All posts by Adam Goerdt

Coronal Rain

On July 19, 2012, an eruption occurred on the sun that produced all three. A moderately powerful solar flare exploded on the sun’s lower right hand limb, sending out light and radiation. Next came a CME, which shot off to the right out into space. And then, the sun treated viewers to one of its dazzling magnetic displays – a phenomenon known as coronal rain.

The footage in this video was collected by the Solar Dynamics Observatory’s AIA instrument. SDO collected one frame every 12 seconds, and the movie plays at 30 frames per second, so each second in this video corresponds to 6 minutes of real time. The video covers 12:30 a.m. EDT to 10:00 p.m. EDT on July 19, 2012.

Workbench upgrade

I decided it was time to upgrade my workbench.  Below are some of the photos I took to document the process.

This is the workbench which came with the house that I've been using for the past two years. This bench had seen better days
There were gouges and paint stains which are probably older than I am
And large gaps between the tabletop boards
Here it is after the old top and backsplash were removed
After dismantling the bench I found that I also inherited some shingles
And that the old owner was too lazy to move the shingles out of the way when they painted the floor
Here are the salvagable pieces from the old bench. I was able to re-use some of it
Here I'm working on building the new bench frame out of 2x4s. Oops
The front and back frames are complete. They're held together with steel plates and pocket screws. The legs are salvaged from the old bench
Frames flipped upside down for attachment of the top rails. Bottom rails are going on now
Flipped back right-side-up with two more top rails to support the new tabletop
New tabletop base is on and bottom rails added to support the bottom shelf. The tabletop base is made from 4 2x10s cut 6' long
Shelf is in. Took a little bit of creative shaving to get it to fit, but it's snug. Now I have a place to store my hand tools!
Here are the screws holding the table top down. They're drilled about 2/3 of the way though the 2x10. The idea was that the screw would act as a clamp to flatten out some of the warp. It helped a little, but in it's current form the table was nowhere near flat. Another reason that the screws were sunk so low was that I knew I was going to have to plane the 2x10s down to provide a flat base for the MDF surface. In order to plane the new top I built a router planing sled
Planing sled components cut to size and dadoed
I needed to wait for a flat-bottom router bit to arrive, so I made drawers in the mean time. These are the cut components for the three drawers
Flat bottom bit arrived. Not bad
I used some leftover MDF from the table surface act as sacrificial guides and provide a parallel surface for the sled to ride. The drawers have also been installed
It was dusty. Really dusty. I needed to take two passes with the sled to remove the warp. The amount of dust from the two planing passes completely filled my 16 gallon shop vac. At the worst point I ended up taking about 1/4" of material from the 2x10s
Tabletop base after the first pass with the planer sled. It left more tool marks than I expected.
I used the sacrificial guide to check the flatness of the tabletop base after the second pass and was happy with the results. You can still see the tool marks from the router. I took a couple of passes with the belt sander to smooth it out, but wasn't too worried about the ridges
I layed the 2 sheets of 3/4" MDF layed on top of the base and framed with 3" poplar to keep it in place. The table is completely flat and starting to get some use
The final touch is a poplar face for the draws cut from leftovers, and vintage 80's drawer pulls salvaged from some previous kitchen work


$25 Crosscut sled

After having a little bit of trouble crosscutting anything wider than about 7″ on my tablesaw I decided that I needed a crosscut sled.  Rather than spending over $100 to buy one I decided to make one myself using a 2’x4′ sheet of MDF and a 5/4″ thick stair step.  Total cost for the build was under 25 bucks.

I didn’t do a very good job taking pictures of the first part of the build, so I’ll do by best to describe the process with text.

The first thing I did was cut two 3/4″ slices from the end of the MDF to use as runners for the sled.  Then I cut a 16″ piece from the MDF using a circular saw.  This cut didn’t need to be exact (or even straight) since it would be trimmed later.  At this point I had the two halves of the sled.  On each half I cut a 3/4″ wide 3/8″ deep dado to hold the runner.  I screwed the runner down from the top of the sled making sure that the tops of the screws were below the surface of the MDF.  Finally I ran each half of the sled through the table saw using the runner as a guide, leaving me with two properly sized sections as seen below.

