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  • Why isn't my laptop battery working?

    I own a Fujitsu AH532/G21 Lifebook, so over a 7 year old laptop, that I've always been taking good care of, despite rather heavy usage for important work. A couple of years back, I cloned the HDD to SSD and it's been running like a dream ever since (including today!). Software wise, I don't have a single problem. However, hardware wise... well, you already read the title.

    The problem occurred around 3 weeks ago. I turned on my laptop on battery, when it was on my lap, and all of the sudden for no reason whatsoever, it turned back off. Well, I assumed that the battery life was already very short as it is, and maybe the batteries finally died, even though I had the batteries changed only 2 years ago. So, I though, no problem, I'll just change the batteries by carefully soldering a new set. Yesterday, I did exactly that, and worked perfectly. Checked the voltage on the new set and it is 11.6V (even though it says that the battery should be 10.8V). The other set was only 9.6V. These are Li-Ion batteries. 

    Anyway, I did a lot of things that were suggested online, but none worked. I first checked my adaptor, and nothing is wrong. I checked the internal connection (disassembled my computer) and also nothing is wrong there. All cables still fine that connect to the motherboard. I uninstalled and reinstalled the battery driver (AHCI Compliant Battery Control Method) and it didn't work either. I have even updated my BIOS just yesterday, and it still did nothing. 

    1 respuestaLaptops & Notebookshace 6 días
  • Is it OK to have  different voltage sources with the same ground?

    I'm going to have two different voltage sources. One is already a well-rectified and smoothed 12Vdc voltage source, and the other will be 220Vdc rectified but not smoothed voltage source. My question is if it is OK to have the same ground or not. The reason I'm asking is that that the circuit components are interconnected and I need a common ground for everything.

    By the way, the 220Vdc is not smoothed because I have yet to find a capacitor with large enough voltage and capacitance (even in parallel) that is 2-poled in my country (I have 4 poled capacitors but I honestly don't know how to work with them). 

    3 respuestasEngineeringhace 2 semanas
  • Attachment image

    What are 4-pole capacitors and how to wire them in parallel?

    Hello everyone. I'm currently designing a driver for a 5 HP BLDC motor that runs on 320 VDC. I've created the circuit for it using 6 power MOSFETS (I used six IRF840) and the microcontroller that will give trigger them is an Arduino Uno. Of course, since 3.3V from the Arduino is too low a voltage to trigger the gates, I also used 2N2222 behind each MOSFET to act as a switch and give out a much higher voltage to the gate of the IRF840s. Naturally, I'll be using power diodes too at the end, right before the connection to the motor so that the circuit is protected from any feedback when the power is cut off. 

    The problem that remains is the usage of capacitors. I realize that I'll need large 400V capacitors, and these were the ones provided for me. However, I've never used 4-Pole capacitors before and have no idea how they work. All I know is that the poles are actually connected to the corners of each plate instead of in the middle like regular 2 wire capacitors. 

    I have looked online and came across a couple of circuits that tell me how to wire them, but I can't simply rely on such circuits without understanding what is going on first. So can someone please explain how to connect not two but NUMEROUS 4-pole capacitors in parallel, as well as an explanation of how they exactly differ from 2-pole capacitors. 

    This is the diagram that I saw:

    2 respuestasEngineeringhace 2 semanas
  • How to rectify very high voltage to get minimum ripple voltage?

    I'm designing a circuit to drive a 5 Ampere 320 V BLDC motor. I had already asked the question before, and I just needed to be sure of the circuit. I'm using the circuit below.

    Naturally, I'm going to use power diodes to protect the circuit from feedback at the output of the circuit (the input of the motor). Since the minimum voltage required at the gate of the power MOSFETs isn't enough coming from the Arduino Uno Microcontroller, I'm going to use 2N2222 transistors as switches too for the gates that will provide them a 12 Vdc voltage. I ran the simulation and it is actually working fine (ran it on Proteus). 

    However, there are some problems in real life, naturally. I need to rectify the high voltage as I need to convert it from AC to DC. I have a power bridge that can support 25 Amps and 800V, so that's not really a problem. The problem is in the smoothing area. I calculated the ripple voltage desired (which is around 5 V), and saw that I would require a whopping 12000 uF 500V capacitor, which I don't even know where to get honestly. The closest thing I have to that is a much smaller 10 uF capacitors, which are nowhere nearly good enough. 

    There is another issue. The voltage I need is 320 Vdc. Would it be enough to get a 1:1 transformer and feed it 220 VAC, and take the peak of that voltage (at the capacitor level) and reach the nearly desired voltage (~314 Vdc)?

    2 respuestasEngineeringhace 4 semanas
  • Did Yahoo! Answers remove the comment section?!?

