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Questions tagged [computers]

Questions regarding architectures or design of specific parts, not consumer-related questions.

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Brand new FPGA burnt?

So, when I plugged in my FPGA for the first time, it started to smell a bit like chemicals, and this showed up. Is it burnt, or is it just some type of residue that popped up once I connected it?
superogg1's user avatar
0 votes
2 answers
92 views

1-bit computing with true one-instruction set architecture

Even though MC14500B is considered as 1-bit computing where it accepts 1-bit data to perform operation, the instruction set itself consisted with 4-bit instruction which leads having 16 total ...
Muhammad Ikhwan Perwira's user avatar
1 vote
1 answer
58 views

Expected voltage when probing a computer PWM-fan socket's sense pin?

I'm using my multimeter to probe a proprietary 6 pin socket on the motherboard of a PC computer that connects to 2 small 25 mm fans. The socket's pins are unlabeled. Both the motherboard and socket ...
Mike's user avatar
  • 13
7 votes
4 answers
442 views

CRT vertical deflection problem

I'm getting an odd CRT problem. When cold, the tube has an area about 1/3 way down that isn't scanned. The area above is compressed and the area below a little stretched. I've attached 2 pictures - ...
squelch41's user avatar
  • 133
2 votes
6 answers
2k views

What can be done with all of the extra address lines in a ROM? Why were they designed to have so few outputs compared to possible inputs?

I am a student in an introductory Digital Logic and Computer Systems course. We have been learning about ROMS, but often we just use them to basically just map truth tables onto them. We have been ...
LeBronJames's user avatar
1 vote
1 answer
132 views

Solder pads ripped - charging via test pads?

My uncle asked me to repair a tablet but when I opened the tablet I saw that the micro USB connector was completly ripped off the board and I lack the tools to scrape free some of the copper to solder ...
Olaf Olaf's user avatar
1 vote
0 answers
55 views

A problem with an old computer PSU (schaffer-bv-223-5-04008)

I'm trying to find out the reason why an old PSU is not providing output voltage. Some times ago, I asked for help on retrocomputing (here is the thread: schaffer-bv-223-5-04008 unidentified ...
Ayeie Brazo's user avatar
-1 votes
2 answers
125 views

Configuring an astable 555 timer to milliseconds

I am working on a Tinkercad project and I would like a 555 astable clock for it. I am trying to configure the astable 555 timer for every millisecond (or something close). I don't know how to do it, ...
some human's user avatar
0 votes
2 answers
158 views

Power electronics on a PCI/PCIe expansion card

I'm not sure if its been done before but how feasible is the idea of building an computer expansion card (PCI/PCIe) that carries mains power on some areas of the expansion card being switched by ...
dazzleworth's user avatar
0 votes
1 answer
115 views

Building a battery powered computer system

I want to power a PC, monitor and modem with one deep cycle 12 V lead-acid battery. The PC is a mini-ITX board with intel N100 CPU. It consumes between 10-40 W depending on usage and has a 19V DC ...
AN C's user avatar
  • 11
-1 votes
2 answers
3k views

Power supply makes a static/coil whine noise when the power supply is off and the PC is off

I have noticed that my power supply (PSU) makes a VERY slight coil whine/static noise while it is plugged into the power outlet, regardless of the power status of the PC and the PSU. It sounds no ...
P. Z.'s user avatar
  • 1
1 vote
3 answers
977 views

How does a PC switch turn on a PC?

Here is my current level of understanding: virtually every PC case has a switch near the top to power on the PC. When the PC is off, pressing the switch once will power it on and the PC will begin ...
David D.'s user avatar
  • 175
1 vote
3 answers
273 views

Electrical/physical difference between Primary Memory and Secondary Memory connection to CPU

It is said that the difference between primary memory and secondary memory is that primary memory is "directly accessible by CPU", while secondary memory is "not directly accessible by ...
Noob_Guy's user avatar
  • 443
0 votes
2 answers
299 views

USB inrush current limiting, charging super capacitor

I am trying to charge a supercap over USB. I understand I need to limit the current (ref: usb.org) This has been discussed a lot here, for example: here and here, but I believe my requirements are a ...
www.jensolsson.se's user avatar
2 votes
4 answers
1k views

How damaging are inrush currents?

Typical power supplies will have 30 to 100 amps inrush current at 220v, sometimes less, sometimes over that. How is it that the power strip rated at max 10amps at 220v doesn't get damaged? Also, if I ...
Sarthak's user avatar
  • 21
1 vote
2 answers
102 views

Problem with the smallest negative number using Signed-2's-Complement

I have a problem figuring out why the smallest negative number we can represent in 3 bits, using Signed-2's-Complement is -4. I understand that in S2C format, we can create numbers from 2x-1-1 (...
Ali A's user avatar
  • 11
1 vote
1 answer
1k views

Is the purple wire on an ATX power supply always +5V stand by?

