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AV and Multimedia Related Thread, Turning off projectors during breaks and lunchtimes... in Technical; In a perfect world it would be nice to get teachers to understand on/off requirements and all the expections to ...
  1. #16

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    In a perfect world it would be nice to get teachers to understand on/off requirements and all the expections to the rules, but it ain't gonna happen.
    A blanket rule of 'swith it off when not in use' is the best here as rooms and classes are timetabled here like a crazy conveyor belt and you never know who needs or doesn't need to use a projector.

    Auto shutdowns after no PC signal for 1 hour are set where possible, as teachers tend to think they only need to shut down the PC and not bother with anything else.

  2. #17

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    I agree with Pottsey. We examined 2 lamps installed on the same date with new projectors. The first to expire was the teacher who had been turning it off and on for lunch, about 1500 hrs I think. The lamp left on at lunch lasted 2500 hrs, again general figs. So the expansion and contraction of a hot/cold/hot/cold lamp precipitated an early demise. Nerdy, eh?

  3. #18

    Sylv3r's Avatar
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    One step at a time for us here.... i'd be happy if they turned the off on a night never mind during the day.

    We've set them all to autoswitch off, but if the staff use the no show or freeze option it seems to be overridden. More often than not, during a half term break when I do a walk around the school I can enter a classroom and hear the fans of the projector running generally on the Thursday or Friday after being left on from the following week.

  4. #19

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    We need projectors with ethernet ports. Then once you have the IP addresses reserved in DHCP or static you can look at the units which are still on, using your browser.
    Can even monitor lamp life too.
    At the very least a batch file to ping the IP and if active tells you the location so you may go and switch it off. Especially Fridays.

    Quote Originally Posted by Sylv3r View Post
    One step at a time for us here.... i'd be happy if they turned the off on a night never mind during the day.

    We've set them all to autoswitch off, but if the staff use the no show or freeze option it seems to be overridden. More often than not, during a half term break when I do a walk around the school I can enter a classroom and hear the fans of the projector running generally on the Thursday or Friday after being left on from the following week.

  5. #20

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    A lot of projectors can be controlled by serial ports (or service ports on the sanyos). I've got this idea of hooking up a raspberry pi board with a serial cable and a cheap wifi interface. Retro-fitting a network cable to each projector seems like a lot of work. I wonder what the cost is of running projectors without turning them off, and how much it would be worth spending financially automating it?

    I think at the moment, setting the timeout and getting staff to turn them off when not in use is the most workable solution. Staff are never going to have the patience to workout how long until its next going to be used. 'Turn it off when you leave the classroom' might not be optimal, but its better than leaving them on all night.

  6. #21

    nephilim's Avatar
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    Generally you could have it set so that if after 30 minutes of no use it switches off. I did this and it generally cut down the energy consumption and saved the site agent a fair few man hours every week not turning them off! (With over 90 on one site, he would spend walking around, locking up, switching off projectors etc.

  7. #22

    Sylv3r's Avatar
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    Quote Originally Posted by nephilim View Post
    Generally you could have it set so that if after 30 minutes of no use it switches off. I did this and it generally cut down the energy consumption and saved the site agent a fair few man hours every week not turning them off! (With over 90 on one site, he would spend walking around, locking up, switching off projectors etc.
    The problem that we find with this and we have it setup here is that the projectors on freeze or blank screen don't switch off even after no signal.

  8. #23

    nephilim's Avatar
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    Depending on your brand of projector, you can turn it off even through this method whilst its on freeze etc. Epson and Sony projectors are good for this IME

  9. #24

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    The striking of a lamp does reduce its life but the compare this to hrs used i would say if you have a break of 90 mins or more turn it off if less leave it on same with Flourecent lamps.

    Marc
    Projector Engineer

  10. 3 Thanks to Marc-Engineer:

    Little-Miss (22nd March 2012), Oaktech (20th March 2012), SimpleSi (20th March 2012)

  11. #25

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    Never do it for 10mins (think of the thermal cycling going on ) - lunchtime is up for debate
    (I vote for leaving on )

    Si

  12. #26
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    Ours here are generally left on all day, every day, which I'm happy with.

