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Thread: Looking for a 'tripwire' flashlight

  1. #1
    Flashaholic* turbodog's Avatar
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    Default Looking for a 'tripwire' flashlight

    I need a light for the following problem. Will likely have to build something... but you never know.

    Have a tornado shelter. Recently needed to get into it in the middle of the night in a big hurry. Did not have time to grab a light.

    When got IN the shelter, needed a light immediately in order to close & lock the door. Depending on who may be in there (ie, not myself) they will not know where a light stashed in there is, how to turn it on, etc. Will quite likely not have time to find/figure this stuff out either.

    I want to put a light in there with a string across the doorway. When you want through, the light comes on as you pull/run into/trip across/etc the string. It would be hooked to a switch that turns on and stays on.

    Could NOT find anything like this using google.

    If I have to I would build using a 4d battery box, emitter, heatsink, spring loaded microswitch with a paperclip holding it closed, and string tied to paperclip.
    This is your life, and it's ending one minute at a time.
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  2. #2
    Flashaholic* LedTed's Avatar
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    Default Re: Looking for a 'tripwire' flashlight

    One way to go would be to make your own with an ATTiny85 and a PIR sensor.

    Simpler and easily set up with a tripwire would be a close pin deadmanís switch. Though I donít recommend the string as it is a trip hazard.
    Enjoy the light show - LedTed

  3. #3
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    Default Re: Looking for a 'tripwire' flashlight

    Have you considered a motion sensor light? I have used a Dorcy motion sensor night light with auto off in the kitchen for years with lithium AAs. It sees nightly operation and I only change the batteries maybe 3 or 4 times in a year.For a limited use space the batteries would last all year.

    The model I use isn't on Dorcy's site anymore but they have some newer models. You may be able to find another brand besides Dorcy that is better quality although the Dorcy motion lights have worked fine for me. If nothing else it could be an interim light until you find or make something better.
    I respectfully reserve the right to purchase yet another light......

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    Default Re: Looking for a 'tripwire' flashlight

    Do you intend for it to be "portable" ?

    The reason I ask, is that this thread might otherwise be more usefully addressed in the Fixed Lighting forum.
    ... is the archimedes peak

  5. #5
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    Default Re: Looking for a 'tripwire' flashlight

    Iíd definitely go with a motion sensor light and maybe some tap lights down the entrance or in easy to find areas
    Big butnotsomuch-burly

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    Flashaholic* turbodog's Avatar
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    Default Re: Looking for a 'tripwire' flashlight

    Given that the room is solid steel, there's enough vibration (for true motion sensing) and heat (for IR motion) that it would likely get tripped all the time. The string would just pull a small pin/wire/paperclip out and allow the switch to trigger.
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    Flashaholic* turbodog's Avatar
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    Default Re: Looking for a 'tripwire' flashlight

    Quote Originally Posted by bigburly912 View Post
    Iíd definitely go with a motion sensor light and maybe some tap lights down the entrance or in easy to find areas
    Not that big. Was retrofit into existing space. Is in corner of garage.
    This is your life, and it's ending one minute at a time.
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    Flashaholic* turbodog's Avatar
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    Default Re: Looking for a 'tripwire' flashlight

    Also, my main reason for not wanting motion sensing is that I don't have to wonder if it's triggering randomly and will be dead when it's needed. We don't go into the shelter very often... found some bottled water in there that was WAY past its prime. I am ok with a yearly battery replacement (due to the heat), but that's about it.
    This is your life, and it's ending one minute at a time.
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    Flashaholic* turbodog's Avatar
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    Default Re: Looking for a 'tripwire' flashlight

    Quote Originally Posted by archimedes View Post
    Do you intend for it to be "portable" ?

    The reason I ask, is that this thread might otherwise be more usefully addressed in the Fixed Lighting forum.
    Probably not.

    If you want to move thread that's cool. This was sort of a weird idea...
    This is your life, and it's ending one minute at a time.
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    Default Re: Looking for a 'tripwire' flashlight

    Ok, moved to Fixed Lighting for you.

    Might get more specific advice here, on what you are really wanting, instead of some kind of makeshift suggestions using kite string, duct tape, paper clips, and tape switches (lol)
    ... is the archimedes peak

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    *Flashaholic* idleprocess's Avatar
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    Default Re: Looking for a 'tripwire' flashlight

    I'd think that a battery box type arrangement with a standard on/off toggle switch and the tripwire removing an insulator from one of the battery contacts would be the way to go.
    I apologize that this letter is so long; I did not have time to write a short letter

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    Default Re: Looking for a 'tripwire' flashlight

    There are "emergency lights" (luminaires) which automatically light when power is interrupted.

