Identify It! Answer for 10-13-2010

Thanks to everyone that played this week’s Identify It! Challenge. For this week’s challenge we asked fans to guess the informal name, scientific name, give several facts, and identify one unique feature of this specimen of spider. Here is the original photograph:

 

Writing Spider : Argiope aurantia

The answers are:

Informal Name: Writing Spider (AKA Black and Yellow Garden Spider)

Scientific Name: Argiope aurantia

Facts:

• This spider is called a writing spider because it often creates zig-zags (that look like the letter Z) or X’s or other patterns that look like letters. It does this because it often weaves very large webs and the patterns make the web visible to birds, squirrels, and other animals that might knock its web down.
• Although incorrectly drawn in the cartoon, Charlotte from “Charlotte’s Web” was a writing spider!
• This spider will bite human beings if provoked but is not aggressive and its venom is usually not very potent. (its still a good idea to leave all spiders alone though)
• Argiope aurantia often leave an egg sack with thousands of eggs at the end of the fall season.
• The size and complexity of its web are a good indication of how well fed it is.
• Males are small and uninteresting marked, often building a small web adjacent to their female mates. Females are much larger (on the order of 3 inches in diameter) and are brightly marked with yellow spots and patterns on their abdomen and back.

Unique to this specimen: If you look closely at the photograph you will notice that this spider only has seven legs. It isn’t clear if the spider lost its leg at some point or if it was born without it.

This specimen has lived for at least the last three years on the side of the Sylvan Learning Center in Burlington NC. (As one fan pointed out its interesting that a “writing spider” would take up residence at a learning center.)

More Higher Resolution photographs can be found at the following link:

Click Here for more High Resolution Photographs

or also at our “photo” tab at our fan page on facebook (http://www.facebook.com/HarrisEducational)

 

Belly View (through the web)

3/4 Side View in Web

Thanks to everyone for playing this week’s Identify It! Challenge. Stay tuned for the next one!

 

 

Identify It! Answer for 5-27-2010

This week’s Identify It Challenge was guessed pretty quickly, and one fan even found a picture (until this post the only picture I know of this device on the internet today!) So great work everyone.  I took the liberty of obscuring the IBM logo on the original picture when it was posted in order to make it a little harder to look up the item. Here is the object without the IBM logo obscured.

The IBM Magnabelt Executary Model 224 dictation recording machine (1960s)

This item is an IBM Magnabelt Dictation Machine (model number 224) also sometimes called an “executary”. IBM first introduced these machines in the early 1960′s. It was used to record dictation in the office and also as a method to record audio in the field by reporters. These machines are fully transistorized which lends to their smaller size and ability to be operated by battery. They did suffer from sound quality issues partly due to tracking problems with the recording belt, but also due to the poor quality of the included microphone. Today’s microphone technology is light years ahead of what was possible in 1960. In spite of these problems these units were a commercial success.

Magnabelt from another Angle

Closeup of the Microphone Connector, Proprietary Connector, and Microphone

As you might know Thomas Edison invented the record player. He first marketed the record player as a business tool to record dictation. Early models used wax cylinders. As time went on other methods to record sound were devised including wire recorders and eventually tape recorders. The “executary” uses “magnabelt” technology where audio is recorded as a helical stripe along an endless magnetic recording belt. The belt is a mylar plastic belt with ferromagnetic material deposited on its recording surface.

Executary with leather carry case removed

The unit could be used in the field on battery power, or in the office connected to a base station via a proprietary power, audio, and control cable. For use in the field the unit had a thick leather carry case (which was the style at the time for portable electronic equipment like transistor radios). The leather case is held to the unit with a large captive thumbscrew. The picture above shows the unit with its leather case removed. Its exterior is a thin steel shell case with a flat gray paint job. The end piece is a black plastic.

Executary Case Slid Open

To gain access to the magnabelt recording media or in order to adjust the recording level (a curious design limitation given there is a recording level meter in the operating controls) you can press a metal button on the back of the case and simultaneously pull the actual mechanism out of the case. There is a stop inside the case that keeps you from removing the entire case.

Recording Head lifted Open

To get to the magnabelt you must first release a catch on the recording head mechanism and it swings open to about 25 degrees.

Magnabelt being removed

Closeup of Mechanism with belt removed

You can then gently lift up the portion of the belt that is pressed down by the recording mechanism and slip it off of its feed rollers. One benefit of the magnabelt over other kinds of tape (reel-to-reel, cassette, or cartridge types) is that it can be folded flat and sent through the mail to another person with another machine at normal postal expense, taking up much less space. One drawback to the technology though is that the physical alignment and tracking on a magnabelt is lost once it is removed or replaced, requiring the use of indexing and pitch controls.  Getting a totally accurate reproduction of the sound is more difficult.

