Night cache ideas.

[+wvmarle]

After caching for two years I've never done a night cache. There simply are none in my area (Hong Kong). There is also only a fairly small group of active cachers, and most go for the numbers - hiking a couple of hours for just one cache is a no-go for them.

 

After creating some 80 caches (mostly traditional, some multi, several puzzles, some events) I'm trying to be more creative and also would like to set up a night cache or two. Unfortunately never had the chance to actually do one, but reading about it most of them are trails of reflectors to follow to the cache.

 

The problem with the countryside of Hong Kong is that it is mountainous, and many trails are too rough and steep to safely traverse at night. Also not many trails so reflector trails are a bit boring.

 

Now I found an area that has night-friendly trails (paved, with steps uphill and so), and am thinking of night caches to set up. The problem is to give them some element that need the darkness, other than those reflector trails. Reflectors of course may be part of the cache, I'm open for any ideas for setting up something.

 

Rough ideas that I've been thinking of myself include:

- invisible ink (UV activated), written on e.g. existing signs, but that will also become visible during the day.

- laser pointer: attach laser pointer in a tree, have it point out the cache location. Have cacher connect a battery to some wires running down the tree to activate laser.

- something with a light behind a display, that coordinates become visible when the backlight is on. Again problem is how to make it (almost) impossible to read in the daylight (shielding ambient light with your hands).

 

Anything that needs distance is rather one-dimensional here: only along the established trail. This as the rest of the terrrain is too rough/steep/overgrown/otherwise inaccessible, especially at night.

[+MartyBartfast]

How about setting up a number of LEDs (which are on a circuit with a electric cell so they only come on when it's dark), direct the cacher to go to point X and connect a battery (which powers two green LEDs), then go to point Y and connect a battery (which powers two white LEDs) then find the point where the two green LEDs and the two white LEDs are visible, that's where the cache is E.G.

 

 G
 . 
 .
 G
 .
 .
 X
    .
       W
          .
             .
                W

X=cache

 

Or going with your light behind a display idea, if you had a board which was camoed to match the surroundings, with tiny holes drilled to spell out the co-ords, you could then direct the cacher to plug in a battery (which could be dozens of yards away) and a backlight makes the writing visible, again if you included a photo-electric cell so it won't turn on during daylight.

Edited December 25, 2012 by MartyBartfast

[+T.D.M.22]

UV ink left out is not a good idea as it will fade. How about giving the cacher a location and instructions to point a flashlight until they find reflectors say across a river. It could be reflective co-ords, or even instruction like "one reflector go to XXX co-ords and 2 reflectors go to YYY Co-ords."

Could also do a backlit box with co-ords with a photo-cell in an inaccessible place, like the top of a tree(the cacher has to bring a battery) That way it is only available in the dark.

[+Isonzo Karst]

I've found an urban night cache, that was an off-set from a neon sign, only visible at night when it was lit. I wasn't terribly taken with the location, but it's the only cache of its kind that I know about.

[+wvmarle]

@MartyBartfast: idea with the LEDs sounds interesting but it's going to be really hard to find a suitable location due to the one-dimensionality of most places (just a single trail, and often curvy, so can't put them more than like 10m apart - foliage is another problem there).

Backlit sign is most suitable I think, weatherproofing is an issue but can be overcome.

 

@TDM: reflector sounds good.

Would be good to have one that is one colour (preferably a dark colour for camo reasons), hidden a bit up in a tree or so, that would light up a number or complete coordinate when you shine a torch on it - reflective material in same colour as the rest of the sign. Should be very hard to do during the day, as torches can't really beat daylight in brightness, especially if hung in a way that it's against the bright sky.

[+edscott]

My night cache has reflectors, but is is not a continuous string. There are only reflectors about 100 meters after every trail junction thus forcing decisions and potential confusion at every junction and some long spans between reflectors. The off trail portion does have reflectors which are within visible range of each other.

