Quick reference: Audio and Video Commands in Linux (Ubuntu)

Extract audio from a movie and save as mp3
ffmpeg -i input.avi -vn -acodec libmp3lame -ar 22050 -ab 256k -ac 2 output.mp3

Extract to wav file:
ffmpeg -i input.avi -vn -acodec pcm_s16le -ac 2 output.wav

More info:
http://howto-pages.org/ffmpeg/

Electrolux fridge freezer fan motor replacement

We took a vacation for 10 days and decided to keep our fridge switched off. We were back, switched on the fridge and got a burning smell after a while. Found that the fan in the freezer was not working. Since it was a Saturday late evening and the service call would not happen until Monday, I decided to give it a try to fix myself. I opened up the freezer back plane and found that the fan motor was indeed not working. Took it out and the next day set out in search of a replacement motor. Went to SP road (The place in Bangalore for all electronics/computer spares) and found most shops closed being Sunday. Enquired at a few places and got to know that I need to look at Chikpet for electrical appliance replacement parts. Headed to Chikpet and enquired in a few electrical shops and got to know that one Prakash Electricals stocks the replacement motors. To my dismay, I found the shop closed and was about to leave. After a few strolls, found another Prakash stores and the small shop indeed had the motor. It didn't looked as good as the original one, but the dimensions matched. I was worried about the rotation direction of the motor, the shopkeeper assured me that all Freezer fan motors have standard direction.


Got back home and replaced the motor in no time and was happy that it worked. But something was wrong, the bottom section was not cooling enough. Since the original fan was not working, I did not know which direction the fan should run. After careful looking, it seemed the direction of the motor was reverse. The fan should blow air into the freezer from behind (the cooling coils), but the new fan motor was blowing warm air into the cooling fins. Since it is an AC motor, reversing the terminals won't change the rotor direction. Disappointed, I decided to call in for service and put the old motor back. But later, I thought why don't reverse the rotor, so that it turns opposite direction. The motor assembly was simple and allowed me to change the rotor orientation. Put the motor back and the fan now works correctly. Though the replacement motor is a bit weak and I am not sure how long it would work.
 
Here are some pictures:

Freezer's back plane removed. The fan motor is mounted on the back plane and has channels for air circulation. The square cavity on the top is where the fan draws air from.

Old motor. Had markings MSP63S 10mm Motor.

 New motor in place. The rotor doesn't rotate as smoothly as the old one. The rotor is exposed.

Electrolux 235L (EKL 235FF) wiring diagram

This is the second time our Fridge needed repair, after close to 8 years of purchase. First, it was the defrost timer that failed and had to replace.

Royaltek RBT2300

I had purchased the Royaltek RBT2300 GPS logger sometime in 2008 and have been using it during my driving trips. This performs reliably well and thought of writing something about it.

Basically, this is a GPS receiver with bluetooth module that allows one to pair a Mobile/PDA/PC and get the GPS data in NMEA format. It has a logger function also that stores the GPS data in its internal flash memory at regular (configurable) intervals. The storage is huge and it has never ran out of memory even with 10-12 hours of logging (5s interval).

Issues that i have found.

• When downloading the GPS data from the device on the same day, the last portion of the data would not come out. If I log some seconds on next day and then try again, I would get the whole data for the previous day without any issue.
• If I switch off the device during some breaks in the trip, the logging gets screwed  up. The continuety is lost sometimes.

Some tips for usage.

• While on a trip, connect the device to the car adapter and never switch off till the end of the trip.
• 5 second logging seems to be reliable and anything less can cause issue for long trips.
• Wait for a day and log a few seconds in open sky (GPS lock) and they download the data for previous trip.

Microsoft PowerToys equivalent

I have been using Microsoft PowerToys since Windows 95. Was really surprised to know that Windows 7 doesn't support the old Powertoys. I was missing SendToX  - the most coolest among them. Also the 'Command Prompt Here...' menu. After a few mins of search on the web found a compatible/equivalent software: http://www.gabrieleponti.com/software/#sendtotoys

My new laptop

Trying out Windows 7 on my new Dell Latitude 6410. A few crashes in the beginning, things are stable now. Trying to find what's in for the developers.

PostScript file for cross platform printing?

I had a tough time printing the PCB layout correctly that I designed using EAGLE software. I designed the PCB on my home PC running Ubuntu 10.4 and printed to a PS file. The plan was to print the board to a magazine paper for toner transfer, on my office printer. So I emailed the PS file to my work address and printed from Adobe Acrobat Professional 7.1. Got my first surprise, the print is actually a slightly scaled down replica, may be 90% of the original. I realized this late after going home and verifying with the actual component that I had. But isn't the postscript (or pdf) file supposed to be hardware independent and vendor neutral? That was my assumption.

I tried various experiments - at my home PC, viewed the PS file at 100% scale and it matched the SMD component pads on screen (I placed the SMD IC on the screen to compare). I repeated the same with my office PC and it also matched. So, while printing something is going wrong. Again at office PC, I used PDF Writer software to print to a PDF file and then print to the Xerox printer, but it also was 90% size. Over the weekend I searched some information online and somewhere I read that PDF prints are not reliable across PCs. Suggestion was to install Eagle in Host PC for printing. Not very convincing.
Came to office on Monday and tried to scale up the print to 110% to get a match. To my surprise the image was way too big - may be 125% of the original. Now I am really stumped. Got the feeling that it was the ADOBE that was screwing up. Just to confirm, I sent the ps file directly to the printer job queue, and it came fine - at actual size! So the PS file was fine, so was the printer. But I doubt Adobe being professional cannot commit such error.

More thoughts and I wanted to try out once more. I have a dual monitor setup at office - both screens having different resolutions. I know that many software have difficulty in working with dual mon setup. Maybe Adobe is one. So I disconnected my external monitor and printed from the PC using Adobe. There you go. The print looks fine! So not a good idea to have dual monitor setup while printing from Adobe.
Lastly, it could be the printer driver also. Since the PS file is handled by the printer driver before sending to the printer, may be its trying to fix the resolution.

Now let me get back to etching!

So, back to the point - postscript file is indeed hardware independent and vendor neutral, just that some software in the chain can cause problems.