Back To School Online

In 1961, FCC Commissioner [Newt Minow] famously described TV as a “vast wasteland.” But TV can do great things; educational programming, news coverage, and great performances do appear, just not all that often. You can draw the same parallels to the Internet. Sure, it’s mostly cat pictures, snarky comments, and posts of what your friends had for dinner. But it can also be a powerful tool, especially for education. Recently, top-name schools and other institutions have posted courses online for everything from Python to Quantum Mechanics to Dutch. The problems are finding these classes and figuring out which ones are gems and which are duds. A site called Class-Central aims to solve these problems.

The site aggregates class descriptions from a variety of sources like edX, Coursea, and more. Users can rate the classes. Many of these courses are free to take. The recent trend is to offer the content for free, but charge for people who want an assessment, such as a certificate of completion or even a full-blown degree. Even then, the cost is typically far less than traditional college costs.

There’s also news about courses. For example, a recent post highlighted that edX now offers nine online master’s degrees in conjunction with major schools. A computer science masters from the University of Texas, for example, runs about $10,000. A Georgia Tech cybersecurity masters degree costs even less. There are another seven not ready yet, including one for electrical engineering.

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A Scanning Electron Microscope For The Living Room

There are hackers who have soldering setups on the dining room table, and then there are hackers who have scanning electron microscopes in their living room. [Macona] is part of the latter group, with a Hitachi S-450 SEM he’s repaired and modified himself. [Macona] has documented the whole thing on The Hitachi came to him and a friend as a derelict. First it was broken, then stored for 10 years. It turned out the problem was a high voltage cable cut and spliced with electrical tape. The tape eventually broke down and shorted out the 500V supply. Thankfully the rectifier diodes were the only parts that needed to be replaced.

analog1The SEM sprang to life and gave [Macona] and a friend their first images. However, SEMs are finicky beasts. Eventually the filament burned out and needed to be replaced. New filaments are $500 US for a box of 10, which is more than [Macona] wanted to spend. It turns out filaments can be built at home. A bit of .089mm tungsten wire and a spot welder were all it took to fix the issue. Next to go bad was the scan amplifier. While SEMs use many exotic parts, the Hitachi used relatively common Sanyo STK070 audio amplifiers for the purpose – an easy fix!

One thing that makes this SEM unique is the is Energy Dispersive X-Ray Spectroscopy (EDX) unit attached to it. The fragile liquid nitrogen cooled sensor was working, but the 1980’s era signal processing computer was a bit too old to bring up. A friend and fellow SEM hobbiest gave [Macona] a slightly newer Kevex Sigma Gold signal processor, which was nearly a plug and play upgrade for his machine. The new processor processor also gave him digital beam controls and a digital output which could be used to capture images with a PC.

Once all the connections were made, the EDX worked surprisingly well, even finding gold in a uranium ore sample placed in the microscope.

Now that old scanning electron microscopes being retired, it’s only a matter of time before more us get a chance to join the ranks of [Jeri Ellsworth], [Ben Krasnow] and [Macona] with our own personal SEMs!