[+niraD]

I've done a reflector-based night cache where the location was relatively open, and we walked from reflector to reflector to reflector.

 

If you don't have an open area like that, then you need to follow trails. I've also done a reflector-based night cache where there were reflectors past each trail junction. Until we reached a junction, we just followed the trail. When we reached a junction, we checked for reflectors down each branch of the trail.

 

If you don't have many branches in the trail, then fluorescent paint can work well. I've also done a UV-based night cache where the stages were located at various points along a trail with few branches. They were all physical stages, with fluorescent paint on objects provided by the CO. They were also designed to protect the fluorescent paint from exposure to sunlight, to reduce fading. Still, the owner needs to refresh the fluorescent paint every now and then. To make it harder to do the cache during the day, the clues used a combination of regular paint and fluorescent paint. During the day (or using a regular flashlight at night), you'd see a jumble of painted symbols. At night, with a UV light, only the fluorescent paint would glow.

[+hzoi]

- laser pointer: attach laser pointer in a tree, have it point out the cache location. Have cacher connect a battery to some wires running down the tree to activate laser.

 

Could work if you have a weatherproof laser pointer.

 

The first night cache we found had a laser component: cache description said AAA batteries were required, and one stage had a laser pointer in a waterproof container. The pointer fit into a hole in a post, and when activated it pointed to the final location of the cache.

 

We've also seen what was described as a "reactive light" -- I believe the stage had a solar cell and a very low powered LED light, which lit up if you shone a light on it.

 

Could also work up some kind of wireless remote that turned on a light. It would require pretty constant maintenance to keep the remote and light batteries going.

 

As far as the UV option, make sure you use something weatherproof. UV permanent markers good, UV paint better.

[+wvmarle]

- laser pointer: attach laser pointer in a tree, have it point out the cache location. Have cacher connect a battery to some wires running down the tree to activate laser.

 

Could work if you have a weatherproof laser pointer.

For weatherproofing I'm thinking of encasing it into silicon sealant. Or maybe a thick layer of epoxy resin is even better.

 

I've no intention to leave any batteries out there. They will run empty, start to leak, whatnot, and the other problem is that in the first few months I think there will be quite some attention from the most active local cachers, after that maybe a few finds a year. No more. There just aren't that many geocachers here. So it may be sitting there idle for months and after that it should still work - tricky, I know.

 

A final option may be to ask the cacher to bring their own laser pointer and only provide a mount for it. But then this mount must be really stable as a tiny off-set makes a big difference 20, 30m down the bush, and a permanent fixture can be firmly attached to a tree.

[Clan Riffster]

If you don't have an open area like that, then you need to follow trails

I own four night caches. The shortest reflector string is just over a mile.

None are in open areas, and none are on trails.

Lots and lots of bushwhacking!

 

A final option may be to ask the cacher to bring their own laser pointer and only provide a mount for it.

I'm digging the laser idea. My concern for having the user provide it is that they are not built to any kind of standard. You mentioned the importance of a stable mount, which is true. But if your mount is rock solid, and their laser is not the proper size, that might set them off course. If you were handy with machining, you could fabricate some sort of mounting system, then solder in a battery lead, then encase the whole works in something to make it waterproof? Maybe? Just rambling out loud.

[+DragonsWest]

Fluorescent paint or uranium glass (whassat? ) Works pretty good for leaving designs, rather than just a trail of pacman dots.

Edited December 26, 2012 by DragonsWest

[+kunarion]

UV ink left out is not a good idea as it will fade.

What about phosphorus? Minerals that fluoresce in UV light won't fade. Place into a transparent container, or glue granules to form numbers or shapes.

[+kunarion]

or uranium glass (whassat? )

I recently bought glass tiles that supposedly glow all night. I'm thinking of painting them so digits of coords glow at night. The tricky part is figuring out how to make them tough to see in daylight, and to get enough light during the day, so they'll glow brightly. And where to place them where people can sit and find them with binoculars (or whatever the plan is).

