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Showing posts from April, 2013

Electrical - Com/NO Relay & LED Resistor Calculation

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Recently, I am playing with alarm I/O and requires something that is common but unfamiliar to me - Electrical circuit wiring.

Equipment Required
1. Breadboard - A breadboard (protoboard) is a construction base for prototyping of electronics. See http://tymkrs.tumblr.com/post/6386624174/how-to-use-a-breadboard on how to use a breadboard

2. 3V LED light - Need to display alarm output (see setup picture below) 3. Some electrical wires 4. Open Switch.(see setup picture below) 5. Resistor - We are using 5V input for a 3V LED light. We need a resistor to control the current flow to prevent providing too much current for the LED light (May result in blowing the LED light). 
Setup

The following picture provided a setup for 2 circuits - Alarm input circuit and alarm output circuit.

Alarm Input Circuit
Alarm input are usually used to provide a trigger signal to the attached system. In the above setup, I am connecting a 5V circuit for the alarm input and I used a open switch as a trigger device. I…

Video - Measuring Video Bitrate Over Network

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There are 2 ways to measure bitrate for a video streams. You can do it via VLC and Wireshark. VLC VLC provide statistical information for user to understand the input bitrate for video. However, the statistic provided by VLC is current statistic, and thus, it is not the overall average bitrate for the video stream.
To use VLC for seeing current bitrate for a video stream, do the followings
1. Open a network video stream via VLC
2. When the video stream had set up and started playing, go to Tools -> Codec Information

3. Click on the Statistics Tab
4. Look at Input/Read -> Content Bitrate. That will be the current bitrate for your current video stream. At the screenshot, it shows 3kbps. This means that during the time of capture, the bitrate for the video stream is at 3kbps. Thus, this value varies over time.

Wireshark Wireshark provide statistical analysis on your captured network information and it is a very good tool to understand the average bitrate, maximum bitrate and minim…

Remote Desktop - No Terminal Server License Servers Errors

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If you had administrative right with your PC and has the following error with Remote Desktop Connection, this post may help.



You can use mstsc command to workaround this error. MSTSC (MS Terminal Server Connection) creates connections to Remote Desktop Session Host (RD Session Host) servers or other remote computers, edits an existing Remote Desktop Connection (.rdp) configuration file, and migrates legacy connection files that were created with Client Connection Manager to new .rdp connection files.

You can use mstsc.exe /admin to create and connect a administrating session with the sever.

Steps as follows

1. Assuming you are using WinXP. At Start menu -> Run, type mstsc.exe


2. It will launch a Remote Connection Application with administrative setup


3. Enter your remote IP and connect.


References: http://technet.microsoft.com/en-us/library/cc753907(v=ws.10).aspx