24 posts • joined Wednesday 27th January 2010 20:22 GMT
It's not just TV
There are plenty of other licenced users of unused TV frequencies. At work we pay an annual fee to enable us to operate a couple of dozen radio microphones in these channels. Are our microphones in this database? How do we go about getting remedies for interference?
What happens when they sell off even more of the spectrum for mobile services, squishing the existing TV multiplexes into a smaller pool and leaving even less space for other paid-up users? Who wins?
Having just spent *thousands* buying new radio microphones and having old ones retuned to move out of the 800MHz band, I would be utterly narked if the 700MHz band were cleared anytime in the next 10 years.
And leaving aside the problem of having them retuned *again*, if they clear channels down to 52 or 51 or wherever, things are going to be rather congested. Where am I going to find 24MHz for my microphones *then*?
Re: I'd like some choice!
It's the power supply that is the problem. You probably do want to change it every time you change a lamp. LEDs may have lifespans measured in tens of thousands of hours, but in my experience (we have a heck of a lot of LED lighting of various types at work) the power supplies are the weak point, often failing well within the lifespan you'd expect for a cheap incandescent. Only this morning I came in to work to find one LED fitting obviously a bit confused and thinking that the lift lobby was a disco. Dead PSU after less than a year.
There are all sorts of "low power" alternatives to "normal" lighting, and we've tried quite a lot of them. The quality of power supplies is a common weak factor and makes a complete mockery of claims of extended lifespans and lower total cost-of-ownership.
We've just bought two "LED" projectors (Panasonic, red and blue LEDs, green from a blue laser shining on a phosphor, DLP imaging unit). They are supposed to have lifespans of 20,000 hours before needing replacing. In our experience Panasonic build things as if they were destined for military service, so maybe, just maybe...?
Re: I'm not sure what the point it.
Oh, and (sorry for replying to my own post), speaking of my place of work (am I allowed to do that?), we have a "science show" this coming Sunday afternoon (the 19th) by members of the Bloodhound team. Come in droves - it's free entry.
Waterfront Museum: SA1 3RD
Re: I'm not sure what the point it.
If you want to see Babs at the moment (for a few more weeks at least) then she is at the National Waterfront Museum in Swansea complete with quite a lot of information panels. I walk past her a dozen times a day :-D
Re: Beth wyt ti'n meddwl?
Cewch pleidlais arall gen i
Re: 1TB? no problem!
"360 x 20W is 7.2kW, about the same as a somewhat weak electric shower unit, so you'd just have to spread the load over two domestic circuits and four 13A plugs if you weren't sure it would never spin up all the drives at once."
You wouldn't need two circuits; a standard "ring final" in the UK is fused at 32A and 7.2kW is 31A @ 230V. You'd probably need to use three plugs (each fused at 13A) to get the power to the racks, though it would be interesting to try pulling 15A through a 13A BS1363 fuse. I'm fairly certain that it will get warm but not fail, at least, not for a long time.
Of course that's assuming that your 20W at startup is correct - isn't it much more likely to be some kind of peaking curve? Might need to swap your B-curve MCB for a C-curve MCB if the transient is large for any appreciable length of time :-)
For those countries not blessed with the UK's rather "interesting" way of wiring houses I believe standard sockets radials are either 16A or 20A (you can do those in the UK too) so, yes, in those circumstances you would need two at 230V.
110V? Don't even go there.
Would just like to second the recommendation of the Epson Perfection. I have a V700 which has holders suitable for 35mm slides (12 at a time) and various sizes of film (if your strips are cut suitably you could potentially scan 24 35mm negatives in one go). The Epson software on the Mac is ok but does sometimes have problems auto-detecting frames. Have only used it under OSX so can't comment on other OSes.