I'm trying to use an old 20 pin ATX power supply as a substitute for the failed power supply in a Dell Optiplex 7040† I managed to find the pinouts for the Dell power supply which only has two output ...
alkaline  trip's user avatar
3 votes
5 answers
2k views

Voltage-drop resistor to power a 19 V computer

I am considering using a voltage-drop resistor to drop the 21.6 V ± 1% on a power supply down to 19 V. If this was an LED, I would use a 1 Ω, 7 W resistor but this seems to be a very big size. In this ...
Bob R's user avatar
  • 263
0 votes
6 answers
2k views

Is there a practical reason for making laptop AC adapter bricks at the plug end?

All laptops require a AC adapter in order to convert electricity into a usable form for the laptop. In most AC adapters I've seen, the plug is directly connected to the power brick, meaning that the ...
Feiri's user avatar
  • 3
0 votes
1 answer
92 views

Reset mainboard from Raspberry Pi

I have a desktop computer with an Asus mainboard TUF_GAMING_B550-PLUS and a Raspberry Pi 4. I log in remotely to the computer, but unfortunately from time to time it has an operating system issue, ...
user7468395's user avatar
12 votes
8 answers
6k views

How many transistors at minimum do you need to build a general-purpose computer?

I'm wondering what the simplest design for a general-purpose (Turing complete) computer is. To my surprise, I haven't found much on the web. Surely this is a known problem?
static_rtti's user avatar
0 votes
1 answer
56 views

How to connect an activity LED to a RocketRAID card? [closed]

So this is more computer-based, but definitely electrical so I'm hoping I can find some help, so here goes... I have a home server (WSE2016) which utilizes a RAID for its primary storage. I had an ...
Ryan Miller's user avatar
1 vote
2 answers
46 views

Driving a DVI monitor from a monochrome source

I have a plasma display EL8358MS that is defective (burnt out.) The display has a signal convertor with these inputs: ...
sergiu's user avatar
  • 21
2 votes
3 answers
346 views

Why do inductors in motherboard VRMs have high-voltage build-up without diodes?

I just watched Bullzoid/Actually Hardcore Overclocking's video on how VRMs actually work, and I have a question. First, in my understanding, the diodes in the VRMs are included to stop the inductor ...
itisyeetimetoday's user avatar
0 votes
2 answers
102 views

How are the transistors in motherboard controlled and timed?

I just watched Bullzoid/Actually Hardcore Overclocking's video on how VRMs actually work, and I have a couple questions. In the video, the Bullzoid mentions how the transistors are switched on and off....
itisyeetimetoday's user avatar
2 votes
6 answers
193 views

Confusion regarding future scope of electrical & electronics engineering jobs (generally world wide and especially in India) [closed]

This question is seeking advice generally for world wide and especially for Indian region(India and its neighbour countries having almost same economic conditions like India) If anyone has no idea ...
cvs's user avatar
  • 43
2 votes
1 answer
726 views

Why do SSDs have a limited lifespan?

Why do solid-state drives even have a limited number of read/write cycles, usually 100,000-300,000 cycles? For hard-disk drives, it is understandable why they wear out. That is because they have ...
CoastCity Lapse 00crashtest's user avatar
2 votes
5 answers
950 views

Way to measure delay propagation between two different systems

I have a system that sends data from one location to another via radio and I needed to find out the point to point delay propagation from the sensor measurement on one side to the reception on the ...
Arcaniaco's user avatar
  • 151
7 votes
3 answers
2k views

How did the vacuum tube computer technicians know when a tube had failed?

I have read that in vacuum tube computers, a tube would fail every couple of days. How did the technicians know that a tube had failed? Wouldn't a broken tube silently cause the calculations to ...
Andrey Bienkowski's user avatar
0 votes
1 answer
50 views

Are there risks to running one computer with two completely different power sources? [closed]

I have experienced two computer power supplies using the same main power utility company here (same breaker, just different circuit). I am planning out an off-grid system, am considering running one ...
I like to code's user avatar
23 votes
1 answer
4k views

How does the switch on the back of older computer power supplies work to vary between 110 and 220 volt input?

There is a little switch on the back of older computer power supplies to select between 110 and 220 volt AC input. I imagine this switch enables/disables a 220 to 110 volt transformer. Or perhaps a ...
sebastian323's user avatar
0 votes
1 answer
1k views

Why does a flip-flop's outputs have to be the inverse of each other and an invalid/forbidden state discouraged [duplicate]

After reading, researching, and asking questions about flip-flops. My understanding is as follows: They are not the only means of storing state but are one of them. The circuit has been constructed ...
Ukpa Uchechi's user avatar
7 votes
6 answers
1k views

Why are flip-flops criss-crossed?

I want to simulate how a computer works using logic gates. Right now I am trying to build the memory aspect of it. After looking at various articles and books I see a lot of them using flip-flops/...
Ukpa Uchechi's user avatar
0 votes
2 answers
282 views

HDMI: Can a computer still detect a monitor properly if some of the TDMS pins/wires are damaged? [closed]

Can a faulty HDMI-cable with damaged TDMS pins/wires still work to the extent that the computer can still detect the monitor, but the monitor just will not display anything (except for no signal)?
huoneusto's user avatar
  • 103
1 vote
1 answer
226 views

A component has blown on my HP elite book 840 G6. I need help identifying it if it all possible

Here are the pictures. It was late and I shorted 2 pins of the smart card reader ribbon connector. Don't know how such a stupid mistake, but this component on the other side of the board went up and ...
Cole Nichols's user avatar
0 votes
1 answer
85 views

I’m getting little more than 12 V in my computer PSU, should I use it?

