Intelligent fan

Of course you "could" build something - but a simply solution probably exists at your home center. Pick up one of the IR motion sensors that is used to control outside motion-sensing lights. You can buy these modules separately (pretty cheap too), and simply wire it up into a junction box and plug your fan into it, then set the sensitivity as required. Will probably work fine.

--- I have an idea; you could do it with speech recognition!

First, build a speech recognition module with a one minute timer on it, and train it to turn off the fan if if doesn't hear "Ouch!!!" every minute.

Then, fix up your chair so that the timer from the SRM (Speech Recognition Module) fires a solenoid with a big, sharp plunger right through the chair' cushion into your butt.

Now, when the plunger hits your ass, and you holler "OUCH!!!" the SRM will regognize it and will let the fan stay on for another minute. However, if you don't holler, the SRM will assume you're away and turn off the fan. It'll keep on firing the solenoid, though, so that if it hears you holler right after it fires the solenoid it'll know you're back and it'll turn on the fan again.

-- John Fields Professional Circuit Designer

To recognise a human, as distinct from a human- sized object, a robot, a gorilla or an alien, you need to detect something which is characteristic of humans, but which the others don't have.

Perhaps an infra red themometer measuring a temperature of 37C- no, that's the core temperature, you'd need a probe mounted vertically on the seat...

Brain activity... No, too many humans wouldn't activate it.

A guilt detector might be useful.

But the one that seems most characteristic is the unique attribute that only humans have- the soul. You'll need to ask theologians or creation scientists about how exactly to do it, but I expect a dowsing rod would help. This method would also be useful, in that whenever someone DIDN'T turn the fan on, you'd know they were not human, and you could promote them to head of department.

Paul Burke

Install a dead-man switch on the fan, with a leash you your wrist. When you get up to go pee, you pull out the plug and the fan stops. Or you could rig up a 1-minute timer, triggered by the dead-man switch. Then, when you get back, plug in the dead-man leash, and the fan will start again.

Good Luck! Rich

Oh, find a medicine man with a dream catcher, a new-age witch with a spirit catcher, a magnetometer, and an electrometer. Maybe a fluxgate and capacitive sensor. With a little thought and feeling, there should be almost nothing to it. ;-)

Designing the actual decoding circuitry is, of course, left as an exercise for the student.

Good Luck! Rich

google for GP2D12

Pressure sensor under the seat. Depending on the design of seat, you may be able to get away with a simple switch to sense the rise/fall of the seat when sat on.

Only works with Catholics.

;-)

-- "Electricity is of two kinds, positive and negative. The difference is, I presume, that one comes a little more expensive, but is more durable; the other is a cheaper thing, but the moths get into it." (Stephen Leacock)