Archive for October, 2011

Monthly Aphorism: On Right Behavior

  • Do what’s right and sleep well at night

Father Vaughn taught that precept to everybody he managed: he expected complete technical and personal honesty. That meant you did your best, reported the facts, and didn’t tell different versions of the same story to different people.

It was painful to watch him in meetings with his manager who had, shall we say, a tendency to skew the truth in certain situations.

Dilbert is a documentary of what happens when you don’t live by that rule…

About these ads

Leave a comment

Expedient Handlebar Mirror Repair

We frequently host touring bicyclists who need a campsite in the Mid-Hudson Valley. The most recent couple has been riding for two years, starting eastward from Paris shortly after their wedding. Yeah, it’s a honeymoon trip.

After riding through Western and Eastern Europe, the Middle East, and several of the ‘Stans, JeanMarc’s handlebar mirror broke in Kazakhstan. Marie toted the carcass out of the ‘Stans, across India, through China, and then from Montreal to here. They’re biking to Houston, where they’ll fly to Peru, ride south and across the Andes, and work their way across the Atlantic on a cargo ship that eventually docks in Germany. Then, a year from now, they’ll just bike back to Paris.

Makes you feel like sludge, too, doesn’t it?

With that as prologue, JeanMarc wondered if I could fix the mirror mount. It started as a 10 mm plastic ball on a molded plastic fitting with an integral worm screw and strap; of course, the ball stem snapped off during a hard landing or some such event that comes naturally during long-distance riding. We kicked around some ideas, rummaged through the heap, and came up with a workable, albeit hideous solution.

I applied a Dremel slitting wheel to a pair of Zerk grease fittings, sliced off the inlet valve, extracted the valve spring, and cleaned up the residue to leave a somewhat misshapen 9.3 mm (really a scant 3/8 inch) ball-like end. A bit of lathe work converted a chunk of PVC pipe into a sleeve grooved for a metal hose clamp. I drilled two #3 holes, tapped them 1/4-28 (which, believe it or not, is the correct thread for a Zerk), bandsawed the pipe in half, introduced the pieces to Mr Belt Sander to round the edges, screwed Zerks into holes, and wound up with a pair of these:

Handlebar Mirror Mount - detail

Handlebar Mirror Mount - detail

Which looks awful on the handlebars, but we’re pretty sure it won’t break and he has a spare if the mirror on Marie’s bike snaps off:

Handlebar Mirror Mount - fixed

Handlebar Mirror Mount - fixed

The Zerk fitting could unscrew, but the threads aren’t exactly in pristine condition after all that fussing and seem to be jammed firmly in place. If we had more time, I’d have heated the PVC and molded it around the handlebars, but we decided that wasn’t really necessary.

They rode off into the distance this morning… may you have smooth roads and a tailwind, JeanMarc and Marie!

JeanMarc and Marie

JeanMarc and Marie

,

1 Comment

Praying Mantis

Praying Mantis on bike rack

Praying Mantis on bike rack

We met this Praying Mantis on the bike rack outside Skinner Hall at Vassar College. Even knowing they’re harmless, I’d have trouble picking it up; we parked on the other end of the rack.

If these things were any bigger, they’d be terrifying…

Leave a comment

Coopers Hawks Drying Out

One of the Coopers Hawks that keep the rodents under control around here landed atop a pine tree and spread its wings to dry out:

Coopers Hawk drying in pine tree

Coopers Hawk drying in pine tree

Shortly thereafter, the second hawk arrived and the pair shared some Quality Body Maintenance time:

Coopers Hawks in pine tree

Coopers Hawks in pine tree

The first image comes from the Sony DSC-H5 with the 1.7 tele adapter. The second is from the Canon DX230HS with the digital zoom set to 2x “digital tele adapter mode” and the optical zoom cranked all the way out; they’re both small crops from larger images. Not much to choose between the two, although the Canon wins hands-down for convenience.

3 Comments

VLC Startup Settings: Audio Sync

While thrashing around with that DVD player, I finally figured out that VLC stores its configuration settings in ~/.config/vlc/vlcrc. I don’t know if it’s supposed to update that file automagically after twiddling the GUI config settings, but it doesn’t; I must manually edit the file to get a sticky change.

Anyhow, the vital setting for that particular drive turns out to be audio synchronization, as set by the audio-desync parameter. The audio must lag the video by 400 ms, thusly:

# Audio desynchronization compensation (integer)
audio-desync=-400

And then it Just Works…

1 Comment

Harbor Freight 1 kg Scale: Warranty Terms and Count Instruction

So I picked up a cheap digital scale at Harbor Freight because it can count parts based on weight. After all the dust settled, it was on sale for about $8, which tells you just about all you need to know, and the “5 Year Warranty” looked generous on the box:

Harbor Freight 1 kg Scale

Harbor Freight 1 kg Scale

Alas, the fine print taketh away (clicky for more dots):

Warranty

Warranty

Ah, well, all this stuff is disposable anyway, right? Nobody’d ever try to fix it…

The instructions for the Count function omit a step. In order to invoke the Count function, do this dance:

  • Turn it on
  • Count exactly 10 pieces on the scale, wait for stabilization
  • Press-and-hold PCS until the display shows 10
  • Release PCS
  • Press PCS briefly; the pcs annunciator turns on (they omitted that)
  • The display will still show 10, which is the number of pieces
  • Now you can weigh stuff and read off their counts

The scale resolution is 0.1 gram, so SMD resistors just aren’t going to count properly at all. It’s best if you add the entire group at one time, rather than trickle parts into the pan.

The instructions in full (clicky for more dots):

Instructions

Instructions

1 Comment

External USB Case: DVD Overcurrent

Well, it turns out that the DVD drive I stuffed into that case really does require a whole bunch of current. I tried playing a DVD and got erratic results, including weird keyboard (!) failures. Finally, I hitched a bench supply to the coaxial power jack on the case and caught it in the act:

Laptop DVD - current display

Laptop DVD - current display

That jack normally connects to the power-only USB cable, which implies an upper limit of 100 mA. A bit of poking around inside shows that the coaxial power jack simply parallels the USB jack’s VCC line, so there’s no fancy negotiation or current sharing going on.

When the keyboard went nuts it was sharing an unpowered USB hub with this thing, which means that the overcurrent dragged down the hub’s supply. I was permuting all the choices to see if the failures suggested anything; eventually it did.

A bit of rummaging in the Basement Laboratory Warehouse Wing uncovered a 5.0 V 3.7 A wall wart switching power supply that is grossly in excess of the drive’s 1.5 A rating. Amazingly, it even had the correct coaxial power plug on the end of the cable, which never happens.

Alas, because the external supply back-powers the USB data cable, it lights up the Q150′s power button when the PC is turned off. I think I can insert an isolation diode into the USB power trace to isolate it from the jack, somewhat along the lines of that hack. However, that seems to require removing the USB connector to uncover a very well protected top trace. For now, I’ll just unplug the drive.

8 Comments