    These might be able to be set up to function in the manner you seek ?
    ... is the archimedes peak

  13. #13
    Flashaholic* turbodog's Avatar
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    Default Re: Looking for a 'tripwire' flashlight

    Quote Originally Posted by archimedes View Post
    There are "emergency lights" (luminaires) which automatically light when power is interrupted.

    These might be able to be set up to function in the manner you seek ?
    No power in the bunker due to it being all steel (conductive).
    This is your life, and it's ending one minute at a time.
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  14. #14
    Flashaholic* turbodog's Avatar
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    Default Re: Looking for a 'tripwire' flashlight

    Quote Originally Posted by idleprocess View Post
    I'd think that a battery box type arrangement with a standard on/off toggle switch and the tripwire removing an insulator from one of the battery contacts would be the way to go.
    Had thought about the same idea.
    This is your life, and it's ending one minute at a time.
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  15. #15

    Default Re: Looking for a 'tripwire' flashlight

    Why not get a flashlight with a tail forward clicky, some PVC pipe, and then have the tripwire release a weight that activates the switch and lights up the tube?

    https://imgur.com/a/7Q3j3oj

    Something along these lines, the moment the pin is pulled the weight activates the flashlight, depending on if you just use a smooth pin for the trigger or something with a bit of a detent to make sure it doesn't get pulled on accident. It'd cost a grand total of some pocket change and can be directly mounted on a wall, board, anything where you can screw, glue, nail, staple, even velcro it onto. You can use any type of flashlight that has a forward tail clicky, throw in some lithium primaries and it's good for 10+ years.

  16. #16
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    Default Re: Looking for a 'tripwire' flashlight

    A simple and very reliable solution would be a light that is lit continually, this is now achievable with disposable batteries.
    4 alkaline D cells and the brightest LED you can get.
    Select the series dropper resistance to give a current of 2ma. That will give a run time of a year.
    Leave a couple of flashlights with AA lithium cells where they are lit by this continually burning light and thus instantly located.

  17. #17

    Default Re: Looking for a 'tripwire' flashlight

    Quote Originally Posted by turbodog View Post
    Given that the room is solid steel, there's enough vibration (for true motion sensing) and heat (for IR motion) that it would likely get tripped all the time. The string would just pull a small pin/wire/paperclip out and allow the switch to trigger.
    Have you actually tried a motion sensor light in there to see how it would work? There are plenty of inexpensive ones that you could experiment with. They don't actually trip with just a certain level of heat you know...they use the Doppler effect to trigger. Even the cheap ones.

    Although some really cheap devices that claim to "detect motion" are only using a light sensor and detecting a change in the level of ambient light...again you could experiment and discover what works.

    Personally I think you're over-complicating it by trying to use a trigger that isn't really designed for that purpose. Especially when there are so many things already purposefully designed to do just what you want.

    It also seems as though you should probably set up a schedule on which to check all of the supplies in the shelter. Checking the condition and functionality of the motion sensor light would naturally be a part of that so you could determine if it needs new batteries. Or that it in fact works at all.

    Also consider the mechanics of the trip-wire, and how maybe over time something may cause it to jam just when you need it most (Murphy's Law) and even if you did decide to make it anyway...back it up with a motion sensor light.

    There are also little battery operated lights with switches that resemble the common household style toggle style and have the LEDs in the faceplate. I found some at my local Parkrose Hardware. They can be stuck on the wall with double-sided tape or screwed into place. They are also inexpensive...less than $5 when I bought mine a year ago.

  18. #18
    Flashaholic* turbodog's Avatar
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    Default Re: Looking for a 'tripwire' flashlight

    Will see what I can come up with. The shelter being a large steel box, tends to resonate with vehicle noise when we are in the garage from engine noise, doors opening/closing, and so on. Given the high ambient temp, from living in the south, and from vehicle heat, batteries there don't last their rated life. On one hand it seems simple but there are complicating issues.
    Last edited by turbodog; 06-09-2020 at 07:45 AM.
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    Flashaholic* datiLED's Avatar
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    Default Re: Looking for a 'tripwire' flashlight

    Quote Originally Posted by idleprocess View Post
    I'd think that a battery box type arrangement with a standard on/off toggle switch and the tripwire removing an insulator from one of the battery contacts would be the way to go.
    ^^^Exactly. This would be the least complicated solution.

