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Thread: USB mini-spotlight

  1. #1
    DIGWDF Engineer member dirknerkle's Avatar
    Join Date
    Nov 2011
    Plymouth, MN USA

    USB mini-spotlight

    So I've got this birdfeeder outside on a webcam ( and without thinking about what I was doing, I decided to put a light on it during the night to see if there was any activity. "Not thinking" in this case applies to my pea-brain and the concept of darkness and diurnal birds (birds that are active during the day and rest at night). Was it a stupid idea? Yes, because owls and only a very few other species of birds fly at night -- certainly not the species of birds that would eat at a bird feeder. That was my first mistake.

    Dumb... dumb... dumb... dumb.....

    BUT.... the pea-brain that I am, I went ahead with the project anyway. After all, I'm a DIY'er and I was curious if I could make a USB-powered spotlight that could be powered by the Pi-3 that runs the birdfeedercam. Of course, it had to be bright enough to illuminate the feeder so the webcam could see it yet it had to be very frugal in the power area because the USB port on a Pi doesn't deliver a powerhouse of juice.... So I forged ahead...

    I made this LED holder for four, white 5mm LEDs with, yes, you guessed it -- my 3D printer. The diameter of the holder fits inside a 1/2" thinwall PVC pipe. The pipe would be the "lens" so to speak, focusing the light into a smaller beam. It only took 15 minutes for the printer to make this little thing...
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    Then I inserted the LEDs into the holes (very snug fit!) wired the LEDs together in parallel and added a pair of 1N4001 diodes to the terminals to drop the voltage from the normal USB 5vdc down to about 3.8v. I figured the diodes would also knock down the current just a bit and the result would be close enough to the juice that white LEDs like. Then I glued it into the end of the PVC pipe with a couple dabs of crazy glue.

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    In one of my many purchases for odd parts that "I might need some day" (another excuse we DIY'ers use), I got out some USB plug parts and made a short cable. I tested it on a desktop PC and it drew only .06A -- that's 60ma of current. Well, what the heck -- there should be enough headroom in a Pi's USB system for that, I should think...

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    But I made my second mistake when I went up to test it on the birdfeedercam. Mrs. Dirk was in the room and she asked what I was doing. When I told her, she said that neighbors would easily see it and she didn't like that idea at all. Oops. Bad tactics.

    But... it did work! It was bright enough to illuminate the bird feeder from about 4 feet through the window -- the webcam picked it up, you could even see the colors of the feeder and it didn't "kill" the Pi-3. However, since it's a wireless Pi also powering the webcam it was probably close to being overloaded and the light pulsed slightly, which tells me that it was perhaps on the edge of crashing the Pi.

    However, while the Pi may not provide enough juice, one could certainly use another cell phone charger to power it directly.

    Then Mrs. Dirk reminded me that (a) most birds sleep at night so there wouldn't be any action to see and (b) humans sleep at night too so nobody would watch it anyway. She's hard to argue with...

    Oh well, it was still a fun little project.
    Last edited by dirknerkle; 06-06-2019 at 12:44 AM.
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  2. #2
    Junior Elf member
    Join Date
    Mar 2017
    Lancaster, Ohio
    Why not rebuild with IR LEDs? You probably won't see too many birds at the feeder, but you might catch some other critters.

    Sent from my Moto Z (2) using Tapatalk

  3. #3
    Frosty member
    Join Date
    Nov 2014
    Sauk City, WI
    this time of year, the birds are chirping loudly well before dawn. are you sure you won't catch some?

  4. #4
    Old Man Winter member
    Join Date
    Mar 2013
    Monroe Township, NJ
    Now I'm wondering if I can use this concept to make some small pin lights for some props for outside - minus the USB of course.

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