Electrical Engineering Stack Exchange
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1500 questions
21
votes
3 answers

What are the ways to make a dual power supply from a single voltage source?

I have a function generator IC XR2206 from EXAR. It's application circuits uses dual power supply +/-9 volts. How can I make such a 9-0-9 dual supply from a single voltage source like a battery or an adapter?
C--
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21
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2 answers

What is the meaning of "half bit" in this context?

In RS-232 specification, the stop bits can be 1, 1.5 or 2 stop bits...I wonder how it's possible to have half a bit? Also some ADC math uses 0.5bit precision in the IC specifications/datasheet. Can someone elaborate in this subject?
mFeinstein
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21
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6 answers

What is the correct command sequence for microSD card initialization in SPI?

I am trying to interface a microSD card (2 GB, Kingston, Sandisk) with a Silicon Labs C8051F931 controller. I am very much confused about the sequence which I have to follow for initialization. In the book SD Card Projects Using the PIC…
gpuguy
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21
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2 answers

What is the "+:" operator called in Verilog?

I am going through a Verilog test case, and I found this statement: assign XYZ = PQR_AR[44*8 +: 64]; What is the "+:" operator known as? I tried to find this on google, but I didn't get any relevant answer.
shailendra
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21
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2 answers

100 MHz probe and 200 MHz probe show very different waveform on 1 MHz signal

Recently I purchased my very first scope and noticed something I'm really curious about its cause. It's a 100 MHz scope, when I was testing to see the ringing of a 1 MHz clock signal with different values of series termination, using 100 MHz probe…
Jimmy.D
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21
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2 answers

What's an alternate pin function on a microcontroller?

I'd like to know what "Alternative Function" refers to in the context of the IO ports of a microcontroller. I don't need to know how to activate it when connecting to a peripherial, but I'd like to know what it exactly is and why we'd need it.
user929404
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21
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3 answers

How to water-protect my Arduino?

I am building a watering system with an Arduino. Basically it runs on a track with a hose that drips water down on plants a couple of times every day. Its outside, and water might sometimes get from the leaves of the plants down to the Arduino…
bogen
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21
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10 answers

Is there ever any reason to prefer 5% tolerance resistors over 1%?

I work at an electronics store and the other day a customer came in who was rebuilding a circuit board. I sold him some resistors, but later he came back in wanting to return some of them because they were only 1% tolerance, and he needed 5%. I'm…
Justin Pederson
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21
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8 answers

Fans: suck or blow?

For a fan, should air be sucked in, or should it blow air out? I'm talking about an enclosure mounted fan.
Thomas O
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21
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4 answers

How do large electrical grids stay in phase?

I am a math student with some background in physics so apologies if the question is naive - but I'm trying to understand how large electrical grids like the Eastern Interconnection maintain locally a consistent phase, when it seems like the grid…
Dominic Wynter
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21
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7 answers

Where to leave the test leads on a Fluke multimeter

I think this is somewhat of a "trade secret". Being a software engineer for embedded devices myself, I often find myself using oscilloscopes and multimeters. I have always wondered about my Fluke 87-V and all flukes before that. They have these…
Stijn
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21
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2 answers

Why do travel transformers have a setting for either 50W or 1600W?

I've noticed this "feature" on a number of travel-oriented voltage converters - they either are meant to be used for small 50W loads, OR for larger loads up to 1600W. But you can't run a small load on the higher setting. Here's an example of one…
StayOnTarget
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21
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11 answers

Op-amp tutorial for electronic noobs?

Can anyone point me to a tutorial for electronic noobs that explains how to use op-amps and what I can do with them, besides amplification?
Nikolaus Gradwohl
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21
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5 answers

How can I detect which arduino board (or which controller) in software?

I have a project that I want to work on either a Uno or a Mega (or even a Due) and it would be nice if I didn't need two versions of the software. For example, on a Mega, to use SoftwareSerial, you have to use different pins than the ones on an Uno.…
tooshel
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21
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9 answers

How can 8-bit processor support more than 256 bytes of RAM?

If a 32-bit processor can handle approximately 4 GiB of RAM (i.e. \$2^{32} = 4 294 967 296\$) bytes, why does my Arduino Mega 2560 have 8 KiB of SRAM, if being a 8-bit processor allows it to handle just 256 bytes (\$2^8\$)? Or am I reading the…
ZaqueoAlejandro
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