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1500 questions
30
votes
4 answers
Why would a modern digital clock rely on mains frequency?
I am in the military, stationed in Djibouti, Africa. We generate 240V/50Hz power on base, but some buildings also have 120V outlets, which I assume is transformed somewhere else on base, probably at the diesel generating station. I also assume…
Chris Gregg
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30
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5 answers
MOSFET symbol - what is the correct symbol
I've been on this site now a couple of months and I notice various symbols used for MOSFETs. What is the preferred symbol for an N Channel MOSFET and why?
Andy aka
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30
votes
3 answers
What is the difference between a PLL and a DLL?
Phase Locked Loops (PLL's) and Delay Locked Loops (DLL) are used in various applications but there isn't yet a salient discussion of the key aspects of these circuits, how they operate, in what applications they might be used, the comparison between…
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3 answers
Is it possible to use just a capacitor to debounce a button?
I have been wondering: why cannot you just hook up a capacitor to a button to debounce it? I have been figuring out how to reduce the work my microprocessor has to do, but I have very limited space on a PCB I am designing, so I don't want to do a…
Anonymous Penguin
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30
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5 answers
How much power is really wasted by a wall wart?
The title pretty much sums it up... Hyperbole aside, how much actual power is consumed by a typical wall wart when the device it's attached to isn't powered on? And are there designs for wall warts that minimize or eliminate this sort of parasitic…
Kaelin Colclasure
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30
votes
2 answers
How can the GPS position update rate be 10 Hz?
Based on stuff on the web (Wikipedia and others) the GPS navigation message bit rate is 50 bit/s. That includes all data needed for user position calculation (time, ephemeris, almanac, etc.) It seems that the packet from a satellite should be much…
Alihaji
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30
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4 answers
How much data could be stored on a standard compact cassette using modern encoding?
My father and I recently dug out his old Commodore 64 from his basement and tried to revive it. Among other accessories, we also found his old Datasette drive, which is essentially a normal tape drive that can be connected to the computer to store…
DLCom
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30
votes
4 answers
Transmission line reflection. I would like a non-mathematical explanation
I am a licensed radio amateur, and find bewildering the many different explanations, which range from folksy urban myth to Maxwell-Heaviside Equations, of what happens at the termination of a transmission line or feeder. I realise that they all come…
Harry Weston
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30
votes
6 answers
What are the advantages and disadvantages of thinner PCB thickness (<1.6 mm or 0.063'')?
What are the advantages and disadvantages of thinner PCB thickness (<1.6 mm)?
My approach:
Better capacitance interplane and better power decoupling.
Better track-plane coupling.
Problems with assembly process with heavy components
Problems with…
Jesus Castane
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30
votes
1 answer
MicroSD card performance deteriorates after long-term read-only usage
I'm using a STM32L432 microcontroller to read data from a microSD card via SPI. In my application, I'm playing a sound file with a length of 10 s in loop.
I found out that after the application ran for approximately 20 - 25 hours, the audio stream…
Hermetica
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30
votes
7 answers
Why do power grids tend to operate at low frequencies like 60 Hz and 50 Hz?
I understand that a two-pole AC generator has to rotate at 3600 rpm (60 Hz USA) in order to maintain a 60 Hz frequency and higher frequencies would require these generators to spin even faster which could be problematic.
I also understand that…
ZekeC
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30
votes
7 answers
Is the NE555 the IC I need, and if not, what do I replace it with?
I've noticed that whilst I have a well-known solution using an NE555, that IC doesn't fulfill my needs perfectly. Others have told me that the NE555 is very rarely an appropriate solution to one of the problems it's being used for.
What are the…
Marcus Müller
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30
votes
7 answers
How to design electronics to last 40 years or more?
I've been reading about the Voyager space probes and am very curious about how you design electronics and instrumentation for a very long life (40+ years) without any physical maintenance.
My guesses so far include:
Physical protection for…
ConanTheGerbil
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30
votes
8 answers
Can I use I2C over 2m cables?
In my current project, I need to communicate between a microcontroller and some sensors over I2C. One of them is a temperature sensor, it needs to be placed at approximatively 2 meters far from the microcontroller. I cannot choose another protocol…
JackOfHearts
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30
votes
5 answers
Would a small hole in a Faraday cage drastically reduce its effectiveness at blocking interference?
I'm shielding the pickup cavity of a guitar to minimize interference. I'm doing this with copper tape that has conductive adhesive, and I'm connecting this tape to ground.
Without getting into too much detail, let's say there's a small spot I miss…
Anthony
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