exhaust fan motion sensor switch?

the only outwardly detectable sign of my grow op is an exhaust vent in a window.

i was wondering if there exists a motion sensor device that will TURN OFF the exhaust fan in the event someone gets too close to the window.

this could help avoid detection by curious power company employees or even l.e.

an exhaust vent could be anything from a portable air conditioner to a clothes dryer... if you have your air filtered it shouldn't matter...


You CAN buy a device that will power everything down, but then you would have to probably plug it into an exterior motion sensor light.

yes, the air is filtered and it's unlikely this vent will be a problem... but, insignificant or not, it is the only real security leak in the op. if a simple fix is possible i'd like to implement it.

do you have a link to the motion sensor device you mentioned? or a brand name or model? all i have been able to find are motion sensors that turn things ON.

they sell montion detector switches all over the web, seeminly you'd have to do a bit of rewireing, as they seem to all be made for lights, maybe wire to oulet with fan?

I'd use a relay. Power the light through the NC contacts and have the motion sensor trigger the relay.

There is a great sensor you can get that will call you when someone enters the room or moves by a certain point. ims100 is the model.

BigBudBalls: thanks! could you go into a little more detail? i'm not familiar with relays or nc contacts. where could i get a relay? and it's actually the fans that i would like to turn off via the motion sensor.

Maybetomorrow: yes, i saw it at walmart! how neat is that!

thebAse said:

BigBudBalls: thanks! could you go into a little more detail? i'm not familiar with relays or nc contacts. where could i get a relay? and it's actually the fans that i would like to turn off via the motion sensor.

Click to expand...

Relays are basically a voltage controlled switch. It will have a coil that energizes the relay (that motion sensor would trigger/turn this on. The NC (normally closed part of the 'switch') So when it get 'energized via the motion sensor, it opens the contacts, turning off the fan. When the motion sensor is 'happy' (been long enough with no motion) the relay relaxes, closes the NC contacts and turns the fan back on.

You would need a relay with 120VAC coil and contacts rated for 30% more amperage then what the fan uses.

BigBudBalls: awesome! thanks for the detailed explanation... i think i understand, and it sounds like exactly what i need!
where should i go looking for such a thing... radio shack?

thebAse said:

BigBudBalls: awesome! thanks for the detailed explanation... i think i understand, and it sounds like exactly what i need!
where should i go looking for such a thing... radio shack?

Click to expand...

i don't think RS has 120vac coil relays. (they really don't have much of anything these days)