Monday, May 13, 2024

The Telex Cordless Tape Eraser


Res ipsa loquitur, the thing speaks for itself.  As you'd imagine, a cordless cassette tape eraser is just some permanent magnets, and it is so. In my lab, my tape eraser of choice is an electromagnetic model. The brand name of mine "Magneraser." But this Telex cost me a whole $5 at a thrift store so I thought I could do a little comparison. Thankfully one of the fine folks over at already dissected one, saving me some time. [LINK]

The verbiage on the side of the box reads as follows:

"Erases standard & micro/mini cassette. For use in the home-office-on the road. — No outside power or batteries required. Can operate practically forever with built in alnico magnet which produces a strong demagnetizing field. Particularly useful with dictation systems which allow erasure of sensitive recorded material with minimal effort."

So I read up on those powerful "alnico magnets." Alnico is a family of iron alloys which, in addition to iron are composed primarily of aluminum, nickel, and cobalt, hence the acronym al-ni-co. The development of alnico began in 1931. Metallurgist Prof. Tokushichi Mishima in Japan discovered that an alloy of iron, nickel, and aluminum had double the coercivity of steel magnets. Before you ask, he does have the patents to prove it. [LINK] Mishima is on the Japan patent office top 10 inventors webpage. [LINK] He had quite a storied career. Born in 1893 in Empire of Japan, Mishima graduated from Tokyo Imperial University and spent his entire career as a metallurgist, eventually returning to Tokyo Imperial University as a professor. He died in 1975. Magnets are cool.

As you'd expect, the first thing I wanted to know is how old this device actually is. The first and only catalog listing I found was in the ICIA Directory of 1999. But the tech is much older. In 1999 you could buy this bulk eraser individually for $20 or a case of 12 for $216. The catalog number isn't on their website anymore of course. Telex is part of the Bosch Communications these days. Founded in 1936, they got bought by Memorex in 1988, got spun off in 1989 and then merged with Electro-voice in 1998. Bosch only bought them in 2006. Telex was in the audio equipment market from the get-go so very little of that corporate history narrows the window down. This eraser could have been made in the mid 1930s, except that the cassette wasn't invented until 1962. But sure enough, the bottom of the box reads "MFG. FOR TELEX COMMUNICATIONS, INC. MINNEAPOLIS, MN. U.S.A.  Based on the company name, and the catalog, this device was probably made in 1998 or 1999.

How well does it erase?  It does a better job than I expected, the results are not as different as I expected between the Telex and the Magneraser. With the Magneraser I get long audible segments interspersed with areas of total loss. The Telex seems to have less of those exaggerated peaks and valleys, though it didn't erase everything by any stretch. Thinking back, the late 90s were the end of the CD/Tape format war. [SOURCE] CDs were now 90% of the market. The CDs had won so cassette electronics were headed to the budget bin. So this wasn't limited to ancillary devices like this Telex. Almost all the tape player erase functions after the year 2000 seem to use permanent magnets. To make cheaper gadgets we got cheaper components. Res ipsa loquitur, the thing speaks for itself.

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