And as for projected slides... yes a bit of a faff to set up, but I've used some *very* nice video projectors as part of my job and there is just no contest at all. Unless the slides have faded ;-)
Re: Old hat - unfortunately
I can see this might work in a very few tourist hotspots - tourist takes snap of self or family outside (shameless plug) Caerphilly castle, pops into the local Polaroid store, has snap slightly tarted up and printed into a format suitable for use as a postcard. Writes message and pops it into the postbox on the corner. We do something similar on a regular basis, except that we take one of those dye-sublimation(*) 6x4 photo printers on holiday with us - could run from a battery pack but we actually use an inverter in the car.
Fly in the ointment is that there's usually a Boots or something already nearby that can do very nearly the same job. In Caerphilly there is a Boots, and Morrisons also have instant printing facilities though sadly the local independent camera shop closed to make way for a Greg's last year (right next to an independent baker's too. How did *that* get past planning?)
The key would be the marketing as neither Boots nor Morrisons make a big fuss about their printing facilities, and certainly not in relation to tourists. I think there *might* be a market for Polaroid-branded self-service booths actually *in* the tourist hotspots, but these would have to work unattended.
(*)Dye-sub, for the bloke worried about longevity, is said by the manufacturers to be good for 100 years or so. Take that with a large pinch of salt, but in our limited experience so far the prints are vastly better quality and last longer than other home printing technologies.
Other hidden costs
I like the *idea* of LED or LASER projector "lamps" but I remain to be convinced.
What no-one ever seems to mention about LCD projectors is that the LCD panels themselves also have a finite lifespan. I work in a museum where we have quite a lot of projectors running the "exhibition" and the original-fit LCD projectors had panels with a 4,500 hour rated life, though I've seen documentation that suggests they were sold to the museum as having a 28,000 hour MTBF. I realise that our 7.5 hour a day use isn't typical of a home, but unless you have a normal TV too and only use the projector to watch two or three movies a week, 4,500 hours will creep up on you quite quickly (4 years at 3 hours a day). Looked at another way, if you have to be replacing the LCD panels every second lamp change (lamps are usually between 2,000 and 3,000 hours) then the cost of the lamps becomes a very minor issue. I wonder whether being illuminated by LED or LASER would increase this lifespan?
In practice it's not just the panels but also the colour filters - you will start to notice lower contrast, even with a new lamp, and maybe colour blotching (LCD failure - the blotches are often blue) or a colour cast (filter failure - yellow). We were quoted 5,000 EUR for a replacement "optical block" (3 LCDs, 3 filters and the prism). This was ridiculous when you consider that the projectors were also beginning to fail in other ways (e.g. PSUs not booting back up after a power down - 1,000 EUR or £3 of capacitors to DIY) . Instead we switched mainly to twin-lamp single-chip DLP projectors, the oldest of which are now around 11,000 hours and are (almost) as good as new (really must get around to that 10,000 hour service!). These particular models have lamps that last twice as long as the lamps in the old LCDs and cost significantly less. Twin lamps are a boon for us giving both security (if one fails, the projector continues to run albeit at reduced brightness) and flexibility (one of the projector models has effectively four output modes - both lamps or a single lamp, high power or low power - allowing us to choose brighness and lamp change interval).
DLP does have its problems, with fringing probably being the most annoying, but if that's an issue then all you need to do is to look at three-chip DLP or possibly (there are still issues, but they're not quite as bad) one of the DLP models with colour wheels with extra colours or which run faster.
A technology no-one has mentioned yet is LCoS. My warning here is that our five LCoS projectors have not lived up to the hype. When new, the picture was excellent but despite being a sort of hybrid of DLP and LCD with the intention of taking the best from both, the panels fade in exactly the same way as LCD, and at about the same age. On top of that the models we have seem to have "open" light paths and dust gets onto the panels quite easily.
As for the subject of the article I have to agree with others here. Half the price and twice the brightness might make it a good choice, but 1,600 lumen isn't really suitable for any room where you have any amount of stray light, unless the image is small enough that you'd be better off spending money on a nice LCD or plasma telly. At the museum, our lowest output projectors are nominally 2,000 lumen (twin lamp units in single lamp modes) which works, but it works mainly because the projected image is no more than 36" horizontally.