    Like the question states. I am unable to comment to any of the answers! Is it a bug, or did they purposefully remove our capability to comment on other peoples' answers? 

    7 respuestasYahoo Answershace 3 meses
  • Any ideas about Quiet keyboards?

    I'm looking for quiet keyboards, and all I'm getting are LIES, LIES AND MORE LIES on the internet! I'm getting tired of links that are telling me that this keyboard or that keyboard is quiet, bu when I look at the reviews on YouTube and other sites, they are LOUD AF!!! 

    I want something as silent as a laptop's keyboard, if not even more silent. Seriously, those things are really quiet, but I want a keyboard that's for a desktop obviously. So, does anyone have any ideas about brands/models about genuine and legitimate silent keyboards? Please provide me with a list if you have any. Thank you! 

    2 respuestasOther - Hardwarehace 3 meses
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    How to create a circuit to drive a 3 Phase BLDC Motor?

    As the question stated. What I saw online was this, but I couldn't exactly understand why I needed 6 MOSFETs and not 3.

    The circuit I had created was actually very similar to this. I have 3 IRF840 MOSFETs for the application, because it is a large motor. For this, I have connected an Arduino and programmed it basically to emulate a PWM with each output pin being on at their respective time for 20 ms (since I need 50 Hz as PWM). 

    Now, since IRF840 requires a gate voltage of at least 10V, I'm going to connect low current/low voltage PNP transistors in cascade with each Power MOSFET, operating at 12V. So, basically, Arduino to control PNP transistors to Power MOSFETs. 

    Below you'll see the circuit I found in the website I linked above. Now, here is my question. If I am to control this circuit with an Arduino, what exactly is the frequency that I need to use for each PWM input in the figure? Should it be 10 ms or 20 ms if I am to achieve 50 Hz, because from what I understood, one set of MOSFETs is affecting the North Magnetic pole whilst the other set of MOSFETs is affecting the South Magnetic Pole. Again, I can easily program this, but I just need to make sure. Note that I only need to run the motor on a single speed, so no need to add additional circuitry for dimming. 

    Thank you all for your answers :)

    2 respuestasEngineeringhace 4 meses
  • How to calculate Network throughput based on Bandwidth and Latency? ?

    How does one calculate the throughput of a network (assuming a certain SNR), affected by latency?

    The thing is that in information theory, the formula that I know of is the Channel capacity formula, which has bits per second (bps) as unit, and is defined by:

    C = B Log_2 (1+ SNR). (B: Bandwidth, SNR: Signal-to-Noise Ratio, C: Capacity).

    Is there a formula that includes the latency as well?

    Thank you! 

    1 respuestaComputer Networkinghace 4 meses
  • Does anyone know what this electronic chip is?

    When I opened the laptop that apparently having power trouble, I decided to check the ICs that are responsible to give power throughout the board. I counted 6 of these, and I think a couple are shot. I want to attempt to repair it as I have the necessary tools as well as an automatic desoldering machine that will automatically heat up and remove the soldered area for replacement. 

    The IC (or Power MOSFET I believe) in question is: A1 KND 900201, but I just couldn't find it online for some reason. As for the laptop in question,  it's the ASUS UX31L. For additional details, I have asked the same answer here 4 months ago, but I got no proper/direct answer:

    Taking it to a technician is also out of the question. People here are literally like "Yea, the motherboard is burnt, and nothing can be done. Buy a new laptop". Heck no! I'm not lazy! I'll attempt to repair it at least, but if only I could know the name of that Power MOSFET to order a new one. (At least I'm guessing it's most likely a Power MOSFET).

    3 respuestasLaptops & Notebookshace 4 meses
  • How is torque affected when converting from AC to DC?

    I know that torque wise, DC is much stronger than AC. So, I am wondering what would happen if I converted AC to DC and gave power to a DC motor?

    The motor in question is actually a large Servo DC motor, that has 5 hp and runs at 320 V. So, what I'm going to do is convert the Servo Motor into a DC motor, and then put a 10 Amp Step-Up transformer that has 220 V as input and 320 V as output, and then I'm going to use a large Full-wave bridge rectifier (using those large diodes) and of course the corresponding capacitors on the other end (corresponding for the application) to run the motor directly. 

    The thing is that I don't have the drive for the Servo motor, nor does it exist standalone, so I'm forced to go with this for now. My question is: How is torque affected here, and will setting up the bridge directly the way described work? 

    2 respuestasEngineeringhace 5 meses
  • What power transistors are there that support high voltage and adequate current?

