Using sensors as automatic 3-way switches


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Old 06-23-16, 08:16 PM
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Question Using sensors as automatic 3-way switches

I'm building a new multi-story house. Moving from one floor to another will be via two staircases separated by a 12' landing. I'm planning to light these staircases using LED strips embedded horizontally at the top of the risers of every second step.

I'd like to use some type of sensor, e.g., proximity or broken-beam, at the top step of the first staircase, and another one at the bottom step of the second staircase so that when I am at the first sensor (either top or bottom), the LED's would automatically turn on, and then turn off when I reached the second sensor. Essentially, I want the pair of sensors to act as "automatic" 3-way switches to turn on or off 115 VAC to the LED's power supply (transformer or voltage driver).

Some sensor-switch company help desks I spoke with, told me turning the LED's on wasn't an issue, but that the best I could do would be to have the LED's turn off via a time-out by using an occupancy & vacancy sensor at one location and a remote 3-way switch at the other.

Does anyone know how I can accomplish this the way I'd like to, and if so, what gear: sensors, switches, electronic relays, etc. would I need.

Thanks.
 
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Old 06-23-16, 08:43 PM
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It can be done fairly easily but before I go looking for the parts please post back so I know you are not a "one-post wonder". Nothing more frustrating that to give a detailed response to someone that never returns.

Warning, it won't be cheap.
 
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Old 06-24-16, 04:22 AM
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I've got two sets of staircases. I've already got the info, including cost for the LED's, transformer, aluminum channel, etc. for both sets, and you're right, it isn't cheap. So, if I have to add another couple of hundred to buy the sensor's and switches to make it work the way I want, that's not an issue.

So as not to have you invest a lot of time in this, I'd be grateful if you could steer me in the right direction(s); I can do much of the Internet surfing to find the parts if I know what to look for.

For example, I don't know what type of sensor I need other than it has to be one that I'll trigger only once when I pass it at the top, or bottom of the staircase (otherwise, my presence will cause it to instantly trip again). I'd like to place it either in, or behind the drywall with only the "sensing tip" or beam protruding. Should I look for a sensor that will "trip" a 115 VAC circuit, or one that will handle only 24 VDC (which will place severe limits on its location)?

Also, I suspect that I'll need some type of electronic relay to provide the if-off-then-turn-on-and if-on-then-turn-off logic, but I haven't a clue what to look for.

So, any help will be appreciated.
 
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Old 06-25-16, 05:29 PM
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Okay, I'll let you do the heavy lifting.

I would use infrared photocell detectors with retroreflectors for the sensors. This is to keep all the electronics on one side of the stairs. You need a single-coil latching, or "impulse" relay for the main power to the lighting. This relay uses a single pulse of power (from the photocell unit) to step the relay from open contacts to closed contacts, every pulse will change the state of the contacts. First beam break pulses the rely contacts closed and the second will pulse them open.

That is the basic concept. There are many other things to consider such as a second person following the first turning the lights off. You will need to refine the design with timing relays to account for your lifestyle. It may be easier, or better, to simply use each photocell to activate the lighting for a set time period rather than an on-off sequence.
 
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Old 06-25-16, 08:51 PM
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Just an opinion here... but I would probably lean towards a occupancy type sensor and a time-out. I can picture two people walking up the staircase, and the lights going off when the first person hits the top. Or if you start going up the stairs and forget something, so go back down... and the lights effectively never turn off. The programming or electronics logic gets a lot more complicated in a real-world situation.

If it were me, I would install a motion detector switch at the top and bottom of the staircase wired in parallel. Whichever one is triggered would turn on the lights for 3 minutes (or however long), and then turn off. It's an off-the-shelf solution that should be pretty easy and reliable.

Just my couple cents on the matter.
 
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Old 06-25-16, 09:01 PM
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If it were me, I would install a motion detector switch at the top and bottom of the staircase wired in parallel. Whichever one is triggered would turn on the lights for 3 minutes (or however long), and then turn off. It's an off-the-shelf solution that should be pretty easy and reliable.
I have to echo this solution. I've done this many times.... usually in a stairwell or a garage.
 
 

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