    The exception is if classes have something like PE straight after lunch, in which case that's anywhere up to 2.5 hours when it would be on pointlessly - I try and encourage them to turn their projectors off for things like that but even then, I'm not going to stress over if they don't.

    From a 'green' point of view they probably should only be turned on just before they want to use them and turned off as soon as they are done - but realistically that's never gonna happen in a school environment!
    Last edited by Pete10141748; 20th March 2012 at 02:24 PM.

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  14. #27

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    OK before I start this is in no way in reference to the above post mentioning GREEN its just so many people quoting GREEN from very old notes, eg. I was told “you must turn off TVs at night at the socket”,…..(oh boy) this is the worst thing you can do for “Green” as this will shorten its life “but” they say “it will use 45% of its electric when in standby” (lol) not even close to true, most 42” TVs now use less than 1w on standby so in a school year if you don’t unplug it, it will cost you about 30p, why will it cost more to unplug it? Because they are designed to come on from standby (electrically warm) not from cold (stressing the components) this is the same of may bits of modern kit. Starting it from cold every time will shorten its life, think about it when you last had a failure lamp or other wise when did it fail? I bet it was at turn on from cold. True even of house lights………

    So be “Green” leave it on............

    question:- Whats the biggest waste of power in a school?
    answer:- laser printers left on overnight (they use a massive amount of power, only very new ones use "proper" power saving)

    Marc
    Projector Engineer
    Last edited by Marc-Engineer; 21st March 2012 at 12:56 PM.

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  16. #28
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    My vote goes to "turn it off when not in use, at lunch and end-of-day". I was always keen, but even keener after we found an HP projector melted after a half-term. The question of power-cycles shortening the life of the lamp? Okay, where's the evidence for this? The physics is clear with incandescent lamps (the filament is low-resistance when cold) and with flourescent lamps (startup surge strips the cathode material), but why would a power-cycle shorten the life of a high-pressure Xenon lamp? Granted, the globe can shatter, but they do that anyway apparently at random - ever wondered why they warranty them for 90 days? End-of-life failure occurs because the electrodes sputter and shorten, the arc gets hotter and the globe mists up with condensed metal vapour. All this happens only at full brightness, not at switch-on.

  17. #29

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    Its just a judgement of statistical chance.

    Their is an x% chance of the bulb blowing at a point in its projected lifetime which I believe increases with age.

    Leaving it on for an hour extra at lunchtime just ever so slightly decreases the total expected number of days that the bulb will last.

    You pretty much know what the downside is.

    Turning it off and on again on the other hand - doubles the number of times the projector is power cycled. Nobody really knows what effect this will have on the lifetime of the bulb but us oldsters all "know" that leaving something on will almost always increases its lifetime over switching it off and on again (They don't like the surge up them captain! )

    So - one one hand you can pretty much say that you'll reduce the number of days between needing new bulbs from 40*5*7 to 40*5*6 (e.g about 15% reduction by leaving it on all the time) but if you double the number of power cycles -?????

    I'd rather take the known hit than the unknown one - but I'm predjudiced as I used to work with thermionic valves costing £10K and by golly - we treated them better than our own children

    Si
    PS who turns their servers off at night????
    Last edited by SimpleSi; 22nd March 2012 at 09:25 PM.

  18. #30

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    Rammie, the reason they fail at startup is because they need a high voltage and current to strike but not to maintain a already lit lamp so it is much more difficult for them to strike and it is two things that age a projector that you are saving if you switch it off, the lamp and the ballest unit as that ages too, the lamp does not have a "bulb" it has a small quartz tube this also contains meurcury too small to see which also deterioates at each switch on. So yes they do age more by switching on than when on, evidence ? i have seen numbers of projectors that are in "consent on" situations with projector lamp hrs of 6,000 to 9,000 (not recomended) difficult to get that on a projector you switch on every day, and still fairly bright too.

    Marc
    Projector Engineer

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