WSANDERS.NET

$15 High Efficiency 5V Buck Regulator

wsanders — Sun, 10 Mar 2013 21:28:37 GMT

High Efficiency 5V Buck Regulator

This is cheaper and safer than buying dubious quality LiPo batteries and chargers. You can power with 8 or more NiMh AA cells, and use the same cells and charger you use around the house for other things. You could even install a USB receptacle and have a less expensive, more powerful, but bulkier version of the popular Minty Boost.

This model has a diode bridge in front of the voltage regulator, which has the advantage that you can't blow it up by connecting input voltage the wrong way. Unfortunately, there's only a smallish (100uF) cap between the bridge and the the regulator input so it might not work well with AC input. The other problem with using input diodes is they waste about 1 volt power, so the dropout voltage increases to about 8 volts. I'll probbaly remove the input diodes to make this a more efficient DC to DC converter.

A 45-Byte Linux Executable

wsanders — Mon, 18 Feb 2013 20:16:03 GMT

On my list of things to try:
http://www.muppetlabs.com/~breadbox/sof ... eensy.html

What R DevOps?

wsanders — Sat, 26 Jan 2013 08:16:10 GMT

What Is DevOps, the philosophers ask?

The famous 2000 EDS superbowl advert sums it up better.

A Slightly Greener WSANDERS.NET

wsanders — Sun, 15 Jul 2012 17:46:18 GMT

The Pentium III box that has been chugging away for years collecting weather data has been replaced by the old G4 iBook. This saves about a kWh every two days. Added benefit, the laboratory is strangely quiet now.

We have over six years of minute by minute weather data for the premises.

Nvidia, KDE, and Xorg Gamma settings: The Three Stooges

wsanders — Sun, 15 Apr 2012 18:51:50 GMT

Wondering why your display is always looking funny? Different displays need different gamma settings and color correction. My cheapo LG E2241 (non IPS) display is very twitchy about display settings - if it's not exactly right it looks like crap. So I was wondering why each time I calibrated the screen the settings seemed to look bad again the next day. My gammas have to be adjusted substantially fo the cheapo LG display, to something like 0.65.

Oh yeah, this is the legacy computer from heck: ancient generic whitebox with ancient nVidia GeForce2 MX 400, CentOS, KDE, and the above 1920x1080 pixel which is kind of pushing the MX400 as far as it was designed to go. (I do have the current nVidia legacy driver installed, which they graciously still support.)

Now the fun starts: There are three different places where display gamma gets set in CentOS + KDE. First, on X startup, /etc/X11/Xorg.conf gets read. This sets up the settings for the login screen only, so just leave this alone unless the gamma is intolerably bad.

That in turn will be overridden by KDE, which appears to run the "xgamma" command to source in gammas it finds in ~/.kde/share/config/kgammarc. This file is updated by the Monitor Gamma tab in the KDE Display Setting widget.

This is turn is overridden only when you happen to run the utility nVidia provides with the driver, /usr/bin/nvidia-settings, which is invoked by the nVidia driver settings widget that gets installed in the KDE System menu. This utility stores its gamma settings in ~/.nvidia-settings-rc.

So to keep these three stooges of apps from messing up your settings:

- Remove the nVidia driver utility from the KDE menu so you are never tempted to run it, and delete the .nvidia-settings-rc file. The settings aren't used unless you run the nvidia-setting utility.

- Use only the the Monitor Gamma tab in the KDE Display Setting widget to set gammas / color correction.

- If you want to make the login screen look nice, edit /etc/X11/xorg.conf.

- You could "lock in" the values by running either xgamma or nvidia-settings from your .bashrc file. Or both, if you are not easilty confused.

And don't forget - with LCDs, "brightness" is really "contrast" and vice versa. http://www.poynton.com/notes/brightness_and_contrast/ has a pretty good sum-up of that.