Finally, and I realise again that our use in a museum isn't terribly comparable to home use, it's worth considering networking. All our projectors have network sockets. Most will email a preset address when there's a problem (for example, they will email when the lamps have run for more than a certain number of hours) and all can be started and stopped by network messages (PJLINK). This is a prerequisite for us (who wants to go around manually starting 30-odd projectors?) but could also be useful in a "connected home".
When we moved house three-and-a-bit years ago the person who was buying our old house was able to disconnect our BT line without our permission, perhaps a fortnight before the move, simply by ringing a BT call centre. Quite apart from inconveniencing us it made things difficult with the bank, the solicitors, the removal company and the children's school, all of whom had our landline number as first point of contact. Three or four days later our ISP also cut us off because the line was no longer "live".
Suffice to say we took the opportunity to move away from BT for our new phoneline, but despite all our protestations and communications with BT and (eventually) the regulator, the consensus was "these things happen, sorry, here's a month's rental back". This incident strikes me as very similar. With just a phone number and a postcode a third party was able to take all sorts of action against a phoneline that isn't theirs.
Have to say we've had great service from our new phone supplier who seem to have a callcentre somewhere on Mersyside with real people answering the phone who actually know what they're talking about and we now use them for our ISP too. For example, "fixed IP sir? No problem" rather than "what's an IP address? Oh, I don't know about that, I'll have to pass you on to someone else".
I too thought it was odd that the boxes were tested in RAID0. Especially for a 4-bay box, RAID0 is just asking for trouble and - to my eyes - the fact that most of them achieved similar data transfer rates implies that there's a networking bottleneck, but I have also found that speed can vary enormously with the file system in use. It would have been nice to see comparative performance for at least RAID5, which is probably the best compromise at home for a unit like this.
We have two QNAP devices at work, one ARM-based, the other Atom-based. Both have four discs in RAID6 and the difference in processor power really shows, especially on writes. The ARM-based processor quickly hits 95% or more according to the GUI's meter and manages perhaps a third of the throughput that the Intel box does. RAID6 is particularly heavy on the processor because of the need to calculate a second, somewhat complex, checksum.
I built a FreeNAS box at home based on an AMD 450 (seriously considered the HP microserver but was put off by needing to throw out the RAM and wanting to use 2.5" discs rather than 3.5") and for work I built a third NAS based on an AMD A4 chip. That has space for 16 2.5" drives (in some very nice caddies which let you slot 4x2.5" discs into a 5.25" bay) and 16GB of RAM. Parts cost (without discs or case) was about £650 IIRC, but this includes three additional SATA cards and the drive bays. On those terms the hardware was a couple of hundred quid cheaper than the larger QNAP. In terms of read and write speed to its current 8 drives in Z2 (equivalent of RAID6) it wipes the floor with the QNAP devices, but I am having some problems with (I think) the onboard LAN. Should have spent an extra few quid on a nice NIC, but that's something I can do later.
Should be working. Better go :-)
Re: Ordered the 'B' flavour of Pi yesterday.
15 weeks? Ordered 20 Pis for work last week, shipped this week, though as I'm on holiday at the moment I couldn't tell you if they've turned up yet. RS have had some component supply problems but Farnell (E14) have stock on-the-shelf.
Or did until we wiped them out :-)
Re: Fast discharge as well?
> Standard in Germany is 3 Phase a´ 63A for a one family house.
> When the standard in UK is one phase, that would mean you have to run a 10mm² wire to your electric cooker
> and a least 16mm² to your fast water heater. Do i understand that right?
The key word in this part of the discussion that everyone is missing is "diversity" it is "diversity" (or in internet access terms, "contention") that allows individual ratings to total more than the supply is capable of delivering. I'm not sure if 2kW allowance per household is still the case in the UK - I suspect that it is a bit higher than that now, but it is certainly not the 20-odd kW per house that houses with 100A main fuses *could* suck because it is pointless putting that sort of infrastructure in when it will *never* be used.
