturer. Asking our competitor about the type seems no viable possibility :)

Second Addendum
Ok, a second source could be of use, I got it.
So here comes the spec:

Pin diameter is 1.3 mm
Outer connector diameter is 3.6 mm
height of connector is 4.71 mm
Minimum spring force for passing the test is 5 N

And it's really spring force not insertion / extraction force, because the crucial parameter depending on the spring force is the contact resistance.


texts:
I made a project of monostable flip flop using 555 timer in pspice. Now I need help with simulation. Problem is that I'm just statring my adventure with pspice and I have no clue what I'm doing wrong. I guess there is something wrong with Trigger configuration (Vtr - rectangular signal) and I don't know how to configure Setup Analysis properly. I'm trying to achieve output waveform and voltage across the capacitor C.

direct link to .sh file.


texts:
What kind of power and voltage can the cable in the photo possibly drive and why is it composed of a lot of small cables? What if the diameter of the single copper cables were a little bigger? How should one pick the right diameter for the given voltage/wattage combo?

link to the original post


texts: Converting a PWM signal to reduced constant voltage or constant current output

texts: I'm dealing with an existing circuit that was originally designed to dim incandescent and halogen bulbs from 12V using low frequency PWM.  This PWM is visible to the naked eye when substituting a 12V LED circuit.  I want to detect when the 12v PWM signal is present and either convert it to a lower constant voltage or a limited constant current value.  Then when the PWM disappears from the line and becomes 100% duty cycle 12VDC, I want it to bypass the detection circuit so the full 12V reaches the LED.  Summary is dimming the LED when PWM is present, full power when PWM is not.  Total LED consumption is roughly 40W, so I was thinking of using a 5 pin relay to change between the 2 states.  The existing circuit is annoying because the PWM happens on the same line as full power mode (only a positive and negative wire). I still need to scope the PWM to find out the exact switching frequency.


texts: Do we include the voltage drop across a diode when calculating the current through the diode, taking into account breakdown has occured?

texts:
So, am doing this question paper for my electronics, and I stumble across a question that asks me to calculate the current through a diode, with a breakdown voltage of 1.7, an Imax current of 20ma, when the diode is hooked up to a resistor of unknown value (calculated on a further question). There are 5 pairs of these LED's/resistors in parallel by the way, but only asks me to calculate the voltage of one diode. My intuition told my to subtract 1.7V from 9V, which would enable me to calculate currents and resistances. I was right. However this is only due to previous experience where I got it wrong.

I don't understand WHY we don't include the forward voltage drop, surely that's part of the overall resistance, as V=R*I and the diode cannot conduct until it reaches 1.7V due to the resistance faced by the PN junction... so, wouldn't excluding the fact that 1.7V is being dropped due to the PN band at the diode lead to false results?


texts: What is the use of resistors or capacitors in a led strip?

texts:
I own an 60 led/m ws2812 led strip. I noticed that every two leds there is an smd component.

What type of component is this? Resistor or capacitor?
In which signal is it connected to?
If i connect the power supply in the middle of the strip, will it still work, or simply burn out?

The component is a capacitor from 5V to GND.
Can i still connect the power supply in the middle?

Thanks!


texts: Capacitor charging efficiency with a constant power source

texts:
It is easy to derive the efficiency for loading a capacitor from a constant voltage or a constant current source, basically because exponential functions and constants are very, well, integration-friendly.
However, what is the efficiency for charging a capacitor with a fixed capacitance C and a fixed ESR R from a constant power source to a defined voltage U within a defined time T, and how do I derive that?


texts:
I'm working on the LT8607 Step-down converter to convert from 12V to 5V/500mA output.
The circuit schematic is as below.

What is the purpose of using the BST capacitor as shown in the schematic.


texts: Posssible Delay for a electric circuit needed

texts:
While I know that it is impossible to slow light down I was wanting to delay an electrical response from a diode using either a resistor or a capacitor but I could not remember, which does which. The idea for the product is to create an electric delay on a row of led lights after a flashlight turn on the photoresitors behind them on so we can see it turn on slowly like a light chaser. I was planning on using a led a diode and resistors in a row with appropriate delays. I'd like it to be compact so no mechanical delays.
PS: This is behind a opto resistor and am wanting one diode to turn on the row of led's then go down the row as the delay is making them react as if slowly like a gradient.


texts: How can the earth ground loop be modelled for this case?

texts:
Below is a single ended system where the source and and the receiver are both earth grounded forming a ground loop through the earth which has a resistance of Rearth = 1 Ohm.

simulate this circuit – Schematic created using CircuitLab

As shown above, the output impedance of the source Rsource is 100 Ohm and the resistance of the return wire Rreturn is 1 Ohm.

