I'm a halloween tinkerer, and I have these  that I use in my decor, but they eat batteries like crazy. They start going dim within an hour or so.   So, since I already have been putting together my own wiring and LED spotlights using bulk LED's etc, I thought I'd experiment with converting them from battery to DC power supply.   The flashlights run on 3 AA batteries in series ( [- +}[- +}[- +} ) and I've been working with a 12v power supply. When I connected it with a resistor in-line (I believe it is a 200 ohm resistor that came with my bulk LED's) it lights up, but it's too dim compared to running on the batteries. I suspect that means I need a smaller resistor but I'm not sure?
I'm trying to work out what value resistor to use in a LED circuit. The equation I'd use to do this is:  $$ R = \frac{V_{cc} - V_f}{I_f} $$  Seems logical, and makes complete sense. The answers to the question  confirm this too.  I have the following LEDs:   \$ V_f = 3.3V \$ \$ I_{f_{typ}} = 20mA \$   Using a 5V power supply:   \$ V_{cc} = 5V \$   Plugging these into the above equation gives:  $$ \begin{eqnarray} R &amp; = &amp; \frac{V_{cc} - V_f}{I_f} \\   &amp; = &amp; \frac{5V - 3.3V}{20mA} \\   &amp; = &amp; 85\Omega \end{eqnarray} $$  All good so far.  However, if I use the calculator at , that gives me 100&Omega;. If I use the ElectroDroid app on my phone, that gives me 85&Omega;.  So, I assume that the linear1 calculator is using a different method of calculating this resistor value; is there some better way of doing this?
Going to any question on the site brings an error page I am trying to import an FBX file from Unity into Blender. Does anybody know how to do that? I have been creating a table from mysql result , but its printing the html markup only and says controller must return a response . what may be the reason ?      LogicException: The controller must return a response ((5   rows)group_nameparent_nameEditDeleteSelect   itemsL2V9http://192.168.1.236/mailusers/usergroup/edit/6>edithttp://192.168.1.236/mailusers/usergroup/delete/6>delete           L3v3http://192.168.1.236/mailusers/usergroup/edit/7>edithttp://192.168.1.236/mailusers/usergroup/delete/7>deleteAdminsV6http://192.168.1.236/mailusers/usergroup/edit/8>edithttp://192.168.1.236/mailusers/usergroup/delete/8>deleteL4Vodafonehttp://192.168.1.236/mailusers/usergroup/edit/9>edithttp://192.168.1.236/mailusers/usergroup/delete/9>deleteVCNONetworkhttp://192.168.1.236/mailusers/usergroup/edit/12>edithttp://192.168.1.236/mailusers/usergroup/delete/12>delete given). in     Symfony\Component\HttpKernel\HttpKernel->handleRaw() (line 157 of     vendor/symfony/http-kernel/HttpKernel.php). Coloring arrows in \xymatrix Is it possible that galaxies' redshift is caused by something else than the expansion of space? I was thinking that maybe photons loss energy naturally when they travel great distances.  Or maybe the mass of all matter is increasing over time and therefore photons emitted in the past are necessarily less energetic.  Or is the expansion of space backed up by so much other evidences that trying to find another explanation is completely foolish? I just tried to access a folder like so:  \\somecomputeronmynetwork\somelocation$   When going to this location I'm prompted for a user name and password.  I put one in, and it let me in fine.  Now I need to remove that login, so I can try a different user name and password.  What's the easiest way to do this? Man clones himself to have the clone do things he doesn't enjoy I read a short story about four years ago and can't remember the title or author. The only thing I know is that it is relatively old -- like Huxley or Asimov era. Can anyone help me?   The basic synopsis is this: a man clones himself and has his clone do the parts of his life that he doesn't enjoy. He deceives his wife about this; she doesn't know he has a clone. Whenever the man and the clone are both home, the clone is locked in the "toolbox" in the basement. The clone starts to treat the man's wife better than he had previously. His wife starts to fall in love the clone, and the man decides he needs to get rid of the clone. When he tries to do so, the clone overpowers the man and locks him in the toolbox in the basement!  I'm hoping to share this story with my English class this school year. Any help is appreciated! Polygon Touch detection Google Map API V2 What’s the correct URL for placing a call on an iPhone? I'm at Reachwater Rock and I've encountered a series of doors, the first I had to open using the Emerald Claw I found near a body, but now the door's telling me to use an Ivory Claw. Where can I find it, because I don't have it in my inventory yet. So I'm making this summary of a course where I've only been getting information from one book. Sometimes I want to show what page from the book a statement is taken from but I can't figure out a clean way of doing it.  