I need to amplify the microphone output to some level about 3-4 Vpp without a DC offset. The output voltage will only be sensed (it will pass through a peak detector). So I assume I don't need any current supplying ability.   I first thought of using a common emitter with around 400 gain, but there is also an option of using a non-inverting or inverting (I don't care phase shift) opAmp circuit with the required gain.   I wonder are there benefits of using one over the another, in which aspects do they differ?   Or, are both these two options a bad idea?
I have built a peak detector circuit using op-amps/comparators to amplify the signal from an electret microphone, hold the peak signal and create a sharp logic edge when a peak is detected to be sent to a microcontroller.  I have built the circuit as follows setting up OA1 as a non inverting amplifier with a gain of 1000, but the voltage out from the OA1 remains fixed at about 4.5V no matter how much noise I make into the microphone. The comparator part of the circuit is outputting approximately 2V low and 5V high depending on how I set the potentiometer. All the components appear to be working.         &ndash; Schematic created using
I am a US citizen and have recently visted the UK  with simply a passport which allowed me to vist for 6months I have heard rumors that I am obligated to stay in the US for a Equal amount of time that I have visited the UK before I am able to return, but I am struggling tour no any proof of this obligation .. Am I missing somthing or is it simply not true How do I kill background processes / jobs when my shell script exits? I am looking for a way to clean up the mess when my top-level script exits.  Especially if I want to use set -e, I wish the background process would die when the script exits. How to construct a pyramid in blender but the edges of the triangles to be equal? How to make a pyramid in blender and all the edges to be equal size? Is there a way to do that in blender? Or if there is no easy way for that, maybe anybody not that lazy can provide me with a math line? Or maybe a link or whatever? I see that one time out of the twenty total tests they run, $p &lt; 0.05$, so they wrongly assume that during one of the twenty tests, the result is significant ($0.05 = 1/20$).      Title: Significant Hover text: "'So, uh, we did the green study again and got no link. It was probably a--' 'RESEARCH CONFLICTED ON GREEN JELLY BEAN/ACNE LINK; MORE STUDY RECOMMENDED!'" What happens when I terminate a process and the socket send buffer is not empty? In Windows (and probably in other operating systems), if a process has a TCP connection with another process on another machine, and then I terminate the process, an RST packet will be sent to the other machine to indicate the end of the connection.  Now imagine that when the process is terminated, there were still some data left in the send buffer. What will happen in this case, will these remaining data be sent to the other machine followed by an RST packet, or will these remaining data be ignored and only an RST packet is sent? A positive polynomial is the sum of two squares in $\mathbb{R}[X]$ Let $P\in\mathbb{R}[X]$ be a positive polynomial.  I want to show that there exists $A,B\in\mathbb{R}[X]$ so that $P=A^2+B^2$    $\displaystyle P=a\prod_{k=0}^q(x-a_k)\prod_{k=0}^{2p}(x-b_k)=a\prod_{k=0}^q(x-a_k)\prod_{k=0}^p(x^2-2\Re(b_k)+|b_k|^2)$ where $a$ is the leading coefficient, $a_k$ are the real rooks, $b_k$ are the complex roots.  What can i do now ? I know that the identity $(a^2+b^2)(c^2+d^2)=(ac-bd)^2+(ad+bc)^2$ should come in handy, but I can't figure out :  1) How to show that the product real roots is a square  2) How to use the above identity for the complex roots.  If I can solve those two points, then I can solve the problem. A program I am using spits out LaTeX tables in LaTeX files (outreg2 command from Stata), which I run using texify to make pdfs of the tables.  I crop these tables (using pdfcrop) and embed them elsewhere.  However, the pdfs include page numbers, which prevent pdfcrop from cropping directly around the table.  I need an automatic way to remove the page numbers before cropping.  I want to insert the command \pagenumbers{gobble} into the LaTeX code to automatically remove the page numbers.    I believe   texify --pdf --texinfo="\pagenumbering{gobble}" filename.tex   should work.  It does not. No exception pops up, but the page number remains. I cannot find documentation anywhere showing examples of using the --texinfo option to splice LaTeX code into the file before running the LaTeX file to create a pdf.   How should I properly use the texify command?  