Friday, April 21, 2006

Line to microphone input.

While in India we had been recording talks by Tibetan Buddhist teachers, both with a mini-disk recorder and a video camera. To transfer these to our laptop for editing with Audacity we had a problem. The Philips X51 only has a micrphone input not a line in, whereas the mini disk and camcorder produce "domestic line out" voltage levels. I knew enough about electronics to know I had an impedance matching problem. My friend Charles, knowledgable about such things was confident that a 100 k Ohm resistor in parallel would do the trick. I set out on my quest to find such a thing in McLeoad Gange (Upper Dharamasala).

Eventually way up near the Taxi stand at the top of town I found a small shed that served as a shop for a man who fixed electronics. He was doing an improvised repair on an old tape recorder. On the way, asking in other stalls selling electrical and electronic bits and pieces I had aquired a lead with a stereo jack plug on both ends and a one male to two female stereo jack adapter. So as not to mess up the moulded plus I got the man in the shed to solder a 100kOhm resistor across between the line and ground pins of another jack plug. It took two of them a quater of an hour to hunt down a suitable resistor from decrepid and dirty circuit boards from broken TVs. This was inserted in one of the holes in the adapter so as to put the resistor in parallel.

Anyway the up shot was that it works, and we were able to get an audable recording of Lama Tenam's talk on the meaning of the Red Crown Ceremony, and Tai Situ Rinpoche's talk on the Four Noble Truths converted to digital form, to the accompniment of many drums and horns playing in the background.

Now back home I could have been more sophisticated, and if you have to solve a similar problem I suggest you consult this helpful page.

Saturday, April 01, 2006

Linux on a Philips freevents X51 laptop

I am in the process of installing Mandriva 2006 Linux on a very cute
little laptop. Its a Philips freevents X51. We bought it from Currys
for the princely sum of £799. Actually they had run out, but
a very nice sales man called Simon let us have the display model.
So far it works. The installation from DVD went smoothly enough. It
resized the Windoze partition for me, autodetected most things, and
then failed to reboot! Well there was one little trick, I had to go in
in rescue mode, and edit /etc/lilo.conf to remove the resume=/dev/?????
flag. Obviously I have not yet mastered the resume from disk! To be
honest not yet tried it in Windoze.
The wireless adapter uses the Intel ProWireless 2200 BG chipset. I
downloaded the rpm from mandriva club. Subscription required but well
worth it. If you are tight you can get the files from sourceforge and
figure out where to put them.
So far so good as I am posting over the wireless connection right now.
I will update this post when I have tested everything else.
Here is a brief specification of the X51

Dimensions 32 x 275 x 225

Battery Type LI-ION see below
Processor Type INTEL PENTIUM M 1.73GHz

Optical Drive Double Layer
DVD±RW drive

Screen Size/Type 12.1 TFT XGA 1024x768 24 bit
Graphics Card Type INTEL GMA900 (Mobile 915GM/GMS/910GML Express Graphics
Xfree drive works fine
Sound card AC97 16bit
works fine
Modem 56k Fax modem Not tested
Wireless adapter Intel(R) PRO/Wireless 2200BG
Network adapter
Needed driver rpm from Mandriva club or can
also get from
Ethernet adapter

Realtek Semiconductor Corp. CPP Div. (Advance Logic)

Not tested

Had a bit of a problem with the power management at first. Basically if you install acpi and reboot the computer freezes. But with the acpi=ht some funny things happen with audio files playing at the wrong rates. Weird. Anyway I think I have fixed this, although not sure exactly why this works. I have the battery monitor working (in klaptop), but not yet tried the hibernate . Here is the relevant section from /etc/lilo.conf

append="splash=silent noapic acpi=noirq nolapci"

See also this posting on a French linux forum

TuxMobil - Linux on Laptops, Notebooks, PDAs and Mobile Phones