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'.

Isuwen:

But I'm not allowed to fix it, because I'm not 'qualified'.

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...
 

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>

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.

 

 

fmobus:

What a stupid design.

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.

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
 

Kazan:

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

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

Carnildo:

Kazan:

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

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

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.

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?

 

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