Need ideas for simple motion sensor

Discussion in 'General Electronics Chat' started by Mike33, Feb 12, 2010.

  1. Mike33

    Thread Starter AAC Fanatic!

    Feb 4, 2005
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    Hi,
    I'm playing with the idea of making a motion sensor to detect deer crossing my yard. I get a dozen or more at odd times, and would like to know when they're there....I have a garden in spring, and they'll be back! Not to mention the photo opportunities - a circuit like this could be coupled to a camera after I get it working.

    I have a photodiode/opamp comparator light sensing circuit working. It's set to go high when light is blocked - a perfect pulse for a 555 I'd think, and would give a negative-going pulse when something passes thru a beam. I'd like to be able to do this remotely, and to have a decent distance to run a beam across. Question is, will a cheapo laser pointer work with a photodiode? I figure it's much more concentrated so could give good results.

    Part 2: So I'll then have a motion sensing setup, but it's away from the house. I'd like to use a 2nd laser, triggered when the 1st one is broken, to shoot to a box by the door. A pulse from it would trip the 555 (monostable) to sound a tone in the house via piezobuzzer or what have you. This way the system is moveable and not invasive, and not too complex (as in using a radio signal for the alarm or something).

    The constraints are 'from the junkbox'....I have photodiodes, LDR's, 555's, and opamps, and don't mind buying 2 laser pointers. I'm trying to stay away from esoteric stuff I'd have to order since this is just a little fun thing.

    Any ideas on this? Am I on the right track?
    Thanks!

    ~Mike :)
     
  2. hgmjr

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    Jan 28, 2005
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    One of the simpliest things to do is use a PIR module that is shovel ready for your use. These modules can be purchased at you local Radio Shack. They are a Parallax product. You will need to provide the means of activating your camera when the trigger signal goes active in the presence of motion.

    hgmjr
     
  3. BMorse

    Senior Member

    Sep 26, 2009
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    I agree with hqmjr, those parallax sensors are available at Radioshack, and it would make the triggering circuit easier to implement, since the output of the PIR module can be selected for active high or active low with a simple jumper on the module.....
    [​IMG]
    I use them quite a bit to detect "live" motion, it wouldn't be triggered by a simple leaf falling down....
     
  4. hgmjr

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    Jan 28, 2005
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    Yeah, that's the ticket. Thanks bmorse for the pics.

    hgmjr
     
  5. GetDeviceInfo

    Senior Member

    Jun 7, 2009
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    the trail cam industry is flurishing, built upon the lowely PIR sensor. Google homebrew trail cams or checkout glolab.com.

    Beam type triggers are difficult to keep aligned, unless you have rigid mounting. The garage door sensors are good for general use.

    Sony is a popular camera of the game cam crew, and you can find lots of information on hacking the cameras to bring out on/off and shutter controls. Shuttering is typically easy, as many cameras have remote shuttering ability. The problem you'll encounter is turning them on/off, as you don't want them powered up for possibly weeks, waiting for a trigger event.

    I use a system where I hack Canon A510/20 models to bring the on/off switch out to the unused USB port pin. I can then turn the cameras on/off, and issue remote control commands via the USB port, with a microcontroller. The micro in turn resolves all the trigger inputs, including RTC alarm for time of day shuttering. In one configuration a PIR sensor turns the camera on, while a beam trigger fires the shutter. This is relatively slow with the point and shoot cameras, but with the SLRs, crisp images of a flying bird for instance, are obtainable.

    Another configuration consists of a PIR with a large viewing field (manipulated with freznel lens), and a second PIR with a highly focused, narrow field of view. The first powers the camera, the second shutters.

    For deer or other large subjects, auto focusing generally works great. It's another story however on small objects within the macro modes. Here you will need to work with fixed focal lengths. This is where beam triggering is a must.
     
  6. hgmjr

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    Jan 28, 2005
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    Actually, I may get me one of the RadioShack PIR sensors to experiment with deer detection. The problem I have with deer is that everything that my wife plants in the yard becomes deer bait. So, my main purpose of detecting them is not to take their pictures unless it is to put up "wanted" posters in the neighborhood:D.


    hgmjr
     
  7. BMorse

    Senior Member

    Sep 26, 2009
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    I have used a couple with a very cheap digital camera (just for fun), I had taped off the top portion of the Fresnel lens to only have a wide field of view (to trigger the Pic16F628A to turn on the camera) then I taped off the other one opposite of the first and just left the very center portion of the second Fresnel lens to give it a narrow field of view (to trigger the cameras shutter when the moving person is in view of the camera...).....

    If you want to scare off the deer maybe you can trigger a piezo buzzer or another noise maker to ward off the deer.....
     
  8. hgmjr

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    Jan 28, 2005
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    I thought about using the PIR to trigger a noise source. My thinking was that the noise source would need to be somewhat random. These cute little guys will soon be conditioned and before I know it the word will get around to the other deer and they will start treating the noise like a dinner bell.

    hgmjr
     
  9. Mike33

    Thread Starter AAC Fanatic!

