RF Transmitter's and Receivers

Yes. Use an infra-red security sensor, with the output wired across the light switch. Then it wouldn't matter which shoe entered the room, as anything warm would switch the lights on.

So when the sunlight enters the window the lights go on, right?

Passive Infrared (PIR) security sensors depend on a change in their infrared field of view, not on the warmth of the "intruder" as you suggest (it's okay. This is just a common misconception). Any object - be it warm or cold - entering that field of view (FOV) changes the stationary IR background that the sensor normally sees.

If you take one of these units apart you'll notice that the optics (both the translucent or white lens, and a reflector if present) are optically segmented. This arrangement facilitates seeing sudden changes in the "image" because as the intruder moves across the FOV, the IR image transitions abruptly from one segment to the next causing the sensing element to output a spike or pulse (PIRs are not imaging devices as such; I'm using the term here for illustration only).

Another reason PIRs do not depend on sensing the warmth of the target is this: they can't "see" the intruder at all if the temperature of the sensor is close to or identical to the temperature of the intruder. This is why highly-sensitive IR detectors and imagers, such as the military's FLIR systems and certain astronomical devices, are cooled - some to cryogenic temperatures. A warm sensor simply cannot reliably sense a warm object.

Because the PIR sensor detects only changes in its FOV, an intruder can get past the sensor only if the IR "image" of the moving intruder blends in with a homogeneous IR background. Consequently, PIRs perform much better if the IR background they normally see is highly non-uniform (and stationary!).

-e

I can help you at this very spot. how much objects will you want to control? how long woll you want to control? you can use simple encode of 4 bits random code generator (decimal) for thousands of objects control. or you can just use some more cheap;er device like ut or audio controller for lamp on/off.

Hi and thanks for you quick response,

I would like to use RF for detection because I would also like to sense objects. Every one says use RFID but I don't need the ID technology. I only need to know if something is there or not that has a "tag." With the given application I have I think I can only use RF. Also I only need to turn one thing off.

Thanks!

Hey KIA,

How about checking into those devices stores tuck into merchandise so they can detect when someone tries to walk out the store without paying for their goods? I'm guessing the insert is basically a diode junction attached to an "antenna" of sorts, to generate harmonics when tickled by an RF field set up around the store exit/entrance doors. Why the alarm isn't tripped by other electronic devices I can't say. There's probably more to it than I'm suggesting here. The insert itself is not powered as far as I can tell, and I suspect that when the checkout clerk passes the article over the pad, the diode junction is either is shorted out or opened by a strong RF field.

If anyone here knows how these things actually work (as opposed to what is sheer speculation on my part), please respond. I know these inserts are not RFIDs. They're strictly passive devices. But they do seem like the sort of thingies you're looking for.

-e

http://www.lctek.com/home2005/

..here is good supplier

Einstein was wrong: In order to verify his theory I once tried to stretch a cat from New York to LA. It doesn't work. I only got as far as Albany before the damn thing went silent.

-e

If you are just looking to detect the presence of somebody and control things like lights, heating, cooling etc then you are going about it the hard way.

If you wish to control things directly then I would suggest, as the Guest in post #2 did, that passive infrared sensors with ambient light detection would be the easiest solution.

This is an example of a passive IR motion detector that can be used to switch anything you connect to it on. The first one is for outdoor use and the second is for indoor use.

You can get an ultrasonic motion detector like this:

https://updates.clipsal.com/ClipsalOnline/Files/Brochures/W0000239.pdf

However, if you intend to use the information to run things from a central computer then the way to go would be to use standard security motion sensors and wire them back to a central computer and use that to do the switching.

The third option would be to use Radio Frequency Identification (RFID) as you can then differentiate between individuals. You can get RFID tag kits on the internet with everything you need to test out your application. They do however have a limited range so this could be a problem.

If this isn't what you are thinking about please post some more detail of your application and we will try and help.

We manufacture RF transmitters and receivers, we don't have anything small enough for a shoe at this time but feel free to check out our website at www.remotecontroltech.com.

However, I've to clarify that RFID is not same as what I described above. Its two different equipment with different transmittance distance. The max rfid has max distance of 10cm its no use for top post completment and what I said has 100m at least. There are lots of method to complete the function the top post requiring. Masu give a very clear describe about either IR or sound. These are very ordinary use for burglar alarm.