Wikipedia:Reference desk/Archives/Miscellaneous/2019 November 12

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November 12

vibrating buildings

I've noticed over the past few months that every building I've spent much time in has its floor continuously vibrating, e.g. from some kind of HVAC machinery in the basement. It's real vibration (mostly felt rather than heard) and not a semi-mystical hum or anything like that. But, it seems independent of the weather, including in apartment buildings whose management wouldn't spend money running heating or AC unless external temperature requires it. It persists well past midnight and starts in the early morning hours, though it sometimes stops in the wee hours like 3am. It is detectable outdoors near the affected buildings (like in the parking lots) and I guess I should go check further away. Any idea what is going on? This is in multiple locations around the SF Bay area. Thanks. 67.164.113.165 (talk) 04:06, 12 November 2019 (UTC)

The timing implies it's a human activity which ceases, or at least reduces, at night. One thought is that vibrations from passing traffic may cause resonance in the buildings. Also, the fact that it's San Francisco, which is prone to major earthquakes, may be relevant. Buildings can be designed in such a way as to alter the resonant frequencies, but in an earthquake zone, they likely put all their effort into avoiding resonant frequencies which would be triggered by quakes, as those could collapse the building, and meaning that avoiding resonant frequencies caused by other sources, like traffic, would be a low priority. SinisterLefty (talk) 04:58, 12 November 2019 (UTC)

I've noticed it in SF and also where I am now, in the east bay. Resonance of road traffic? Hmm, maybe. There is no open space to speak of in SF but in the east bay there are some parks that I might visit to check for this. OTOH I remember noticing a vibration and hum in Ed R. Levin County Park that got louder and stronger as I got nearer the summit of "Mount" Ascension or whatever they call that hill in the park (about 1200 foot vertical iirc). Sure enough, right at the summit, there was a shed full of vibrating equipment, presumably diesel generators powering the radio transmitters that are also up there. 67.164.113.165 (talk) 05:17, 12 November 2019 (UTC)

Yes, there may very well be multiple sources for the vibrations, with traffic being just one. SinisterLefty (talk) 05:48, 12 November 2019 (UTC)

It could also be from pumps that maintain the water pressure in a high-rise building. This could be pneumatic tanks in the basement or reservoirs on the roof. It could also explain why there is less vibration at 3 a.m. - people are typically sleeping so water demand is low and the reservoirs and tanks are full. See: https://www.quora.com/How-does-water-distribution-work-in-high-rise-buildings 41.165.67.114 (talk) 07:20, 12 November 2019 (UTC)

Hmm, this is sort of possible. There aren't really high-rise buildings outside of downtown SF, but maybe there are water pumps in these 3 to 5 story buildings. It's odd that they run almost all the time though, rather than turning on when the tank level gets below X, and stopping when it gets above Y. Thanks for the new (to me) idea since I've been thinking more along the lines of heating and ventilation. I'll keep looking around since it is really puzzling me now. 67.164.113.165 (talk) 08:35, 12 November 2019 (UTC)

For max cost efficiency you'd want pumps that barely meet the demand, so must run nearly constantly. The tanks would provide a buffer for when demand exceeded the pumping rate. SinisterLefty (talk) 03:01, 13 November 2019 (UTC)

Is the first statement correct? In place where I live, in almost all buildings, every morning/night pumps run for an hour or two to fill overhead tanks that supply water for next 24 hrs. If running pump constantly is efficient, at least a few buildings would have opted for it, since cost cutting is always a priority for housing societies. manya (talk) 04:47, 13 November 2019 (UTC)

If electricity prices are lower at night, that changes the equation. Then you may want pumps that can fill the tanks overnight, then turn them off when the price goes up. But pumps that can supply a days worth of water in an hour or two still seem like way more than is needed. Perhaps the problem is that water usage is hard to predict, and they need a huge overcapacity, in case somebody leaves the tap running full blast all day. SinisterLefty (talk) 04:57, 13 November 2019 (UTC)

Electricity price is same for all 24 hrs. Couple of years back an AC technician explained me that it is energy efficient to run a larger AC that cools room to desired temperature and switches off and on at regular intervals than to run a smaller AC perpetually. Water pumping problem appears to be in similar lines. manya (talk) 05:51, 13 November 2019 (UTC)

Did you get an explanation as to why ? All I can think of in the case of the A/C is if the small unit is so underpowered that it can't keep up, it would then be necessary to cool the room below the desired temp at night, in order to keep the temperature from rising to an unacceptable temperature during the day. SinisterLefty (talk) 06:30, 13 November 2019 (UTC)

Here in the UK, I work in a college. In one of the buildings, a couple of the interactive whiteboards in the first floor classrooms, wobble when you walk by them. These are mounted on internal walls, which are just partitions, so I can understand that. What is strange is that a board mounted on an outside wall wobbles when a truck goes by on the road outside. TrogWoolley (talk) 14:56, 13 November 2019 (UTC)

That is consistent with my theory of passing traffic causing resonance in the building structure. The boards could be mounted with rubber behind them to absorb and dampen this vibration. SinisterLefty (talk) 16:25, 13 November 2019 (UTC)

