Questions about how cold temperature affects Parallax PIR sensor #555-28027?

garyg

Hi
I'm planning on using a Parallax PIR sensor to control my Big Mouth Billy Bones toy display.
Deer keep eating all the feed from my bird feeder.
I mounted Billy Bones only to discover that it uses a photo resistor to detect shadows and will not work in the dark.
I have a Parallax PIR sensor and according to the specs, it should work in this application.

My largest concern is that the temperatures here in Wisconsin get very cold in the winter months.

Has anyone attempted to use the Parallax PIR sensor in very cold temperatures, About -15 degrees F. ?

I have a plan that after the sensor starts my Billy Bones I will wait until the Bad to the Bone tune has finished.
During the time Billy is operating, it sets up a vibration on my bird feeder pole.
When all has calmed down again, maybe after several minutes, I will look again for another deer.

I'm planning on assembling this over the next week or two.
I'm trying to get a feel for if I need to put some type of temperature controller in the box that houses the PIR Sensor.

Thanks for any creative comments or suggestions.

Tracy Allen

Note that the data sheet says, "This device is designed for indoor use. Operation outside or in extreme temperatures may negatively affect stability. Direct exposure to sunlight or other forms of radiant heating may cause undesired operation." That aside, I don't see any obvious reason it would not work outdoors at -15°C. brrr. The signal output is based on temperature difference wrt background and rate of change as the hot body moves in the field of view. Try to point it at a consistently cold background. Condensation could be a problem, so seal it in a protected box with desiccant. Eclectic glue can seal pretty well to the edge of the polyethylene dome. Definitely keep the dome out of direct sunlight and protected from precipitation.

CircuitMage

PDF states "Operating temperature: 32 to 122 °F (0 to 50 °C)", but I would bet it would be OK, as long as it didn't get wet. Sealing the electronics may be a good long-term solution and allow self-warming as well (??).

I have been using similar type PIR sensors and love them. I have found a wide variation in reset time, that is the time it takes the sensor to go back to no output after being activated, among different types.

If the sensor moves, it may continually output as if activated, there is some settling time required, so best to keep it stationary. The PDF states a 40 second warm up time, but in my use these type of sensors only take about 20 seconds to warm up.

AND, I have found most of these have a wide sense range (about 180degrees!), so I tend to limit them with a directional device (black tubing that fits the lens, cut about 1") to cut it down to about 90degress. I don't see sense angle information on this PDF.

I have another thread in this forum (unsolved) asking this question, so if you have any feedback on that, I would appreciate it. These sensors are also sold at Rat Shack now, so was thinking of picking some up, but without knowing the reset time it is not useful to me.

Mike

garyg

Thanks
I'm working on a housing design that will keep the PIR sensor out of the elements.
I had not thought about using a desiccant to keep the moisture consistently low.
I will use that.

Since the sense range is so wide, I'm also planning on using a tube to shield from the sun during the day and
limit the PIR range.
That should keep leaves that blow across the yard from giving false triggering.

Thanks all for your comments

garyg

I've started working on my PIR sensor housing.
I decided to mount the entire PIR sensor in an all weather electrical box.
I thought I could put a piece of clear PETG plastic in front of one of the fitting openings, but the PIR sensor could not see through it.
After trying several different materials, I came to the conclusion that I had two choices.
The top of a crystal clear Krylon paint can works well or a piece of the bottom of a gallon milk plastic container.
I think I'll use the milk container because I can cut it with a scissors.
I'll be using a bit of silicone caulk to glue it to my opening.

I'm also looking for a desiccant. I believe I can use the desiccant capsules from some of my wifes medication bottles.
The plan there is to warm the desiccant to about 100 degrees F. for a couple of hours to dry it out.
then warm my housing for a while, but not hot enough to distort the plastic.
place my PIR sensor circuit and 9V battery inside, along with the desiccant and seal the works up.

It'l take a few days to sort out the particulars.

Tracy Allen

Reactivating a silica gel desiccant may take longer time and higher temperature. From 24 hours at 150°F in a food desiccator to 3 hours ramped up to 300°F in a convection oven. The peak temperature will depend mostly on the tolerance of the packaging. I've seen it done in a microwave, but it has to use the lowest power setting, cycling on and off over a long period of time, otherwise it will develop bad hot spots.

What are you using to power your PIR?

CircuitMage

I was thinking silicon seal or hot glue would be sufficient.

And, as for covering the lens, that may not be good. Not sure why you are wanting to do that, save for a custom enclosure (??). I was thinking of poking the curved lens through the opening and/or covering with a tube for directional limiting.

And, as always, when you are done...pics or it didn't happen!

garyg

I'm planning on using 9V battery, 12V Radio Shack relay with 300 ohm coil and 7805 voltage regulator.

The relay will operate my Big Mouth Billy Bones

I'll keep in mind your suggestion about drying the desiccant. I have a food dehydrator that runs at about 135 degrees.
maybe 24hrs or so in that unit would do the drying job.

The reason for wanting to put a window in my PIR housing is that whenever I'm trying something for the 1st time,
I hesitate to modify anything. If the unit gives trouble in very cold weather, I may be able to use it in another application.
I'm intending that the housing is made from an electrical box that I only know as an LB. I have the window mounted in behind the pvc conduit tube, that part of the construction seems pretty clean looking and I believe absolutely weather tight.

The circuit appears to work as drawn, at least on my breadboard.
The window appears to work only if the jumper setting is in the L position.

I'll take some photos of the housing and assembly when I have them completed.

Thanks for the comments and suggestions

garyg

I've completed my PIR sensor weatherproof box, installed it on my Billy Bones plaque and mounted it on my birdfeeder.

While building the sensor housing, I noticed that I could fit four AA batteries.
That would give me much longer time between replacing batteries.
I did not put a switch on my sensor, but I can put a cap on conduit piece in front of the lense to block any motion and
basically deactivate the sensor.
I was able to put 12 grams of Silica Jel desiccant that was heated in my food dehydrator for 36 hrs.
The jel packet fits in the 7/16 spacer box under the 6v battery pack.
below are photos of the circuit and sensor housing.
The weather around here is in a warm front condition.
It's raining and about 45 degrees. Next week I believe we will be back in the normal weather pattern of
35 degree highs and <20 degree lows.
I think I will soon find out if my deer chasing strategy actually works in practice.