proximity workspace needs to know when I'm around, what about theremin sensor?

Hi, my idea for a project is to have a workspace that is active when I'm around (computer powers up, lamps comes on, coffee brewing etc) and powers down when I leave. Ideally, for this to happen I need the sensor to pick up a presence as opposed to movement. I understand IR fails in this department. Also, a radius of say here to the coffee machine (i.e. 5m) should be regarded as a safe zone.

I was came cross heterodyne schematics and I was wondering if that would fit the bill ? Theremins kind of do what I want, they detect a presence. And I think the active radius should be scalable. Also, if I were to massively upset the signal by bringing my cell phone into the zone, hat would still work.

What do you guys think ?

I think a PIR sensor would be fine, and active IR does not reley on movement.

The RF field on a Therimin will not scale up like you think and it will be disturbed by every movement of every conducting thing like you, the cat, you coffee, tools, computer and many other things.

I know naf all about such things but one thing I do know is that whatever you do it better be bloody reliable or you're going to be cutting power from a lot of things that you would really rather not and at times that may cause problems.

Also what about loo breaks etc.


Rob

that theremins don't scale well might be the dealbreaker here, the fact that I can't find any reference in the arduino community for this type of use speaks volumes too I think. Regarding the interference, I figured that I am looking for differences in the signal, not a disturbance of a clean signal and that thebpresence of my person would introduce a more significant delta. But I think that when my computer powers on and my cell phone is in the vincinty this would cause more disturbance than I would imagine.

Active IR is something I need to look into, but Also I need to think about dividing behaviour into seperate sensors, timing and actuation. For instance, loo-break is a valid point regarding my computer, I don't think I want it powering down every time, but go into standby.

But my desk light can definitely be proximity based, so I'll look into that one first with a sharp IR sensor and see where it takes me.

Office lights are more tricky, as I want them to turn on/off when someone/nobody is present and I found this to be more of a pickle.

Anyway, thanks for the input, theremin is neat, but not for this.

S

But my desk light can definitely be proximity based,

Office lights are more tricky, as I want them to turn on/off when someone/nobody is present and I found this to be more of a pickle.

Funny you should mention all that, I'm about to start a contract to help design exactly that. Unfortunately it's all under an NDA.


Rob

Office lights are more tricky, as I want them to turn on/off when someone/nobody is present and I found this to be more of a pickle.

We had lights like this in some labs at one company I worked for. Everyone in those labs hated them as they would often go on and off for no apparent reason.