I bought a refurbished computer ATX PSU, it had the most generic PCB I have ever witnessed. Seems like has a optocoupler and works with sdc2921 IC. In 12 V rail I’m getting 12.25 V. In 5 V I’m getting ...
BigBlackDuck's user avatar
1 vote
1 answer
468 views

ESD Wrist Strap When Working on Monitors and Power Supply

My book for the A+ exam specifically says not to use ESD for repairing monitors or power supplies. Why is this? I understand that their capacitors hold lethal amounts of charges, but the motherboard ...
MathApprentice's user avatar
1 vote
1 answer
869 views

Looking for an explanation of grounding in relation to computers and DVI-HDMI adapters

I recently found that a DVI-HDMI adapter, purchased to connect the micro-HDMI port on my new Raspberry Pi 400 to the DVI port on my monitor, behaves strangely: it works well when connecting to my ATX ...
Theo d'Or's user avatar
  • 113
12 votes
6 answers
2k views

My Professor and I are debating about absorption law

So the question is \$(w+y)(wz+wz')wy+y\$ and this is my answer by absorption law where \$A+AB=A\$: $$ (w+y)(wz+wz!)w y + y\\ B A + A $$ So the answer is \$A=y\$. My professor said I ...
Ryan's user avatar
  • 159
0 votes
1 answer
75 views

Old computer socket disconnection, cleaning, and repair [closed]

I have very old computers; from time to time the RAM disconnects. I remove the DIMMs, clean the sockets using Isopropyl alcohol many times until it works again. It will be fine for few weeks, but I ...
Hamed's user avatar
  • 19
2 votes
2 answers
145 views

Calculating the required voltage supply [closed]

There is a Single Board computer that gives a range of input supply as xvolts - yvolts. Let's say we add a few more additional components like webcam or additional storage drive. Taking these into ...
John's user avatar
  • 139
18 votes
4 answers
8k views

Electrical reason for the minimum altitude (-50 feet) in the computer specs?

Are if there any electrical reasons not to operate or store my Dell OptiPlex computers below the altitude of -50 feet, as written in the specifications? Screenshot of the original Dell OptiPlex ...
eXtranium's user avatar
  • 183
7 votes
1 answer
1k views

Enable vendor-disabled hardware on tablet? [closed]

I have a nextbook tablet (one of those cheap things from walmart) that I was looking to try to improve the RAM situation on to breath some new life into it as it apparently only has 1G of it. I ...
Adam V's user avatar
  • 89
8 votes
1 answer
2k views

Backwards compatibility of PCIe AC coupling capacitors

The PCIe base spec mentions that platforms operating only at 2.5GT/s or 5GT/s may use AC coupling capacitors in the 75nF-265nF and that platforms supporting 8GT/s and above must use 176nF-265nF. ...
user2005848's user avatar
3 votes
3 answers
3k views

Why aren't current CPUs designed for more powerful cooling systems? [closed]

Chips on the present can't get smaller, higher speeds and voltages increase heating, so why don't CPU manufacturers aim for more powerful cooling systems instead of looking for parallelization? We are ...
Lerian Acosenossa's user avatar
-1 votes
2 answers
174 views

What is the most important CPU price factor [closed]

I have two intel CPUS with distinct features. intel i7 8550U intel i5 8300H Which have big performance difference with the cheaper 8300H being higher in memory ...
Abraham's user avatar
  • 99
0 votes
1 answer
116 views

Where or when is it unsafe to clean using compressed air? [duplicate]

There's this lesson on ICT for us in cleaning computers and their equipment. One of the components that can be used for cleaning is something called compressed air. Just to make sure, which computer ...
user avatar
10 votes
9 answers
3k views

Was the Intel 186 chip commonly used anywhere? Was it only found in industrial computers? Why not PCs?

I don't think the Intel 186 was in any "home computers" or PCs, but I see other people referencing it as a common chip. Also, I've heard that NEC V20s had the 186 instruction set in addition ...
Cuvtixo's user avatar
  • 117
0 votes
1 answer
93 views

Will a computer fail sooner the more you use it? [closed]

Is a computer like a car in the sense that the more you use it the quicker it will break down? Assuming that we have a regular computer with SSD that is running 24/7 versus a computer that is run ...
Joey Smith's user avatar
3 votes
1 answer
172 views

Why can't you make a thunderbolt 3 hub?

So laptops with thunderbolt 3 are pretty common, docks are common, every other kind of USB seems to be able to be used with a hub. I know thunderbolt 3 can be daisy chained, theoretically eliminating ...
Delaney Fitzpatrick's user avatar

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