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1500 questions
65
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4 answers
Can a CPU function with nothing more than a power supply and a ROM, using only the internal cache as RAM?
Can a CPU (such as the Intel i3/i5/i7/Xeon) with on-chip cache RAM use that as its only functional RAM, without any external memory banks attached?
Or must there be external RAM, and the cache cannot be accessed or used alone?
Modern desktop/server…
Dale Mahalko
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65
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10 answers
Fan and heatsink - suck or blow?
This question covered it for enclosures. However, from the point of view of the fan attached to a heatsink does it matter whether air is blown through the fins, or sucked through the fins. In other words, is the pattern of airflow different enough…
Dirk Bruere
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65
votes
6 answers
What is the voltage range of a standard headphone jack from a phone?
I want to connect the output from the audio jack of an iPhone to an Arduino.
What voltage range can I expect to see on the audio lines from the iPhone? I assume that turning the volume up on the phone will produce a large AC voltage, but how large…
manuelBetancurt
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65
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7 answers
Is it true that a SD/MMC Card does wear levelling with its own controller?
I can't find any reliable information about this. I don't have the full specification of the SD/MMC Card hardware.
Is it true? My high-level application doesn't need to be concerned with wear leveling when working with these cards?
EDIT
Could…
ivarec
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65
votes
8 answers
Why are there so many relays used in a car, instead of transistors?
Recently I did some work on my car electric circuits. I see many relays are used in car circuits. These relays are used for simple switching, and I wonder why these circuits are based on relays and not on transistors or other electronic components…
Al Kepp
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65
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12 answers
How can we be sure that computers will never accidentally switch a 0 by a 1?
I've read a bit about the construction of a digital computer in Shocken/Nisan's: The Elements of Computing Systems. But this book says nothing about certain electrical aspects in computers, for example: It's often said that 0's and 1's are…
Red Banana
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65
votes
11 answers
Why do electronics have a low temperature limit?
Apart from condensation why do electronic components usually have a low temperature limit? For example my laptop says something along the lines of -10 °C to 75 °C temperature while in use.
I can understand the high temperature limit, as things will…
George
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65
votes
9 answers
How do I saturate an NPN transistor?
I understand that in "saturation mode", a BJT functions as a simple switch. I've used this before driving LEDs, but I'm not sure I understand clearly how I got the transistor into that state.
Does a BJT become saturated by raising Vbe above a…
Mark
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65
votes
17 answers
How do you cut PCB?
I just spent about 20 minutes trying to cut through a PCB with a hacksaw. These things are really tough.
What is the correct tool to cut PCB material, and get a nice straight line?
I saw something about a guillotine, but can't find a vendor.
littlebirdceo
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65
votes
5 answers
Why do some tactile switches have 4 terminals?
I am wondering why some tactile switches have 4 terminals instead of two? For example, take a look at these switches, like the image below:
(source: pranelectronics.com)
What is the use of the two remaining pins? If the pins of the exact opposite…
rajat
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64
votes
3 answers
Why are there only four passive elements?
I've read that there are four types of passive elements: resistances, capacitors, inductors and memristors.
The memristor was predicted 30 years before it was produced. But why couldn't you invent other type of passive element? Is there a proof?
The…
jinawee
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64
votes
5 answers
What exactly fries the chip when you invert power supply?
From my own experience, burning microcontrollers is quite easy. Put the 5V at ground, GND at VCC and in an instant your chip is burned.
What exactly goes on internally that causes it to stop functioning entirely? For instance, if I were magically…
triplebig
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64
votes
20 answers
Version control systems for hardware projects?
What are some of the good versioning systems for hardware projects? Is there equivalents of Google Code, CVS and SVN? Are such version control systems suitable for hardware projects involving PCB files, schematics..(even firmware code)?
cksa361
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64
votes
4 answers
JTAG vs SWD debugging
After skimming through this article, I am wondering what are the benefits of SWD debugging over JTAG debugging?
I understand SWD uses less wires/pins, takes up less space etc. But how does it play out in terms of performance, features and cost of…
josef.van.niekerk
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64
votes
6 answers
What makes smartphones tilt-sensitive? Will they retain this ability in zero-gravity conditions?
Most smartphones are tilt-sensitive, but what device makes this possible? Additionally, how does it (and the sensors associated with it) work?
Also, since the working of these sensors seem, almost certainly, based on the presence of an external…
paracetamol
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