Re: 100% honesty 90% of the time
Eddies in the space-time continuum.
Mine's the one on the sofa.
12 posts • joined 21 Apr 2018
It's likely that the emergency generator had harmonic content that was tripping the cheap clock's zero-crossing detector multiple times per cycle. Or perhaps the generator's output was not as "stiff" (low impedance) as the mains source, allowing harmonics generated by some other load (switching power supply, perhaps?) to propagate when the generator was sourcing power.
My wife's digital alarm clock runs crazy fast when the washer runs. It started when we replaced the old top-loader with a new front-loader. The old one had a mechanical timer and an induction motor. The new one has electronic controls and a direct-drive motor for the drum -- not sure whether it's DC or variable-frequency AC. But whatever it is, the drive electronics must be putting spikes on the power line, causing the clock to run crazy. Our solution was to ignore the clock and use the alarm function of our mobile phones.
When I was in college it was impossible to sleep in on the days they would test the dorm's emergency generator. The exhaust pipe ran up through interior partitions to exit through the roof, and it was so loud that I doubt that it had a muffler. It made an awful blatting noise if you were outside, too.
Early, full-height 8 inch floppy drives had synchronous spindle motors. We added CP/M systems at field sites that had 10KVA UPSes to support a redundant minicomputer system. Some of the backup disks from field sites were unreadable at the home office. Turns out that these 1970s-vintage UPSes had free-running oscillators and were not crystal-controlled or phase-locked to the mains. The frequency could be off by a couple of hertz, changing the spindle speed proportionately.
We set up an audio oscillator, a 100-watt public-address amplifier, and a transformer to power one of the system's 2 drives, tweaked the frequency until the drive could read reliably, and PIPed the data to a fresh disk in the other drive, which remained powered by the utility.
The later, half-height drives ran on DC and did not have the issue.
I do field service work. A lot of calls read something like "repair/replace the cabling to X". It usually isn't the cable. When it is, it's often the jack, particularly in the deli department or the meat department prep room -- anywhere that's moist or gets washed down. The (supposedly) gold-flashed contacts in the network jack turn green, or the punchdown contacts do. Replace the offending jack, and the problem is solved for a few years.
Some of the companies that hire my services treat me like a monkey with a screwdriver, not trusting my diagnostic skills. Being directed by levels 1, 2, AND 3 of contracted tech support from "Bob" in Bangalore (or wherever) to replace the cable from the modem to the router, and try it again, and again, when it is clear to me that the router's WAN port was fried by the electrical discharge that caused the ISP to replace their modem the previous day, is an exercise in frustration. The restaurant manager said that he'd lost printers and a dishwasher to the same storm. I had the fault diagnosed within 20 minutes of arrival, but it took 4-1/2 hours to persuade their Level 3 that the magic smoke had been let out of the WAN interface, and they needed to send a replacement router. I console myself with the fact that I am paid hourly for these gigs.
I carry a $50 cable mapper that will detect some of the gross faults. High-end cable certifiers are pricey and hard to justify. But I have a laptop with a Broadcom network interface, and a copy of Broadcom Advanced Control Suite (BACS). This software uses the NIC's inherent diagnostic capability to perform cable analysis, I assume through time-domain reflectometry. It will tell you the length of each pair in meters (the measured lengths vary due to different number of twists per foot from one pair to the next, to reduce crosstalk). It also detects crossed pairs (such as when you misread the colors and exchange the white-of-blue for the white-of-green, for example). It seems to be accurate to within a meter or so.
It's not calibrated, certainly not traceable to NIST standards, but it will give me enough indication that the fault is at the near or the far end of the cable (or, in one case, 50 feet from one end) that I bring it to all the gigs. It is quite persuasive to be able to say "My laptops connected to each other at 1Gb/s over that cable, and cable analysis didn't show any faults".
I've made adapters to be able to test telephone cables terminated in 6-position jacks, and even CCTV coaxial cable, using it. The velocity factor of other cable types may differ from Cat5, throwing the length measurement off. But it's certainly good enough to tell you whether it's the near, or the far, end of the coax that has the badly-crimped connector. If you care to know the actual length, use BACS to analyze a known length of the cable in question, and divide the measured by the actual length to get a correction factor.
So give that old Dell D610 a new life as a cable analyzer, or get a more modern (and portable) device such the Pockethernet, so you can have some more substantial evidence to point to and get those outsourced cabling guys to do their job right the first time.
I've recently done some site surveys for which I signed papers in which I agreed to wear safety shoes, high-vis, hard hat, and safety glasses, among other things. . . to do a site survey in which I was taking photographs and notes in the network closets of a big-box retail store.
The high-vis did seem to be an effective deterrent to customers buttonholing me to ask product questions, which they otherwise tend to do when they see someone wearing a badge.
Mine's the high-vis one.
Just last weekend I was sent over an hour away to a shop that had lost network connectivity to one of its cash register servers. The machine was up, but there was no link light. Got out the cable tester; it showed open circuit on all pairs. I poked around and discovered a patch cord plug that wasn't fully seated in its jack. Shoved it that extra millimeter home, the latch caught with a snap, and I was a genius.
I was told that it had been installed 2 weeks previously, and had been working fine. Just took that long to creep out far enough to lose connectivity.
Had to buy my own cuppa, but hey -- emergency overtime!
Well... Inflammable is the original word, from the Latin, I think, meaning "capable of becoming inflamed, a.k.a. being set afire". The "in" part is not a negative in this context. So non-inflammable is only a single negative. But the poorly-educated didn't understand this, so the back formation "flammable" was created (by the lawyers, I suspect). Perhaps if the original had been spelled "enflammable" the confusion would not have existed in the first place. I blame the Académie Anglaise for not properly instructing (by analogy, structing?) us in the first place.
Mine's the Nomex one.
I did something similar at my daughter's apartment recently. Hung a shelf on the outside wall of the bathroom. Used the toggling plastic wall anchors and screws provided with it. Didn't notice that the screws were long enough to catch the pocket door, until someone went to close the door to use the facility. Was able to cut off the tip of the screw for clearance, once the plastic toggle had been drawn up. I still owe Mr. Landlord a spackle-and-paint repair of the door.
We were looking to install fiber optic links from one building to another to get away from stuff getting all blowed up when there was a lightning strike. The AT&T sales dude who called on us apologized for the pens that he was about to give us. They were starting to rust, inside their cheesy packaging, Death Star logo and all. We took them off his hands to help him get rid of them. They didn't write so well, either.
We didn't buy his fiber optic connectors, for other reasons.
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