Interestingly, the vibration has currently stopped, though the amount of outdoor noise is about like usual. I still have the impression it originates in the building or very close by. I'll go outside to check the surroundings. But I figure it could start again at any moment. 73.93.155.83 (talk) 22:11, 13 November 2019 (UTC) (Hmm, my IP address suddenly changed too, typical of a network reset. Could that be related? Maybe there was a power interruption nearby that stopped some machinery and also made the upstream network reboot. Power here in the house has been steady, I think. But I might not have noticed a temporary network outage if I was away from the computer). 73.93.155.83 (talk) 22:15, 13 November 2019 (UTC)

Let us mention here the existence of the Tuned mass damper. Temerarius (talk) 20:12, 15 November 2019 (UTC)

Yes, thanks. That's one method of damping harmonic vibrations at certain frequencies, but, as I said above, in an earthquake zone priority must be placed on damping out probable earthquake vibration frequencies, so vibrations at other frequencies, which are merely annoying, must be tolerated. SinisterLefty (talk) 20:44, 15 November 2019 (UTC)

Does this phone voice amplifier exist ?

My elderly mom has a quiet voice, which is a problem on her phone, which works just fine when I speak into it. Specifically, many phones she calls think her quiet voice is background noise and filter it out. I am hoping there is a device she could screw into the receiver part of her phone, which would amplify her voice, without distorting it. Ideally it would have a power cord, not batteries, since if the batteries went dead it might be worse than nothing. Does such a device exist ? If so, what keywords should I use to find it in a Google search ? Alternatively, are there phones specifically designed for people with quiet voices ?

I did find this device: [1], but it's $120 and uses a battery that only lasts for 20 hours of talk time, so I would need to go to her house and replace it for her maybe once a week. I'm hoping there's something both cheaper and better. SinisterLefty (talk) 08:24, 12 November 2019 (UTC)

Look at some of these. It could also be that her existing phone has low mic level (especially if it's an old phone with a carbon mic), in which case a normal new phone could help. Here is a weird old page that you might also like. 67.164.113.165 (talk) 08:53, 12 November 2019 (UTC)

Also this. Relevant search term seems to be "weak speech" along with "outgoing voice amplification" and the like. Note that if your mom has hearing loss, you might be able to get this assistive phone stuff for free from state disability programs. 67.164.113.165 (talk) 08:59, 12 November 2019 (UTC)

Thanks, the Clarity XLC4 at the first link looks like the best option. (I can't figure out why their XLC3.4+ costs almost twice as much. The only advantage I can see is that it amplifies incoming calls 50 dB instead of 49. Am I missing something ?) SinisterLefty (talk) 09:38, 12 November 2019 (UTC)

Don't know. Some of them say "digital" which might mean voip phone? You could call the company and ask, maybe. I don't like that they are all DECT i.e. cordless. I like landline phones to actually plug into the phone jack. I'd consider keeping on looking. You can probably homebuild something very cheaply, but it might not be worth the effort if you can afford the ready made stuff without straining. Or you could look at a headset mic, if your mom is willing to use one. I had one for a while (used for work related conference calls when we had those) and it was great for that. 67.164.113.165 (talk) 18:29, 12 November 2019 (UTC)

Digital Enhanced Cordless Telecommunications is as you may guess from the name, digital. There's no such thing as analog DECT. The connection between the handset and the base is always digital, it's part of the standard. Analog cordless phones used to exist, but I'm not sure anyone makes them anymore. I'm not that familiar with the details of the DECT standard, but I don't believe it would be accurate to call it VoIP. For starters, I doubt they use Internet Protocol. The DECT base can connect directly to a VoIP network e.g. IP-DECT, most likely connecting to SIP. Or it could have an analog output to connect to a POTS system, probably still the most common type at least for consumer oriented devices. Nil Einne (talk) 04:34, 14 November 2019 (UTC)

I should clarify I was mostly thinking of old more traditional DECT systems when I said I don't think they use internet protocol. From a quick read of the article, it's possible that stuff like DECT Ultra Low Energy or maybe some of the even newer developments use IP internally. I don't know. Nil Einne (talk) 04:45, 14 November 2019 (UTC)

I don't think she'd wear a headset. Too worried about messing up her hair. SinisterLefty (talk) 04:54, 14 November 2019 (UTC)

Voting systems in the FLA precincts in 2000

Hi, I corrected my request: even if this system was widespread in only 24 out of 67 counties, is it possible that the punched card system was the most widespread method of voting at the state level, what about the general precincts? I say this, because these machines were the ststemi also used in the most populous counties, and this affects. I would have found the source to be reliable, I need a confirmation. If you go to this link on page 633 (9/74) there is a table with the voting systems and the numbers expressed with the systems themselves. Out of 6 million votes in total, 3.7 million preferences were expressed with punched card systems.I need the percentage of the precincts, but I think it's a forbidden request, however it is easy to presume that the majority of state voters in that year used and voiced their votes with the Votomatic machines, the sucittate ones. It is the first table. Thanks. https://scholarship.law.berkeley.edu/cgi/viewcontent.cgi?article=2525&context=facpubs — Preceding unsigned comment added by 93.41.100.198 (talk) 14:30, 12 November 2019 (UTC)

Did you know...