[+DragonsWest]

or uranium glass (whassat? )

I recently bought glass tiles that supposedly glow all night. I'm thinking of painting them so digits of coords glow at night. The tricky part is figuring out how to make them tough to see in daylight, and to get enough light during the day, so they'll glow brightly. And where to place them where people can sit and find them with binoculars (or whatever the plan is).

 

You're always going to have the cacher determined to make the find in daylight and brings a cloak or such with them. Look past them.

[+kunarion]

You're always going to have the cacher determined to make the find in daylight and brings a cloak or such with them. Look past them.

I want it to be mysterious. "Invisible" in daylight, so cachers are convinced there's nothing to see. Yet very visible in the dark. That's the effect I'm going for. Glowing tiles don't rely on electrical power, which is good, considering the placement. My idea is they'd be kind of a "camo" idea (camo that I haven't invented yet), tacked 30 feet up several pine trees, among a stand of hundreds. Sit at a certain spot, everything lines up, wait for sunset, find glowing numbers. I've located a likely sitting spot with suitable trees. This doesn't work at your average Walmart LPC. It's just an idea that might be adjusted to a one-of-a-kind night cache site.

 

One thing that would be pretty cool is a tritium light.

http://www.cpfmarketplace.com/mp/showthread.php?195648-FOR-SALE-Tritium-Cubes-and-a-Key-chain-US

Cool variety. Someone in that forum says they sell for as little as $15 for a "5mm" (in 2009).

While you're at it, check out Glow Powder: http://glowinc.com/detail.aspx?ID=42

 

I hunted a night cache recently that I supposed would be one of those, but was told it's an LED. And I'm not certain that LED is functioning (none of us found anything, including the guy with us who had found it previously). Whatever you do with a night cache, be sure you can tell when it's not working, and place a notice as soon as possible, so people know.

Edited December 26, 2012 by kunarion

[+hzoi]

Interesting. Are tritium and uranium products available these days? I've got an old military compass with tritium markers, but the newer versions I've seen have all used photoluminescent paint, probably strontium aluminate. And I've never even seen uranium glass.

[AZcachemeister]

I've done a night-cache in an urban park that used reflective tape to guide the finder to the final location.

 

If they were discreetly placed, I wonder why reflective tape stages couldn't be used 'on the streets' in an urban environment?

[+MartyBartfast]

Another idea I've seen for using standard reflectors is you attach a container (e.g. a 35mm film pot) to an object and then stick the reflector inside the pot (with no lid on), therefore in order for the reflector to work you have to be stood directly in line with it and shining the torch straight into the container.

[+wvmarle]

But if your mount is rock solid, and their laser is not the proper size, that might set them off course. If you were handy with machining, you could fabricate some sort of mounting system, then solder in a battery lead, then encase the whole works in something to make it waterproof? Maybe? Just rambling out loud.

Indeed, size matters. And I think it's more interesting to just ask them to bring a battery, as then the suspense is more. There are so many things that can happen that way!

 

And machining a good mount isn't too hard. Use some brackets to screw it to a piece of wood, and then use a screw to attach it to a tree. Gotta be a big tree to make sure it's stable, and minimise damage. The fact that people don't know what's going to happen, or what direction the laser is pointing, makes daytime searches that much harder.

 

In the end it's gotta be a series of four caches and a bonus: the four elements (air, fire, earth, water) with the fifth (spirit) as bonus. Fire, earth and spirit are going to be night caches (fire: "light your fire", connect battery to light up a display, bonus if I can find flickering candle-like lights that work on 1.5V; earth a "down to earth" reflector trail; spirit is the laser). I have ideas for water (probably a floater) and air (blow in a tube and the coords pop up - have to bring a friend to read it for you) but that are not night caches

 

Bushwhacking is out of the question for me. Mostly the bush is way too dense to get through without chopping (those so-overgrown-they-are-invisible trails can be followed by the fact that the trail is where you can actually pass through the bushes), and secondly on >30° slopes which most are it's simply way too dangerous in the dark.