Basically I would like to have something (in function) similar to:  "Statement[Book p123]"  Do you have any suggestions? How do I complete the square from the point I have left off at, and is this correct so far?   I have a normal prior for $\beta$ of the form $p(\beta|\sigma^2)\sim \mathcal{N}(0,\sigma^2V)$, to get:  $p(\beta|\sigma^2)=(2\pi\sigma^2V)^\frac{p}{2}\exp[-\frac{1}{2\sigma^2}\beta^T\beta]$  where $\beta^T\beta$ is   $\sum\limits_{i=1}^p \beta_i^2$.  My likelihood has a normal distribtuion for the data points y of the form $p(y|\beta,\sigma^2)\sim\mathcal{N}(B\beta,\sigma^2I)  $  $p(y|\beta,\sigma^2)=(2\pi \sigma^2V)^\frac{n}{2}\exp[-\frac{1}{2\sigma^2}({\bf y}-{\bf B}{\bf \beta})^T({\bf y}-{\bf B}{\bf \beta})]$  (Note that $\beta$ is a matrix/vector too, \bf does not work.)  To get my posterior for $\beta$ I combined the above, took the exponential parts only, and then expanded to get:  $\exp[-\frac{1}{2\sigma^2}({\bf y}^T{\bf y}-{\bf y}^T{\bf B}\beta-\beta{\bf B}^T{\bf y}-\beta^T{\bf B}^T{\bf B}\beta)]\exp[-\frac{1}{2\sigma^2}({\bf \beta}^T{\bf B})]$.  I dropped the $({\bf y}^T{\bf y})$ term, as is not a function of $\beta$.  Putting into one expression without the exponential:  $-\frac{1}{2\sigma^2}(-{\bf y}^T{\bf B}\beta-\beta{\bf B}^T{\bf y}-\beta^T{\bf B}^T{\bf B}\beta+{\bf \beta}^T{\bf B})$.  I know I need to combine the similar terms and get into the form of the multivariate normal distribution, which is what I am aiming for, but I am unsure how to do this? I probably have to add an extra term to the expression to get it into the correct form?  Note: This is not homework, it's a project, but my Bayesian working knowledge is not good at all and so I need to understand the working out. I intend to integrate out the $\beta$ and then the $\sigma^2$ after getting into the multivariate form. To what extent is WhatsApp's statement on secure messaging realistic? How can I change permissions on external drives? I wanted to change permissions on my external drives that are automounted however I have tried by sudo nautilus and then going to gui and permissions and changing it however it does not let me.  I ran the ls -l and get  drwx------ 1 xbmc xbmc   the gui shows below.  owner xbmc folder access create and delete files file access ---  Group xbmc folder access none file access ---  others folder access none file access ---   how can I change it so that everyone has permission to access the drive and ALL folders/files inside of it. I am trying to get plexmedia server running and I cant see my drives via the webpage manage to add it to my source to be able to stream my content.  I want to change the "others" access so that I can access all my drives on the /media path to get read and write for all my folders from anywhere.  you can see my drives that are mounted here (external drives are #18,19,20) Series involving log $\sum_{n=1}^{\infty} \left( n\log \left(\frac{2n+1}{2n-1}\right)-1\right) = \frac{1-\log 2}{2}$ I want to select questions that are only tagged as SQL, SQLServer, SQLSever 2008. I am not interested in questions that have anything more than these tags. How do i select such questions only ? How does Delta baryon decay conserve angular momentum? I'm a chemist so bear with me:  I understand the  $\Delta^{+}$ and $\Delta^{0}$ to be in some sense spin (and isospin) quartet states of the proton and neutron. These can decay straight to a proton or neutron through emission of a pion, which is spin-0.  I've been puzzling about the mechanism by which this decay conserves spin. I note via Wikipedia that  into either a lepton pair or a photon pair, for which it's easy to show spin is conserved, however pion production seems to induce a loss of $J=1$.  This seems to suggest momenta of:  $\Delta^{+} (J=\frac{3}{2}) \rightarrow{} p^{+} (J=\frac{1}{2}) + \pi^{0} (J=0)$  Am I missing a boson? Is my understanding of spin flawed? I assume that if this decay exists, similar things turn up everywhere else. centos: using epel repository on a server machine Are there any downsides in enabling epel repository on a server machine or is it something every sysadmin does? How to remove \xa0 from string in Python? Why am I getting strange results when using a power meter to measure CFLs?