Reducing Sensitivity of Motion Sensor with a Mask

I have several motion sensors and those that cover bright sunlit areas with moving shadows such as a driveway partially shaded with a blowing in the wind tree. I would get lots of notices only minutes apart.

I noticed that some lenses for PIR motion sensors were translucent instead of a dark color, and wondered if a mask made of translucent plastic such as used in milk bottles would dampen the Wyse motion sensor’s sensitivity? I found that the milk bottle material would pass infrared light from a tv controller. Although human eyes cannot see the infrared emitted by a tv controller, most cell phone cameras can. My cell phone camera picked up the controller infrared passing through the milk jug plastic. This is no guarantee that this plastic material would work for what I wanted.

The next step was to tape a piece of milk jug over one of my motion sensors to see what happens.

The motion sensor for the back patio picks up a lot of roaming cats at night, but cat images dropped to zero while still sensing me as I would enter the patio area and was about 15’ from the sensor.

My testing of moving shadows on a hot surface was cut short today because clouds moved in and frequent notifications stopped. Testing should resume tomorrow and I will check back with the results. The group of photos below shows the trial testing.
Trial 1-4
The next group of photos shows how I made the mask.

Now that I have spent this time heat forming, maybe I should have folded the four sides and creased them in the jaws of a vise. No wood blocks or heat gun needed.
Victor Maletic


Interesting…let us know on your testing update.

On the motion sensor I’ve used a small short piece of PVC tube to limit the detection angle down to 5 degrees or so.
Placed the motion sensor across the driveway aimed at a wall on the other side with nothing that will cause false trips.
This is acting as a laser sensor.
At night anyone crosses the driveway our bedroom Alexa says, “Driveway detected motion”, turns on a floor light in the living room and makes a dog barking sound for 2 minutes then turns the floor light off.
It’s been working like a charm…no false trips !


Hello gku2.
Testing the sensitivity of the mask is good and surprising so far.
Good, because not one shadow on a hot surface notification was received. Further testing is needed because today was not that hot.
Surprising, because two cat notices were received. My back patio test masking picked up no cats. This difference may because the mask used for the patio sensor is about 1/2" away from the tip of the sensor’s lens whereas the front driveway mask touches the sensor lens. Very pleased with the results so far. Other sensor responses to people and my car were not affected by the mask.

Great idea of reducing the reception of the motion sensor to a narrow beam with a length of PVC pipe. What diameter and length of pipe were used and how was it attached?
I really like the barking dog response. I wonder if the sound of a shotgun being racked along with the barking would help. On second thought, keep the gun out of earshot. Someone may break in to steal the gun.
Check out this link of what my nephew did to restrict a motion sensor area.
[Motion Sensor Shield](http://Motion Sensor Shield)
I will keep you informed of further test results.
Till later.
Victor Maletic

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Like the idea of the shotgun …lol
Not sure on the specs for the PVC pipe I used but it will need to be customised to the diameter of the area needed to minimize false trips…some pics though.
I used 3M removable putty …it is great and leaves no residue when removed to do a battery replacement …Used it also on a sensor to completely water proof it from the rain. It sticky enough to hold it to the surface you want to mount it on. …it’s also re-usable.

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Thanks gku2.

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Hi, again gku2.
After thinking about the pictures you posted, you and others may be interested in this simple, cheap and elegant way to restrict the field of view of a Wyse motion sensor:
Motion Sensor Shield

Also, I noticed what appeared to an analog camera nearby. If you ever wanted to tap power from them, this post has a lot of detail on how that can be done:
Powering V2’s with old 12 cctv systems
Till later.
Victor Maletic

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Great idea! Tried it and added two extra pieces in front of lens to futher reduce sensitivity. Simply cut two squares and stuck them inside of the mask in front of the lens. Works great and never missed a person yet. I like the idea of reducing the viewing angle also with a PVC piece. I’ll try that next.

Hello @bobinpensacola and others.
Here is an alternate (easier) method of making a sensitivity reduction mask. Reducing Sensitivity of Motion Sensor with a Mask - 2
Below are some links to methods of mounting motion sensors at angles other than straight out level (90°).
New Motion sensor and magnetic mounting post # 12 and 15.
Hemisphere and Plate motion sensor mount. Simple and elegant post #1.
I will soon post some STL 3D printer files for various angled motion sensor mounts for your use.

Victor Maletic.


Hello @bobinpensacola and others.

This link to my latest post will give you access to the stl files I made for 3D printing motion sensor mounts.
3D Print files for Motion Sensor mounts 20° to 45° at 5° intervals
Victor Maletic.

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Hey Victor,
I tried your milk jug filter on 2 of my motion sensor with good results …thanks !
I molded mines to the dome shape by heating it up and using the sensor as a mold…looks like a white eye ball. LOL

Hello gku2.

How did you heat up the plastic? Torch, heat gun, hot wire, hot water?
I would like to see a picture of it.
Victor Maletic

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I used a small torch.
Heated it up and used the sensor as the mold. Press it down with the scotch tape dispenser hole. The plastic piece was larger I rough trim it down round in the picture.


Simple and elegant, I’m impressed
Thank you.

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