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Comment Good, more for me.... (Score 4, Interesting) 89

Have tried all of DFH's "Ancient Ales" (except the Kvasir which hasn't showed up locally yet), and they were all interesting and surprisingly drinkable. Their "Theobroma", a cacao-based beer based on a Honduran recipe is one of their best products.

Dogfish beers aren't for everyone. But their slogan "Off-Centered Ales for Off-Centered people" should explain that...

Comment I'll see your 6900, and raise you a 7AK7... (Score 1) 165

, which was arguably the very first electronic component specifically designed for use in computers. Most of the magic was in the ultra high purity nickel used in the cathode sleeve, to prevent interface formation and "sleeping sickness", which would result from even the slightest trace of silicon impurity in the nickel.

http://www.radiomuseum.org/tubes/tube_7ak7.html

Every electronics geek needs one of these on their desk. Fortunately, there were millions made, and they come up on eBay cheap, as they have no value to the audiophools....

Comment Mass tube swapping ignores the "bathtub curve"... (Score 1) 165

This was a major lesson that was learned during the early tube computer era. The best approach was NOT simply swapping out tubes after so many hours "to prevent in-service failures", but periodically running diagnostics checking pulse levels, etc.to identify tubes that were actually starting to slump off.

The failure rate vs life curve for most components (tubes included) has a high initial failure rate (so-called "infant mortality"), followed by a long period of low failure rates, which eventually trends upward at an increasing rate at end-of life. This produces a curve with a flat bottom and 2 peaks at the ends, like a cross-section of a bathtub.

By swapping out tubes before they hit the end of life, you push the entire tube complement in the equipment over toward the "infant mortality" end of the curve, actually INCREASING the failure rate over careful monitoring and replacing only those tubes that are actually starting to fail. All that tube swapping also results in increased failures through the increased handling of the glass tubes (breakage and seal leaks), wear on the sockets from pulling and inserting tubes, etc. The highest equipment uptime was achieved by not actually replacing tubes on a fixed schedule, but by overall system checks to identify and replace individual failing tubes BEFORE they progressed to the point of total failure.

Experience with electronic installations containing tens of thousands of tubes produced a huge amount of statistical data on component reliability, laying the foundations for modern reliability models and MTBF calculations.

A good read from 1960, when all this was being figured out is "Getting the Most out of Vacuum Tubes" by Bud Tomer, available on Archive.org:

https://archive.org/details/GettingTheMostOutOfVacuumTubes_105

Comment Filaments are generally under-run, as well... (Score 1) 1146

A typical "rough service" incandescent lamp intended for use on 120V contains a filament actually designed for normal light output at 130V. By underheating the filament, the filament retains more strength when lit, and is better able to handle shock and vibration in hand-held worklights, etc.

This negatively impacts efficiency, though.

Comment Re:Various applications in electrical equipment??? (Score 1) 216

Sold by 3M under the trade name "Fluorinert FC-43". Used primarily as a heat transfer fluid in exotic electronics.

The best known application to Slashdotters would be the Cray 2 supercomputer, which used a fluorinert "waterfall" to remove waste heat from the densely packed electronics. Some overclockers use it on high performance gaming rigs and the like, with the entire motherboard submerged in a bath of the stuff.

Because of the very high dielectric strength and low RF loss, it was used as a cooling medium in military radar gear, particularly airborne stuff.

Comment Not exactly a great idea for a legal defense... (Score 1) 670

Once you talk about making extracts (hash, hash oil, etc.) from your pound of weed, you move from "possession with intent to distribute", to "manufacturing of a controlled substance", the same charge that running a meth lab would get you.

Since you are now manufacturing, and not simply presumed to be selling, you move to the top of the food chain, and will make a great trophy for some ambitious narco-swine.

Comment I have 3 'scopes in the home lab at the moment.. (Score 1) 215

From newest to oldest:

Rigol DS1052E--A "cheap and cheerful" Chinese import 50 MHz 2 channel DSO. A good general hobby scope, easily upgradeable to 100MHz bandwidth with a simple reflash of the firmware. Has a sizable following in the hardware hacker community because of the high "bang for the buck" factor.

Tektronix 7623: A 3-slot mainframe with 75 MHz bandwidth An 1969 vintage analog storage scope, which accepts various interchangeable plug in units to give a huge range of features. Actually has an on-screen display for V/div and Time/div, which was bleeding edge stuff at the time it was introduced.

Tektronix 453: A 1963 vintage portable field service scope (designed for servicing IBM mainframes). Dual channel, 50 MHz. Built to take constant abuse and just keep working. Still a VERY usable scope for general purposes, and has the sharpest brightest trace of any scope I have ever used.

Comment Re:A **teacher** in every classroom (Score 2) 152

It's embarassing b/c essentially its the same thing as that plastic mold machine at tourist attractions that can make you a plastic souvenier of the Washington Monument.

At least those "mold-a-rama" machines demonstrate real-world manufacturing techniques. There are a hell of a lot more injection molding machines out there cranking out parts than there are 3D printers, that's for sure.

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