Monthly Archives: May 2010

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)

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

Magnabelt from another Angle

Closeup of the Microphone Connector, Proprietary Connector, and Microphone

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

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

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

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

Magnabelt being removed

Closeup of Mechanism with belt 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

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

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

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

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.

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Identify It! Challenge Answer for 5-19-2010

After too long an absence I’ve finally brought back the Identify It! Challenge and I’m pleased to say we’ve had more guesses and feedback than any other challenge so far.

Identify It Challenge Image for 5-19-2010

Identify It Challenge Image for 5-19-2010

The answer to this challenge is… A Hexacon model 30H 80W 90-degree bent soldering iron with bench mountable holder/heat guard.

Hexacon Model 30H 80 Watt Bent Soldering Iron

Hexacon Model 30H 80 Watt Bent Soldering Iron

Design and what makes this iron special:

All soldering irons work by heating up the metal connections that are being soldered to a temperature high enough that the connection itself will cause solder to melt, flow over the joint, and then when the iron is removed, quickly cool forming a hardened metal connection that ensures a good electrically conductivity and seals the connection from moisture and oxidation. Solder joints are never structural.

The wattage of the iron (and the size of its tip) are picked based upon the surface area and volume of metal being soldered. For most through-hole soldering connecting a small gauge wire or component to a very thin copper trace only requires a very low wattage iron with a small chisel or pencil tip. This is the kind of iron and work hobbyists are probably most familiar with. For larger components, like soldering a ground strap to a metal chassis, or soldering the lugs on a large electrolytic filter capacitor or the pins on a vacuum tube socket a higher wattage iron with a larger tip to quickly conduct heat to the larger surface area is required.

Most soldering is done with the work being soldered either below and in front of you (like on a bench top) or directly in front and parallel to you (like a chassis sitting up on its side on a bench). Heat rises and so the larger the wattage of your iron the hotter your hands will get as you solder especially when soldering downwards. This might not be a big problem if you are soldering one connection but for workers in a production environment soldering hundreds of connections over multi-hour work periods this gets uncomfortable very quickly. The right angle design of this iron helps alleviate this problem by getting your hand further away from the rising heat.

Seeing what you are soldering is important especially in cases where you are soldering lugs of components inside densely packed areas in a hand wired assembly. With a conventional straight soldering iron, the iron and your hand are directly in your line of sight and obscure your vision. With the right angle design of this iron the bulky handle and your hand are removed from your line of sight making it easier to see what you are doing.

Hexacon 30H Soldering Iron in typical use position

Hexacon 30H Soldering Iron in typical use position

The story of this iron:

This soldering iron was manufactured at some point in the mid to late 1970’s by the Hexacon corporation, a well known brand name to soldering enthusiasts. There is still a paper tag on the power cord that says the iron was assembled by #7 and so whoever #7 was they should be proud that nearly 40 years later their iron is still in good working order.

The iron was purchased along with a batch of others by the GTE corporation for use in assembly, troubleshooting, and rework at their Sylvania Color TV manufacturing plant in Smithfield North Carolina. In the mid 1980’s the Sylvania brand was sold to North American Phillips corporation (a division of the Phillips name that still exists today) and assembly of TV’s was moved to the Magnavox plant in Greenville Tennessee. Sadly this meant that the production plant in Smithfield was closed down with some workers moving to Greenville and others staying in Smithfield. One of the people that stayed in Smithfield was the manager of troubleshooting and reworking. He went on to become the Electronics instructor at Smithfield Selma Senior High School (where I went to high school). He bought the batch of irons for use at the school at Sylvania’s liquidation sale. Later when I went to high school I took his electronics class and he gave this iron to me as a graduation present. I’ve treasured it and made use of it ever since. Its my go-to iron for any heavy duty work.

You can still purchase this iron (and variations on its design) from the Hexacon corporation or one of their resellers. Here are some links:

The Hexacon Corporation still makes a similar iron as well as other good soldering equipment.

http://www.hexaconelectric.com/

80 Watt version of the 30H (called a Power House)

http://www.bertech.com/product2/soldering_irons.htm

A 75 watt modern version of this iron with a slightly different handle design.

http://stellartechnical.com/30h75wiron.aspx

And don’t forget the holder:

http://www.hexaconelectric.com/holderaccess.html

p.s. I don’t own stock in, or get anything from Hexacon for this, it just made a neat picture good for guessing and identifying. I also thought the story of this particular iron as well as the lessons that could be taught from its design might be useful. All brand names cited in this article are the respective property of their owners and no infringement or endorsement is intended. Go forth and solder in safety and peace!