 

Great ideas coming up here, fantastic.

[knowschad]

If you don't have an open area like that, then you need to follow trails

I own four night caches. The shortest reflector string is just over a mile.

None are in open areas, and none are on trails.

Lots and lots of bushwhacking!

Is it true that you have been known to put reflectors on the tails of alligators?

[+Sharks-N-Beans]

I'm going to go off on a different direction here. I think all of the ideas that the OP mentioned are great, but a night cache needs to take advantage of GZ at night. We started caching in late October, so it got dark early. We found 90 percent of our caches after dark that first year. The best ones were a little creepy. Usually, there was an aspect of previous occupancy...abandoned structure etc, element of surprise...we found one where an owl was roosting just a few feet above our heads, or after dark creatures (bull frogs etc.) add an element of darkside ambiance. Oh, then there are stars. We love when caches take us away from the urban glow and give us a view of the stars that Beans remembers from his rural childhood. Gimmicks are fun, but a night cache needs to capture the essence of the night.

[+kunarion]

a night cache needs to capture the essence of the night.

The only one I've tried has you wait on a specific spot for nightfall, and it's a scenic place to be, during and after sunset. So that's pretty cool, except for the flaw of not having anything to see once it gets dark. [OK, I'm sure it's fine, I just didn't see it]

[Clan Riffster]

If you don't have an open area like that, then you need to follow trails

I own four night caches. The shortest reflector string is just over a mile.

None are in open areas, and none are on trails.

Lots and lots of bushwhacking!

Is it true that you have been known to put reflectors on the tails of alligators?

No! That is an utter fabrication! A falsehood most foul!

(Besides, the buggers wouldn't hold still...)

[Clan Riffster]

Lots of great ideas popping up in this thread. I've been recruited by a friend to help him build a night cache which requires a lengthy kayak paddle to get to the starting point. (Paddle out, pitch a tent, wait till dark, go hunt. Once found, return to camp and sleep till morning) Our original plan was your basic reflector trail, with a twist. It would have several points where the seekers would need to pick a direction. If they picked correctly each time, their total bushwhack would be one mile. If they picked incorrectly, they would come to a dead end. If they picked incorrectly at each decision point, their total bushwhack will be about two miles.

 

Reading all this input has got me to pondering. Maybe make it a night cache multi, with the various ideas in this thread used for different stages? I can't help but think that would be stellar, if we can find someone bright enough to muddle through the electronics.

[+wvmarle]

Lots of great ideas popping up in this thread. I've been recruited by a friend to help him build a night cache which requires a lengthy kayak paddle to get to the starting point. (Paddle out, pitch a tent, wait till dark, go hunt. Once found, return to camp and sleep till morning)

Sound awesome. Just have to make sure you have an epic location for the camping part. I'm not going to do that; otherwise won't get any finds on my caches. Too few campers among the geocachers here.

 

And maintenance is an issue of course. Electronics great, but don't leave batteries. They run out, break, start to leak... guaranteed problems there. Have the cachers bring them. And if you have to kayak in yourself to do maintenance that's also going to be an issue.

[+BlueDeuce]

I'm going to go off on a different direction here. I think all of the ideas that the OP mentioned are great, but a night cache needs to take advantage of GZ at night. We started caching in late October, so it got dark early. We found 90 percent of our caches after dark that first year. The best ones were a little creepy. Usually, there was an aspect of previous occupancy...abandoned structure etc, element of surprise...we found one where an owl was roosting just a few feet above our heads, or after dark creatures (bull frogs etc.) add an element of darkside ambiance. Oh, then there are stars. We love when caches take us away from the urban glow and give us a view of the stars that Beans remembers from his rural childhood. Gimmicks are fun, but a night cache needs to capture the essence of the night.

 

'bout what I was going to say. Provided I'm allowed to venture on site I have no problem just following my gps.

