Motion detector WTF



  • A quite common device used to save energy and work at home is a motion detector.

    What does it do? It detects when you enter the room and switches the light on. When no motion is detected for some time, it switches the light off again. Simple, isn't it? Just a motion detector, some simple circuit to keep it on for some seconds without motion, and a relais to switch the light.

    Well, it is SUPPOSED to be simple. However, some of them have an extra master switch to switch the light permanently off.

    Wait, isn't that extra feature EVEN MORE simple than the rest? It is impossible to do wrong, so why the beep am I writing this post?

    Because düwi found a way to do it wrong. Even when that switch is in the "off" position, I always hear a click when entering the room... so obviously, they put that switch BEHIND the motion detector, keeping the motion detector and the relais running (and wasting a little amount of energy) even when it is explicitly switched off. WTF didn't they put that master switch BEFORE the motion sensor logic, or ANDed it with the motion sensor output before the relais?



  • That's better than the one I have - I have one of those motion detectors that you put in your back yard, so if you're working out there at night the light automaticially comes on.  The switching logic says that when the switch is off, the detector and lights are off, and when the switch is on, the detector is on.  BUT, if you switch it off and then on again with 30 seconds, it goes into "perminant-on" mode, where the light won't turn off.  To clear this setting, you have to switch it off, then wait 30 seconds, then switch it back on.  But then you have to wait for the inactivity timer to time out (2-3 minutes) to see the light goes out to see if it is still stuck in perma-on mode, which it could very well be, because it's difficult to wait a full 30 seconds when you're in a hurry to leave/go to bed!  Arrgh!!!! </rant>



  • Where I work, we have this 'one way door'. How it's supposed to work is it stays locked. When someone approaches it from side A, it unlocks, allowing them to pass. How it really works is that is always stays unlocked. When someone approaches it from either side, it locks. To exit, you must press the 'override' button to unlock the door. It does it's job - it's a one way door - but it does it in a totally senseless way. And, amazingly, none of the dozens of contractors and electricians they've had look at it can fix it. I looked at it once. Took a voltmeter to it. Found what was wrong immediatly; the motion sensors are hooked up wrong. But I'm not allowed to fix it, because I'm not 'qualified'.



  • [quote user="Isuwen"]But I'm not allowed to fix it, because I'm not 'qualified'.[/quote]

    WTFs always come in pairs, it seems. I'd say you just hit on the biggest WTF of modern civilisation: a piece of paper - what somebody believes - often gets more credit than reality.

     Last time I checked, this was called schizophrenia. But what do I know...
     



  • [quote user="Albatross"]

    That's better than the one I have - I have one of those motion detectors that you put in your back yard, so if you're working out there at night the light automaticially comes on.  The switching logic says that when the switch is off, the detector and lights are off, and when the switch is on, the detector is on.  BUT, if you switch it off and then on again with 30 seconds, it goes into "perminant-on" mode, where the light won't turn off.  To clear this setting, you have to switch it off, then wait 30 seconds, then switch it back on.  But then you have to wait for the inactivity timer to time out (2-3 minutes) to see the light goes out to see if it is still stuck in perma-on mode, which it could very well be, because it's difficult to wait a full 30 seconds when you're in a hurry to leave/go to bed!  Arrgh!!!! </rant>
    [/quote]

    What a stupid design. It would me much simpler to have a 3-state switch where user could select between 3 modes: "off", "auto", "on". Problem solved.

     This sort of half-assed solution kinda reminds me of my car's odometer. It has a LED display that can either display a clock or mileage. And one single button. To switch between 2 modes, you just press the one button. Now, to adjust the clock, you must hold the button, wait a bit, release and adjust the hour by pressing the button. Then, to adjust the minutes, you must HOLD the button again, wait, release and adjust the minutes accordingly. To reset the odometer, you must enter odometer mode, hold the button, wait, release. Oh, I nearly forgot. These adjustments require you turn the engine on.

    I guess it never happened to them using two buttons for this task.

