I am trying to build a variable power supply to replace my batteries.  The power supply should have a constant DC voltage just like batteries maximum current will be 10mili Amps Max voltage should be 100V Should be able to change voltage between 0-100v  Input is 240v AC Please suggest some ways of doing that
I want to make a power DC supply with voltage rating 0-200V. I want it to be a variable power supply with voltage from 1V to 200v. What should be my approach?
In general relativity (GR), spacetime is viewed as a differentiable manifold of dimension $D$ with a metric of Lorentzian signature $(-,+,+,...,+)$.  My question is why differentiable? Does cinnamon 2.0 really break your 13.10 desktop? Logical volume is not mounted but is in use. Please close all applications using this device (eg iscsi) Evaluating $\int_0^\infty \sin x^2\, dx$ with real methods? I have seen the Fresnel integral  $$\int_0^\infty \sin x^2\, dx = \sqrt{\frac{\pi}{8}}$$  evaluated by contour integration and other complex analysis methods, and I have found these methods to be the standard way to evaluate this integral.  I was wondering, however, does anyone know a real analysis method to evaluate this integral? Copy specific file type keeping the folder structure Recover files from hard drive that has been formatted thrice I have a situation.  I got married 6 months ago and stored some very important pictures on my laptop which was running Linux. Later I formatted the whole hard drive, installed Windows and a hacked version of Mac (just to play around) and I have been using the laptop for last 8 months or so after that.  Is there any software that can recover the files for me? I am happy to pay money! Any Video formats that render with Alpha Channel? Does anyone know if there are any video formats (besides the HUGE uncompressed avis) that you can render in that maintain the alpha channel? (i.e. for after FX etc.)   I used to use quicktime, but that's no longer an option.  I know you can render in png. or other image formats, but video is significantly smaller, and I often work on machines with less space &amp; resources. C++ templates that accept only certain types Lightning: why can you not have an expression combined with text in an HTML attribute? So, I've been struggling with this for a while, trying to figure out how to get it to work. Here is what I originally did:  &lt;button class="btn btn-primary {!v.isLink1 ? 'active' : ''}"&gt;   And so on. Here's the documentation on it.   However, when you actually try to save this in the developer console, you get the error:  Field Integrity Exception: Failed to save undefined: Cannot mix expression and literal string in attribute value, try rewriting like {!'foo' + v.bar}: Source   I finally figured out that you have to put all of the classes inside of the expression, like so:  &lt;button class="{!v.isLink1 ? 'btn btn-primary active' : 'btn btn-primary'}"&gt;   This doesn't seem very intuitive. It's also not documented anywhere I could find. Could someone explain to me why it is this way and if it will ever change?   (and hopefully this question saves someone some headaches in the future) How to use exclamation marks in Minecraft commands? I know that you can use exclamation marks in Minecraft commands to check for an entity that does not have a specific tag. For example, you can use /kill @e[type=!Player] to kill all entities except for the player. I have, however, encountered two problems with using exclamation marks that I can't find a solution for.  For my first problem, I've set up a series of command blocks to summon shootable fireballs above the player’s head when a certain item is being held;  /scoreboard players add @a Fireball 1 {SelectedItem:{tag:{display:{Name:"Summon Fireball"}}}} /execute @a[score_Fireball_min=1,score_Fireball=1] ~ ~ ~ /summon Fireball ~ ~2.5 ~ {direction:[0.0,0.0,0.0]} /scoreboard players set @a Fireball 0   I used a comparator and a redstone torch so that the last command would activate when the first command would deactivate, that is, when the player is not holding the item.  The problem is, that when I move far away from the setup, the redstone stops working, leaving me unable to summon any new fireballs. Instead, I'm trying to use a command block to check when anything except for item is being held;  /scoreboard players set @a Fireball 0 {SelectedItem:{tag:{display:{Name:!"Summon Fireball"}}}}   I’ve either put it at the wrong place, or you simply can’t use exclamation marks in NBT tags. Could someone tell me where I should put the exclamation mark, or in the latter case, how I can check for anything except for a specific item?  