[Clan Riffster]

Lots of great ideas popping up in this thread. I've been recruited by a friend to help him build a night cache which requires a lengthy kayak paddle to get to the starting point. (Paddle out, pitch a tent, wait till dark, go hunt. Once found, return to camp and sleep till morning)

Sound awesome. Just have to make sure you have an epic location for the camping part. I'm not going to do that; otherwise won't get any finds on my caches. Too few campers among the geocachers here.

 

And maintenance is an issue of course. Electronics great, but don't leave batteries. They run out, break, start to leak... guaranteed problems there. Have the cachers bring them. And if you have to kayak in yourself to do maintenance that's also going to be an issue.

Sound advice. If we do this, we won't worry too much about how many visits it gets, as we both like lonely caches. But I certainly agree on the maintenance aspect. We'll need long term solutions for most of these stages.

[+edscott]

Lots of great ideas popping up in this thread. I've been recruited by a friend to help him build a night cache which requires a lengthy kayak paddle to get to the starting point. (Paddle out, pitch a tent, wait till dark, go hunt. Once found, return to camp and sleep till morning)

Sound awesome. Just have to make sure you have an epic location for the camping part. I'm not going to do that; otherwise won't get any finds on my caches. Too few campers among the geocachers here.

 

And maintenance is an issue of course. Electronics great, but don't leave batteries. They run out, break, start to leak... guaranteed problems there. Have the cachers bring them. And if you have to kayak in yourself to do maintenance that's also going to be an issue.

Sound advice. If we do this, we won't worry too much about how many visits it gets, as we both like lonely caches. But I certainly agree on the maintenance aspect. We'll need long term solutions for most of these stages.

 

Complex and difficult hides do require more maintenance. Over the years I've visited stages of at least 4 of my caches more often than all the finders combined, but I'll continue keeping them up for those that are willing to get away from their cars and trails.

[+Kit Fox]

I've used three volt, blinking red, LEDs, in one night cache. I powered them with four C batteries, and they blinked for over a year. Combining the 35mm canister, and the blinking LED, would certainly prevent the trail from being visible from other directions.

 

 

[+wvmarle]

I've used three volt, blinking red, LEDs, in one night cache. I powered them with four C batteries, and they blinked for over a year. Combining the 35mm canister, and the blinking LED, would certainly prevent the trail from being visible from other directions.

That owl was in the tree above the cache? Or what was its purpose?

[7rxc]

But if your mount is rock solid, and their laser is not the proper size, that might set them off course. If you were handy with machining, you could fabricate some sort of mounting system, then solder in a battery lead, then encase the whole works in something to make it waterproof? Maybe? Just rambling out loud.

Indeed, size matters. And I think it's more interesting to just ask them to bring a battery, as then the suspense is more. There are so many things that can happen that way!

 

And machining a good mount isn't too hard. Use some brackets to screw it to a piece of wood, and then use a screw to attach it to a tree. Gotta be a big tree to make sure it's stable, and minimise damage. The fact that people don't know what's going to happen, or what direction the laser is pointing, makes daytime searches that much harder.

 

In the end it's gotta be a series of four caches and a bonus: the four elements (air, fire, earth, water) with the fifth (spirit) as bonus. Fire, earth and spirit are going to be night caches (fire: "light your fire", connect battery to light up a display, bonus if I can find flickering candle-like lights that work on 1.5V; earth a "down to earth" reflector trail; spirit is the laser). I have ideas for water (probably a floater) and air (blow in a tube and the coords pop up - have to bring a friend to read it for you) but that are not night caches

 

Bushwhacking is out of the question for me. Mostly the bush is way too dense to get through without chopping (those so-overgrown-they-are-invisible trails can be followed by the fact that the trail is where you can actually pass through the bushes), and secondly on >30° slopes which most are it's simply way too dangerous in the dark.

 

Great ideas coming up here, fantastic.