I need to modify that circuit to model and simulate a 50Hz ground loop and see the effect of it on Vmeasured. I named the nodes as A, B, C, D, X and Y.

Will a ground loop current in such case loop through only A B C and D? Or will it also loop through A X Y and D?

Most importantly what kind of source and where I should add a source to model the ground loop. If possible, a  modification on my circuit would help a lot.


texts: PCB design cost for 0.4mm pitch bga, 0.1mm drill hole, 4-layer routing using via-in-pad

texts:
I am doing a development board for a IC with 36 WLCSP package. My PCB layout has 16 via over pads, minimum 0.1mm drill holes, 4-layers. I need to fabricate my PCB. And I could not find a exact pricing for PCBs in the required design quality. I sent sample Gerber file for some PCB manufacturers. And they replied with extreme high prices and I can't afford their pricing (eg: 200$ for 10 boards with 2.5cm * 2.5cm). And most of manufactures are not willing to share their pricing strategy to optimize my design.

My target is to deliver my demo board for the lowest price (to make it lower than 10$, while component cost around 6.5$) . So I need to keep the PCB cost lower than 2$ with the minimum area of 2cm * 2cm.

Could I achieve that much lower PCB cost?
what are the possible PCB fabricators with lower cost with required technology?
What would be the unit PCB cost if fabricate at least 500 boards?
Feasibility of my project to make it under 10$?

Thank you


texts: What is this item and why would it be in-line in a starter

texts: Is this item a resistor, transistor, capacitor? What is it and most importantly, why would it be inline in the power wire between the "start" position of a switch and the starter on my generator?


texts: Is it OK to reduce the charging current for a Li-ion 18650 battery?

texts:
I am using NCR18650 batteries with the tp4056 charging module.

When I connect the charger at 2.8 V (fully discharged), the tp4056 IC is getting hot at a 1 A charge current. Is it OK to reduce this charge current by changing the charge current selecting resistor? So the tp4056 IC heat would be reduced, wouldn't it?

For my application I don't need a quick charge. With a low current, charging time will be increased, but it does not matter for my application.

Will reducing the charge current affect the battery's lifetime? Or will it damage the battery?

I am trying to reduce the heat of the tp4056 IC by reducing the charging current, maybe from 1 A to 500 mA or less. The 18650 battery never heats for a 1 A charge current.


texts: Picking the right sensor for a military style alarm

texts:
as a "squad engineer" of our airsoft team, I have been asked to create a device that will help us with our "capture the hill" tournaments.

As I mostly work with software, I have an hard time picking the right sensor to use. My first idea would be to build something similar to a trail camera, used by hunters to study the preys trails. In order to do so, I thought about getting a PIR sensor and link it to an Arduino Micro I have in my drawer from another project. Then, I could use a spare team radio to transmit alarm codes (morse tones).

My sensor specifications are the following:

outdoor operation capable
~10m range
~60° angle
at least 24h operation on battery (sharing the Arduino power supply)
false positives resistant

Is PIR the right technology to pick in this case ? If so, I really need to know if there are some sensors with the aforementioned specifications; all the Arduino DIY projects I have seen so far employ short range sensors. I would prefer something already packaged (fresnel + diode) from an european dealer.

In the following picture, you can see what I thought.

