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Sunday, February 21, 2010

Battery Internal Resistance

Vdrop = Vbatt*(Rbatt/(RL+Rbatt))
Rbatt = Vdrop*(RL/(Vdrop+Vbatt))

Vdrop is the difference in your two readings above
Vbatt is the open circuit voltage measured above
RL is the resistor you load the battery with
Rbatt is the battery internal resistance you're looking for


Monday, February 8, 2010

Microsoft remote desktop connection tips

Ctrl + Alt + End
Send Ctrl + Alt + Delete to remote session; Brings up the Windows Security dialog box.

Ctrl + Alt + Break
Switches the client between a window and full screen.

--- LESS USEFUL

Alt + Page Up
Switches between programs from left to right.

Alt + Page Down
Switches between programs from right to left.

Alt + Insert
Cycles through the programs in the order they were started.

Alt + Home
Displays the Start menu.

Ctrl + Alt + Pause
Toggles between full screen and windowed mode
(note that this does not set the client desktop to the correct size)

Alt + Del
Displays the Windows menu

Ctrl + Alt + Num -
Places a snapshot of the client’s active window on the clipboard

Ctrl + Alt + Num +
Places a snapshot of the client’s entire desktop area on the clipboard

Ctrl+Alt+Shift+Home
To invoke task manager for nested terminal services sessions (two levels deep)

http://www.online-tech-tips.com/windows-xp/ctrl-alt-del-remote-desktop/

Friday, February 5, 2010

Bash script- Kill a process if it runs too long

#!/bin/bash

# Can hang (google actually doesn't respond to ab useragent)
ab -c20 -n100 http://www.google.com

# get pid from previous command
pid=$!

# Wait for 10 seconds then send an interrupt
# apachebench will produce output if ctrl-c (or kill -2)
sleep 10 && kill -2 $pid > /dev/null 2>&1&

wait $pid

Thursday, February 4, 2010