 

That part would be a BAD idea, but keep thinking about non damaging methods. Clamps, lashings etc.

 

Another thought. Reflective is one thing, and retro reflective is another. A small plastic mirror mounted at an angle to the path (line of sight) could reflect light from a flashlight onto something you want them to see, but would normally be unlit at night. One would have to be set up so that foliage etc. would not overgrow the sight lines involved. Using the shielding idea there might help avoid accidental illumination. Only dead on would work.

 

Doug 7rxc

[Clan Riffster]

Another idea I've seen for using standard reflectors is you attach a container (e.g. a 35mm film pot) to an object and then stick the reflector inside the pot (with no lid on), therefore in order for the reflector to work you have to be stood directly in line with it and shining the torch straight into the container.

I plotted out a reflector trail that would require a tracklog as part of decyphering the puzzle. It spelled out a word in cursive, as you went from reflector to reflector. Because the lines cross each other when writing cursive, I had planned on that exact idea. Players would only be able to see the reflectors I wanted them to see. By cutting a notch out of the side of the film can, wide enough to fit a staple gun, I was able to easily affix one to a tree in my front yard. While that particular reflector trail never panned out, (permission issues), I did retain the idea in case the land manager ever changes their mind.

 

Edit to add picture:

Edited December 29, 2012 by Clan Riffster

[+Sharks-N-Beans]

Another idea I've seen for using standard reflectors is you attach a container (e.g. a 35mm film pot) to an object and then stick the reflector inside the pot (with no lid on), therefore in order for the reflector to work you have to be stood directly in line with it and shining the torch straight into the container.

I plotted out a reflector trail that would require a tracklog as part of decyphering the puzzle. It spelled out a word in cursive, as you went from reflector to reflector. Because the lines cross each other when writing cursive, I had planned on that exact idea. Players would only be able to see the reflectors I wanted them to see. By cutting a notch out of the side of the film can, wide enough to fit a staple gun, I was able to easily affix one to a tree in my front yard. While that particular reflector trail never panned out, (permission issues), I did retain the idea in case the land manager ever changes their mind.

 

Edit to add picture:

Very cool in theory, but I would guess the average track log would not look so nice. OK, mine wouldn't.

[Clan Riffster]

Very cool in theory, but I would guess the average track log would not look so nice. OK, mine wouldn't.

I have no doubt the average tracklog would look like chicken scratch.

A similar night cache of mine has two seperate reflector trails. When you complete both, you should have drawn a number "42" roughly half a mile tall, in something like a comic sans font. If you squint really hard, most folks can make out what the number is. But since some can't, I left a good clue at the end of the second trail.

[+wvmarle]

That part would be a BAD idea, but keep thinking about non damaging methods. Clamps, lashings etc.

Which have to be really tight to be secure, and as such may also damage a tree... maybe even more than a screw... the only way to really not damage is to not touch it.

 

Another thought. Reflective is one thing, and retro reflective is another. A small plastic mirror mounted at an angle to the path (line of sight) could reflect light from a flashlight onto something you want them to see, but would normally be unlit at night. One would have to be set up so that foliage etc. would not overgrow the sight lines involved. Using the shielding idea there might help avoid accidental illumination. Only dead on would work.

And that is the problem: the person shining their light must be in just the rigth position as well, and shine in the exact correct direction, to make it work.

The number of variables with just a mirror is just too big. You will likely want to use distances of 10 meters or more, and then minor off-set gives you quite an abberation. Requiring the light source to be in just the right place is also difficult, if that spot is too small it's giong to be really hard for a cacher to find it: they have to find the right spot, and the right direction, without knowing very well where to search. A normal GPS off-set is easily in the tune of five meters, while this requires much greater accuracy.

Then the reflection of the mirror is really weak, as the light always spreads out. So seeing where the reflected light beam hits is going to be really difficult - even when it's dark, as you have the much brighter light source that blinds your eyes, and usually illuminates a large part of the surroundings as well.