Or is there another way to splice in  \pagenumbering{gobble} before running texify? For every prime of the form $2^{4n}+1$, 7 is a primitive root. I want to write batch or something, that will write output of top into a file on login.  I did top &gt;&gt; output-file, but it contains some strange character!  Can somebody give a simple tutorial about how to write batch file in Linux? How can I tell if two Minecraft mods are compatible? If I want to use two mods together, e.g.  and  (which don't state compatibility with one another), how can I tell if they will work together (and not break Minecraft - forcing me to re-download a fresh copy)? How to access the Index Of A Generic.List By Reflection? ok, ive a class and i pass an object as property.  the object that i pass is a List&lt;X&gt;  in my class im trying to access the Object index by reflection BUT I CAN'T!!!   Example:  this class works i just wrote down the part i want to show you and i need help.  class MyClass {     private object _recordSet;     public object RecordSet     {         get { return _recordSet; }         set { _recordSet = value; }     }      public string Draw()     {         system.reflection.Assembly asem = system.reflection.Assembly.getAssembly(_dataSource.GetType());          object instance;          instance = asem.CreateInstance(_dataSource.GetType().UnderlyingSystemType.FullName);          //to access de Count of my List         int recordcount = int.Parse(_dataSource.GetType().GetProperty("Count").GetValue(_dataSource,null));          //i need to do a          for(int cont = 0; cont &lt; recordCount; cont++)         {             _dataSource[cont].Name; // &lt;-- THIS PART IS NOT WORKING!!! because i cant access the Index Directly.... WHAT TO DO!! ???         }     } } Tikz: adjusting pin anchor I was looking for a possibility to adjust the anchor of the text of a pin. Tikz does not allow this out of the box.   This question was already asked on the mailing list , Sept. 2009 without any reply till today or feature addition to pgf/tikz:  \documentclass[tikz]{standalone}  \begin{document}      \begin{tikzpicture}[          every pin/.style={anchor=west},          every pin edge/.style={anchor=west}]          \node [pin=60:test] at (0,1) {};          \node [pin={[anchor=west]60:test}] at (0,0) {};      \end{tikzpicture}  \end{document}   There is also a question with a suggested workaround here on  by defining an aligned pin style consisting of another node positioned at the end of the pin using \tikzlastnode:  \tikzset{     aligned pin/.style args={[#1,#2]#3:#4}{         pin={[inner sep=0pt,%               pin distance=#2,% new option, default = 3ex               label={[append after command={%                     node[inner sep=0pt,%                         xshift=-0.1cm,% modified, default = 0                         at=(\tikzlastnode.#3),%                         anchor=#1,%                     ]{#4}%                 }%             ]center:{}}%         ]#3:{}}%     } }   In this code, I have added a second unnamed option for pin distance within the square brackets.  MWE using the workaround showing the desired result:  \documentclass[tikz]{standalone}  \tikzset{     aligned pin/.style args={[#1,#2]#3:#4}{         pin={[inner sep=0pt,%             pin distance=#2,% new option, default = 3ex             label={[append after command={%                     node[%                         inner sep=0pt,%                         xshift=-0.1cm,% modified, default = 0                         at=(\tikzlastnode.#3),%                         anchor=#1,%                     ]{#4}%                 }%             ]center:{}}%         ]#3:{}}%     } } \begin{document} \tikz[pin distance=15mm, every pin/.style={fill=blue,text=white}] \node [circle,draw,     aligned pin={[west,3ex]0:X-Value},%     aligned pin={[west,3ex]45:Y-Value},%     aligned pin={[west,3ex]90:Z-Value}] {my circle}; \end{document}     I would like to add further options such as pin edge to adjust the style of the edge. Another addition would be xshift to finetune the position of the text (and yshift).  Is it possible to change the workaround to allow named options with default values if not specified?  Usage could look like this (without using necessarily all options):  node[aligned pin={[pin anchor=west,pin distance=1cm,pin edge={thick}]90:{txt}}]{};   If someone is interested in the implementation of the pin feature in tikz see  and do a textsearch for pin.  