    Use a switched 2D battery box with a cover and a heatsink with a reasonably large surface area. Add a NexGen converter board set to 250 - 333mA with a decent LED and you would be set. An extra set of batteries would give you days of runtime. *Remember to leave the switch in the on position.*

    Cut a slit in the battery box cover (or back, depending on construction) above the contact and add an insulator between the battery and contact as idleprocess mentioned above. I would recommend using a pull chain or weighted string rather than a trip wire. Simply grab, pull and activate the light.

    Glue several neodymium magnets to the box and mount it to the ceiling. (You mentioned the room was steel.). The box could be positioned as needed and moved once inside. Simple, inexpensive and effective.
    Be still, and know that I am God; I will be exalted among the nations, I will be exalted in the earth!
    Psalms 46:10

  20. #20
    Flashaholic* turbodog's Avatar
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    Default Re: Looking for a 'tripwire' flashlight

    Tripwire (string) goes across doorway so you can't get inside without turning the light on. The other night... we needed to get inside extremely quickly. Should have been in there ahead of time.

    To keep from reinventing the wheel I will find an existing magnetic light and retrofit a switch that I am looking for.
    Last edited by turbodog; 06-09-2020 at 11:47 AM.
    This is your life, and it's ending one minute at a time.
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  21. #21
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    Default Re: Looking for a 'tripwire' flashlight

    You may have seen these cheap LED cabinet lights which come on when a door is opened, after a small magnet
    normally close to the unit is pulled away. They use internal reed switch or Hall-effect sensor. I have a few and
    they are not very bright, use button cells. Something brighter no doubt exists, or principal could be applied to
    custom but not very complex interface. Just connect trip wire to a suitable magnet and position it close to light.

    Dave

  22. #22

    Default Re: Looking for a 'tripwire' flashlight

    For your consideration:

    Buy a household wall switch, the kind that is mounted just inside the door and flips up and down. Buy a box to mount it in. Drill a small hole through the end of the switch and thread through a small split key ring. The ring is there to make it easy to tie a thread to it. Mount it by the door, but mounted sideways, not up and down.

    Run a thread from the latch side of the door to the switch - the ring makes it easy to fasten a thread securely. If the door is steel, a magnetic hook stuck on the inside would be easily adjustable and so perfect for the door side.

    When the door is opened it pulls the thread, the thread first flips the switch and then breaks. Leave enough slack in the setup that you can reach around an almost closed door and rig a new string on your way out. Now you have a tripwire, but it uses the door instead of your face to activate.

    The direction you mount the switch in is whatever matches up the "ON" position to the swing direction of the door. You will need to experiment to get the right thread. You want it to reliably flip the switch but not tear it off the wall. The switch of course controls a light setup that is mounted in the shelter. How plain or fancy is your call.
    Last edited by Ken_McE; 06-10-2020 at 04:26 PM.

  23. #23
    Flashaholic* turbodog's Avatar
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    Default Re: Looking for a 'tripwire' flashlight

    Quote Originally Posted by Ken_McE View Post
    For your consideration:

    Buy a household wall switch, the kind that is mounted just inside the door and flips up and down. Buy a box to mount it in. Drill a small hole through the end of the switch and thread through a small split key ring. The ring is there to make it easy to tie a thread to it. Mount it by the door, but mounted sideways, not up and down.

    Run a thread from the latch side of the door to the switch - the ring makes it easy to fasten a thread securely. If the door is steel, a magnetic hook stuck on the inside would be easily adjustable and so perfect for the door side.

    When the door is opened it pulls the thread, the thread first flips the switch and then breaks. Leave enough slack in the setup that you can reach around an almost closed door and rig a new string on your way out. Now you have a tripwire, but it uses the door instead of your face to activate.

    The direction you mount the switch in is whatever matches up the "ON" position to the swing direction of the door. You will need to experiment to get the right thread. You want it to reliably flip the switch but not tear it off the wall. The switch of course controls a light setup that is mounted in the shelter. How plain or fancy is your call.
    Could be ok. I have to deal with the door opening different amounts. Could be halfway, could be wide open if the wind hits it.

