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IR "floodlight" using LEDs?

Discussion in 'Electronic Basics' started by Don Bruder, Jun 27, 2004.

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  1. Don Bruder

    Don Bruder Guest

    OK, guys... you've all been having so much fun with LED flashlights, now
    here's one for ya:

    Show me some plans for a floodlight/spotlight (ideally, adjustable
    between the two) *USING IR LEDs* that will light up a goodly section of
    territory - Enough to make decent moonless-night video of deer with a
    camera that has demonstrated itself to be QUITE nicely sensitive to the
    IR wavelength used by all the remote controls I've got in the house.

    Using several of the remotes together, I can get good detail out to a
    few feet during testing in the makeshift darkroom of my bathroom. I can
    clearly see and videotape my IR self in the mirror from about 5 feet
    back using the remotes as the only light source. The picture fuzzes out
    more the further back I get, with about 10 feet seeming to be the limit
    of visibility. Only the remotes, merrily twinkling away, remain visible
    beyond that point.

    I'd like to improve on that concept. (not to mention make it more
    convenient to handle than a fistful of remotes!) - Ideally, I'd like to
    be able to "paint" a 20-30 foot wide area with enough IR to shoot video
    with, at anywhere out to a couple hundred feet with decent image
    quality. (Yes, I realize I'll never achieve color this way. I'd hope
    *ANYONE* who'd consider a project like this would realize that, too! :) )

    Any thoughts? Drawings? Magical inspiration? Suggestions on power
    sources (Ideal unit would be hand-held, no cord. Corded to 12 volts of
    DC (car battery clips or a cigarette lighter plug) would be acceptable.
    AC powered need not apply, although I may eventually get around to
    adapting one to AC if they work out nicely)? How about which LED is
    likely to work best for this project?

    Key here is "lighting them up" without scaring them off, like the
    visible spotlight I've got does. Since I understand deer to be
    UV-sensitive, but close to IR-blind (if not completely - jury still
    seems to be deliberating on whether they can see it at all, or if
    they're totally blind to it), I figure this would be the ideal solution
    - Bathe 'em in IR light that they can't see, and then use a camera that
    sees in IR nearly as well as it sees in daylight to catch 'em on tape.
     
  2. R.Lewis

    R.Lewis Guest

    Buy one or more of the many varieties of IR illuminators readily available
    (manufactured specifically for the purpose you propose.)
     
  3. For large areas, if power is available, LEDs may not be the most
    efficient. Brood lamps with IR filters may be cheaper and they put
    out a lot of IR.

    But if you want ot experiment with some LED arrays, get a bunch of
    high power 850 to 880 nm (the 940 nm ones do not match the
    sensitivity of most cameras as well) LEDS and build some arrays. To
    keep them from getting hot, space the LEDS apart about a diameter or
    so. You can series quite a few and run them off something like 48
    volts DC with a single resistor to limit the current.

    I like the LEDs from Vishay like this one:
    http://www.vishay.com/docs/81091/81091.pdf

    Since their forward current at rated 100 ma is about 1.5 volts, you
    can connect something like 25 of them in series with a 120 ohm 2 watt
    resistor and apply 48 volts DC. This will use almost .1 amp or 4.8
    watts of power. But you will probably find that you need a half dozen
    or more of these arrays to light the area you describe.
     
  4. For the long distances, you will need some kind of reflector. And since
    LEDs, even IR, put out a beam that's already somewhat concentrated, they
    aren't amenable to being in a reflector. So the best way is to use a
    regular incandescent lamp., which puts out tons of IR. All you have to
    do is filter out the visible light and let the IR thru. You can get
    much more IR that way, since the lamps are natural IR emitters.
    subject.
     
  5. buck rojerz

    buck rojerz Guest

    You also may need to use manual focus on your camera. Depending upon how
    the auto-focus works on your camera, auto-focus may not work.
    IR illuminated objects focus at a differnt point than visible light
    illuminated objects do.

    If you are at a fixed distance from a given object and switch from
    visible light to IR illumination, you will find that you may need to re-
    adjust the focus on the camera.

    cheers

    buck
     
  6. Gordon Youd

    Gordon Youd Guest

    What size shells does your camera take???

    Gordon.