    I am looking for particular transistors that have especially high DC voltage handling capability. When I say "high", I mean, at least 350-400 V DC voltage (the application requires 320 V, so naturally, I don't want it to be barely on the level). The current rating is also important. If it can be 1 A each, then that would be great. 500 mA is also fine, because I can use them afterwards in parallel and use load balancing resistors. 

    So, why am I asking this? First, because I have a few applications that could use such particular transistors, so it would be nice to know about them, and second, I want to try and drive a 5 HP 320V motor, a continuous DC servo motor to be exact. Of course, I know that there are dedicated circuits for this type of applications, but due to the specificity of this particular board, and where I live in as a country, they aren't just readily available. So, I wish to try and construct one on my own. Naturally, I know about the PCBs, soldering, etching solutions, etc., so those aren't a problem. 

    Also note that I am intending to use the transistors stated in parallel to be able to increase the current throughput. Now, I noticed the BUL743 transistor, but the thing is that there is a power limitation. From the datasheet, it says that it can handle only about 256 W, but I could be wrong. So, any ideas about transistors, and any inputs on the project itself? Much appreciated :)

    2 respuestasEngineeringhace 5 meses
  • What's causing my mom to have health issues concerning her stomach?


    My mom is have strange issues with her stomach lately it seems. At least, that's what it appears to be. The symptoms appear completely out of random. She feels like she has nausea, and before you know it, she is in the bathroom vomiting. From what she described, it feels like a certain pressure slightly above her belly button, and right below her thoracic cage, kind of like below her heart. 

    Last time we went to the doctor, she didn't have any heart issues. She had a glucose level that was a bit over the limit, but nothing particular to worry about. 

    Another thing I've noticed about her is that it sometimes take her a long time to go poop, like 2-3 days or something, and given the bathroom is within earshot, it sounds like her poop is more of a diarrhea than your regular solid chunks. 

    She just got out of the toilet now (she vomited), and she said that she has a headache as well as an earache. What could she possibly be experiencing? What possible illnesses could she have? We all eat the same food, so if it is food poisoning, it would have been evident by now. But from the looks of it, she's the only one affected. Can you please help me out? Of course I'll take her to the hospital for checkups but I need to know your opinion on what this could be.

    Thank you

    3 respuestasOther - Diseaseshace 6 meses
  • Why are there such weak protections for PDF files? ?

    As the question stated. I've tried numerous PDF locks, and every time I go to this site to make sure it is secure, it always gets unlocked! All I want is the PDF file to be protected against editing and copying. I don't mind it being printed though. So, I set up a password to restrict access to the file, and save it. Later on, I go to this site and see if it unlocks it. Lo and behold, it does! 

    Does anyone know how to properly secure a PDF file such that when it is uploaded online, it doesn't get unlocked? 

    I can't share the site name as it may break the rules, but it is rather easy to find. Just Google "PDF Unlock" and see for yourselves. I just want it protected from being copied, that's all. (By copy, I mean opening the file and copying its contents of course), not copying the file itself. 

    1 respuestaSoftwarehace 6 meses
  • What is the difference exactly between the 3D-NAND (or V-NAND) architecture TLC and the regular non-planar MLC?

    I really can't tell the difference exactly, because stupid Google always compares 3D-NAND TLC vs Planar NAND MLC. 

    The only difference I found was when I went to compare two of such SSDs on an online benchmark, and it was slightly in favor of the 3D-NAND TLC SSD.

    The SSDs in question were:

    Samsung 860 EVO vs Kingston HyperX Savage.

    For 5 years now, I've used the HyperX Savage (250 Gebibytes, which translates to the 232 Gigabytes. It's actually 222 on my drive now, but that's a technicality), and the performance never disappointed me. The only issue I have is with the storage, which is slowly becoming more limited. Of course I'm planning to do a clone and migrate, but I just want to know what exactly is the difference between the aforementioned architectures (I mean, what EXACTLY is the difference, and how it affects their longevity).

    Thank you! 

    1 respuestaOther - Hardwarehace 8 meses
  • How to mount a camera on a microscope?

    The microscope in question is an Olympus CH30. I noticed that there are some cameras out there that can be mounted on such microscopes, and that they are placed on the ocular lenses (the eyepieces from which an individual observes everything). The thing is that this is rather new to me and I don't want to mess it up with an incompatible piece. Does anyone know an inexpensive camera (c-camera or maybe u-camera) that can be mounted on the aforementioned microscope? The budget is around 100$ and it will most likely be delivered from a site like Aliexpress. Any help/suggestions about camera types (along with links to them) are greatly appreciated. Thank you! 

    2 respuestasCamerashace 8 meses
  • How to repair my laptop? ?

    I have a rather old laptop, an ASUS UX31L to be specific that has an m.2 128 GB SSD in it (SanDisk brand). Long story short, it doesn't turn on. Here is exactly what happens.

