Light detector

[ereyes]

We keep forgetting turning off the lights in the basement. I would like to install a sensor to detect when a lamp is on in any of the zones, and if so, trigger a circuit that will activate a blinking LED located upstairs, somewhere in the kitchen. When a lamp is on, the circuit should flash an LED at a rate slow enough to be noticed by someone in the kitchen, but not so fast that becomes a distraction or annoyance.

The basement is 30ft x 24ft divided in 4 equally sized quadrants. Each quadrant ceiling has a 4-ft fluorescent lamp, but there are also some table lamps with incandescent bulbs.

There are windows in each zone that bring in a good amount of light during the day. Therefore, the circuit shouldn't go off under natural light conditions.

Is anyone aware of a reasonably priced commercial product to do this job? If not, can anyone point me to a circuit that I can build?

This circuit ought to be pretty elementary for many of you. I am not an electric or electronic engineer, but chemical, and I wish I could design this circuit as easily as I design a chemical plant. Any all assistance is appreciated!

Thanks!!!

 

[johneppen]

take four components, a light sensitive resisistor(cds cell?) and a potentio meter of about the equal resistance, and a transistor, and a blinking led, and hook the two resistors to the base and the led at the collector, or emitter depending upon what kind of transistor you use and adjust the sensitivity with the potentiometer. Oh yeah, you probably need a resistor to limit the current going to the led too.

 

[Gene]

From another view, the job of isolating the photoresistor from daylight will have to be your invention.

 

[Scubasteve]

Am I missing something here? Why not use the power going to the ballast as the signal that the lamp is on? This way, perhaps, one circuit could be testing the power at the source or wherever it happens, hopefully common to the other three lamps. I have heard of modulating power lines in your house with information, could this be useful? If this could happen, then there could be a circuit upstairs such as a nightlight or whatever that has a built in LED that will listen for this signal and flash through a simple oscillator circuit..

Steve

 

[ereyes]

Thanks for all the replies above. The diagram is specially useful since I can identify the exact parts and how to put them together. (I am not capable of translating textual description into a diagram.)

The 4 zones are served by 6 circuit breakers, and each ballast is on a separate circuit. Monitoring would need to take place on all of the circuits so that a table lamp (plugged to an electrical outlet) is not left out. It is for this reason that I thought that detecting light (beyond that from the outside) would be easier than monitoring circuits.

 

[Gene]

Scuba - I totally agree that your idea is the most fool-proof way of knowing what is going on in the basement. I guess there are 6 circuits to be monitored which would probably not be too hard.

I never know a new poster's experience and ability from the forum so I tend to stay away projects that deal with higher voltage.

 

[Scubasteve]

I guess the light detection way is simple, but I am concerned about all of the wires needed to be run throughout the house. If most of the circuit is located at the source, then there is simplicity. If you can plug in another circuit to recieve information modulated into the power (from the source), then you get away with using your home's wiring. It is a more complex way, but I will look into some circuits today on my free time.

Steve

 

[lavenatti]

I was thinking about this problem, have you though about some cheap fiber optic strands?

You could run one from each lamp, pointed at the bulb, of course, to where ever you wanted to see it. Some .5mm unjacketed cable should only run you a few dollars.

 

[Scubasteve]

This would still leave the problem of too much running of cable, but it could work. You would have to keep in mind to respect the maximum bend radius of the fiber optic cable, or else no light will be transmitted at all.

Steve

 

[stevez]

You might also consider a motion sensor or two to control the circuit(s). Local home supply stores carry the sensor/switch. Lack of activity for some period(adjustable) results in power going off. Activity turns it on.

We have one variation of the device here at the office - walk in the room and the lights go on. After 10 minutes a tiny alarm starts to beep - indicating that lights will go off in 10 minutes if nothing trips the sensor. That allows for someone sitting at a desk that is not in view of the sensor (or wakes them up if they fall asleep).

 

[lavenatti]

I have a motion sensor/timer in my laundry room, bought it for $2.50, fit right where the light switch was. The wife and kids never shut the light off!!

Another alternative may be some X-10 controllers. You won't even have to go downstairs to turn off the light.

 

[Scubasteve]

You might also consider a motion sensor or two to control the circuit(s). Local home supply stores carry the sensor/switch. Lack of activity for some period(adjustable) results in power going off. Activity turns it on.

We have one variation of the device here at the office - walk in the room and the lights go on. After 10 minutes a tiny alarm starts to beep - indicating that lights will go off in 10 minutes if nothing trips the sensor. That allows for someone sitting at a desk that is not in view of the sensor (or wakes them up if they fall asleep).

I like this idea. I had a friend that had these sensors throughout the house, it was cool!

Steve

 

[ereyes]

Great range of options. The motion sensors would most likely replace the light switches. I would still need to consider the table lamps plugged to a wall outlet. I would presume that there motion detector devices for the wall outlet would be avalable... I will check on this idea.

How do x-10 controllers work?

 

[lavenatti]

They send signals to modules through the power lines in your house.

Check out X-10.com

 

[ereyes]

After considering the various ideas, I think that I want to pursue building the circuit that Gene posted on Sunday. It gives me a chance to learn a little about electronics, and expand from there.

A couple of questions:
a. Will this circuit be able to work with four photoresistors in parallel to cover the four quadrants?
b. Or should I build a separate circuit for each basement quadrant?

In any case
a. what is the longest wire run that I can have to/from the photoresistors?
b. what is the longest wire run that I can have for the LED (if I locate the LED remotely from the rest of the circuit)?

Thanks.