Standard cable for a cooker (oven, 4 rings, attached socket) in this country is 6mm² which is protected with a 32A MCB (7.3kW @ 230V). It is assumed that everything is thermostatically controlled (so switches on and off all the time) and is not turned on at exactly the same time. Diversity allows 5A for an attached "13A" socket. A 32A MCB will take *minutes* to trip at a small overload - I don't have the tables to hand, but I think it is something like 5 minutes at 36A. Under some circumstances normal 6mm² "twin and earth" can be used under a 40A MCB, which deals with nearly all cookers, and for the others yes, 10mm² would be used.
"Fast water heaters" are not common in this country. Most people will heat domestic hot water using gas or another burnable fuel, and those that don't will use one or possibly two 3kW immersion heaters in the cylinder (ignoring solar).
Showers up to 7kW (not common these days) are wired in 6mm² cable while other showers (11.5kW is not uncommon) use 10mm². Diversity does not apply to "instantaneous water heaters". However, my advice (when I used to do the electricianing) was always that electric showers should be the last resort. If you have a cylinder full of hot water, use that instead. If you have a "combi" boiler it will be rated at 24kW or more - it will be able to heat at least twice as much water as an electric shower, and more cheaply as gas is *still* about a quarter the price of electricity per kWh delivered.
To other commentators - UK houses are almost without exception single phase 230V. Older premises have a 60A "service cutout" (main fuse that belongs to the supply company), a few are 80A and most modern houses (since the late 1980s probably) are 100A. All modern switchgear assumes 100A and more than 100A single phase is not (as far as I'm aware) available domestically. You would certainly have trouble finding a domestic consumer unit ("fuseboard") with more than a 100A main switch and 100A-rated busbars.
"Anyone else thinking of the Tommorrows World sketch on Not the Nine O'Clock news and the device to let deaf people know when their telephone is ringing!"
Not wanting to bring a downer on what was (mostly) an excellent programme, but deaf people do (or did, in the days before they all got SMS and email and instant messaging) use telephones. For one-to-one conversations there is the textphone (basically a modem with a keyboard and a small display) which can be used directly to another textphone user or via BT's typetalk service. For other things a lot of deaf users used fax machines.
Either of those works a lot better if you know when there's an incoming call :-)
Not all BT's fault
Anecdotally I find that a good speedup can often be had on ADSL simply by sorting out the internal premises wiring. We live perhaps 3km from the ("rural", BT-only) exchange in a straight line, probably double that by cable as there's a hill in the way. Our ADSL1 sync speed (which of course bears little relation to the actual download speed) is rarely under 6Mbps while neighbours are on 5Mbps or less. The difference? Our modem is connected directly to the master socket using a replacement splitter faceplate. A lesser difference (given that the splitter is good) is that extension telephones are wired in Cat.5 so there's less spurious noise.
An aquaintance was very pleasantly surprised when he moved his modem from the back of the house at the end of standard telephone extension wiring to the front of the house near the master socket. Of course it did mean installing network cable to the computers which stayed at the back, but the well-over 1Mbps sync speed increase was worth it he thought.
Already in production and not *terribly* expensive...
One of our suppliers has already sold their initial stock of these screens. They list both 46" and 22" screens, the 22" having 1680 x 1050 pixels. The 46" is available for around £1,150, which while a bit more expensive than your bog standard LCD TV isn't totally unreasonable. When I first heard about these things (which are, after all, just a standard LCD screen with no case and no backlight) I thought "niche product, it'll be around £5,000)". We have several possible uses...
> "- and I'm sorry to all those Linux coders out there, but your documentation *stinks* (*)"
> I don't agree. Some Linux-oriented projects have very good documentation, but some do have bad documentation...
Point taken - I think I probably meant FOSS coders, though I am also known to complain about commercial software, particularly that beast of a system Director (hence the Lingo reference). But then I'm using Director under duress, as it were. Anyone got any hints for something that can do similar things, preferably cross-platform, but is "nicer" to work with?
