I brought a relay module which works when 5V are given to its input pin to switch on high voltage.  But my raspberry pi GPIO pins give out only 2.9V (measured from multimeter, it was supposed to give 3.3V).  I have only below mentioned things available in my locality :- BC-557 (PNP), BC-548b (NPN), LM-317t (Voltage Regulator), some resistors.  How do I operate relay using above mentioned electronics components? Please keep the circuit simple BUT safe for my raspberry pi.
I have a atmega8 that is working with 3.6V dc, I need to control some 12V relays with a not chip (7404), what is the simplest way to do this? I have connected a 12V dc to the relays, so when I connect the relays to the chip and then the atmega8, the current returns to the atmega through the not chip. Is this solution correct? There a better way to do this?
Why does the Prime Directive not apply to Rubicun III? In a first season episode of Star Trek: The Next Generation the Enterprise visits a planet named Rubicun III where () the Edo live.  It is often mentioned in Star Trek that the Prime Directive requires that pre-Warp civilisations be ignored until they discover Warp mechanics. But this planet and civilisation appears to be exempt from that status. Why? So I am in an introductory linear algebra(with proofs) class, and I came across the following theorem:  If $S$ is a subspace of a vector space $V(F)$ and is generated by $\{a_1,...,a_n\}$ then any subset $\{b_1,...,b_m\}$ of $S$ with $m&gt;n$ is linearly dependent.   The proof in the textbook is done through induction (as most proofs regarding finite sets are) but I really do not follow it and I feel there is a simpler way of doing it. A hint would be appreciated. No 'Open with' option to open/run jar file with openjdk How to get glare on "Quick Smoke" (Fire & Smoke explosion) I would that the images would appeared for each overlay. Eg, in overlay 1 I have img1.pdf, in overlay 2 I have img2.pdf, and in overlay 3 I have img3.pdf. How I do this?  \begin{center}   \begin{tikzpicture}     \node (img1) {\includegraphics[width=.5\linewidth]{img1.pdf}};     \pause     \node (img2) {\includegraphics[width=.5\linewidth]{img2.pdf}};     \pause     \node (img3) {\includegraphics[width=.5\linewidth]{img3.pdf}};   \end{tikzpicture} \end{center} Intersecting overlapping polylines using ArcGIS for Desktop? I have 4 multipart polyline shapefiles (download a sample dataset ).   The geometries are identical, except for the length of segments in each shapefile. They represent 4 variables describing an identical shoreline. From these 4 overlapping polylines, I would like to create a resulting polyline that has segments for each unique set of the 4 input lines.    My approach was to use an intersect. This, however, breaks down when I try to run it on 4 huge feature classes.  My question is whether there is a more efficient way to combine polyline attributes stored in separate layers. I thought a union would be good, but it only works on polygons. Spatial Join seems inefficient, as I would end up with many to many joins for a single segment. Turning the segment end points into a point layer, then splitting the line at those points?  I have access to arcpy, PostGIS, and shapely.  Has anyone had experience doing this before on large datasets? Is there a more efficient way to store these variables? Divisor in $\mathbb{C}[X]$ $\implies$ divisor in $\mathbb{R}[X]$? let $P \in \mathbb{R}[X]$ be a real polynomial divisible by a polynomial $Q \in \mathbb{R}[X]$ in $\mathbb{C}[X]$. How can I easily show that $P$ is also divisible by $Q$ in $\mathbb{R}[X]$?  A simple argument without using higher algebraic theorems is desirable. If I could use instruments of higher algebra, the exercise I have to do in whole would be done in two lines. But I'm not allowed to use. I think there would be an easy argument which I can't see yet because of my mental fogginess that I have sometimes.  Thank you beforehand. "Access denied" when trying to end a process on Windows 8 What Happens to electrons after Alpha Decay and Nuclear Fission? Where do the electrons go? In alpha decay do 2 electrons follow the alpha particle and make stable Helium or does the larger daughter nucleus become an anion?  Also what do the electrons do in the mixture of fission and alpha decay? With Beryllium-8 it decays into two alpha particles and 4 lonely electrons or do you get two Helium atoms?If someone could add an entry to Holocron it would be greatly appreciated, thanks. Maximum area of isosceles triangle with perimeter 6 cm Maintain the aspect ratio of a div with CSS Flattening iterator Retrieving Wikipedia's coordinate information? I'd like to add icons to my map showing locations which have Wikipedia entries.  The  is a great resource for determining Wiki entries near an XY location, but it has limitations (20km radius, 50 points only) which make it unsuitable for my purposes.  Ideally I need the map to show ALL locations with Wiki entries, so I guess I'll need to download the Wikipedia dump file and parse it for geocoded entries.  Where is this information found in the Wikipedia dump files?  The Wiki database may be downloaded from  but I can't see which file(s) I need to search for the coordinates.  For example, the  includes:  Coordinates:    33°51′35.9″S 151°12′40″E   Where is this found in the dump files? Another way to phrase the question is "how can I determine which Wiki entries are geo-coded?" My laptop's cable broke and sadly it seems like I need to buy a new power supply.  What I wonder is, I've found that universal power supplies are much cheaper than the official HP ones. Are they really worth it?  Another question: the original supply has these specs: 65W, 18.5V, 3.5A. However the universal supplies are more powerful (90W, 100W) and come in integer voltages (17V, 18V, 19V, etc). Are they compatible? Should I set them to 18V or 19V? I have very old Computer  What's the Best Operating System for Old Computer? How to correctly specify coordinate system? Using QGIS v. 1.9 (1.7 does not seem to be available for Ubuntu Linux 12.04), do the following:   Create new project, specify coordinate system by clicking on button in bottom right hand corner, enable on the fly CRS transformation, set projection to WGS 84 / UTM Zone 18S. Pass mouse over project window and UTM coordinates appear in coordinates window in status bar at the bottom. Add delimited text layer in decimal degrees. When asked for projection, specify same projection as in (1). Points in the layer are plotted but, mousing over the map, the coordinates in the coordinates window are now in decimal degrees (even though the projection is set to UTM).   Is there something I am missing here? I have tried doing this in so many ways, so many times, but the result is always the same. I seem to be setting the projection correctly but only decimal degrees show in the coordinates window.  With thanks, Martin I'm looking for a short story from about 50 years ago about a robot who escapes after being slated to be melted down and discovers while in hiding that it has evolved to have some supernatural powers. Find all solutions to the functional equation $f(x) +f(x+y)=y+2 $ Photoshop To CSS: How do you translate Fill to CSS How can I define a mathematical function as a LaTeX macro?