I am wondering what problems might occur if i reduced the voltage from the usual 5v down to 4.2v.
In AVR datasheets under the Electrical Characteristics section you will typically find a graph like this (this one is from the ATMega328):    I've seen designs that seem to "work" but operate outside the shaded envelope. Specifically, I've seen 3.3V (Arduino) designs that run the clock from an external 16MHz crystal. Clearly, this is out of spec. What are the practical negative consequences of running outside this envelope?
Every Group is a Fundamental Group Why is it true that "I before E, except after C"? If every ideal is principal show the same is true for the image of a homomorphism. I have this question :  Proof if $f$ continuous in $x_0$ then there is a neighbourhood of $x_0$ so $f$ bounded.  I want to know if my proof is valid :  If continuous in $x_0$ then :  $$\lim_{x \to x_0} f(x)= f(x_0)$$  Therefore :  All $\epsilon&gt;0$ exists $\delta&gt;0$ so any $x$ that implies $|x-x_0|&lt;\delta$ implies $|f(x)-f(x_0)|&lt;\epsilon$.  Therefore for $\epsilon=1$ there is $\delta&gt;0$ so any $x$ that implies $|x-x_0|&lt;\delta$ implies $|f(x)-f(x_0)|&lt;1$.  $|x-x_0|&lt;\delta \rightarrow x_0-\delta&lt;x&lt;x_0+\delta$.  Lets choose $x_1,x_2$ that implies $x_0-\delta&lt;x_1&lt;x_2&lt;x_0+\delta$  Therefore in $[x_1,x_2]$ from Weierstrass from theorem bounded there. std::auto_ptr to std::unique_ptr Need help with a work around I need to take the 'Office' display of the 'Created By' column and display the first 5 digits of it so that my flows can run a conditional check on it. The reason is that Microsoft flows has all the 'Created By' dynamic contents besides 'Office'.  I figured simple enough I'll just do a calculated column on the SharePoint list. Then I find out that 'Created By' cannot be used in calculated columns.   So I figured I'll have my PowerApp write the Users 'Office' as a default to a field when submitting a form and calculate it off that column. Unfortunately PowerApps only has User().FullName, Email, and Image.   I have pretty much exhausted the options for a workaround that my knowledge will allow. Hopefully someone might have some ideas. Adding/updating field to polygon feature class that lists bordering (neighbor) polygons? I have a dataset of zipcodes.  I want to add a new field "NEIGHBORS" that includes bordering polygons in a comma delimited manner such as attached image: How to check whether a JavaScript variable defined in cross-browser way?  I ran into this problem when writing some JavaScript utilizing FireBug logging. I wrote some code like below:  function profileRun(f) {     // f: functions to be profiled     console.profile(f.constructor);     f();     console.profileEnd(f.constructor); }   It works fine in FireFox/FireBug, but it reports error in IE8 RC1. So, I'd like to do some checking whether console variable exists in the execution environment.  Below code works fine in FireFox, but not in IE8 RC1.   function profileRun(f) {     if (console != undefined) {         console.profile(f.constructor);     }      f();      if (console != undefined) {         console.profileEnd(f.constructor);     } }   However, if I do it this way. It works in IE8 RC1. Why?   function profileRun(f) {     if (window.console != undefined) {         console.profile(f.constructor);     }      f();      if (window.console != undefined) {         console.profileEnd(f.constructor);     } }   Is there any cross-browser way to check it? How to make a meta box field a requirement What is a "loop device" when mounting? Private IP address in public DNS We have an SMTP only mail server behind a firewall which will have a public A record of mail..  The only way to access this mail server is from another server behind the same firewall.  We do not run our own private DNS server.  Is it a good idea to use the private IP address as an A record in a public DNS server - or is it best to keep these server records in each servers local hosts file? How to validate an email address in JavaScript asp.net mvc put controllers into a separate project I'm just learning asp.net mvc and I'm trying to figure out how to move my controllers into a separate project.  Typically when I have designed asp.net web apps before, I created one project for my models, another for my logic, and then there was the web.    Now that I'm learning asp.net mvc I was hoping to follow a similar pattern and put the models and controllers each into their own separate projects, and just leave the views/scripts/css in the web.  The models part was easy, but what I don't understand is how to make my controllers in a separate project be "found".  Also, I would like to know if this is advisable.  Thanks! How do I install KDE? I want to have both KDE and Gnome shells on Ubuntu. Ubuntu only has Gnome installed by default. How do I install KDE? How do I copy a property from an active object to selected objects? I have been using the Copy Attributes add-on to copy some properties from active object to selected objects. This add-on is not enabled by default and must be explicitly enabled. But its a very useful workflow enhancing tool.    There is a limitation though. Not all properties can be copied and even those that can be copied are copied in groups (Its hard-coded in to the add-on).  My question is if there is a built-in feature or any another other way to copy any property from the active object to the selected objects? There are two vectors called $\vec{a}$ and $\vec{b}$. Vector $\vec{c}$ is the bisector and it can be given as  $$\vec{c} = |b|\vec{a} + |a|\vec{b}$$  How to prove that? I have used the dot product method. But there I can't find the angle between them. Then I tried to do this by using unit vectors. Then I got an answer like in the given picture. . Can you help me to get the correct answer memoryless property of exponential distributions with random variables It is true that $P(X&gt;t+s|X&gt;t)=P(X&gt;s)$ for certain values $t$ and $s$.  However, how can I show that this still holds if:   $T$ is a continuous random variable. That is $P(X&gt;T+s|X&gt;T)=P(X&gt;s)$ Both $T$ and $S$ are continuous RVs: $P(X&gt;T+S|X&gt;T)=P(X&gt;S)$   All the random variables are independent. Replace dynamic content in XML file I have been reading through the  and was curious about the  declaration. I personally have never used it, however I am interested in exploring the language.   What is a good example of using friend?    Reading the FAQ a bit longer I like the idea of the &lt;&lt; &gt;&gt; operator overloading and adding as a friend of those classes. However I am not sure how this doesn't break encapsulation. When can these exceptions stay within the strictness that is OOP? Can't do comparison on PageReference In my page constructor I call a method isFirstPageLoaded, to  check if the loaded page is the first page of the wizard.   private final PageReference FIRSTPAGE = Page.Maintenance_Lock_1;   private void isFirstPageLoaded() {          if(ApexPages.currentPage()!=this.FIRSTPAGE) {              throw new MaintenanceLockException(this.FIRSTPAGE + ' --- ' + ApexPages.currentPage());          }      }   The problem is: Even if I open the first page of the wizard, the exception is thrown. How can I compare two PageReferences? I would like to avoid to parse the URLs and remove parameters etc...