     

     



  • [quote user="fmobus"]What a stupid design. [/quote]

    That's a pretty strong statement without any regard as to the intention of the design.  I for one would gladly (and I do) setup with this scenario rather than having to pull down siding, sheeting, and repull wire for a simple light.  Likewise I wouldn't want to spend the mega bucks it would cost to have someone else to it.



  • [quote user="Albatross"]

    That's better than the one I have - I have one of those motion detectors that you put in your back yard, so if you're working out there at night the light automaticially comes on.

    [/quote]

     

    the people behind us facing the next road have one - there is no ally, and their trees are not tall enough to screen it.  shines right into our bedroom all night whenever there is the slightest breeze because the trees set it off (when their dogs don't)

     

    we want to kill them
     



  • [quote user="Kazan"][quote user="Albatross"]

    That's better than the one I have - I have one of those motion detectors that you put in your back yard, so if you're working out there at night the light automaticially comes on.

    [/quote]

     

    the people behind us facing the next road have one - there is no ally, and their trees are not tall enough to screen it.  shines right into our bedroom all night whenever there is the slightest breeze because the trees set it off (when their dogs don't)

     

    we want to kill them

    [/quote]


    May I suggest an airgun?  Reasonably quiet, but it should still have power enough to put the lights out.



  • [quote user="Carnildo"][quote user="Kazan"][quote user="Albatross"]

    That's
    better than the one I have - I have one of those motion detectors that
    you put in your back yard, so if you're working out there at night the
    light automaticially comes on.

    [/quote]

     

    the
    people behind us facing the next road have one - there is no ally, and
    their trees are not tall enough to screen it.  shines right into
    our bedroom all night whenever there is the slightest breeze because
    the trees set it off (when their dogs don't)

     

    we want to kill them

    [/quote]


    May I suggest an airgun?  Reasonably quiet, but it should still have power enough to put the lights out.

    [/quote]

    Don't
    forget to shoot from an angle which casts suspicion elsewhere (e.g.,
    neighbor's yard, street, grassy knoll), in case the local CSI-wannabe
    squad comes knocking...

    My problem is a building/parking lot
    light for the townhouse complex which is located just outside of my
    bedroom window.  It was apparently off when we moved in and was
    recently fixed.  I'm not sure which is more annoying, the amount
    it illuminates my bedroom through the blinds (my fault for not buying
    the "dark" ones, I guess) when it's on, or that fact that it turns on
    and off approximately every sixty seconds.  I think the next time
    I have the cover of darkness under a power outage, I'm going to climb
    out the window and loosen the bulb.



  • [quote user="OpBaI"]

    A quite common device used to save energy and work at home is a motion detector.

    What does it do? It detects when you enter the room and switches the light on. When no motion is detected for some time, it switches the light off again. Simple, isn't it? Just a motion detector, some simple circuit to keep it on for some seconds without motion, and a relais to switch the light.

    Well, it is SUPPOSED to be simple. However, some of them have an extra master switch to switch the light permanently off.

    Wait, isn't that extra feature EVEN MORE simple than the rest? It is impossible to do wrong, so why the beep am I writing this post?

    Because düwi found a way to do it wrong. Even when that switch is in the "off" position, I always hear a click when entering the room... so obviously, they put that switch BEHIND the motion detector, keeping the motion detector and the relais running (and wasting a little amount of energy) even when it is explicitly switched off. WTF didn't they put that master switch BEFORE the motion sensor logic, or ANDed it with the motion sensor output before the relais?

    [/quote]

     

    you are making some pretty big assumptions about how the thing works. 



  • @Kazan said:

    there is the slightest breeze because the trees set it off
     

    You can't sneak over the one day and turn the sensitivity down?

    @Kazan said:

    shines right into our bedroom all night

    Or get curtains?



  • They've probably moved in the intervening 3 years between posting and now.



  •  What? This thread was on the front page of the Side Bar.



  • @Zemm said:

     What? This thread was on the front page of the Side Bar.

    There was spam on the thread today. Removing the spam doesn't relegate the thread back to where it was.



  • Ah well now it's up here I might as well add a motion detector WTF to the thread myself.