Reflectors are designed to reflect light back in the direction it came from, and that's what makes them so visible. All that light goes directly back to your eyes.

[GrandPotentate]

i am currently working on making a night cache that uses infrared LEDs. These LEDs are not visible to the human eye at anytime of the day or night. Digital cameras are very sensitive to the IR spectrum, so there is a filter installed in the lens, during the day, there is enough visible light that the camera doesn't register the LED, but at night, the LED glows very nicely. You can try this out for yourself, point any TV remote at a digital camera in a dark room and press a button on the remote, you should see a bright flash on the view screen of your camera.

[+MartyBartfast]

You can try this out for yourself, point any TV remote at a digital camera in a dark room and press a button on the remote, you should see a bright flash on the view screen of your camera.

Interesting, I never knew that. I'm sat here on my laptop and just happen to have a remote and a camera next to me so decided to try it, unfortunately it's the middle of the morning in the UK so I had to sit here with a blanket over my head to keep the light out (glad there's no-one around to see me), and it works!

[+wvmarle]

i am currently working on making a night cache that uses infrared LEDs. These LEDs are not visible to the human eye at anytime of the day or night. Digital cameras are very sensitive to the IR spectrum, so there is a filter installed in the lens, during the day, there is enough visible light that the camera doesn't register the LED, but at night, the LED glows very nicely. You can try this out for yourself, point any TV remote at a digital camera in a dark room and press a button on the remote, you should see a bright flash on the view screen of your camera.

I have seen this demo'ed before with a remote control. Never thought of using it for a cache - sounds like a great one for the "spirit" element. Far more mysterious than a laser pointer's beam. Now I'll have to go and scavenge an old remote control (to harvest the LED) and a good length of cable (some 50-100m). This as I've no intention to leave an active blinker out in the woods (no idea how long the batteries last - and predicting far too few visits to alert me of weak signals before batteries run out). Running some cable and hiding it is easy enough to do.

 

Then I just have to make up a good story for the cache page on how the spirit is invisible for us but can be seen by a digital camera. Can be great fun. I already have an abandoned house in mind where it can be set up.

[Clan Riffster]

I'm utterly clueless where electronics is concerned, so I beg for forgiveness if this won't work;

How about a preform with an infrared LED blinkie in it, and the guts (battery/processor) from a solar powered sidewalk light?

Run a short wire from the solar panel to the preform. Suspend the works up in a tree.

Maybe?

[+Mr. 0]

Now I'll have to go and scavenge an old remote control (to harvest the LED)

 

I've been working on a similar idea. If you don't have an extra remote laying around or want to use multiple LEDs, infrared LEDs can be found cheap on eBay.

 

From my experimenting, using something in the 940nm wavelength range (as opposed to say 850nm) works better. The 850nm wavelength tends to show a slight red light to the naked eye. Depending on who's looking at it, it may be very noticeable to some, and ruin the effect. The 940nm LEDs still show up with digital cameras, but did not show any light to the naked eye. Even in a completely dark room with the smallest resistor I could use I couldn't see anything from the 940nm LEDs.

 

Though I don't know the exact wavelength used, most remote controls I've seen are high enough to not show light to the naked eye.

 

Like CR mentioned, I'm working on using a small battery with a solar panel to charge it, and a light sensor to turn it off duing the day. LEDs use very little power so it shouldn't be too difficult to keep it going all night. Though it could be more complicated if you are going to use it inside a building.

Edited December 31, 2012 by Mr. 0

[+kunarion]

I'm utterly clueless where electronics is concerned, so I beg for forgiveness if this won't work;

How about a preform with an infrared LED blinkie in it, and the guts (battery/processor) from a solar powered sidewalk light?

Run a short wire from the solar panel to the preform. Suspend the works up in a tree.

Maybe?

Yes, that's good. Those lights might not stay bright all night, something to test. The battery will fail eventually, and temperature is the killer. The circuit board (charger/controller for the light) is all one piece and the LED is also on it, so there's some extra work to get the circuit board to fit in a thin tube.