    -----------------------------------------------------------------------
    subject.
     
  7. Don Bruder

    Don Bruder Guest

    It can chamber Hi-8, 8mm or VHS-C. I find it likes Maxell Hi-8 120s,
    with the full plastic jacket, best. Less jamming when they're ejected. A
    couple of years ago, I tried some Sony VHS-C 160s that I found on
    clearance at Wal-Mart but those kept jamming, and left a lot (to the
    tune of several feet) of tape residue wrapped around the record head
    when I cycled the action. Something about those magnum loads just
    doesn't agree with this camera, I guess, since I had the same problem
    with the TDK 8mm 160s I tried a few months ago.

    And as for your insinuation that this is going to be a poaching tool,
    five words sum it up nicely: "You *GOTTA* be kidding, right???"

    If I should decide I want venison on the table, I can poke my head out
    the back door (or open the bedroom window, or step out on the deck, or
    open the living room window, or... You get the picture? Deer are
    *EVERYWHERE* around here) at nearly any time of the day, year 'round
    except for maybe April and May (when all the does around here go into
    hiding, presumably to do the "lets be a mommy" thing, and apparently,
    take all the bucks with 'em in the process - they're just now starting
    to show up, tiny little still-spotted fawns tottering along behind,
    after their annual "disappearance" - they're about three weeks behind
    schedule this year for some reason) and shoot as many deer as I have the
    energy to dress out, without needing to resort to the time, expense, and
    difficulty of creating/building/using what amounts to a "night-vision"
    system to do it with. Never mind facing zero consequences for doing so.
    (unless you count tolerating the flies that a gutpile from a
    mass-slaughter like that would likely attract as a "consequence". But
    seeing as I've also got horses (and the attendant flies), I'd likely not
    notice that.)

    It's a bit harder, though, to do night-filming, since once the sun goes
    down, they *DO* get spooky about headlights, hand-held floodlights,
    flashlights, and other visible light sources.
     
  8. Here is another very useful trick.
    Use a light dimmer on a standard incandescent lamp, and turn it down to
    the point where the lamp is just braaely lit. Now the output is almost
    entirely IR and a pair of cheap filters can get you a very clean beam of it.
    So use one of those directional spotlights such as a track light or reading
    light and put a fairly high wattage bulb inside. Dim to barely glowing.
    Cover with a piece of red plexiglass and a piece of blue plexiglass. The
    results will be a very nice sharp spotlight of infrared light that is almost
    completely invisible even if you stare right into the reflector.

    Cheers!

    Sir Charles W. Shults III, K. B. B.
    Xenotech Research
    321-206-1840
     
  9. If you put two lamps in series, so that they run at half voltage, you
    don't need the dimmer.

    If you use 250 watt brood lamps (reflector floods with red filters
    painted on them) you only need to add the blue filter to get rid of
    the visible.

    I have a pair of brood lamps wired in series to hang over our bed for
    when my wife's arthritis acts up in winter. They are dim enough they
    we can sleep with them on. But I keep dreaming about developing
    pictures.

    If you has some of these running through sunset, I doubt that animals
    would pay much attention to them with no further filtering. The Farm
    Bureau and lots of hardware stores sell these for a few dollars each.
    And at half voltage, they last a very long time.
     
  10. Don Bruder

    Don Bruder Guest

    It CAN'T be that easy... Can it?!?!?!?

    I'll definitely try it. Thanks!
     
  11. John Miller

    John Miller Guest

    Please let us know how you get on.

    I want to do the very same thing - deer, raccoons, possums, foxes, turkeys,
    ground hogs. We get them all - right up to the back door (handing a raccoon
    a slice of bread and having it take it with its "hands" is just one of the
    pleasures).

    On a vaguely related note, I have put a UV bulb in one of the outside
    lights - attracts lots of interesting insects at night and you can get
    fire-flies to signal en masse if you turn the UV light on and off at about
    1Hz....

    John.


    subject.
     
  12. Gordon Youd

    Gordon Youd Guest

    Hi, Don, Points taken, no offence meant , I just could not let a joke slip
    by.

    In the UK we don't exactly have deer "outside our door".

    I do like your in depth reply.

    Kind regards, Gordon.

    ----------------------------------------------------------------------------
    ------------------
    subject.
     
