Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

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1500 questions
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4 answers

Why does my blue LED keep burning out?

I am using a blue LED (InGaN) in a simple circuit to show me when my garage door is opened by looking through a window. The door is usually closed and may get opened once per day for a couple of minutes but sometimes longer. The LED will work for…
Beamish Boy
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Why are multimeter batteries awkward to replace?

I teach introductory physics labs, and inevitably when we do our labs on introductory circuits or mapping electrostatic potentials, there are one or more multimeters whose batteries die or fuses blow. This is always something of a hassle, since you…
Michael Seifert
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Zero ohm resistor tolerance?

This 0Ω resistor has a tolerance of ±1%. Well it would only be +1% at best because you can't have a negative resistance* but still 1% of zero is still zero? Shouldn't it be something like 0\$\Omega\$ + 0.001R? *except in very special cases with…
Thomas O
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LEDs on boards - pros and cons?

OK - I tend to design high value low volume boards so my view of this is biased. I like to sprinkle a lot of LEDs around my boards. One (red) LED for every power voltage on the board. Multiple s/w driven LEDs that show different execution paths in…
Dirk Bruere
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What do HDLs compile/synthesize to?

I'm a software engineer. As a programmer, I have an understanding of what my compiler does for me because I've manually written a close textual representation of what it outputs (e.g. assembly). For precise details of what's output I can look at the…
Jake
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What went wrong with my DIY project?

I have been teaching my son the basics of electronics by taking apart his old toys. We got to the level where we can fix things and put them back together. Last weekend we spent several hours putting the circuitboard of RC car #1 into RC car #2,…
Wapiti
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3 answers

UART signal is "rounded"

I am trying to debug a UART driver for the STM32F405. It does not work above a certain baud rate (about 50 kBd). I connected it to a logic analyzer with analog capability, and I saw that the signal is rounded; it takes time for the signal to rise.…
BillThePlatypus
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What is this inductor symbol from a video circuit?

This is from the datasheet for the TDA8217 PAL decoder and video processor. This is the "Applicaton Diagram". The circled item is unfamiliar to me, I asked at my local electronic components distributor and no-one there recognized it either. It…
hyarion
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Why are Alkaline, NiMH, and Li-ion AA measured differently (mAh, mWh, etc)?

Looking around Amazon, it seems that different types of batteries are measured differently: Does anyone know why? Li-ion are measured in mWh 1200mWh ALTIZURE (Cheap-Os) 3200mWh Deleepow 3000mWh AmpTorrent NiMH are measured in mAh 2000mAh…
coolaj86
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Why are off grid solar setups only 12, 24, 48 VDC?

I am looking to produce 50kW for an off grid solar project. Ideally, I'd like to have a high voltage DC battery system with a high power battery inverter and charge controller. I have only found a couple high VDC (384V) inverters and charge…
Lost Puppy
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4 answers

LED glows slightly during soldering

I recently soldered a number of white LEDs to a PCB using a Weller "standard" soldering station. I noticed some LEDs were glowing slightly during soldering. The PCB was placed on an ESD mat, but I doubt that this had an influence. Is that a thermal…
Junius
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Does it matter if a fuse is connected to the negative or positive terminal of a battery?

I am currently going through the conundrum of where to place a fuse in my DC battery-powered circuit to protect the circuit components and the DC battery. I've been googling for a definitive answer, but I came across diverging opinions... Which one…
DryRun
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6 answers

Is it truly impossible to tell what a CPU is doing?

Computer programmers often recite the mantra that x86 instructions are totally opaque: Intel tells us they are doing something, but there is no hope that anyone can verify what's happening, so if the NSA tells them to backdoor their RNGs, then we…
user14717
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How are circuits which use complex ICs normally simulated?

I understand that it is common practice in electronic design to simulate a circuit in some spice program before building it. Sometimes a project requires the use of complex ICs, for instance an IC which performs charge control for a Li-Po battery or…
Blargian
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What is the difference between level shifter, voltage regulator and dc-dc converter?

What is the difference between level shifter, voltage regulator and dc-dc converter? My understanding is: level shifter is used to convert one voltage into another voltage voltage regulator is used to produce constant output voltage from high…
nee
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