Fonts again

wsanders — Sun, 08 Jan 2012 19:25:42 GMT

I am still in font hell since my screen res changed from 95 to 101 DPI. On my box there are four separate font rendering systems:
- "Classic" X fonts, those which would use XFS if I was running XFS. These are ancient X apps like xterm, etc.
- KDE, which uses Xft.
- Mozilla / Firefox
- OpenOffice

All these use four different DPI and antialiasing settings:
- No antialiasing at all in the case of classic bitmapped X fonts
- KDE allows you to control the Xft antialiasing setting via Control Center abd DPI via /etc/X11/Xresources
- Mozilla does its own thing, which looks like crap.
- Openoffice does its own thing, which looks even crappier.

Setting "Xft.dpi: 100" in Xresources helped the most. At 96 (the old default DPI) and 101 (as the video driver calculatea the DPI) some kind of rounding error caused all kinds of problem with kerning, 0's looking like O's, etc. I think I've just about straightened it out.

New Monitor, Old Eyes, Linux Fonts

wsanders — Thu, 05 Jan 2012 17:48:24 GMT

The venerable 1280x1024 flat panel I've had for 11 years finally died on Sunday night so I had to run out to Best Buy and settle for what they had in stock. I ended up with an LG "Flatiron" E2241 (21.5", 1900x1080, 100dpi) for now (the IPS panels were way too expensive), which is your basic consumer model. It's still a TN panel, and the gamma is quite nonlinear, so my photos look like poo, but it's fine for office use.

The increase from 95 to 100 dpi makes quite a difference (I probably should have bought the 23-inch model; same price). Either:

- Linux fonts still suck
- My eyes are getting old

I vote for a combination theory - Linux fonts are developed by young whippersnappers with perfect vision. We need more geezers designing fonts.

Funniest Slashdot comment ever, regarding announcement of Debian release of Hurd:

wsanders — Thu, 14 Jul 2011 23:28:25 GMT

BSD userland on top of GNU Hurd.

"What the hell do you call an OS like that?"

"I'll call it 'The Aristocrats'"

Good GNUPLOT Intro

wsanders — Sat, 18 Jun 2011 20:54:02 GMT

The Gnuplot docs are not very well organized for beginners (hey, I know what a sine wave looks like. What if a have a big file of disorganized, real-world data, with missing data points?) Here's a good guide:

http://t16web.lanl.gov/Kawano/gnuplot/index-e.html

I'm still trying to figure out how to load only lines N through M of a data file.....

Launching Ganglia Daemons at Mac OSX Bootup

wsanders — Wed, 15 Jun 2011 00:10:39 GMT

The daemon launch process at http://www.deanspot.org/comment/reply/261 says "could use some help here", so here's how I did it:

I never got gmond and gmetad to start under launchctl as background daemons at boot, gmetad would die after a while and gmond would go nuts and respawn over and over until the machine was unusable. Running in the foreground works, this is how to set it up:

OSX 10.6.7, ganglia built in /opt/local from sources, rest of dependencies from Ports, daemons are in /opt/local/sbin, using OSX's Apache and PHP:

- Create two files in /Library/LaunchDaemons:

org.ganglia.gmetad.plist:

"http://www.apple.com/DTDs/PropertyList-1.0.dtd" >

Labelorg.ganglia.gmetad
ProgramArguments

/opt/local/sbin/gmetad
-d
1

RunAtLoad

org.ganglia.gmond.plist

"http://www.apple.com/DTDs/PropertyList-1.0.dtd" >

Labelorg.ganglia.gmond
ProgramArguments

/opt/local/sbin/gmond
-d
1

RunAtLoad

- Incorporate them into launchctl's config:

sudo launchctl load -w /Library/LaunchDaemons/org.ganglia.gmond.plist

sudo launchctl load -w /Library/LaunchDaemons/org.ganglia.gmetad.plist

- Reboot to test. You should see

54 - org.ganglia.gmond
55 - org.ganglia.gmetad

in the output of "sudo launchctl list", the first column is the PID which you will see in the output of ps. Output goes into the system log.