Thread: Quick Question About Motion Sensors

Tweet

I should know this, but I was wondering, do motion sensors need a small amount of light in order to function, or can they work in total darkness?

Depends on the type of motion sensor. I find that decent PIR's don't care, although some have issues with daylight. Most problems likely come from temps being too similar (subject vs ambient) or having the sensor in direct sunlight. In my experience, PIR's do seem to be more sensitive and reliable in the dark. However, if you live in a very warm area, they may have trouble seeing a moving heat source.
A CdS "motion" sensor just sees the difference in light levels on the sensor surface. They don't work worth beans in the dark unless you direct a light beam on them that will be interrupted by the TOT. Strobe lights will drive 'em crazy.

Originally Posted by Otaku

Depends on the type of motion sensor. I find that decent PIR's don't care, although some have issues with daylight. Most problems likely come from temps being too similar (subject vs ambient) or having the sensor in direct sunlight. In my experience, PIR's do seem to be more sensitive and reliable in the dark. However, if you live in a very warm area, they may have trouble seeing a moving heat source.
A CdS "motion" sensor just sees the difference in light levels on the sensor surface. They don't work worth beans in the dark unless you direct a light beam on them that will be interrupted by the TOT. Strobe lights will drive 'em crazy.

Okay, I'm a total newbie! LOL! PIR's, CdS and TOT... New terms I'm not yet familar with!

The type I was wondering about is like the self contained units seen at Frightprops.com, like this: http://www.frightprops.com/controlle...imer-0579.html

If these work in total darkness, they would be perfect for controlling the electric firecrackers I bought! If not, guess I'm stuck buying the more expensive controller and pressure pad...

Most of the detectors that I used (walmart cheap ones (10 or 12 dollars) that comes with floodlights) didn't need light. They work by picking up a change in heat that a body gives off.

Originally Posted by madmax

Most of the detectors that I used (walmart cheap ones (10 or 12 dollars) that comes with floodlights) didn't need light. They work by picking up a change in heat that a body gives off.

Thank you for the info! I happen to have one like that laying around! The electronic firecrackers only need be on like 2-3 seconds though, and go off when a group of patrons pass by, then rest for the next group. Thus, I figured the Frightprops controller with built in timer would be great, if it could be used in total darkness in my haunt! I was told running the electronic firecrackers for longer than that would burn them up quicker...

PIR = Passive Infrared sensor, CdS = Cadmium sulfide detector, or light/dark sensor and TOT = Trick or Treaters, AKA "victims"!

Don't sweat it, you'll soon know all the jargon!

Originally Posted by Otaku

PIR = Passive Infrared sensor, CdS = Cadmium sulfide detector, or light/dark sensor and TOT = Trick or Treaters, AKA "victims"!

Don't sweat it, you'll soon know all the jargon!

LOL! Thanks again for that info! I wasn't thinking Trick or Treaters... That one should have been obvious! I guess I was stuck in the thought process of patrons since I was wanting to put the motion sensor and electronic firecrackers in a haunted house... Silly me! LOL!

Originally Posted by Nathan Voorhees

Thank you for the info! I happen to have one like that laying around! The electronic firecrackers only need be on like 2-3 seconds though, and go off when a group of patrons pass by, then rest for the next group. Thus, I figured the Frightprops controller with built in timer would be great, if it could be used in total darkness in my haunt! I was told running the electronic firecrackers for longer than that would burn them up quicker...

Be careful of something that says "approximately" 2-3 seconds because it's probably only a test setting and not a dial that you can set exact seconds with. Just like the test setting on the cheaper Walmart detector have...some will test for 4 seconds, some 5, others 6 and others up to 7 seconds.

Here's another problem you will run into with a motion detector like I suggested and the one from Frightprops. One more thing before I get to what I was going to say. The Frightprops controller with built in timer is misleading because while it will control a prop (turn one on and off)...it's not a "prop controller".

Now back to the important part because a motion detector will stay on as long as someone is in front of it or in the pick up range of the detector. So if you have two, three, or more people in a group it's likely the fire cracker will stay on till the last person gets past the view range of the detector.

What you would need is a timer to go along with a motion detector, with the motion detector only being used to turn on the timer. I'm sure you can find both for under the $60 price on the Frightprops motion detector. With the timer you can set the time you want the fire crackers to run and also set a time limit before they can be activated again.

Search the forum for timers or prop controllers and I'm sure you can find what you need. Or maybe Otaku can give you a link to one that will work. I hope I didn't confuse you too much because it really isn't a very difficult set up.

Madmax, I was wondering about a unit like this: http://www.frightprops.com/controlle...imer-0665.html and if it would work for what I'm needing with the motion sensor I have laying around. The description on that timer always confused me though the way it is worded. Especialy this part: "•Will not keep triggering prop until trigger is removed and re-applied. For example, when someone steps on switch mat prop will activate for specified time, prop will then turn off and not re-activate until person steps off mat and another person steps on." What do they mean "Will not keep triggering prop until trigger is removed and re-applied."?

Something like that is exactly what you would need. It would be better if it had a set time for the prop to be off but it would do want you want it to.

If it works like Product Description states (it should) then when someone steps in the range of the motion detector (the one you have should work) the fire crackers should come on for ever how long you set the timer for.

If it's 2 seconds, then the fire crackers turn off after the 2 seconds and won't activate again till the motion detector turns off and some one steps back in the view of the detector....just like someone stepping on a pressure mat then stepping off and back on.

It's best to block the view range of the motion detector with tape so it will only pick up where you need it to. Other wise most detector will pick up in 180 degree range.