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Any ideas on alternative garage door type beam? — Parallax Forums

Any ideas on alternative garage door type beam?

T ChapT Chap Posts: 4,223
in General Discussion
I want to use a garage style beam to detect if someone walks in an area. This idea is just like a garage door IR beam from point to point. This cannot be cameras or motion sensors other methods, it must be point to point for a very tight precise detection and easy concealment. I have other thermal and IR devices to detect motion and presence which don’t apply here. This is point to point and the goal is to make it as inconspicuous as possible. The distance is 50’ to watch. I bought several types that have more than enough range but these devices are very large and would require some effort to conceal including having to cover with IR plastic. The other goal is very long life without maintenance or repairs. Once I experimented with a cheap laser pointer and an opto device and could run the light through a 1/4” hole and it was perfect but the laser pointer didn’t last long and it didnt have the range. Any ideas on a small method to do this?
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Comments

  • kwinnkwinn Posts: 8,697
    edited 2018-12-07 17:22
    A modulated IR led and receiver as used in IR remote controls. If you have electrical outlets in the area you could possibly disguise the emitter and receiver as night lights or electrical outlets.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    Did you run the laser continuously? One might last longer if you pulse it instead. At a distance of fifty feet, anything besides a laser is going to require some sizable optics to focus the beam. OTOH, the beam from a visible laser will show up if there's dust or fog in the air. Is this for use indoors or out?

    -Phil
  • kwinnkwinn Posts: 8,697
    Quite a few inexpensive IR diodes with viewing angles in the 10 - 30 degree viewing anle range that should work with a remote IR receiver at 50 feet or more. My tv remote at home works from 22 feet away without any problems.
  • T ChapT Chap Posts: 4,223
    edited 2018-12-07 21:29
    Actually it is both inside and out. Forgot to mention that. The modules I have will work in or out. An issue with a wide angle lens is that it can get reflections. The laser was ideal but a pain to keep on target. Also I was testing the laser at 5’. 50’ will be a real challenge for a laser to stay dialed in over time.
  • DigitalBobDigitalBob Posts: 1,513
    What about the good old photocell and light source
  • MicksterMickster Posts: 2,693
    Does it need to be thru-beam......what about a laser displacement sensor?
  • T ChapT Chap Posts: 4,223
    That would be interesting. Low profile too only 2” long. I’ll see if I can get one to tryout Thanks.
  • MicksterMickster Posts: 2,693
    I want one too now...dammit...I have a gun project where I want to adjust the virtual scope elevation based on range. 👍
  • MicksterMickster Posts: 2,693
    Hmm response time ranges from 0.03s to 3s...I wonder if it gives an immediate signal but might need time for accuracy.
  • ercoerco Posts: 20,256
    Phil Pilgrim (PhiPi) wrote: »
    Did you run the laser continuously? One might last longer if you pulse it instead. At a distance of fifty feet, anything besides a laser is going to require some sizable optics to focus the beam.


    +1. The only thing cheaper than a bag of laser diodes is a bag of photocells. You could use either, but laser is accurate & easy to set up, and has a nice narrow beam. You could pulse (modulate) it or lower the voltage/current to make it last "forever".

    https://www.ebay.com/itm/332696407504 10 lasers/$1.61 OBO

    https://www.ebay.com/itm/152798815211 20 photocells/$0.75
  • MicksterMickster Posts: 2,693
    edited 2018-12-28 11:09
    T Chap wrote: »
    That would be interesting. Low profile too only 2” long. I’ll see if I can get one to tryout Thanks.

    Well mine arrived a few days ago but with no documentation regarding hook-up and comms protocol. Messaged them twice, via eBay and all I get is "our products are tested prior to shipment"..... Grrrr >:(
  • T ChapT Chap Posts: 4,223
    edited 2018-12-28 13:36
    They never replied to me do I didn’t order it. I have resigned to using these optix bulky units which work great. I’ll put them inside a wall or nice looking box and get IR plastic and make custom flat covers. Let me know how you laser range finder works. On the eBay site it gives some simple instruction like “send command C for distance”. Send it a C and see what happens :)
  • ColeyColey Posts: 1,110
    You've already got the best thing for the job, in Security there are two optical beam manufacturers I would trust, Optex and Takex.
    Takex do a minute beam set but only 33' range.
    https://takex.com/pb-10ns-pr-1801.php
  • T ChapT Chap Posts: 4,223
    That’s a neat sensor coley. I can use that in some applications. Thanks
  • JordanCClarkJordanCClark Posts: 198
    Would retroreflective work? They'd be a bit more forgiving for alignment.

    https://www.ifm.com/us/en/product/O1D106
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