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Delete the old OS boot option from the OS boot screen

For windows 7 and higher versions: 1.open the command promt with administrator privilege. (Goto C:\windows\system32 and right click on cmd.exe, run as administrator)    2.Type bcdedit command   (you will get a list of the OS boot files) 3.copy the IDENTIFIER of the OS you want to delete from the boot menu 4.Type bcdedit /delete IDENTIFIER  For windows XP and lower versions: http://www.howtogeek.com/howto/windows/how-to-delete-modify-or-disable-an-incorrect-or-duplicate-entry-on-the-xp-boot-menu/

Guide to install wifi drivers for ubuntu 12.04

1. Download this file (b43) it includes the broadcom series drivers. 2. Extract the zip file b43 3. Copy the extracted file b43 to filesystem /lib/firmware unfortunately you wont be able to paste it and it will give an error permission denied. This is because you dont have the root privileges To grant root privileges through nautilus: 1.open the terminal and type sudo nautilus enter your password (it will open a folder through which you can modify the root contents) note:after this do not terminate the terminal running nautilus 2. Make a new folder in file system rename it to .config In .config make one more folder named nautilus path should look like filesystem/.config/nautilus 3.Copy the downloaded file b43 to the path filesystem/ lib/firmware it should be copied 4. open a new terminal window type sudo modprobe -V b43   (hit enter) enter your password (hit enter) (it will display module_init..............) this means you have successfully installed th...

How to calculate the battery standby time according to the load?

Things we should know:   P = V . I                     (ie. power in watts = volts x amps) Every battery has a amps/hr (Ah) rating which signifies for how many hours it can deliver that much amount of current? for eg. 2000mAh battery can deliver 2000mili Amps per hour  Eg.1 Inverter battery standby calculation 1.Calculating the total battery capacity in Watts/hr:  if our inverter battery has a rating of 150Ah and voltage 12V thus it can deliver 150Amps per hour. thus power delivered per hour will be 1800Watts/hr  (1800 = 12 x 150) .............................(  P = V . I  ) 2.battery threshold level : (actual battery capacity) now before proceeding take into consideration that the battery wont be fully discharged due to the internal protection circuit in the inverter so we have to first take 85% of our total battery ca...

Deleting a virus via DOS

1. l ocate the directory or drive: 2.  Find a file extension in a directory: 3. Delete files with a particular extension: 1. l ocate the directory or drive:   cd <path of the folder/drive> or   <drive letter>: for eg my virus is located in D drive, type: cd windows/system32 for eg my virus is located in D drive, type: D: 2.  Find a file extension in a directory:         dir *.<ext>  (restricted to a particular directory)          or         dir *.<ext> /s /p    (all files in folders and subfolders of a particular extension(drive): The  /s  option directs a search of all folders on the hard drive;  the  /p  option pauses the display   after each s creen  of text. Double-check everything <ext> extension for eg. you have to find all files(viruses) having extension .inf,  type: ...

Why do we use log?

"Logarithm" is a word made up by Scottish mathematician John Napier (1550-1617), from the Greek word logos meaning "proportion, ratio or word" and arithmos meaning "number", ... which together makes "ratio-number" ! In its simplest form logarithm gives the info about:            how many a number can give another number basically its used to get the power ie. the exponent of the base number in the log with respect to the log number for eg:  1.  log 2 ( 8 )= 3     ie   2 3   = 8 how many a number (to the base number) (2) another number ( log  number) (8) raise to power (3) 2.    log 2 ( 4 )= 2     ie   2 2   =   4  same goes for the negative logarithms: 1.                    since            reference:  www.mathsisfun.com/algebra/logarithms.html

AC mains current and transformer current

These are two separate issues: 1) How much current the transformer can supply? 2) How much current can your mains AC supply deliver? The answer to (2) is easy. Go to your fuse box and look at the rating on the fuse or circuit breaker. If the rating is 40A, then the maximum power delivered before blowing the fuse is 220V x 40A = 8800W. Generally it is between (20A-50A) and the answer to (1) is, The maximum current delivered by the transformer will depend on the size and construction of the transformer: 1. As an example, let us say the transformer steps down from 220VAC to 20VAC.     This is approximately 10:1 reduction. 2. Then if the transformer is rated at 1A on...