lightingmotion-sensor
I had to make changes in my office and now the main light switch (which is slave to an occupancy sensor, very likely passive infrared) is blocked from seeing me.
The result is that every 5 min or so my lights go out and I have to wave my arm to get it to turn on the light again.
Is there any kind of device I could buy (or build) that would emulate infrared changes that I could leave on while I'm at the office so as to keep the sensor triggered?
I think your strategy of making a cone out of aluminum foil was on the right track, but your choice of material was not. Think about what happens when you put various materials in the microwave. Paper, glass, ceramic: no effect, these will be ineffective. Aluminum foil: unintended consequences, do not use. Then consider what the microwave itself is made out of. You are essentially making the window (which is a person window, the negative image of a sensor window) This suggests the use of a grounded metal mesh or foam. Locally in NYC, the SpyStore sells copper-nickel mesh fabric for unstated purpose. You should also be able to find self-adhesive EMI/RF shielding foam at various industrial suppliers such as McMaster-Carr. You will want to wire either material to ground. I would start by trying to disable the sensor completely by this method (of covering it with grounded metal mesh or foam.) Then open a small aperture in the opposite direction of the corridor. Increase the size of the aperture until the functionality is as you desire. Use white self-adhesive paper label stock cut slightly larger than your masking material to return the sensor to an all white appearance if that is important.
You can purchase and utilize a common DPDT type relay (Double Pole / Double Throw) to create a cross over switch. It is pretty easy to understand from the following relay diagram:
You connect one circuit to the two NC (normally closed) terminals of the relay. The other circuit connects to the two COM (common) terminals. Then you add two additional wires which cross connect the two NC terminals to the opposite NO (normally open) terminals.
The coil of course is driven with the control voltage that you have selected. The simplest control voltage to use would be +12V DC. There are plenty of relays available that have 12V DC coils and your remote automation control can use simple transistors to drive the relay coils.
If you go ahead and use 24V AC for the relay coils then you would have to use an additional relay for each switch control to translate the switching from the AC realm to the low voltage DC realm. (There are circuit components available that can switch the 24VAC but it gets more complex than necessary for an application where +12V DC can be easily used instead. And then you can derive the needed +12V DC from a re-purposed computer power supply.
A major concern when building any type of system such as this, where you bring remote control wiring into the mains wiring boxes of your house, is safety and isolation. Only relays rated properly should be used and you would bear the safety liability associated with stringing the control wires around your house.
Best Answer
Many occupancy sensors allow you to adjust the amount of time that they can't see you before they shut the lights off. I'm not sure what model you have, so I can't instruct you exactly how to adjust, but setting the timeout time to something longer would probably save you the trouble of building something to circumvent it.
For example, a panel on this Leviton switch pops off to reveal some adjustment controls.
PDF instructions
If your office is managed by your company or a building manager, it may be worth asking the maintenance guy.