Sled sections cut to size with runners installed
Close up of the MDF Runner
Stair step which will be converted into a fence
The stair step has been cut down into three pieces which will be the sled fence
Squaring the fence to the blade. The fence will be screwed down from the bottom
Clamping on back fence. This one doesn't need to be square, it just helps hold the two sections together
Clamping and screwing down the second piece of the front fence

The Voder

The Voder by Homer Dudley (Bell Telephone Laboratories, Murray Hill, New Jersey) was the first device that could generate continuous human speech electronically. The flowing composition of the many speech sounds had to be done manually in realtime on a special keyboard shown in this video.

In 1939, Alden P. Armagnac wrote in “Popular Science” about this speaking device: “He hasn’t any mouth, lungs, or larynx—but he talks a blue streak. His name is Pedro the Voder, and you may see him in action at the New York and San Francisco world’s fairs. His creation from vacuum tubes and electrical circuits, by Bell Telephone Laboratories engineers, crowns centuries of effort to duplicate the human voice.
To manufacture Pedro’s conversation, his operator employs a keyboard like that of an old-fashioned parlor organ. Thirteen black and white keys, fingered one or more at a time, produce all the vowels and consonants of speech. Another key regulates the loudness of the synthetic voice, which comes from a loudspeaker. A foot pedal varies the inflection meanwhile, so that the same sentence may state a fact or ask a question. About a year’s practice enables an operator to make Pedro talk glibly.”

And the “Time” wrote on January 16th, 1939: “The Bell Telephone demonstrators took pains to make it clear that Voder does not reproduce speech, like a telephone receiver or loudspeaker. It originates speech at the touch of an operator, synthesizing sounds to form words. The men who built it were able to do so because in their telephone researches they had made a close study of how speech sounds are made by the human larynx, mouth, breath, tongue, teeth and lips. With electrical filters, attenuators, frequency changers, etc. they found that they could produce 23 basic sounds; that intelligible speech could be synthesized from various combinations of these sounds, controlled by a skilled operator manipulating a keyboard and foot pedal.
The machine’s possible sound combinations are so various that Voder can imitate the inflections, overtones and shading of human diction. By altering pitch it can change from a man’s voice to a woman’s or a child’s. It can mimic animal sounds, locomotive whistles, the noise of an airplane engine. Since the fluent production of speech on a keyboard is not so simple as pounding a typewriter, Bell Telephone picked 24 of the cleverest telephone operators from 300 candidates, gave them about twelve months’ intensive training as Voder operators. Like concert pianists, they have to keep in trim by practicing several hours a day. The most difficult speech component they must coax out of Voder, and the one that sounds least natural, is the letter l. When someone at last week’s demonstration asked for the words ‘Bell Telephone’, they came out something like ‘Behrw Tehwephone’.”

The Voder was to some extent a by-product of the Vocoder, as S. Millman stated it: “In conceiving the vocoder, Dudley recognized the carrier nature of speech. He observed that the speech signal is formed by modulating (with the slowly changing vocal resonances) the spectral shape of the sound produced by vocal sources. The vocal sound sources may be periodic, as produced by vocal cord vibration, or aperiodic, as produced by turbulent airflow at a constriction.
The modulations in shape of the speech spectrum could, therefore, be measured in terms of the relative energy in contiguous filter bands, and the periodic (voiced) or aperiodic (unvoiced) sources could be characterized by a ‘pitch’ detector (a frequency meter). The signal could be reconstituted (synthesized) from these data by allowing to amplitude modulate the respective outputs of an identical filter bank which was excited by either a periodic pulse source or a noise source.”

M. D. Fagen, S. Millman, Amos E. Joel, G. E. Schindler, A History of Engineering and Science in the Bell System: Communications sciences (1925-1980), Vol. 5, Bell Telephone Laboratories, inc, p. 101 f.