μblog: engineering from the trenches

As the deadline for abstract submission for the American Epilepsy Society meeting looms near (4th June), the whole lab is in a rush to get some final experiments done for presentation. This is partially the reason that the last few posts have been fairly low-quality. Unfortunately, this trend will continue until 5pm EST on Monday as most abstracts from experimentalists for conferences are written at the very last moment. IC Friday is still on for tomorrow and will feature a very popular microcontroller. Finally, next week, when there will be a little more time, I plan to implement a electrocardiogram system with a driven right-leg ground.

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Hide the children and lock the doors, Phrack #64 is available. This news is a few days late since I didn’t pay too much attention to the security mailing lists this weekend, nevertheless, better late then never!

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CMOS: Circuit Design, Layout and Simulation by RJ Baker is probably one of the leading texts on subject. The book is pretty reasonably priced and access to the digital versions of the figures is publicly available. The figures may not be able to teach you everything, but they are worthwhile to take a look at if you happen to enjoy IC Friday.

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This was the other Realtek chip, a highly-integrated ethernet controller, that I subjected to the sulfuric acid two weeks ago. Unfortunately, just as the previous chip, I did a poor job gluing the die to a microscope slide resulting in some glue on top of the chip. Like the previous chip, this one shows little surprises and no artifacts. The designers of the chip did include labels for each processing steps, somewhere around ten different procedures.

( rtl8101lv15.pdf )

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Sorry it took so long, but here they are: scale bars. To accomplish this, I took pictures of 50, 125 and 250 micron wire from California Fine Wire at 4x, 10x, 20x, 40x, 60x, and 100x magnification. The wire has a thin coating of polyimide insulation (~3-5 microns thick) that can be seen in the higher resolution 50 micron wire images. These images were taken on the same scope, with the same camera and objectives, as all of the previous IC Friday images, so the image dimensions are exactly the same for each magnification. I didn’t bother with 60x and 100x for 125 and 250 microns since their diameter was larger than the field of view.

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I really enjoy using my gyration mouse and keyboard set, so much so that I have recharged the mouse battery pack enough times to reduce its operating capacity to about an hour. I decided that it was time to replace the NiMH battery pack. Having taken apart portable electronics before, I was sure that the battery pack was actually built up from standard battery sizes to conserve on costs instead of a custom battery pack that one would find in an iPod or PDA. After carefully opening the pack with a razor, this notion was confirmed. The battery pack was simply three AAA rechargeable batteries held together with plastic. I promptly went to the store and bought a pack of 1000mAh NiMH batteries and constructed a replacement battery pack using the original metal pieces and electrical tape. Being careful not to use too much or too little, the resulting pack fit snugly into the mold and onto the mouse. After letting the whole system charge fully, I was able to get several days of use out of the mouse without running out of energy. On a final note, in retrospective, it may have been easier to just buy the replacement battery pack, if it was available, as its cost is comparable to the cost of the four rechargeable batteries, but that would not be as much fun.

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For a long time, I thought printing to PDF was limited to those owning Adobe Acrobat Professional. I was pleasantly surprised to find out that there is a free tool aptly named PDFCreator.

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Warning: This project deals with potentially dangerous voltages and should not be undertaken by those who are not properly trained in applicable safety practices. 

This post describes the final design of my power meter as promised in a previous post.  The basic ideas are the same: measure the current and voltage then multiply them and extract the DC offset for the average delivered power. The schematics and a bigger writeup are included in the PDF files below as well as a few results. It is not indicated in the schematics, but the power strip I chose has both surge protection as well as a re-settable fuse for further safety.

( power-meter.pdf ) ( power-meter-schematic.pdf )

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This is the die of a Realtek ALC655 AC’97  audio CODEC. This came off a P4 mainboard that burned out. Sulfuric acid was used to liberate this die, however, the black coatings at the top left and bottom right sides of the die are simply super-glue and the result of a sloppy mounting job by myself. Still no artifacts and a lot of metal on the surface. Some interesting features can be seen in the three successive 100x images with varying depth.

( alc655_datasheet_13.pdf )

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Bank of America, one of the largest financial institutions in the United States is having a promotion where they offer free admission to almost a hundred museums to their members in the month of May.  Basically, if the museum is on the list, you can get in free when you show them your Bank of America card. The museums are in New York, New Hampshire, Massachusetts, Maine, California, Florida, Delaware, Pennsylvania, New Jersey, Rhode Island, Connecticut and Vermont.

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