  13. I have found that further adding green plexiglass to the red and blue
    makes the output much less visible still. Haven't tried that with a lamp
    dimmed to barely glowing however. But with a lamp dimmed that severely,
    the infrared seen by most cameras will certainly suffer in comparison to
    longer infrared wavelengths.

    With red, green and blue plexiglass, the "visible" output is mostly from
    nominally infrared wavelengths longer than about 730, maybe 740 nm or so.
    With a high wattage incandescent at full blast, I suspect it will be dim
    enough for animals to not notice. CAUTION - do not stare into the beam,
    since your pupils may be more dilated than without the filters and you
    might cook your retinas.

    - Don Klipstein ()
     
  14. Rich Grise

    Rich Grise Guest

    What about an ordinary heat lamp like you see on that platform between
    the kitchen and the wait station at restaurants? They're _designed_ to
    put out lots of IR!

    For that matter, your wife's iron on "linen." ;-)

    Cheers!
    Rich
     
  15. What kind of bulb is that? An uncoated Fluorescent lamp? I know that
    the mercury UV lamps with a screw base like the ones they used in dryers
    have to be on for a few minutes before they put out UV. They wouldn't
    work if you turned them on and off at 1 Hz. Then there's the neon tube
    UV lamp with the little beads of mercury inside the tube. It puts out a
    nasty spectrum of UV with the short wavelengths that can badly 'sunburn'
    you in ten minutes. I think I still have one of those old timers in the
    garage.
     
  16. Chris Hodges

    Chris Hodges Guest

    I think it will be a fluorescent with a special coating (not the same
    as a blacklight coating - they typically let more - bluish - vis
    through than that).

    Why do they need a few minutes to put out UV? If it's a temperature
    (elctrode/plasma) issue then warming up before pulsing at 1Hz might
    keep the temp high enough (especially in a reasonably enclosed
    fitting).

    Chris
     
  17. John Miller

    John Miller Guest

    Actually, it's an incandescent one from the local grocery store - cost about
    $5. GE Blacklite 60Watts. Barcode 43168 22767. It's a standard bulb
    coated in a UV transmitting/vis blocking material.

    John.
     
  18. The drier lamps put out shortwave UV (2537 nm and 184.9 nm) and not much
    longwave, and won't be that useful for attracting insects. These are now
    collectors' items. They put out a fair amount of UV before they warm up -
    not that much different from fluorescent lamps in warmup requirements.
    I used to have one - puts out 253.7 nm and not much UV of any other
    wavelength. I once (25 years ago) saw one in a thrift shop, and it was
    supposedly a sunlamp. The 253.7 nm wavelength is used for germicidal
    lamps.

    Then there are the high pressure mercury vapor sunlamps - the RS
    ("reflector sunlamp" floodlight with a medium screw base or the RSM
    version with the mogul screw base), and some models, mainly by Sperti
    with bare arc tubes and heating elements as resistive ballasts. These put
    out plenty of 365 nm (not much effect on human skin) and 313 nm (UVB), and
    a lesser amount of wavelengths that were shorter but in the UVB range.
    The mercury vapor pressure in the arc tube when fully warmed up was
    close to atmospheric pressure, but according to "The High Pressure Mercury
    Vapor Discharge" by W. Elenbaas these fit the description of high pressure
    mercury vapor lamps.

    - Don Klipstein ()
     
  19. buck rojerz

    buck rojerz Guest

    (Don Klipstein) wrote in
    I actually have one of those "dryer" lamps as you refer to them, except
    mine is in a hand-held mineral light. It has a filter in front of it to
    block out most of the visible light. By todays standards it isn't a very
    bright black light. I have some B.L. leds that are much brighter than
    the mineral light is. The mineral light has a small ballast on a line
    cord going to the hand-held part, that encases the bulb. It still works
    just fine. When you take the filter off, you quickly notice that the
    bulb is also an ozone producer, as well. But I don't stare at it that
    way... bad news, for sure. It looks just like the un-coated flourecsent
    tubes. (I know, I said I didn't look at it.) ;)

    cheers

    buck
     
  20. Guest

    A bit like the sign on the laser cutter "do not look into laser with
    your remaining good eye"
     
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