    I've got some magnetic mount lights on order. Will see what I can do. Pics will follow eventually.
    This is your life, and it's ending one minute at a time.
    Be prepared for the truth.

  24. #24
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    Default Re: Looking for a 'tripwire' flashlight

    Whatever you go with I'd recommend (Energizer) Lithium batteries instead of alkaline.

  25. #25
    Flashaholic* turbodog's Avatar
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    Default Re: Looking for a 'tripwire' flashlight

    Have tried 2 ready-made lights.

    https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

    https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

    #1/Square one is terrible. Turns on, stays on, Won't turn on. Etc.

    #2/round one is ok. Will mount it.

    Have no way of knowing if they false positive and run batteries down.
    This is your life, and it's ending one minute at a time.
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    *Flashaholic* idleprocess's Avatar
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    Default Re: Looking for a 'tripwire' flashlight

    Quote Originally Posted by turbodog View Post
    Have no way of knowing if they false positive and run batteries down.
    PIR sensors - which those appear to use - consume power, thus I'd expect to be swapping cells on a schedule.
    I apologize that this letter is so long; I did not have time to write a short letter

  27. #27
    Flashaholic* turbodog's Avatar
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    Default Re: Looking for a 'tripwire' flashlight

    Think I may take the housing that does NOT work and rewire it with a manual switch for the string.
    This is your life, and it's ending one minute at a time.
    Be prepared for the truth.

  28. #28
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    Default Re: Looking for a 'tripwire' flashlight

    Quote Originally Posted by idleprocess View Post
    PIR sensors - which those appear to use - consume power, thus I'd expect to be swapping cells on a schedule.
    I have used a number of LED battery-powered PIR motion sensing lights; there are good ones and less good ones.

    Many run on 3xAAA, better ones take 3xAA or 4xAA. I've measured standby current which can slowly run
    the batteries down even with lights off. For good design its is 100uA or less (or maybe a bit higher). One case
    was >1mA, which for a set of AAA alkalines will last mere weeks. This spec (standby current drain) is never
    listed for the product.

    Other type of lights like this are ones with IR remote control. The IR receiver has to be on all the time. Same
    considerations apply.

    I use a 4xAA PIR light in back shed and it normally holds up for several months including some on-time,
    even in winter. Similar for a 3xAA light in the basement.

    Dave

  29. #29
    *Flashaholic* idleprocess's Avatar
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    Default Re: Looking for a 'tripwire' flashlight

    Quote Originally Posted by Dave_H View Post
    I have used a number of LED battery-powered PIR motion sensing lights; there are good ones and less good ones.

    Many run on 3xAAA, better ones take 3xAA or 4xAA. I've measured standby current which can slowly run
    the batteries down even with lights off. For good design its is 100uA or less (or maybe a bit higher). One case
    was >1mA, which for a set of AAA alkalines will last mere weeks. This spec (standby current drain) is never
    listed for the product.
    I have a generic 3xAA model that I got off of a surplus site years ago that I have used in the guest bathroom (infrequently used). If positioned so as to minimize nuisance trips it lasted 3-6 months on a set of LSD 2Ah NiMH cells.

    Mr Beams is a brand that's had some staying power on the likes of the 'Zon.
    I apologize that this letter is so long; I did not have time to write a short letter

  30. #30
    Flashaholic* turbodog's Avatar
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    Default Re: Looking for a 'tripwire' flashlight

    Quote Originally Posted by turbodog View Post
    Have tried 2 ready-made lights.

    https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

    https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

    #1/Square one is terrible. Turns on, stays on, Won't turn on. Etc.

    #2/round one is ok. Will mount it.

    Have no way of knowing if they false positive and run batteries down.
    The #2/round one is decent. Turns on like it should. No word on battery life. Magnets are pretty weak. Slides down a steel plate wall.


    I took #1 and salvaged the small leds from it. Soldered 4 of them in parallel. Wired a microswitch into place. Fed it all with a standard 123 lithium cell (can withstand the heat/cold) in a spring loaded cell holder. Mounted all this to a 2x4 board about 1 foot long.

    Stuck the board to the wall of the shelter using some magnets from amazon. Put another magnet on opposing wall. Pulled string between magnet and metal 'pin' that holds microswitch down.

    When you walk through the door, the string pulls the pin out, microswitch contacts close, and leds come on.
    This is your life, and it's ending one minute at a time.
    Be prepared for the truth.

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