Electrical Engineering Stack Exchange
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1500 questions
34
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14 answers

What makes the stack concept useful in embedded programming?

Below is an illustration of the stack concept: I have read many times about the stack pointer and how some variables are stored in SRAM on a stack. Many tutorials explain how it works, but not why this concept exist at all. Imagine I am the program…
GNZ
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2 answers

What's the difference among these static protection bags?

I have some old modems & other cards stored in plastic static bags and noticed that a few of them were distinct... these are all from the 1990s or maybe early 2Ks. Here's a sampling: From left to right, there are: Opaque and…
StayOnTarget
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6 answers

In an NMOS, does current flow from source to drain or vice-versa?

In an NMOS, does current flow from source to drain or vice-versa? This Wikipedia page is confusing me: http://en.wikipedia.org/wiki/MOSFET The above image confuses me. For the N-channel, it shows the diode's polarity going towards source in some,…
PitaJ
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5 answers

Testpoints: Vias versus pads

I was fixing an ultra cheap home router few days ago and noticed that it had vias marked TP_12V, TP_3V3, TP_GND and similar. The problem turned out to be leaky electrolytic crapacitors in the buck converter and the vias really helped debugging that,…
AndrejaKo
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7 answers

Can we not simply connect a battery to a RAM to prevent data loss during power cuts?

So, I was just wondering about how volatile memory storage loses data when the power to them is cut off. But can we not solve that problem by using a battery in conjunction with a RAM and a ROM and when there's a power cut i.e. when the computer…
Vishal Dalwadi
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34
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5 answers

Is it a bad idea to plug the other end of ESD strap to wall ground?

I have gone through this answer on Superuser, while it provides good information, I still have a specific question from electrical/electronics engineering point of view. Is it wrong and unsafe to connect the other end of the ESD wrist strap to the…
rajeev
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5 answers

How do devices like the Game Boy Advance achieve their frame rate?

I've been designing my own handheld gaming device based around an AVR microcontroller and a small OLED display. I started off with a monochrome display 128x64 pixels and can comfortably draw to it at over 60 frames per second. I recently reworked it…
MalphasWats
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3 answers

Why does power dip during a lightning storm?

If lightning were to strike power lines, wouldn't you expect it to increase the power, and hence your room lights get brighter? Why do they go dim for 1 second at a time?
PJazz
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1 answer

How do volume control headphones work?

A recent question over on Android Enthusiasts got me to wondering how volume control headphones work. I don't mean volume control which works by attenuating the incoming signal, but the kind of volume control that signals to the device to increase…
Mark Booth
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34
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2 answers

Connect load to collector or emitter of transistor

When setting up a transistor as a switch is there any difference between putting the load on the collector or emitter? As far as I can see the only difference is in calculating the Vbe i.e. calculating what voltage is required to turn the transistor…
Paul Sullivan
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4 answers

What software tool was used to draw these circuit schematics?

I was reading online and found this site: http://www.cppsim.com/ I was very curious how this professor drew all these circuit diagrams in his lecture notes (such as this one: http://www.cppsim.com/CommCircuitLectures/lec9.pdf). They just look very,…
Leo
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11 answers

Why do we "need" resistors (I understand what they do, just not why...)?

I have always had a basic understanding of electronics. I am now starting to learn a bit more, using an Arduino as a test platform, and I have a question about resistors that I can not seem to solve through research. Why do we use them? I understand…
Louis van Tonder
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34
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2 answers

How did USB 2.0 avoid collisions?

Looking at the pins of USB 3.0 receptacles, I can see that there are separate transmission and reception pairs, however for USB 2.0 there is only one "data" pin pair. How does USB 2.0 ensure that the devices aren't communicating simultaneously?
VortixDev
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2 answers

What is an "XY" rated safety capacitor, exactly?

Please help me understand this. In a prominent, 480v, 6kW AC servo drive, across three input phases, three 22mm "XY" class 10nF caps are placed for EMI suppression. Also, from these three phases, three of the exact same "XY" caps go to chassis…
rdtsc
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8 answers

How do I develop for STM32 discovery on Linux?

I have an STM32 discovery board and would like to be able to program it on Linux. What is the easiest way to do this?
Gordon Williams
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