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infrared sensor (irs) help — Parallax Forums

infrared sensor (irs) help

brdjambrdjam Posts: 2
edited 2010-09-04 00:36 in Accessories
I have several irs's installed through out my building in seperate rooms to control the lights for energy conservation.· Is there·something I can put in·one room that will cause the lights in that room to remain on without a person having to pass through it that can be easily removed?

Comments

  • ElectricAyeElectricAye Posts: 4,561
    edited 2010-08-04 20:05
    I've never tried this, but if it's a passive infrared sensor, then you might be able to fool it by having a far infrared emitter periodically blink on and off. But it might require two or three such emitters spaced 1-2 feet from each other and taking turns blinking on and off so it thinks there's something warm moving around.

    I'm just guessing, though.
  • brdjambrdjam Posts: 2
    edited 2010-08-04 20:22
    Thanks for your reply. The only problem with that is that there are no other sensors in that room sooo I can't try that.
  • ElectricAyeElectricAye Posts: 4,561
    edited 2010-08-04 20:36
    brdjam said...
    Thanks for your reply. The only problem with that is that there are no other sensors in that room sooo I can't try that.

    If it's like most PIRs, then EACH sensor has a field of view that it breaks up into a number of independently monitored sectors. As a person moves through ONE room, that person will move from sector to sector in the ONE sensor's field of view, and when the ONE sensor detects things are changing from sector to sector, that's when it triggers its electronic circuit. The only thing I don't know is how to make a cheap and easy far infrared emitter. Several small incandescent lights might work, but you'd probably have to get the spacing just right so you're sure each sector of the sensor will get triggered.

    I hope that helps.

    smile.gif
  • ElectricAyeElectricAye Posts: 4,561
    edited 2010-08-04 20:38
    To see how they probably work, check out this:

    www.panasonic-electric-works.com/peweu/en/downloads/ds_61802_0002_en_napion.pdf

    media.digikey.com/pdf/Data%20Sheets/Panasonic%20Electric%20Works%20PDFs/AMN%20Design%20Manual.pdf?cshift_ck=null&client_id=5042
  • FranklinFranklin Posts: 4,747
    edited 2010-08-05 02:33
    You could always put a switch across the sensor leads.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    - Stephen
  • whtguitarwhtguitar Posts: 2
    edited 2010-08-10 12:37
    ElectricAye wrote: »
    I've never tried this, but if it's a passive infrared sensor, then you might be able to fool it by having a far infrared emitter periodically blink on and off. But it might require two or three such emitters spaced 1-2 feet from each other and taking turns blinking on and off so it thinks there's something warm moving around.

    I'm just guessing, though.

    Hi, sorry to intrude, but my question is related to this comment. Is it wrong to have 2 PIR's in the same room? I want to make my AC turn off when I leave the room, and I am thinking about using a PIR, but there is already one in there used by the security system. Would one cause erronous readings to the other?
  • ElectricAyeElectricAye Posts: 4,561
    edited 2010-08-10 13:11
    whtguitar wrote: »
    ...Is it wrong to have 2 PIR's in the same room?...

    No, it's not wrong. PIR stands for "Passive Infra Red". Passive means it does not emit any energy (like the way a radar emits energy then waits to see if energy returns, for example). Instead, a passive sensor merely observes the infra red spectrum to see if any changes have occurred in the environment, and if changes have occurred, then it triggers an alarm or whatever. What these sensors detect is the heat from a person's body or from some other warm object, but they only trigger if that person or object is moving.

    So, you should be able to install as many PIRs as you like, and they won't interfere.

    hope that helps
  • whtguitarwhtguitar Posts: 2
    edited 2010-08-11 12:15
    ElectricAye wrote: »
    No, it's not wrong. PIR stands for "Passive Infra Red". Passive means it does not emit any energy (like the way a radar emits energy then waits to see if energy returns, for example). Instead, a passive sensor merely observes the infra red spectrum to see if any changes have occurred in the environment, and if changes have occurred, then it triggers an alarm or whatever. What these sensors detect is the heat from a person's body or from some other warm object, but they only trigger if that person or object is moving.

    So, you should be able to install as many PIRs as you like, and they won't interfere.

    hope that helps

    Thank you so much! It will help.
  • SeariderSearider Posts: 290
    edited 2010-08-11 14:12
    You could try a servo that waves a hot resistor on the end of a stick back and forth. While it is not terribly elegant it should be effective.
  • APSpijkermanAPSpijkerman Posts: 32
    edited 2010-08-12 12:43
    I have tried something like that, we put some PIR sensors in a museum so a CD or DVD track started if someone approached an exhibition. I wanted to add some sort of self test .. so not all the sensors need to be tested everyday. But i think the according to the datasheet the PIR sensors work with a wave lenght that is like 10 times longer as the IR LEDs.
    So they only work with warm objects, apparantly they are tested with a warm black object with a forked wheel in front of them. I tried it with a couple of IR leds, but it never reacted.
  • ElectricAyeElectricAye Posts: 4,561
    edited 2010-08-12 12:53
    APSpijkerman wrote: »
    ... according to the datasheet the PIR sensors work with a wave lenght that is like 10 times longer as the IR LEDs.....

    There's an interesting graph about this on this data sheet:

    http://media.digikey.com/pdf/Data%20Sheets/Panasonic%20Electric%20Works%20PDFs/AMN%20Design%20Manual.pdf?cshift_ck=null&client_id=5042

    :)
  • SeariderSearider Posts: 290
    edited 2010-08-12 13:46
    Wow, that is more information about PIRs in one place that I have ever seen. Complete with cartoons :)
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