    At the college where I studied in every classroom they had motion detectors to turn the lights on if someone entered the room. If nobody was in there for a while, they would shut off. There are two WTF's about it though:
    - The motion detectors weren't really sensitive so when you would just sit there with your laptop and code, the lights would go out after a while. Even waving your hands or whatever didn't turn them back on again (although it looked funny!). You had to get up and walk a little bit to get them to turn on again.
    - Almost every classroom has a beamer and a beamer screen, but with the lights full on and the blinds open it could become quite difficult to see the screen. And when (for whatever reason) a video had to be shown, you were basically out of luck: there was no 'manual override' to turn the lights off so the video would be near impossible to see.

    Yay for modern technologies.

    Editors note: re-placed the intended line breaks



  • @PJH said:

    @Zemm said:

     What? This thread was on the front page of the Side Bar.

    There was spam on the thread today. Removing the spam doesn't relegate the thread back to where it was.

    I always wonder how this happens.  I think the spammers are searching google for keywords and stumbling onto the thread that way.  I've noticed that particular threads seem to attract spam from many different sources over many months, probably because of keywords.  Anyway, I just lock rezzed threads after deleting the spam to keep people (myself included) from being confused.



  • Since the light doesn't come on when the relay engages, they obviously did AND it with the motion sensor output before whatever controls the actual illumination of the light.

    How do you think the switch is wired now? How do you think the relay engages without turning on the light?



  • I was in a extremely new building a couple months ago, where they had motion sensors for the bathroom lights.

    Very nice if you get to the point where you need toilet paper and suddenly the light turns off, and now the sensor isn't very sensitive, so you have to get up and wave like an idiot to get the lights back on.



  • @morbiuswilters said:

    Anyway, I just lock rezzed threads after deleting the spam to keep people (myself included) from being confused.
     

    I think this thread is interesting enough to keep alive. There are some cases where it needs locking but this is not the one. Also I hadn't seen this thread before as I only came to this site about a year ago. Most threads before 2008 I haven't seen.



  • My family owned a restaurant and we had some motion detectors connected to an alarm system. These things were sensitive enough that a beetle walking on the floor could trigger them. We had to go to the restaurant by late night a few times, chasing a "ghost" until we discovered the real culprits. We changed the detectors a handful of times and it still wouldn't solve the problem, so by the third change we declared the supplier fucked and went on with another one.

    One fun thing I did at college once: one of the professors was toying with matlab in a class, and he showed us how he could turn a webcam in a motion sensor. He calculated the differences in images between every consecutive frame the camera shot, real time. So we would see a blank screen on the monitor, and when someone moved in front of the camera, the "shape" of the movement would appear in red. He then proceeded to make an alarm system out of that as well, so the more movement there was on the screen, the louder a sound would play. When we put that to work, the PC would output something that looked like a dalek trying to mimic a barn owl screech, upped a couple octaves. It was torturing to hear it but it was fun dancing in front of the camera to annoy the hell out of everyone else.



  • @b_redeker said:

    I was in a extremely new building a couple months ago, where they had motion sensors for the bathroom lights.

    Very nice if you get to the point where you need toilet paper and suddenly the light turns off, and now the sensor isn't very sensitive, so you have to get up and wave like an idiot to get the lights back on.


    Yeah, I was in one one those places this summer. The lights went out two or three times while I sat there. It's creepy to sit there in the dark, and wiping does'nt really work for me without sight.



  • @JTSandvik said:

    @b_redeker said:

    I was in a extremely new building a couple months ago, where they had motion sensors for the bathroom lights.

    Very nice if you get to the point where you need toilet paper and suddenly the light turns off, and now the sensor isn't very sensitive, so you have to get up and wave like an idiot to get the lights back on.


    Yeah, I was in one one those places this summer. The lights went out two or three times while I sat there. It's creepy to sit there in the dark, and wiping does'nt really work for me without sight.

    Which leads to the question, how do blind people do it?



  • @Zemm said:

    Also I hadn't seen this thread before as I only came to this site about a year ago. Most threads before 2008 I haven't seen.