Detail of Recording Head

The “executary” used a single head for recording and playback and does not include an erase head. Recording over used magnabelts would be possible but you would have to have used an external degaussing machine to scramble the magnetic domains on the tape to erase it first otherwise you would likely have had a mixture of old and new sound recorded. (especially if the belt had been removed and replaced… due to the tracking problem as mentioned above). The head is visible in the photograph above. The head is moved from left to right by a rotating threaded rod, this rod is geared to the motion of the magnabelt’s drive by a toothed belt. As the mangabelt moved below the head the head slowly moved to the left thus recording a helix around the belt. There is a tone/tracking adjustment wheel on the body of the recording mechanism (indicated with a tuning fork symbol). This adjustment moves the head slightly to the left or right in relation to the screw mechanism so that you can find the track if the belt is moved or if a belt from another machine is being played back.

Battery removed from the unit

The “executary” was powered by a proprietary 10.7 volt non-rechargeable battery that is marked with the IBM logo but manufactured for IBM by the Mallory corporation.

Typical use position

The unit was typically used by holding in the right hand and using the thumb to operate the controls. Inside the recessed blue square are the following controls and indicators: A tiny recording level meter, the power and playback volume control knob, the record button (which can be used as on/off or locked on for continuous recording), and a manual tape advance control lever that starts the tape moving for playback or recording. Also on the unit is the tone/tracking control, an indexing control that in some way marks the index strip of paper to indicate a start/stop/edit point and a manual release that disengages the tape head mechanism from its drive screw so that you can advance the listening/recording position on the tape. This is all relative from 0 to 100 on an index strip of paper that is held in place by friction inside the tape record head mechanism. This strip would be kept with the magnabelt if removed and used to label it.

Closeup of User Controls

In the later 1970′s advances in micro-cassette recording technology, integrated circuits, and better microphone technology replaced the “executary” style magnabelt recorders for office and portable use. Today micro-cassettes are still used but are largely being replaced by tape-less technologies such as recording directly to flash memory. In fact most cell phones have a recording capability for audio notes!

To learn more about the Magnabelt “Executary” and other older and proprietary audio recording technology check out this website: http://www.videointerchange.com/audio_history.htm

Check back again in the future for more Identify It challenges and their answers.

Identify It! answer for 12-08-2009

Another round of great guesses. The answer to this Identify It! Challenge is:

Identify It! for 12-08-2009

These items are Nuvistors. Nuvistors are the smallest mass produced vacuum tubes and were invented and produced by RCA for use mostly in consumer electronics. Nuvistor is a play on words including “Nu” which sounds like “new” and vistor which sounds like the end of transistor. “Nu” is also similar to “Mu” which is a symbol which stands for the amplification factor of a vacuum tube.

Unlike most vacuum tubes Nuvistors are enclosed inside a metal shell that both provides structure and shields the elements inside the tubes from radio frequency interference. Being metal they are a little more rugged than glass tubes, although unlike transistors they are prone to problems due to vibration. Nuvistors are unique in their manufacture in that instead of each tube being evacuated of air individually and then sealed, entire sets of tubes were placed into a large vacuum chamber, the air removed from the chamber, and then each tube sealed roboticly before all tubes were removed from the chamber. Being small reduced weight and due to the physical smallness of the elements within the tube (cathodes, grids, plates) Nuvisors worked well with high frequency (such as VHF and UHF frequencies used in television transmission.)

Like all tubes, Nuvistors contained a heater, cathode, at least one grid, and a plate. The heater was a wire made of tungsten which is not unlike a filament in a light bulb. Electricity passing through the filament to glow and produce heat. This heat is transferred to the cathode a metal sleave that is wrapped around the filament (but not electrically connected to it). The Edison Effect (noted by Thomas Edison) is that any metal heated in a vacuum will release a charge of electrons into space. When the heater heats the cathode it produces electrons (which can be replenished by supplying the cathode with a fresh supply of electrons by electrically connecting it to a negative voltage supply). As the electrons are emitted from the cathode they can be attracted to another cylindrical conductor known as a plate if it is charged to a positive potential. The plate is connected to a positive voltage source which attracts the electrons from the cathode. Between the cathode and plate are one or more “grids” which are screens of wire. The grid can be connected electrically to an outside voltage source. If the grid is at a potential that is more positive than the cathode but less positive than the plate then electrons can be made to flow to the plate. Since electrons are repelled by negative charges if the grid is connected to a potential that is more negative than the cathode then electrons will be repelled and will not reach the plate. Thus a vacuum tube can act as an amplifier since a small signal applied to the grid can control a larger voltage flowing from cathode to plate.