I have evaluated those other solutions also:

steel/nylon tripwire: I would prefer the device to stay undetected as long as possible (it is not a claymore mine, but a silent alarm)
hacking an airsoft claymore mine (small PIR range, remote unit useless)
laser tripwire: the reflector (or external laser) unit adds usage complexity, detection is only linear
doppler radar: my understanding is that this kind of device is only good for linear detection of movement to/from the unit. I could be wrong, though.


texts: What is this component marked "ZW1" on a LED doorbell button PCB?

texts: It's packaged in glass, like a diode.  The PCB is out of a lighted doorbell button.  The silk screened moniker is "ZW1".  Google and my Electronics Dictionary fail me.  Can you please suggest a generic type for this guy, e.g. diode, resistor, etc.?


texts: How to show that it is not possible to exceed the power rating of a 1/4 watt resistor of resistance greater than 1k?

texts:
I am currently studying The Art of Electronics, third edition, by Horowitz and Hill. Exercise 1.5 says the following:

C. Power in resistors
The power dissipated by a resistor (or any other device) is \$P = IV\$. Using Ohm’s law, you can get the equivalent forms \$P = I^2 R\$ and \$P = V^2 / R\$.
Exercise 1.5. Show that it is not possible to exceed the power rating of a 1/4 watt resistor of resistance greater than 1k, no matter how you connect it, in a circuit operating from a 15 volt battery.

I don't understand how I am supposed to do this. I've gone back through the earlier pages, but I cannot tell whether I'm just misunderstanding something, or whether the authors have not introduced sufficient information to complete this exercise. Am I supposed to use \$P = IV\$, \$P = I^2 R\$, or \$P = V^2 / R\$ somehow? There's literally 2 sentences of information here, and none of it describes what is being asked in exercise 1.5.


texts: \$V_{BE}\$ increasing from saturation to active mode of BJT with \$I_{B}\$ constant

texts:
Consider the configuration of common emitter BJT

Suppose that \$I_B\$ is held constant (regulating \$V_{BB}\$) and \$V_{CE}\$ is increased from \$0V\$ (regulating \$V_{CC}\$), while \$V_{BE}\$ is measured.

When I tried this measurement I noticed that passing from saturation mode \$V_{CE}<0.2 V\$ to active mode \$V_{CE}>0.2 V\$ (increasing \$V_{CE}\$) \$V_{BE}\$  increased rapidly.

How can this be explained? I mean, the value of \$V_{CE}\$ does not influence the value of \$V_{BE}\$ necessary to have the same \$I_B\$, does it?


texts: What kind of breadboard and prototyping board do I need for this right-angle DB25 connector?

texts:
What kind of breadboard and prototyping board do I need to fit this right-angle DB25 connector?

I'm new to soldering and don't know what the standards are. Additional information on this subject would  be helpful as well.


texts: Why do BLDC ESCs have more than 3 mosfets?

texts: Most of the BLDC ESCs that I've seen use 6 or more mosfets for switching. In my understanding, they should only need 3, one for each lead of the motor. Do they have half-bridges for each lead?


texts: A question about circuit design with a multivibrator

texts:
I want to implement a pulse extender with a retriggerable multivibrator IC called CD74HC123EE4. Here is the datasheet.

The input will be a 32Hz pulse train with a 5 µsec duty cycle; and at the output the duty cycle will be stretched up to 1.5ms. It is okay to keep the duty cycle between %30 to %60.

Based on some examples I came up with the following circuit:

Even though it is extremely slow to simulate this, it seems fine in simulation.

There is also this document and it has a section called "Operating Rules". And somewhere else I read that the input better not exceed 4V(Thats why I use R4 and R2 at the input to lower 5V to around 4V input). I tried to follow "Operating Rules", but before I implement this I wanted to be whether there is some fundamental error or mistake. Is this circuit fine enough for the purpose?


texts: How to simulate an Open Drain Output (for I2C) in LTSpice?

texts:
I am trying to simulate an I2C line in LTSpice. The part I have trouble is, how can I generate an Open Drain Output?

How to make V1 as an Open Drain Output? Here are the configuration Options for V1 that I see.


texts: How are registers implemented in microprocessors?

texts:
A register is a temporary storage facility within the CPU that holds data for computation purposes.

What I question is how this is structured via engineering principles within the circuity:

1.I had first thought that all information held electrostatically was implemented in capacitors. Am I right or am I wrong within the context of CPU data storage?

2.I also had thought that maybe a logic gate can loop data until appropriate action/machine code changed the flow of logic/data within the circuit to take appropriate action from memory. Yes?

3.Last I can think is that the data enters the CPU from RAM in correct format, is parsed by the CPU's microsequencing circuity, and enters an electrolytic capacitor within a motor capacitor.

Do I have it right, or please correct me.