    Feb 4, 2005
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    LOL...I hear you, hgmjr. They're all over, mild winter and they're well-fed. I really just want to know when they're there, not necessarily to take the pics...my fiancee is a photographer and can do a great job on her own, but they are sneaky.

    I don't want to buy a PIR unless (until) we decide we want to trip a camera; I'm just thinking of building a garage-door type sensor using a laser pointer to trigger a tone in the house, using junkbox stuff! It would be temporary, nothing that one would 'depend on' or anything.
     
  10. Wendy

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    Mar 24, 2008
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    I don't have schematics, but I've seen U/S motion sensors using 555s and two speakers that would seem to fit the bill too.
     
  11. hgmjr

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    So you are expecting the deer to interrupt the beam and set off some sort of audio alert signal inside the house when they do?


    hgmjr
     
  12. Mike33

    Thread Starter AAC Fanatic!

    Feb 4, 2005
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    Yup...but I was looking for a rather simple way to do it. I can do it in 2 stages (essentially have a 2nd beam that will trip "on" when the 1st beam is interrupted, triggering an alarm indoors (box mounted near door, fine wires in to piezo element...)).

    But that might be more than simple, having 2 beams to align. Another thought I've had is for the detector to just emit a tone burst on AM, and have a receiver in the house.
    I know this stuff can be purchased, etc., it's more for my own edification that I want to figure this out!
     
  13. hgmjr

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    Yesterday, I purchased one of these sensors from my local RadioShack to do some experimenting. In looking at the spec sheet it appears that the mode set jumper to which have you eluded in your reply above places the sensor into either a retriggerable mode or a pulse on detection of movement mode. In either mode it is still high-true and low when in idle. Is that what you meant to say? I guess it is possible that the design may have been altered at some point to change this feature.

    hgmjr
     
  14. BMorse

    Senior Member

    Sep 26, 2009
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    Yes, it seems they have revised the sensor module, here is the pic of the last one I bought at Radio Shack, on the back where the jumpers are it shows the L and H for Active Low or Active High output...... what does it show there now??

    PIR Sensor back.jpg
     
  15. hgmjr

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    Jan 28, 2005
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    Mine is labeled the same way as yours. I guess the labeling is there to indicate that the mode control signal is high or low. I have mine set to the H side (retriggerable mode) of the module. I built it up with a single NPN and an LED along with a few support discrete components. I often get immersed in using my laptop to the point of tuning out everything around me. The problem is that my wife sometimes unexpectedly enters the room from behind me and startles me. After I jump a foot off my chair she swears that she did not mean to scare me. Meanwhile I excuse myself and go change my pants now soiled. Anyway, this little ever-vigilant rascal lights up when she is still around 20 feet away. The flash is enough to alert me to the motion. Even if I trigger it unintentionally it serves as an attention grabber. Maybe it will serve to recondition me to the unexpected.

    At $10 it is a pretty nifty sensor requiring very little in the way of support circuitry to make it do something useful.

    hgmjr
     
  16. BMorse

    Senior Member

    Sep 26, 2009
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    they do come in handy, and for the price, it can't be beat :)

    Here is a link to a circuit for driving a relay with the output of the PIR sensor, comes in handy if you need a "dry" contact for the output, very useful for Halloween props :)....

    http://www.scary-terry.com/itw/pirsensor/pir-relay.jpg
     
  17. hgmjr

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    Jan 28, 2005
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    Bmorse,

    Thanks for the link. There is not much in the spec sheet to give one a feel for the output current available. From your experience, do you know what is reasonable to expect? I am only asking it to source 500 microamps and it seems to be working fine.

    Sorry mike33 for the off-topic drift.

    hgmjr
     
  18. Mike33

    Thread Starter AAC Fanatic!

    Feb 4, 2005
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    No problem, actually, hg, I am now starting to become a fan of the PIR, LOL!! I didn't realize they were only $10, and that they are 'moddable'. I may have to run out to the local RS and see if they have them here....1 to use, 1 to play with >;o)

    I really enjoy the 'total home brew' stuff, but in this case, it seems that having it all in one might be the best route! Any other functionality can be modded in....
     
  19. BMorse

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    Sep 26, 2009
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    500 Microamps should be something the Module can handle, I have not actually tried to run a "load" directly off of it, I have always used it with a uc.
     
  20. Mike33

    Thread Starter AAC Fanatic!

    Feb 4, 2005
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    Has anyone tried to couple the PIR with something that can send a signal to a remote receiver? For alarm purposes. This would make 1/2 of what I have in mind. Think of a car driving up your driveway (or a deer in the garden...), and you get an audible notification in the house. Perhaps my actual question has more to do with radio than the detection aspect! The area I'm looking to cover is too far away to run wires (plus, that's messy...).
     
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