I want to take the 5V output from a USB port and make it 12V, so that I can run a cooling fan which is 12V. Is there any circuit I can make at home myself? If the output voltage is not exactly 12V, it can be at least 11V so the fan can run smoothly.
I would like to transform 5V 500mA (from USB power) into 12V with a few cheap components.  Is this possible with the help of some generic parts (and not with the help of some expensive transformer, etc.)?  Also, how many milliamps would this provide?
I am a non-EU national, permanent UK Resident. Recently, my work issued me with a multiple Schengen visa with Norway as the first (main) point of entry. Now I want to go on holidays to Greece - do I need to apply to Schengen visa again, as Greece is not Norway and I am not going there for work? Can US citizens go to Cuba freely and vice versa after the recent diplomatic relation restoration? A recent full diplomatic relation restoration between the US and Cuba took place, does that mean that US citizens can go to Cuba freely and vice versa? When I create beamer frame, the content is centred in the slide. How do I make the content move to the top of the slide by default? Thus is a picture of both of my hard-drives:    My C Drive and my D drive. I want to put Ubuntu onto my D Drive. Now my question here is if i do install onto my D Drive then how should I do it in order to retain use of the drive. I intend to partition about 60 gigs from it. Now after doing that I should still have about 830 gigs left. I want to still be able to use that in Windows. So how and will I be able to retain use of the drive after Installing? I have installed once before and I believe i did it wrong because not only could Windows not recognize my D drive but I also lost all the data on it.   My computer is a Lenovo Y700 It is a UEFI (I believe i got that right). What does the big intersection or union sign of a set mean? In some cases, we will have to consider the union or the intersection of several, even infinitely many sets, defined in the obvious way. For example, if for every positive integer $n$, we are given a set $S_n$, then   $$\bbox[border:1px solid red]{\bigcup_{n=1}^\infty S_n}=S_1\cup S_2\cup\cdots=\{x\mid x\in S_n\text{ for some }n\},$$   and   $$\bigcap_{n=1}^\infty S_n=S_1\cap S_2\cap\cdots=\{x\mid x\in S_n\text{ for all }n\}.$$   Two sets are said to be disjoint if their intersection is empty. More generally, several sets are said to be disjoint if no two of them have a common element. A collection of sets is said to be a partition of a set $S$ if the sets in the collection are disjoint and their union is $S$.   Normally what I know is that you can make a union or an intersection between only two sets. In this expression, there is a big union of sets. I'm asking about the meaning of this expression – what does it mean? What does the infinity sign do at the top?  Things are even more complicated with De Morgan's laws, which use the same expression:     Two particularly useful properties are given by De Morgan's laws which state that   $$\left(\bigcup_nS_n\right)^c=\bigcap_nS_n^c,\quad\quad\quad\quad\left(\bigcap_nS_n\right)^c=\bigcup_nS_n^c.$$   Anyone who can explain to me the expression or De Morgan's laws would be much appreciated. How do I get jQuery to select elements with a . (period) in their ID? Given the following classes and controller action method:  public School {   public Int32 ID { get; set; }   publig String Name { get; set; }   public Address Address { get; set; } }  public class Address {   public string Street1 { get; set; }   public string City { get; set; }   public String ZipCode { get; set; }   public String State { get; set; }   public String Country { get; set; } }  [Authorize(Roles = "SchoolEditor")] [AcceptVerbs(HttpVerbs.Post)] public SchoolResponse Edit(Int32 id, FormCollection form) {   School school = GetSchoolFromRepository(id);    UpdateModel(school, form);    return new SchoolResponse() { School = school }; }   And the following form:  &lt;form method="post"&gt;   School: &lt;%= Html.TextBox("Name") %&gt;&lt;br /&gt;   Street: &lt;%= Html.TextBox("Address.Street") %&gt;&lt;br /&gt;   City:  &lt;%= Html.TextBox("Address.City") %&gt;&lt;br /&gt;   Zip Code: &lt;%= Html.TextBox("Address.ZipCode") %&gt;&lt;br /&gt;   Sate: &lt;select id="Address.State"&gt;&lt;/select&gt;&lt;br /&gt;   Country: &lt;select id="Address.Country"&gt;&lt;/select&gt;&lt;br /&gt; &lt;/form&gt;   I am able to update both the School instance and the Address member of the school.  This is quite nice!  Thank you ASP.NET MVC team!  However, how do I use jQuery to select the drop down list so that I can pre-fill it?  I realize that I could do this server side but there will be other dynamic elements on the page that affect the list.  The following is what I have so far, and it does not work as the selectors don't seem to match the IDs:  $(function() {   $.getJSON("/Location/GetCountryList", null, function(data) {     $("#Address.Country").fillSelect(data);   });   $("#Address.Country").change(function() {     $.getJSON("/Location/GetRegionsForCountry", { country: $(this).val() }, function(data) {       $("#Address.State").fillSelect(data);     });   }); }); Why does the (relativistic) mass of an object increase when its speed approaches that of light? I'm reading Nano: The Essentials by T. Pradeep and I came upon this statement in the section explaining the basics of scanning electron microscopy.     However, the equation breaks down when the electron velocity approaches the speed of light as mass increases. At such velocities, one needs to do relativistic correction to the mass so that it becomes[...]   