In the late 1950′s and early 1960′s transistors existed and were being used in electronic devices, however they were not as reliable at high frequencies and were more expensive to produce. Vacuum tubes were still less expensive for a time due to the mass production facilities that already existed for their manufacture.

In our picture we show a 2CW4 and a 6CW4. Both are triodes. The first number indicated the filament voltage, one being 2.1 volts and the other 6 volts. The 4 indicated four elements inside the tube, a filament, cathode, grid, and plate. These tubes are triodes and were used as part of the tuner circuit of early color television sets.

To learn more please visit these pages:

http://www.thevalvepage.com/valvetek/Nuvistor/nuvistor.htm

A reproduction of an article from “Practical Television” magazine from December 1962. This article has a great diagram showing the construction of Nuvistors as well as example circuits that used them.

http://nuvistor.org/1630.htm

An article with some excellent pictures of “Acorn Tubes”… a style of vacuum tube that were the smallest tubes before the production of the Nuvistor. Also some interesting links to some reproductions of 1960′s era electronics magazines relating to amateur radio and “high frequencies”

http://en.wikipedia.org/wiki/Nuvistor

Wikipedia entry on Nuvistors which includes a useful list of part numbers and types.

(insert standard disclaimer on wikipedia article accuracy and non-primary-ness here)

Identify It! Answer for 11-20-2009

Thank you everyone who guessed in this week’s “Identify It!” challenge. Sorry that its taken us longer to get our answer posted than usual but its been a busy week getting ready for Thanksgiving. We’ve done three of these challenges so far and I’m always interested in people’s responses and their thought process.

We had some really good guesses this week but amazingly I was able to stump the fans because no one guessed the correct answer. I was actually expecting this one to be guessed very quickly but I guess we don’t have very many hardcore geologists or mineralogists in the audience at the moment.

Here is the answer: The object in question is a 6 inch diameter by 4 inch tall crystal formation of the mineral Fluorite. This formation is partially transparent (around some corners of some crystals) but is mostly translucent having a purple to violet color. It exhibits a cubic crystal formation typical of fluorite. More images (showing translucency and better coloration) can be found at our fan page on Facebook under the photo’s tab inside the “Rocks and Minerals” folder.

(see: http://www.facebook.com/album.php?aid=125560&id=86177094101 )

Another View of our Fluorite Crystal

Fluorite is a widely occuring mineral that is often found in large deposits. It is a halide made of calcium fluoride (CaF2) and is found most often as cubic crystals though octahedral and more complex forms are possible. Fluorite occurs in a wide variety of colors including colorless, yellow, green, blue, purple and more rarely black, brown, red, pink, and white. Some fluorite samples fluoresce under ultra-violet light (fluorescence is actually named after fluorite, one of the first minerals discovered to posses this trait)

Fluorite uses include: ornamental use, as a gemstone, as a flux in steel and aluminum production, as a substitute for glass in some high quality optics applications, in some semiconductor manufacturing processes involving ultraviolet light, and in the production of hydrofluoric acid.

You can learn more about Fluorite and find pictures of very interesting samples at the following links:

A data table containing lots of information about Fluorite: http://www.minerals.net/mineral/halides/fluorite/fluorite.htm

Pictures of museum samples of Flurite: http://hyperphysics.phy-astr.gsu.edu/HBASE/Minerals/fluorite.html

Bob’s Fluorite Gallery: http://www.peaktopeak.com/fluorite/index.php3

Lots of information and pictures of Fluorite: http://www.galleries.com/minerals/halides/fluorite/fluorite.htm

Wikipedia Entry on Fluorite: http://en.wikipedia.org/wiki/Fluorite

(standard disclaimer: Wikipedia is not a primary source and since the site is publicly editable by anyone the accuracy of information should be called into question. Nevertheless Wikipedia is an interesting experiment as a publicly edited and maintained information repository similar to an encyclopedia and can provide interesting links to other primary sources. Please use appropriate caution when viewing articles on Wikipedia)

Thanks again to everyone who guessed in this week’s “Identify It!” challenge. Keep an eye on the Harris Educational fan page on Facebook for the next “Identify It!” later next week.

Have a wonderful Thanksgiving everyone!