Electrical Engineering Weekly Newsletter
Electrical Engineering Weekly Newsletter

Top new questions this week:

What makes solder harden?

Soldering wire is very soft and pliable, but solder on a circuit board is hard. Why? I haven't been able to find a definitive answer, but some ideas that come to mind are: Some kind of chemical ...

asked by Michael 23 votes
answered by Olin Lathrop 29 votes

Why are consumers located near high-voltage lines typically not connected to those lines but instead are connected through a lower high-voltage line?

A typical grid uses 110..500 kilovolts lines to deliver electricity to substations which lower that to 6..20 kilovolts and then lines with that lower voltage get to consumers where yet other ...

high-voltage power-distribution  
asked by sharptooth 17 votes
answered by Li-aung Yip 55 votes

Can the fake USB flash drive attack happen over Ethernet?

You may have seen the article This USB Drive Can Nuke A Computer where it shows how a flash drive shaped device can completely fry out all the components of a computer. This is very shocking (pun ...

ethernet damage  
asked by user3900751 12 votes
answered by Ignacio Vazquez-Abrams 28 votes

Why isn't the Fourier transform of a single sine wave cycle a single bar?

I have tried different Fourier transform codes out there on single sine waves, and all of them produce a distributed spectrum with a resonance at the signal frequency when they should theoretically ...

signal control signal-processing fourier  
asked by Mister Mystère 8 votes
answered by Li-aung Yip 21 votes

Why do I keep burning my mosfet?

Following this question, I ended up with the following diagram to drive a custom made dc motor using Arduino (omitting the 5V and 12V power supply stages which work properly): I keep burning ...

mosfet dc-motor mosfet-driver  
asked by Miguel El Merendero 4 votes
answered by Olin Lathrop 11 votes

Using a microcontroller ADC to measure a 4-20mA sensor

Question from a SW Engineer again. I've got a device which is mains powered and outputs a 4-20mA current depending on the flow rate in a pipe. I'd like to measure that flow rate with a ...

sensor adc 4-20ma  
asked by jwhitmore 4 votes
answered by Olin Lathrop 3 votes

How can I read the graph of a low pass filter

Given information I have the following circuit, and frequency graph. The capacitor is connected to ground at the bottom. Unfortunately the graph is in dutch, but it won't matter much. Just understand ...

asked by user1534664 4 votes
answered by Greg d'Eon 4 votes

Greatest hits from previous weeks:

Designing a Santa alarm (honestly)

You read the title and that's what I am trying to do. Synopsis: I have a young son who is determined to catch Santa (to what ends I don't know). He even dreamed up using some kind of pressure plate ...

sensor solid-state-relay proximity-sensor  
asked by Christian Bongiorno 113 votes
answered by Dan Laks 87 votes

What is input and output impedance of an opamp?

I have never understood input and output impedances of an op-amp. If anyone can explain what these two terms mean in an op-amp I'd highly appreciate it. Thank you! ...

op-amp impedance  
asked by user734861 11 votes
answered by Phil Frost 17 votes

Can you answer these?

POE external Magnetics Alternative to magnetic RJ45 jack ieee803af

I can't use a magnetic jack for this POE PD (ieee803af), because we use another connector (M12). Looking for components to replace the internal magnetics, I found that almost all components and ...

ethernet magnetics poe rj45  
asked by lode 1 vote

MSP430G2553 WDT ISR compilation error - GNU v4.9.1

I'm using GNU v4.9.1 compiler, and I'm just trying to work with WDT timer: void __attribute__((interrupt(WDT_VECTOR))) WDT_ISR(void) { P2OUT ^= BIT1; } When trying to build it, I keep getting ...

msp430 watchdog gcc  
asked by Rainy 1 vote

How to connect a TVS to protect the data lines in a USB device port?

TVS is a good practice to protect USB ports. A USB (at least 2.0) connection has the power path supplied with a 5 V source (Vbus=5V0) at the host side and the data path supplied with a 3.3 V sources ...

usb ftdi  
asked by asndre 1 vote
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