Light Automation

Hi. Does anybody know a good way to install home automation lights? For example the bathroom, when you are about to enter the lights will automatically light up and when you leave the lights will turn off.

I initally thought of a PIR sensor to get the lights on but the lights will turn off after awhile, soo i thought of adding a mircocontroller to controller this.

I'm stump on how to get the lights to automatically shut off by itself. When there is no one in the bathroom

You could setup some kind of IR trip sensor on the door so that when you enter the room, the trip sensor toggles the light, and then when you leave the room it turns off the light. You'd just have to figure out a way to differentiate entering and leaving a room.. Not sure how to do that exactly... maybe two trip sensors that are tripped in succession.

Then you could setup some simple logic to keep count of the total number of people in a room so that the lights dont turn off when the first person leaves.

Alternatively you could just put a motion detector in the room and hope people keep moving. Maybe make it timeout after 10 minutes, but then the lights would remain on for 10 minutes after you leave the room...

It would get a whole lot more fun when you have multiple doors too! The IR trip sensor sounds like a good idea...you could also make it so that sensors that aren't going to have people trip them are turned off... For example lets say you have to go through a bedroom door and then another to get to the bathroom...well then the bathroom door wouldn't be wasting power waiting to be tripped until someone is in the bedroom. Neat idea. Might need a central processing system. Could save a lot on power though.

Thanks for the input. I guess the hardest part is the logic. I was also wondering if a relay is the way togo for the lights to be turned on? If it is then how would i configure this, since the wall voltage is 110-120VAC and the output of the sensor or controller is only 5V? The conductor (wires) would be thicker for the relay since the line will have about 15A max.

X-10

Do a search on X-10. I use X-10 motion sensors and light controllers. I also use a box that connects my computer to the X10 network. My home automation computer can get information from the motion sensors. The computer turns on/off light in the house and barn. The motion sensors can turn on/off light directly or in my case they talk to the computer and the computer then switches the light depending on some logic.

as Ron points out, X10 is the way to go for automation. I'm a big fan of building versus buying, but when it comes to stuff that needs to be reliable or could be dangerous if it fails, then I often look to commercial products. controlling line voltage lights and appliances with 'logic' is not difficult, but it can be dangerous, and the parts to do it safely cost more than pre-built commercial products.

the X10.com website is kinda trashy, advertising spy cameras and bikini wearing models, but their products are pretty good. Smarthome.com is higher end stuff, and I'm sure google will list other purveyors of x10 related goods.

lets take your bathroom example:

1) place an "eagle eye" PIR sensor somewhere so it can see the door, but is not triggered by people passing by the outside of the door.

2) replace the light switch with a "wall switch module", or use a "socket rocket" which installs between the bulb socket and the bulb.

3) set the PIR's unit code to correspond with your switch's control code, and set the PIRs off-delay time to something reasonable, usually 2-5 min.

that's it!

person walks into the bathroom, PIR detects motion and sends a ON command using its unit code (which is the same as your switch) and the lights come on. After no motion is detected for the off-delay, the PIR sends an OFF command using its unit code, and the lights turn off.

if you wanted to be fancy, you could involve a computer, running sensors on one house code (house codes a-m, units 1-16). PIR sends an ON command, computer reads this and sends a DIM command to the light module (or other proprietary command) so it lights up at something other than full power. problem here is most light modules won't "start" at anything but full power, so it's something to play around with. one suggestion, using the computer you can do time of day based event handling. if it's after midnight, turn on a nightlight, if it's during waking hours, turn on the main lights.

alternately, forget x10 and just invest in some electroluminescent night lights. I've got some that take 0.07 watts ... it costs me roughly 10 cents/year to run each one. Only bad thing is, they hog an outlet that would otherwise serve a hair drier, razor, etc.