Update after answer by Qrrbrbirlbel:  To achieve almost the same result as my MWE use following code  % use preamble from Qrrbrbirlbel answer \begin{document}  \begin{tikzpicture}[every pin/.append style=draw, every pin edge/.style={thick}] \node[c] [ pin={[pin anchor=south west,pin edge pin anchor=south west,pin distance=6ex]90:Z-Value}, pin={[pin anchor=west,pin edge pin anchor=west,pin distance=6ex]45:Y-Value}, pin={[pin anchor=west,pin edge pin anchor=west,pin distance=6ex]0:X-Value} ] at (0,0) {}; \end{tikzpicture}  \end{document}     However, I would like to finetune the text positioning using inner sep=0 and a slight shift:  \newlength{\xshiftlength} \setlength{\xshiftlength}{0.5\widthof{Z}}   Following works:  \tikzset{   pin inner xsep/.style={tikz@pin@post/.append style={inner xsep=#1}} }   Apparently xshift cannot be added in the same way. It shifts more than only the text. How could a pin text xshift be added? Flagged emails keep returning and won't synchronize between Apple Mail and Gmail I've had this problem before and can't recall how I managed to fix it last time. I use Apple Mail to access my Gmail and normally flagged emails show up correctly. Starred emails in Gmail equate to flagged emails in Apple Mail and I can unflag an email in either Gmail or Apple Mail and it works.  But now I've got four emails that I can't unflag. They're not flagged in Gmail at all (although they used to be). When I see them in the Flagged folder in Apple Mail, they don't even have flag icons next to them but they're still counted in the number showing next to "Flagged". If I manually re-flag them and then unflag them, they disappear from the Flagged box. But then if I click into Inbox and then back into Flagged they show up again.  Any ideas about how to make these guys disappear for good?! Prevent parameter expansion in shell script I often have to do a recursive search in files. Tired of typing the whole "find/grep" combination all the time, I just created a script with the following line:  find . -name $1 -exec grep $2 {} + 2&gt;/dev/null   The idea is that I should be able to run it as, for example:  myfind '*' hello   The problem is, when '*' gets passed into the script, the script is expanding it to each file in the directory.  I tried putting a quote around $1:   find . -name '$1' -exec grep $2 {} + 2&gt;/dev/null   However, this turns $1 into a literal string.  Would appreciate your help in finding the right syntax. Must be something simple that I am missing. Suppose $x&gt;0$ and we have function $f(x)=\frac{\sin x}{x}$ how can we show $$\forall n \in \mathbb{N} :|f^{(n)}(x)|\leq \frac{1}{n+1}$$ I need a hint to show this property .Thanks in advance . I tried for $n=1 ,2$  by finding maximum of $|f'| ,|f''|$ but I get stuck to show for $n$ Often I see code blocks pasted into questions with no formatting, or terrible formatting.  It's sometimes quite a chore to fix these: you have to either manually space out each line, or paste the code into an IDE, format it there, and paste it back.  Could we have a button/function where you could highlight a code block, and it would turn this:  foreach (var i in stuff) { if (i==1) { Whatever(); } }   into this:  foreach (var i in stuff) {   if (i==1) {     Whatever();   } }   I realise the function would have to work differently based on the language in the code block. Perhaps  it could use the same rules as the prettify code.  Also, it wouldn't be a big deal if it gets the language wrong and breaks the code, since you can always just ctrl+z. Can the Force be used to fly? In The Empire Strikes Back Yoda uses the Force to lift Luke's X-Wing out of the water and put it on land.  In Attack of the Clones and in many instances in the second series of The Clone Wars, Anakin (and others) use the Force to jump higher than they could otherwise, or to jump from very high locations, but I don't think I've ever seen the Force used for outright self-levitation.  But if Yoda could lift the X-Wing, shouldn't a strong Jedi be able to lift himself and, essentially, fly with the help of the Force? My account has been , besides the following restrictions:  an account will be locked at 1 reputation the user page will have a visual indication that the account is in timed suspension, and for how long the account holder will be unable to vote, ask, answer or comment  What else does timed suspension prevent me doing? For example, can I still edit my own posts or delete content? And what is a network-wide suspension? $|f'(x)| \le g(x)$ implies $|f(b) - f(a)| \le \int_a^b g(x) dx$, without assuming $f'$ to be integrable. Multiple disks vs single disk on virtualized environment We're planning to install a SQL Server on this physical architecture:  A hyper-v cluster based on windows server 2019 A cluster shared volume where all VMs live A full-flash SAN that contains the CSV  I've always read that is a common best practice to have multiple disks for data files, log files, temp db files ect... But that best practice is referred to a bare-bone installation. So, what I'm asking is: what are the actual benefits of doing so on the above described architecture (if any)?