Further, I’ve tried using exclamation marks to set the score of all entities, including the ones with a blank score, but except for the ones with a score of 2 or higher, to 0;  /scoreboard players set @e[score_arrows_min!=2] Arrows 0 /scoreboard players set @a Arrows 1 {SelectedItem:{tag:{display:{Name:"Rain of Arrows"}}}} /scoreboard players set @e[type=Arrow] Arrows 2 {inGround:1b}   The code does change the scores of entities without scores to 0, but it doesn’t exclude the arrows with a score of 2. Could anyone tell me what I’m doing wrong here? I know how to detect when resistors are arranged in parallel or series arrangement and I can also find their equivalent resistance in simple circuits or when resistances are connected in form of triangle but what happens when the arrangement is complex like this :   Which resistors are parallel and which are in series ? How can I find the equivalent resistance in such cases ? Is there rule or method for figuring this out ? How can I disable the Windows key from opening the Activities overview? How can I disable the Windows key (or Super) from showing the GNOME Shell Activities overlay? Limit of $\lim_{n\rightarrow \infty} \sum^{n}_{i=1} \frac{1}{\sqrt {n^2 +i} }$ How can I display keyboard shortcuts as I press them? NOTE: this question is sorta like a follow-on question to  I asked. In that question, the main suggestion was that I was trying to show two polys. Now, I'm asking about a SINGLE poly.  I have the following GEOGRPAHY of Los Angeles in my Sql Server 2008 :-     (or in )  It's bascially ..  -- Shape of Los Angeles.  DECLARE @WKT VARCHAR(MAX) = 'POLYGON ((-118.66815700000011 34.181235000000029, ... )) SELECT GEOGRAPHY::STGeomFromText(@WKT, 4326)   Now when I just try and render this out, It now looks like this (NOTE: this is different, but still not correct .. compared to my previous GIS Question).    Now, in the previous question people were suggesting that the previous data was a MULTIPOLYGON so there was some bad stuff I must have been doing, trying to render out holes in polys.  This time, this is a single polygon. So i'm assuming the hole theory still doesn't work. Now, I understand that by looking at this image, there's a number of holes ... but the Well Known Text data which Sql Server gives me is a POLYGON which to me means .. one single shape. So i'm not sure how I can fix this :(  This is why i'm asking the a similar question to my previous one.  Can anyone help? Can they see the data I've posted and see what happens in other systems? (I don't have any other software besides Sql Server 2008).  Maybe I need to extract all my data from Sql Server 2008 .. and clean it up (whatever that means) through another system. For example. If Sql Server is saying that the shape of Los Angeles is a single Polygon .. but when cleaned up .. it's actually 7 Polygons .. and then those shapes then get rendered correctly .. then we have a solution!   Any suggestions?  Can -anyone- render this shape onto a Google map? How are ETF prices calculated after the market is closed For example:  Because the NASDAQ: DAX is tracking the index INDEXDB: DAX should its trading value be completely flat when the market the markets are open in the US, but closed in Germany? I'm not seeing that artifact in any of the charts I can find. Html form in email My MWE:  \documentclass{report}  \usepackage{amsmath}  \begin{document}  \begin{align} y &amp;= a \\ =&amp; -2c_1\bar{z}_1^2 + 2\bar{z}_1\bar{z}_2 + 2\bar{z}_2 \left ( -\bar{z}_1 -c_2z_2 - \frac{3\epsilon}{2}\bar{z}_2 -\sigma_{2,1}\cos(x_1)\Delta x_1 \notag \right. \\ \left. &amp;- \sigma_{2,2}\Delta x_2 -\sigma_{2,3} \Delta u +c_2 \chi_2 \vphantom{\frac{1}{1}} \right ) - 2\gamma \sigma_{2,1}^2\cos^2(x_1) \Delta x_1^2 - \gamma \sigma_{2,2}^2 \Delta x_2^2   - 2\gamma \sigma_{2,3}^2 \Delta u^2 \end{align}  \end{document}   The error I get:  Extra }, or forgotten \right.   The expected result: ls -la symbolics... what does that last symbol mean? Why is the picture not inserted? When I pdflatex the text below it doesn't insert the picture, but writes the name of the file instead (pic).  And the geometry line gives the error  ! LaTeX Error: Missing \begin{document}.   The picture I am using is at  and the floatrow package .  Question  Can anyone see what is wrong?  Text  \documentclass[a4paper]{article} \pdfpagewidth=\paperwidth \pdfpageheight=\paperheight \usepackage{aeguill} \pdfcompresslevel=9 \usepackage[pdftex,colorlinks]{hyperref}  \usepackage{a4} \usepackage{fixltx2e} \usepackage[danish]{babel} \usepackage[latin1]{inputenc} \usepackage[T1]{fontenc}  \usepackage[draft]{graphicx} \usepackage{floatrow}  \usepackage{geometry}  \geometry{margin=10pt,paperwidth=\textwidth+20pt,paperheight=\textheight+20pt}  \begin{document}  The first paragraph.  \begin{figure}   \includegraphics{pic} \end{figure}  And the second.  \end{document}