How often is the front page "Did you know..." section updated? Thanks Anton 81.131.40.58 (talk) 15:26, 12 November 2019 (UTC)

See WP:DYK. It's a chaotic institution prone to fits of drama but you can see its output on the relevant project and talk pages. 67.164.113.165 (talk) 18:31, 12 November 2019 (UTC)

Once per day. See Template:Did you know/Queue#Local update times for the specific times when it is changed. --Jayron32 18:41, 12 November 2019 (UTC)

Latest cameras using photographic film

What are the most recent camera models to use photographic film? Thanks. 212.180.235.46 (talk) 18:09, 12 November 2019 (UTC)

There are dozens or hundreds of film cameras still being manufactured today. Here is a list from Amazon; I am not endorsing that seller, merely posting it for examples. --Jayron32 18:44, 12 November 2019 (UTC)

Nothing on that page says that these are newly manufactured cameras. One of them is even identified as "vintage". --76.69.116.4 (talk) 20:13, 12 November 2019 (UTC)

Yes, one of them is. Not all of them though. --Jayron32 20:37, 12 November 2019 (UTC)

My point was only that it doesn't say. --76.69.116.4 (talk) 07:19, 13 November 2019 (UTC)

It appears that the Nikon FM10 is still being made. And according to Google, there is still film being made for film cameras. One funny thing, checking in Google, is that there are guides on how to use film cameras. Not that there's anything wrong with that. But it shows how dominant digital has become. The situation reminds me of the "buggy whip" speech from Other People's Money. But there is still a market for buggy whips. Just not a large one. Like with vinyl records, which appeared to be dead but have made a comeback in a niche market. ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:51, 12 November 2019 (UTC)

And newspapers (the physical kind) are becoming a niche market, too. SinisterLefty (talk) 21:29, 12 November 2019 (UTC)

I don't think we're there yet. That niche is still pretty good sized. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:05, 12 November 2019 (UTC)

A pity the newspapers aren't. --76.69.116.4 (talk) 07:19, 13 November 2019 (UTC)

If you've got a deep pocket, the Leica M-A is still being manufactured. (They also offer a digital camera in their famous M series.)

Or if you're on more of a budget, you could get a Fuji single-use ("disposable") camera.

Plus there are still instant cameras being made (not by Polaroid, though), and I think a few pro-level large-format cameras are still available, but I'm not sure where to look for those.

ApLundell (talk) 23:27, 12 November 2019 (UTC)

The Nikon FM-10 (actually made by Cosina) was introduced in the 1990s and the ones being sold now are surely from inventory manufactured quite a few years ago. Yes there are lots of film cameras that you can buy off-the-shelf new with warranty (Nikon F6 is probably the most serious of these in 35mm format) but I thought the question was what models were introduced the most recently. And I'd guess that the answers for ordinary photography at the pro level would be incremental updates to medium or large format cameras. Plus there would still be new special purpose scientific or medical cameras like x-ray cameras, and disposable and Holga-like cameras that are always coming out in new variants (Flintstones logo or whatever). But yeah it's mostly a dead medium.

I still have a bunch of 35mm gear that I haven't used in maybe a decade. Ironically it includes a Nikon FM-10. I'd advise against buying one of those since the film advance mechanism breaks very easily. Mine was fixed under warranty but if you're thinking of buying a mechanical Nikon as a keeper, look for a decent FM2. 67.164.113.165 (talk) 23:48, 12 November 2019 (UTC)

X-ray (film) cameras are practically extinct now, in favour of digital. The instant image availability is one aspect, but the reduced operator (or patient) X-ray exposure with more sensitive digital sensors is the main advantage. Andy Dingley (talk) 00:07, 13 November 2019 (UTC)

Oh that's interesting about medical x-ray film. I wonder if industrial x-ray film is still used. I remember seeing some mil-spec resistors each packaged with an individual x-ray to show it had no internal defects. Nice about the Leica M-A having no metering system. The classic was the M3 double stroke and they continue to increase in value (just checked ebay and they are well over $1000). Here is B&H Photo's (a reputable pro-oriented photo/video dealer) page pointing to its remaining film camera selection. It's all medium and large format except for the Nikon F6 and Leica M-A and some cheap P&S/disposables in 35mm. But surprisingly some of the old stuff is holding its value on ebay. It's all over the place. Craigslist is also a good place to look if for some crazy reason you are trying to buy this stuff. Can I ask OP what prompted the question? 67.164.113.165 (talk) 05:07, 13 November 2019 (UTC)

X-ray film is still widely used in the life sciences for things like autoradiography and in the more old-fashioned labs for Western blots. Fgf10 (talk) 09:07, 13 November 2019 (UTC)

15 Film Cameras You Can Still Buy Brand New; admittedly this page is three years old. Alansplodge (talk) 17:09, 14 November 2019 (UTC)