Author Archives: Jay

New electric bicycle motor mount

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motor mounted over the front tire of a bicycle using PVC pipe

The simplistic motor mount I made for my electric bicycle (which consisted mostly of me bolting a motor to my wire basket and holding the basket away from the axle with a piece of PVC pipe) had been working well for five months. Until, that is, I ran over a particularly large pothole and the chain fell off. I took the hint that the PVC pipe and wire basket were not exactly up to my exacting quality standards and decided it was time to make something better.

I decided that the main problem was that my wire basket was not rigid enough, so my construction material of choice remained 3/4″ schedule 40 PVC pipe. This time I used TWO upright supports, one on either side of the axle and some C shaped metal shelf brackets bolted to my motor mount. (I also used PVC elbows and pipe to join the top of the supports.) This picture gives a good view of how the whole thing fits together. I am still using a hose clamp connecting it to my wire basket for left-to-right stability, but this produces much less stress on the basket, and a little left-to-right wiggle is unlikely to allow the chain to come off the gears.
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New Years Resolution: Mysterio Costume!

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Silvery glass sphere on the top of a christmas tree

One of my new year’s resolutions is to build a high quality Mysterio costume. In my opinion, the hardest part of a Mysterio costume is the silver sphere that serves as Mysterio’s helmet. Others have used a glass bowl, or tinfoil, but I was not happy with their results, and decided that I wouldn’t commit to making the costume unless I could get the sphere just right.

It’s amazing what you can buy for $48 on eBay! The image to the left is showing off my Mysterio sphere (44″ circumference, 14″ diameter) on top of a Christmas tree. The sphere is even mirrored inside, perfect for Mysterio’s helmet! It was originally an outdoor lawn ornament (reflecting ball) sold by Pottery Barn.

The only problem is that the hole in the bottom of the sphere is only about 1.5″, too small for my head! My options are clear: 1) Make a “headless horseman” type costume, where my head is actually under the costume’s “head”. 2) Find a way to cut the 1/3″ thick glass sphere! I’m trying really hard to get option two (cut the sphere!) working, as I want the costume to be in proper proportions, and besides, having my head inside of a mirrored glass sphere will be cool! (Visibility may be a problem, imagine wearing mirrored sunglasses at night.)

The Perfect Christmas – Holiday Music 2006

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Bath & Body Works paired with the Make A Wish foundation to offer “The Perfect Christmas” Holiday Music 2006 2 CD set which contains Christmas songs from contemporary stars.
The two disk set includes Glisten and Glow, with the following tracks.

Glisten:
01-Santa_Baby.ogg
02-Someday_at_Christmas.ogg
03-God_Rest_Ye_Merry_Gentlemen.ogg
04-Up_On_The_Housetop.ogg 05-A_Marshmallow_World.ogg 12-Forget_December.ogg
06-The_Christmas_Song.ogg
07-The_Man_With_The_Bag.ogg
08-Stay_A_Little_Longer_Santa.ogg
09-Santa_Claus_Is_Coming_To_Town.ogg
10-Mr._Heatmiser.ogg
11-Last_Christmas.ogg

Glow:
01-Rob_Thomas-A_New_York_Christmas.ogg
02-Jason_Mraz-Winter_Wonderland.ogg
03-The_Click_Five-My_Girlfriend_(Forgot_Me_This_Christmas).ogg
04-Chris_Isaak-Let_It_Snow.ogg
05-Linda_Ronstadt-Have_Yourself_A_Merry_Little_Christmas.ogg
06-Brian_Setzer_Orchestra-Boogie_Woogie_Santa_Claus.ogg
07-Doris_Day-The_Christmas_Waltz.ogg
08-Dolly_Parton-Hard_Candy_Christmas.ogg
09-The_Pretenders-2000_Miles.ogg
10-Barenaked_Ladies-Green_Christmas.ogg
11-Ramones-Merry_Christmas_(I_Don’t_Wanna_Fight_Tonight).ogg
12-Gia_Farrell-Christmas_Everyday.ogg

Low power (CPU) visualizations for MythTv / MythMusic

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I recently checked out all of the music player visualizations for the MythMusic module (part of MythTV). They vary widely in CPU usage and visual appearance. I wanted the CPU to be at least 50% free to work on transcoding or commercial flagging in the background while music was playing, so I avoided the especially fancy ones. I also found that the ones that used OpenGL used small amounts of the CPU (as they offloaded much of the processing to the GPU).