    Then do what BTK is doing and read through the archive in your spare time.  My problem with rezzing threads is that the conversation is long over, but you have somebody stumbling in 3 years later and replying to people who may be dead, for all we know.  Then you get a lot of confused people who think the thread is current; yeah, it may take off again on its own with new responses, but why not just create a new thread?  If you really like the topic, creating a new thread is the best way to revisit the conversation while still giving people a bit of a "blank slate".  Finally, it's just annoying for those of us who saw the thread a year ago to go back and read through it all again.

     

    Anyway, my point was that it's best to lock right after you delete spam to keep people from accidentally posting in a dead thread.



  • [quote user="Renan "C#" Sousa"]how do blind people do it?[/quote]Hopefully with the lights off, unless it's two hot chicks, in which case, lights on so I can watch.



  • @morbiuswilters said:

    it's best to lock right after you delete spam to keep people from accidentally posting in a dead thread
    I disagree, but mostly because I don't care about rez.  I mean, not even the ektron thread annoyed me.



  • @belgariontheking said:

    @morbiuswilters said:

    it's best to lock right after you delete spam to keep people from accidentally posting in a dead thread
    I disagree, but mostly because I don't care about rez.  I mean, not even the ektron thread annoyed me.

    Personally I don't mind it so long as the rez actually contributes to the thread.



  • In one of the toilet blocks where I work they have a different approach to saving money on bathroom lighting. They thought motion sensors would be too expensive, so they have what looks like a normal light switch, until you use it and stay in there for too long. It works a little like this: If the light is off and you toggle the switch (on->off or off->on for those who are unsure what 'toggle' means) then the light comes on. If the light is on and you toggle the switch, the light goes off. If you leave the light on for more than 3 minutes, then it goes off also, so the switch can be in the wrong position, and therefore should be a push instead of a toggle (but apparently that would confuse people). 

    So, your sitting there in a cubicle and the light goes off. You then either have to be daring and toggle the switch again, hoping that no one notices you naked from the waste down, or wait for someone else to come in and switch the light on again. Most people seem to opt for the later, considering how often the room is used, and the fact I've never seen anyone naked (and a WTF in itself - if a room is used every 5 minutes, are you really saving energy by switching the light off, or just costing yourself more by having to replace the tubes more often?)



  • @morbiuswilters said:

    but why not just create a new thread?

    Because then you get snarky comments from the old guard that say "we discussed this already."

    Personally, I don't mind either way, so long as the post is good or funny.



  • @tgape said:

    Because then you get snarky comments from the old guard that say "we discussed this already."

    Reference the original post in the new thread, just to head off those complaints.  The big benefit is that you get a fresh conversation, rather than people replying to a bunch of old guys who are probably all dead now.

     

    @tgape said:

    Personally, I don't mind either way, so long as the post is good or funny.

    I would say only about 1% of fresh posts are good or funny.  It's much, much lower for rezzes.



  • @Kazan said:

    Albatross:

    That's better than the one I have - I have one of those motion detectors that you put in your back yard, so if you're working out there at night the light automaticially comes on.

     

     

    the people behind us facing the next road have one - there is no ally, and their trees are not tall enough to screen it.  shines right into our bedroom all night whenever there is the slightest breeze because the trees set it off (when their dogs don't)

     

    we want to kill them

     

     

     

    I have exactly the same problem - i keep thinking about buying an airgun

     



  • @Isuwen said:

    Where I work, we have this 'one way door'. How it's supposed to work is it stays locked. When someone approaches it from side A, it unlocks, allowing them to pass. How it really works is that is always stays unlocked. When someone approaches it from either side, it locks. To exit, you must press the 'override' button to unlock the door. It does it's job - it's a one way door - but it does it in a totally senseless way. And, amazingly, none of the dozens of contractors and electricians they've had look at it can fix it. I looked at it once. Took a voltmeter to it. Found what was wrong immediatly; the motion sensors are hooked up wrong. But I'm not allowed to fix it, because I'm not 'qualified'.
     

     

    Probably so it complys with saftey regs, i.e not locked with the building power down if there is an emergancy, yet still forfills the contracted design plans


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