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1500 questions
21
votes
6 answers
Cell Phone as Microcontroller
I have a couple of cell phones laying around, one of them being this one:
http://www.gsmarena.com/sony_ericsson_elm-3057.php
Is possible to clear the flash memory and replace it with a bootloader and then upload arduino sketches or pic32…
Harry Svensson
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21
votes
6 answers
current sourcing, current sinking
I'm a student studying electronics and I'm having trouble understanding the concept behind current sourcing and current sinking. We've covered it in a lab using a 7404 and an LED and all that. Just having trouble getting an intuitive understanding…
user217
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21
votes
3 answers
How to view and customize beta of a transistor in LTspice
If I need to set beta to a custom value, is it possible to make a customized transistor with a beta of my choice? In other words, can I edit a ready or generic transistor's beta and save it as a custom transistor? How can I do that?
user1245
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21
votes
2 answers
Why so many pins for the MOSFET's drain?
The FDC855N comes in a 6-pin package, 4 of which are connected to the drain, and only 1 to the source. Why this difference? The source sees the same current as the drain, doesn't it?
Federico Russo
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21
votes
5 answers
Side effects of using large resistances
Are there any problems that can be caused by using resistors of large resistances (in the order of megaohms)?
I'm designing a feedback network that is just a voltage divider, and I want the feedback to drain as little current as possible from the…
Tendero
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21
votes
4 answers
Removal of unused pads?
I was reviewing a design earlier, and I noticed something interesting. The designer had removed unused pads on the chip. I have never seen this done before.
Is this something that is good practice? Is it even okay?
Reid
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21
votes
1 answer
What does the "L" in inductance stand for?
"R" is resistor/resistance, and "C" is capacitor/capacitance, that makes sense. But where comes the "L" for inductor/inductance come from?
edit: Wikipedia says it's possibly in honor of Heinrich Lenz, but I'd like to hear something more affirmative.
Federico Russo
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21
votes
5 answers
If the silicon wafers from which the processors are made are so sensitive that workers wear special suits how is delidding a processor possible?
I saw many videos on YouTube in which people delid processors and then apply better liquids for cooling the processor. Example: i5 & i7 Haswell & Ivy Bridge - FULL Delid Tutorial - (Vice Method)
However I also saw that people working in fabs are…
yoyo_fun
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21
votes
11 answers
What is the difference between a buzzer and a speaker and are there any other basic electric/electronic things that output sound?
I am playing with a speaker and a microcontroller and in some documentation the speaker is called buzzer. The assistant told us that is a mistake and we are dealing with a speaker.
I am wondering what exactly is the difference between the two,…
yoyo_fun
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21
votes
2 answers
Can you place vias inside a QFN footprint?
I am designing a very dense PCB containing a 0.4mm pitch QFN chip. In parts it is proving very difficult to fan out. It is made all the more difficult by the huge thermal pad that all QFNs have for some reason.
It is reasonable to place tiny vias…
Rocketmagnet
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21
votes
1 answer
ESP8266 eLUA (NodeMCU) vs MicroPython
I am searching for an unbiased, up-to-date comparison of the eLUA (NodeMCU) and MicroPython on ESP8266.
I can only find very superficial reports/blogs of users trying out one or the other. - All of which lacking entirely of technical details.
The…
ARF
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21
votes
3 answers
What is a Patty Code?
In my digital logic lecture today, my professor introduced a symbol code called Patty Code. I copied this table off the whiteboard:
| Symbol | Binary | Odd Patty | Even Patty |
|--------+--------+-----------+------------|
| a | …
Winny
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21
votes
3 answers
Difference between bit rate and baud rate and its origins?
Everyone seems to have different definitions everywhere I look.
According to my lecturer:
\$ R_{bit} = \frac{bits}{time} \$
\$ R_{baud} = \frac{data}{time} \$
According to manufacturers :
\$ R_{bit} = \frac{data}{time} \$
\$ R_{baud} =…
Psi
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21
votes
3 answers
Lithium Battery Protection Circuit - Why are there two MOSFETs in series, reversed?
I was studying a battery protection chip and reference circuit (below) commonly used in cell phone Li-ion batteries, and am confused by the two MOSFETs in series on the negative terminal EB-.
According to this question, I now understand that MOSFETs…
Ryan Griggs
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21
votes
8 answers
Two resistors in series
I know the summation equation for two or more resistors in parallel or series, and I know two parallel resistors will give more power.
But sometimes I saw some circuits that used two resistors in series, and I am wondering why that method was used…
M.A.K
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