As for apps that are well documented, well the aforementioned BBC BASIC for Windows is pretty good and one of my other main apps - Xara - even comes with a chunky printed manual!
Must have a purpose
I, too, grew up on Spectrum and BBC Micro. The problem was what to do with them. The two hardware purchases that "unlocked" the Beeb for me were firstly a disc drive and secondly a printer, but without that *excellent* manual and the community (magazines) I would have been stuck and, as a previous poster has already pointed out, being able to "keep it all in your head" was phenominally useful.
I've recently come back to coding (of sorts(+)) after a <mumble> year gap and so in some ways I can see the problems of kids just starting out - the ecosystems are so vast and complex now that even just getting started is like dropping a weak swimmer off on Flat Holme and asking him to swim to Minehead. He has the basic moves, but he's not going to get very far without a lot of effort. Why bother? Light a fire on the beach and someone will come to rescue you. Need a simple utility to (oh, I dunno) crop a JPEG? Don't code one yourself, five minutes with a search engine and you'll get one already built and tested.
Something simple like this, or the Lego Mindstorms or that mbed thing or an Arduino or a Stamp is great - so long as the system is as well put-together as my Beeb was, and so long as there is an incentive to learn - i.e. a "killer project" that gets you interested.
So the problems I see with a bit of hardware like this are that
- you have to add hardware to it before you can do anything
- so if you're having problems with the ethernet, it isn't in the manual
- if it's running a Linux then it is not simple enough to keep in your head
- and I'm sorry to all those Linux coders out there, but your documentation *stinks* (*)
What it needs, is to look back to the Beeb, or the Psion series 3 or (better, I reckon) series 5 and work out what those systems did that made them such an easy-in and yet so flexible. Personally my favourite things were:
- the Beeb was almost fully documented and there was one official way to do everything
- there was even a circuit diagram in the back of the manual, right next to the memory map
- BBC BASIC (don't laugh) was way ahead of its time and an excellent launch point
- in fact some of my current coding is being done in BBC BASIC for Windows. Love it!
- the built-in assembler with its exceptionally easy integration into BASIC
- OPL's excellent user guide and documented API
- a small OS that is fully modular
- so that you only load up the functionality you need and so that other developers are forced
to assume nothing. It's more than that (I hate the way *ix scatters config files, for example) but
I can't think of a better way to put it
And on-line manuals are no substitue for the printed thing. If you're developing in one window, where's the convenience in having to have another open for the manual? Even my two-monitor setup is a pain, focus-switching being my particular rant.
Better stop and do some real work.
But at £15, even though I don't have an HDMI-capable telly, I'd buy it.
(+) Anyone else ever used Lingo? Talk about fighting to get it to do the simple things...
(*)Particularly (pet hate) VLC. In-app documentation is abysmal and the online documentation, help pages and community pages are so disorganised it's a wonder anyone not directly involved in developing the software can get anything slighly out-of-the-ordinary done with it.
The Diamond Age
Anyone else read William Gibson's The Diamond Age? I remember thinking when I first met a 3D printed object in 2001 (a spanner) that it sounded just like the first generation of machine that would end up as the "matter compiler" of Gibson's 1995 book...
I know these things take time, but most of the stuff given as examples here doesn't seem terribly far advanced over the parts I met 10 years ago, and it was obviously not new technology then sitting, as the spanner was, in a post-grad's desk drawer up (near) Sheffield...
My solution to the macro problem
Well, it's mostly a solution. I have a Logitech 525 and the trick is *not* to use the device "power" command to turn it on. Most of the kit I have will come out of standby if you press (for example) one of the numeric keys on the remote, so on my 525 I tell it to do that instead of sending the power command and that way if the device is already on, it doesn't turn off.
The downside is that for devices which will accept one digit as a valid channel number (e.g. most TVs) you end up switching channel, but that needn't be as much of a problem as it sounds.
In the subject of touchscreens versus real buttons; real buttons every time.
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