hard drive data recovery

At 17:51 13-07-98 -0700, you wrote: Good! We'll be watching, Sam! :-) Yes there is a device used to count particles in the air. But you may not like the cost of them. My job involves work in our Class 10,000 cleanroom at my place of employment. A few of you others out there either once had or now work in such a company that has cleanroom(s), or possibly had spent time in a cleanroom as a service person. I can give a brief primer on how a cleanroom is built and short definition of the federal standard of cleanroom classes if some of you are interested. That would give a picture of the environment within which the drives had been manufactured and what one would do to make a simple one for his/her use. We make linear encoders of which the finest line size of the ronchi ruling on the encoder substrate is 4 microns (157.48 millionths of an inch.) Figure one micron = 39.37 millionths of an inch (0.00003937"). Most dust particles in 'free air' (the air we normally live in and breathe everyday) are in the 0.5 to 10 micron range. Therefore, keeping the air _clean_ during the manufacturing process has benefited us extremely well. Of course, semiconductor manufacturers fabricate microprocessors, transistors, all other IC's in cleanroom environments. Those hokey Intel TV advertisements with cleanroom workers in full body suits are actually not far off the mark with regard to the actual need to keep a class 10 or 100 cleanroom clean when making chips with sub-micron features. I had purchased a particle counter at work to check the "cleanness" of the air in various zones in the cleanroom. These machines are somewhat complicated though the basic concept used for counting particles is not. Most particle counters are sensitive. The one I bought is able to "see", therefore count, a *single* particle as small as 0.5 micron. Our unit has similar specifications as other typical brands of particle counters but it still cost us a little over US$10,000. Used equipment dealers have them for less but it's still not reasonable for the hobbyist or even a very small business. Maintenace parts and calibration is also a bit high. BTW, the air quality in most areas of our cleanroom stays at less than 100 particles per cubic foot. Very clean when considering that outside air which is relatively clean (say, the proverbial fresh mountain air) has 100,000 to 500,000 particles per cu. foot -more with forest fires, etc. nearby. If I do decide to tinker with some of my dead hard drives, I plan to bring them to the plant some weekend and have at it :-) I'll just slip on a boufont (sp.?) cap as a hair cover, special gloves, my lab coat and maybe a face mask of some sort, setup at an empty table and away I go! This is an extremely simplified version of a particle counter. I can envision it as having a simple LED emitter, probably IR, on one side of the hose and a photodetector on the opposite side. The detector and the analog front end may be rather sensitive to differentiate minute changes in light intensity. When significant amounts of dust and crap are sucked thru the hose the light is slightly occluded whichs lowers the output of the photodetector which then trips the circuit driving the red LED on your Panasonic vac. This is much too coarse of a device to measure air quality in any home-built glovebox/cleanroom any of us may build. It serves to show the homeowner that the Panasonic company's wonderful Model Such-and-Such is doing a great job at cleaning their house. Pure marketing gimmick but kinda neat on a home vac anyway IMO. Thanks for starting the discussion Sam, as a few of us who have the resources will need to get into it in the future -if not now. I can offer additional ideas and advice from my own cleanroom experience to the group on setting up a work area using either homemade or used commercial "clean benches", etc. Regards, Chris -- -- Christian Fandt, Electronic/Electrical Historian Jamestown, NY USA Member of Antique Wireless Association URL: http://www.ggw.org/freenet/a/awa/