We all know about the famous theory of relativity, but I couldn't quite grasp the "why" of its concepts yet. This might shed new light on what I already know about time slowing down for me if I move faster.  Why does the (relativistic) mass of an object increase when its speed approaches that of light? pgAdmin to display multiple result sets Ubuntu copy dialogue stops at the last moment for a long time Whenever I try and copy a file to an USB flash disk, the progress bar runs till the end very fast and stops for an indeterminable time before it is complete.  Is there an issue with ubuntu or my flash disk is what I am not able to figure out. All I want is a realistic copy dialogue I'm using Linux (centos) machine, I already connected to the other system using ssh. Now my question is how can I copy files from one system to another system?  Suppose, in my environment, I have two system like System A and System B. I'm using System A machine and some other using System B machine.  How can I copy a file from System B to System A? And, copy a file from System A to System B? Edits on closed posts Should questions or answers on questions that are closed be edited, even if the question is closed and the edit does not change anything about the reason it's closed? Example:  was just edited, which I saw in the review queue. It certainly improves the answer, but since the answer doesn't really have to exist on SE at all (because the question is off-topic), should this edit be made? In my understanding, the only reason that the edit option for a closed question is not greyed out is so that it can be edited to make it comply with the SE rules. I got a positive definite matrix $B,$ that is, $V(x) = x^TBx &gt; 0$ for any vector $ x \neq 0.$  I want to show that $ \lambda_\min \|x\|_2^2 \leq V(x) \leq \lambda_\max \|x\|_2^2$ for any $x \neq 0,$ where $\lambda_\min$ and $ \lambda_\max$ are defined by $$ \lambda_\min = \min \lbrace | \lambda|: \lambda \text{ is an eigenvalue of } B \rbrace$$ and  $$ \lambda_\max = \max \lbrace | \lambda|: \lambda \text{ is an eigenvalue of } B  \rbrace$$  Any hint please? Are there constants in JavaScript? Is there a way to use constants in JavaScript?  If not, what's the common practice for specifying variables that are used as constants? GUI/Unity crashing in 16.04 LTS after updates 2018-01-04, compiz segfaults The latest updates (4/1/2018) make my laptop constantly crash the GUI/Unity:  (Intel Pentium su4100 processor)  syslog:  Jan  5 11:38:53 1810 kernel: [ 1850.327738] compiz[11911]: segfault at 0 ip 00007f6c7baf0c16 sp 00007ffd5ec71c60 error 4 in i965_dri.so[7f6c7b513000+82d000]   After login I end up with an empty desktop, just a wallpaper, GUI/Unity are in a crash loop:   No panel.  No dash.  Can't start a program. Launcher disappears. Sidebar disappears. System crash. Windows key not working. The key combination Alt+Tab not working.   Simply, the computer is not usable. Same for guest login. The only thing working: open up a terminal CTRL+ALT+T to examine log files.  I somehow forced  to let me log in and file the bug, but still lots of problems:   Dash not working Alt+Tab not working Sometimes windows all disappear for a few seconds     Any ideas for a solution or workaround?   UPDATE     If you have the same/ very similar problems, follow the link to my    report and mark there that you're affected too. Or file your own. Please leave a comment   if you wish, or upvote - this is a nasty problem - but an answer should   offer a fix or a workaround so users can use their computer again.    Without , Ubuntu can't fix issues. let $x,y,z,w&gt;0$,show that $$(x+y)^3+(y+z)^3+(z+w)^3+(w+x)^3\ge 8(x^2y+y^2z+z^2w+w^2x)$$  it seem use AM-GM inequality to solve it,But I can't it,Thanks Prove the divergence of the sequence $\left\{ \sin(n) \right\}_{n=1}^{\infty}$. I am looking for nice ways of proving the divergence of the sequence $\left\{x_n\right\}_{n=1}^{\infty}$ defined by $$x_n=\sin{(n)}.$$ One (not so nice) way is to construct two subsequences: one where the indexes are picked such that they lie in the intervals  $$I_k=\left(\dfrac{\pi}{6}+2\pi(k-1),\dfrac{5\pi}{6}+2\pi(k-1)\right)$$ and one where they lie in $$J_k=\left(\dfrac{7\pi}{6}+2\pi(k-1),\dfrac{11\pi}{6}+2\pi(k-1)\right).$$ If ${x_n}$ converges, then all its subsequences must converge to the same limit, but here the first subsequence has all its values in the interval $\left[ \frac{1}{2}, 1\right]$ while the second has its values in $\left[-1,-\frac{1}{2}\right]$. Contradiction.  Filling the details of this proof is rather tedious and not very elegant. Anyone has a better idea? How can I prove that $n^7 - n$ is divisible by $42$ for any integer $n$? I can see that this works for any integer $n$, but I can't figure out why this works, or why the number $42$ has this property. I have a solid understanding of most OOP theory but the one thing that confuses me a lot is virtual destructors. I thought that the destructor always gets called no matter what and for every object in the chain. When are you meant to make them virtual and why? How do I check if an integer is even or odd? Suppose $f:(a,b) \to \mathbb{R} $ satisfy $|f(x) - f(y) | \le M |x-y|^\alpha$ for some  $\alpha &gt;1$ and all $x,y \in (a,b) $. Prove that $f$ is constant on $(a,b)$.   I'm not sure which theorem should I look to prove this question. Can you guys give me a bit of hint? First of all how to prove some function $f(x)$ is constant on $(a,b)$? Just show $f'(x) = 0$?