    As soon as I give it power (AC/DC SOURCE), the power led turns on, and then it turns back off. And then it turns back on again along with the Caps lock led. All this in a matter of 4-5 seconds. After around 30 seconds, the fan also starts working. There is no display though. Keep in mind that this happens as soon as I plug it in REGARDLESS if I had pressed the power button to turn the laptop on or not. The charger is seemingly fine. I checked, Ns gave me 19.4V. It is rated 19V and 2.37 amperes DC. 

    Fixes that I have tried:

    - Power cycle trick. Disassembled the laptop,  disconnected the power supply, removed the battery, and pressed the power button. Nothing. 

    - Removed the SSD to see if I could maybe boot to the BIOS (though I know it doesn't make sense, but I was desperate) . Nothing. 

    - Checked the temperatures of both the processor and the SSD on touch. They were warm, a bit on the hot side, but definitely nothing noticeable (like extremely hot). Same with the motherboard. 

    - Removed the BIOS battery, waited a while before plugging it back in, and retried starting the laptop up. Still nothing. 

    - The CPU and RAM are integrated, so I couldn't remove them (especially not the RAM, which is 4 GB in capacity by the way). 

    - The charger shows an Orange LED light when plugged into the laptop, by the way. 

    5 respuestasLaptops & Notebookshace 8 meses
  • Why do SSD prices increase?

    Why do SSD get more expensive per GB after the 500 GB mark? For example, your regular Samsung 860 EVO with V-NAND TLC based Architecture would cost around 55$ for 250 GB and around 85 -95$ for 500 GB. But after this mark, when reaching for 1 TB and above, it suddenly gets up to over 200$, which makes no sense. The price per GB decreased when going from 250 to 500 GB, but then increased back when going from 500 GB to 1 TB. I am very well aware of the conversion units, that 1 TB is meant as 1000 GB which translates to around 931 Gibibytes, etc., and technically, it should decrease even more. Should be around 160-170$ for one TB. So, why the increase instead??

    Thank you for all responses in advance. 

    10 respuestasOther - Hardwarehace 8 meses
  • What brand of 8TB external HDD is reliable or the least prone to fail? ?

    Hey guys. I want to buy an 8TB External HDD. I've so far always used Seagate expansion and/or ADATA. I have one Seagate Expansion drive 4TB storage capacity, and it's so far working great. It's been 4 years now. 

    I am aiming to buy an 8TB version of it, but reviews aren't as promising as they seem. The 5 star ones don't offer much information, as they are based usually on open on arrival and plug and play (which shows nothing about its longevity), whereas the 1 star ratings are usually the ones that hold information about how long they lasted (some 2 months, others 6 months, some barely a week!, etc.). I'm really worried because I have HUGE amounts of data that are based on years of work and backup, and I do not want to lose any of them suddenly should my 4TB storage fail. I also have like 570 GB of space left on the latter, so I will have to upgrade soon enough (well, relatively speaking). 

    So yea, what brands would you guys recommend, and can you please send me links for great sales on either Amazon, bhphotovideo, newegg, aliexpress, etc. I saw one great deal today on Amazon for an 8TB drive for just 125$, but again, the reviews aren't as promising. I've always used Seagate, but I am just so scared of losing my data. I know other brands like Kingston, WD, but I don't know. What do you guys recommend? Anyone have any experience on an 8TB external drive they have? Let me know in any case. 

    THANK YOU!! 

    7 respuestasAdd-onshace 10 meses
  • How many pulses does the magnetic encoder have? ?

    When I googled MIG105-14-080A, I didn't get any search results for some reason. I'm guessing that they are discontinued. Anyway, I was able to figure out that the 105 and the 14 correspond to the Flange and Shaft diameter respectively.

    Results about the encoder itself yielded only results from BEGE MIG Encoders and MIG Nova encoders by STRÖTER - Sels. 

    Now, after some more snooping around, I found that the last numbers could be a reference to the number of pulses for the encoder. Here is an example:

    Now, I'm more and more inclined to believe that the 80 is actually the number of pulses per rotation, but I am a bit confused since I never did see such encoders before (with such low number of pulses). The ones I'm used to are usually 200, 360, 500, 512, 1000, 1024, etc. 

    Thank you!

    1 respuestaOther - Electronicshace 11 meses
  • SEN0198 Low temperature equivalent?

    I've read the data sheet of the SEN0198, and I've found that its operating range is from 30-350 degrees Celsius. Now, this does not work for me, and I'm wondering if there is a low temperature equivalent for such a circuit. Something that works in the range of -50 degrees detection, maybe something like -50 to 0 degrees.

    2 respuestasEngineeringhace 1 año