Selected visualizations (good effects, but minimal CPU usage):

  • blank (83% idle, not much happening on-screen ) – This is the ultimate “low power” visualization, against which all others are measured. The fact that it takes my computer 17% of it’s CPU time to play ogg vorbis files should indicate why I’m somewhat CPU conscious.
  • Album Art (70% idle)
  • Squares (75% idle, simple but classy)
  • lv_gltest ( 40-60% idle, 3d histogram)
  • Gears (60% idle, simple)
  • lv_flower (50% idle, very nice!)
  • madspin (30-50% idle, fast and sparkly)

Here is a list of visualizations that might be worth the extra CPU hit based upon their cool visual effects:

  • BumpScope (20% idle – roving spotlight on embossed scope)
  • Goom (20% idle, space tunnel effect)
  • oinksie (0% idle, kind of cool)
  • infinite (0% idle, but looks good!)
  • corrona (0% idle, falling/flowing effects)
  • jess (0%, but very very cool!)
  • jakdaw (0% idle, psychedelic flowing water effect)

I suggest avoiding the following visualizations, as they use too much CPU for what they produce:

  • monoscope (40% idle, one red line)
  • SterioScope (30% idle, two red lines)
  • lv_scope (20% idle, white scope on black background)
  • nastyfft (20% idle, bars, almost 3d look scope) – Use lv_gltest if you like this one
  • bumpscope ( 0% idle – slightly faster movement than BumpScope, ball rolling left/right) -Use BumpScope (with capital letters) for less CPU usage, and better effects.

The following three visualizations gave me problems:

  • analyzer (crashes computer in fullscreen!)
  • Synaesthesia (40% idle, but no visible output?)
  • Spectrum (80% idle, simple spectrum scope w/ colors, looks weird in fullscreen)

Mythexport not working with mythbuntu

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If you are getting ERROR: AtomicParsley type messages in your mythexport.log file, it may be because ffmpeg isn’t exporting the files correctly. One reason for this is that config’s in mythexport that have spaces in the name cause problems. The workaround reported here is to remove the old config, rename it into something that doesn’t have a space, and then re-create the user-job using the new config. (For good measure, I made sure the user-job didn’t have spaces either.) After this, be sure to re-start the mythtv backend to make your changes take effect.

MythTV power usage

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Switching to an eMachines EL1300G computer drastically cut the running power consumption of my MythTV setup, to an average of 45 watts when idle. (The old computer used 141 watts when idle.)

This makes it practical to leave the computer on 24/7. I had set my old computer to shut itself down when not recording, but this required a 2 minute boot-time wait anytime we wanted to watch TV. (When it was not already awake recording a show). Even when the old computer was off, the constant current draw from the other devices (UPS/HDHomeRun/Amplifier) was 17 watts.
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eMachines EL1300G-02w – HTPC with MythTV on Linux

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Executive Summary: The eMachines EL1300G-02w is a good choice for a low power home theater PC (HTPC) or media computer. Pros: Small form factor, low energy use, low noise with stock fans, DVD-DL R/W +/- optical drive, lots of media card readers. Cons: 160GB stock HD will need to be swapped out for back-end use, VGA video out (only), Analog Audio out (only), minimal expansion capabilities.
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Setting up lircd with the hdhomerun and a Tivo series 2 remote

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To set up lircd with the hdhomerun to see a tivo series 2 remote control, you should first program the HDHomeRun to send UDP packets to your linux computer with a command such as the following:

hdhomerun_config <device id> set /ir/target "<lircd ip addr>:<port> store"

You can test that this is working by running:

irrecord -H udp -d 5000 "testing"

If you get dots when you press your remote control buttons, the HDHomeRun is sending IR information to your linux box. (remember to unblock UDP port 5000 for incoming transmissions if you are running a firewall!)

Once that is working, just set up your /etc/lirc hardware.conf and lircd.conf files to support the Tivo series 2 remote.
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How to move a mythtv database from one machine to another

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Backup the database on your source machine. Newer versions of mythtv do this for you automatically. Check out the mythconverg_backup.pl script if you have to do it manually.

Delete any existing database on your destination machine:

$ mysql -u root
mysql> DROP DATABASE IF EXISTS mythconverg;
mysql> quit

Re-create the empty database on your destination machine:

$ mysql -u root < mc.sql (You may need to use the -p option and enter your root password)

You may also have to set up the mythtv user with the correct password:

$ mysql -u root < mc.sql UPDATE user SET Password=PASSWORD('YOURPASSWORDHERE') WHERE user='mythtv'; FLUSH PRIVILEGES;

After this, run the mythconverg_restore.pl script:

mythconverg_restore.pl --filename mythconverg-1214-20091010150513.sql.gz

You may have to specify hostname, database name and enter the password if you don’t have a mysql.txt file set up in my .mythtv directory. You may also have to specify the fully qualified path to the file if it’s not located in your default backup directory.

How to add XBMC to MythBuntu 9.10 (or Ubuntu 9.10)

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Xbox Media Center is no longer for just the XBox. It’s UI is slicker than MythTV’s Frontend for playing music, videos, and showing slideshows of pictures. (It’s weather applet is also much nicer…) If you have an existing Ubuntu 9.10 based system, the PPA:team-xbmc repository makes it dead easy to install xbmc on a ubuntu computer with the following commands:

sudo add-apt-repository ppa:team-xbmc
sudo apt-get update
sudo apt-get install xbmc
sudo apt-get update