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Problem, Solution = gerbils??

Discussion in 'Electronic Design' started by Randy Day, Jul 12, 2004.

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  1. A heat lamp or small Quartz spot lamp (saw some at Home Depot yesterday 45W)
    pointing at the PIR detector through a floor fan (fan on a stand) (also at
    HD) running on slow might do the trick. If that doesn't work you could have
    the fan oscillate back and forth to move the lamp in and out of the field of
    view of the defector, use some foil to baffle, shield, the heat source.
    Most of the PIR detectors I have seen are looking for a rate of change above
    a certain threshold in the 11 micron range (Black Body radiation peak for 98
    degree F object). If the rate of change is to slow the detector will not see
    it so a 555 driving a lamp might not heat up and cool off fast enough to do
    the trick.
    Do however let the group know how you solve the problem that we all may
    By the way if this new building also has Flame detectors a candle might
    work, all the firemen running around looking for the fire will set off the
    PID just fine, but be sure to where a rain coat.
  2. Real simple - plug a lead light into a AC outlet, then you dont have
    to worry about the main lights. Most techs have one in the back of the
    truck for situations where there is no AC lighting.....
    73 de VK3BFA

    PS - the hi tech stuff IS interesting, but sometimes the problem
    becomes so complex it stops you doing what you originally set out to
  3. John Fields

    John Fields Guest

    No. The warm body has to be moving; it can't just "be there"
    I've done a lot of work designing the optics and electronics of PIR
    motion detectors for use in daylight and night time detection of deer
    and other game.

    The "single sensor" is usually a windowed TO-5 or T0-39 can housing
    two pyroelectric transducers connected differentially to a FET preamp,
    the output of which exits the sensor. The lens is an array of Fresnel
    lenses molded to give the desired focal length and field of view so
    that some of the heat being radiated by a warm object moving across
    the desired field of view will be focused on and will also move across
    one transducer and then the next in order to generate the signal which
    will be amplified by the FET and then output from the sensor for
    processing by the motion detector circuitry. For your "holes and
    mask" analogy to work properly, the holes would have to be arranged in
    such a way that when, say, someone was walking across the field of
    view and you held the mask and your head and your eyes steady, you
    would see them first with only one eye, then with both, (or neither)
    and finally with only the other eye.
  4. Most people don't realize that you can modulate the incandescent lamp
    with audio and detect it with a photovoltaic cell. It does sound
    muffled, tho. So I would say that the lamp would have no problem
    responding to the on/off cycles of a 555. And it's a helluva lot more
    portable than a light, fan, foil, etc.
    Well, I stopped by OSH and bought a clamp-on lamp socket with aluminum
    reflector and a few 40W appliance bulbs. I'm planning on plugging it in
    at each workstation, leave it on the floor or clamp it on the desk edge,
    and to hell with the IR sensors, let 'em go off. I got my own light
    Yeah, really! Thanks.
  5. Yeah, drain the proverbial swamp.. Thanks.
  6. Guy Macon

    Guy Macon Guest

    of course it does. That's how it goes from the state of being
    where you could see it though a hole in a chunk of cardboard
    to being where you could not see it though a hole in a chunk
    of cardboard - it moves sideways. (the real system uses lenses
    insteasd of holes in cardboard but the effect is the same; be
    at one location and your heat reachs the sensor, move sideways
    and it doesn't, move sideways some more and it does.
    We evaluated one of those. *Much* better performance than the cheap
    ones we used in the security system, and different optical (and I
    presume electronic) design. It may be that the light switches use
    some other scheme, of course.
  7. Yummy! You think I can find that flavor at Baskin Robbins? It's
    getting to be Ice Cream weather! ;-)

    Actually, recently I went into Coldstone, where they custom mix your
    favorite flavors. Yummy, but more expensive.
    It makes sense to have a pair to balance out any slow changes in
    temperature, otherwise the thing would trigger every time the sunlight
    hit it. I reverse engineered one security light circuit, and I was
    surprised that they used a pair of electrolytics, 470 uF IIRC, back to
    back as coupling caps to give the high pass filtering, aka keep the DC
    out of the next stage amplifier.
  8. Mjolinor

    Mjolinor Guest

    Boring in the extreme. All these good ideas and I was waiting for a
    modulated cat passive heat dissipating shields with remote control tied to a
    fan and you go and buy lamps, most unsatisfactory.
  9. Guy Macon

    Guy Macon Guest

    Boring, but a superior solution. It gets quite dim under a desk with
    the only illumination bring the overhead lighting.

    (Why are so many people crossposting to alt.binaries.schematics.electronic?
    don't you people know what the words "binaries" and "schematics" mean?)
  10. I think.. Why? Because it's a small fraction of the volume of the
    other NGs, and one can find one's post among what's there, instead of
    getting lost in the clutter. :)

    I pulled the top half of the faceplate off of one of the PIR sensor
    switches (it just snaps off). Turns out that under this faceplate,
    there is a berg jumper labeled override, which apparently disables the
    sensor when it's removed. I haven't tried it yet, because I've been
    doing other more important things, so I'll have to check it out later.
    But I _still_ haven't seen any manufacturer's ID on it.
  11. A lot of the movement sensor Lights I have seen have an over-ride function
    where the light stays permanently on if you flip the light switch off and
    back on in less than a couple of Seconds....
  12. Ahh missed this bit of the thread .... The Sensor switches I have seen give
    you a couple of Seconds to toggle them off and On - however it does sound
    like these ones may not be designed for this option but if they use a
    standard Chip/Circuit this still might work have you tried turning them On
    ..... then off and on again to see if they do stay on ?
  13. Guy Macon

    Guy Macon Guest

    You are also losing all replies by users of the largest news server,
    which does not propagate crossposts to binary groups.
  14. Well, it would have to sell for less than a shop light. After so much
    discussion, I came to the conclusion that I should just go to the
    hardware store and buy a shop light with a rough service blub, and plug
    it in to the power as I go from room to rokom, and screw the sensor
    lights, let 'em go dead. This seems like the most straightforward

    I was talking to the network cabling contractor this morning and he said
    that he found the sensor lights to be a big pain in the neck, too. But
    the sales rep for Fluke was trying to sell him a new DTX-1800, (see this
    price grabber list for prices).

    So if he can afford one of these. maybe the price of your small device
    wouldn't be of much concern. ;-)

    Hopefully, maybe in a few years all the light switches and such will
    have an ethernet controller built-in, and be each assigned an IP
    address. Then we can just send a message out over the network to enable
    the light's sensor override.
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