 

If you find an IR LED with the same specs as the existing LED, it can be swapped in. It should be the same voltage rating, but if it uses less power (which it probably will), that also keeps the battery charged longer.

Edited December 31, 2012 by kunarion

[+hzoi]

i am currently working on making a night cache that uses infrared LEDs. These LEDs are not visible to the human eye at anytime of the day or night. Digital cameras are very sensitive to the IR spectrum, so there is a filter installed in the lens, during the day, there is enough visible light that the camera doesn't register the LED, but at night, the LED glows very nicely. You can try this out for yourself, point any TV remote at a digital camera in a dark room and press a button on the remote, you should see a bright flash on the view screen of your camera.

 

This is true, although some cameras will do this better than others.

 

I believe all digital camera manufacturers install what's called a "hot mirror" over their sensors -- it allows the visible light spectrum to pass through but greatly filters both IR and UV light. They vary from camera line to camera line. The irony is that, the nicer someone's camera is, the more difficult it's going to be to pick up an IR light, because they're going to have a better hot mirror.

 

That said, I did test a remote with the live view on both my camera phone and my Canon 5D Mark II DSLR, and I can see the IR light on both. But my cheapo camera phone did a much better job of picking it up.

 

(I also have a camera that I sent in to have the hot mirror replaced with a filter that only passes IR and near-IR light -- not surprisingly, this one picks up the IR light on the remotes VERY well.))

[+wvmarle]

Over the past weeks I've done quite some work on my night caches. Two are out now; one is a traditional reflector trail; the second (not found as yet) a bit more elaborate. I'd like to share this with you here, maybe useful as inspiration.

 

 

If anyone from Hong Kong is reading this; maybe you should stop reading as there are spoilers ahead.

 

 

What I've done: I've taken an old bicycle taillight (that has seven kinds of flashing patterns, and five really bright red LEDs), and rigged it up to some electronics that can "press the button" to change the flash pattern.

That in turn is powered by a dyno torch: the LEDs of that torch removed, the power of the dynamo powers the taillight contraption. Then some electronics to boost the 3V AC to some 8-9V DC and a series of yellow LEDs to limit the actual voltage to about 6V DC. That gives some extra yellow light flashes for even better effect. So you can imagine this is quite a light show.

 

The box with the lights in it is spray painted. The cover has a single thin layer of paint on the outside, and a thick layer on the inside, with the coordinates scratched in the paint on the inside. When the lights are on and flashing the whole box lights up, and you can clearly read these coordinates which stand out brightly. The thin outside layer makes sure you really can not read the coordinates without the light from the inside. The intended effect is as if you set the box on fire, and I must say it's pretty successful for that part.

 

Now a reflector trail takes hunters in the woods (over an established but faint trail), to this contraption. There they find on the ground the box with the dyno torch, and a lot of wire going up a tree. Pumping the torch activates the lights (only at night: there is even an LDR in the circuit that makes sure it just doesn't work during the day), which are rigged inside a lock&lock box that's hung up in a tree.

 

After writing down the coordinates they are to pack up the torch again, and follow the reflectors out of the woods, from where they can follow the regular paths to the final location which is about 1 km away.

 

I didn't make photos of the work in progress, and don't have a camera that can capture anything useful in the dark of this one so you have to do with words alone

[+wvmarle]

About IR leds. I've done some experimenting there, too.

 

From some electronics forums I learned that remote controls use a lot of current to power those LEDs, like 500 mA. That normally kills a LED but the trick is the pulses are so short (10s of milliseconds) that the LED does not get overheated but instead shines really brightly.

 

I took apart an old RC, and harvested the LED out of it, with some other components, including a 100 uF capacitor. That's probably what provides the current boost. With that LED and my mobile phone's camera I did some testing, and realised you can not see the LED on your camera more than about 2m away. It is just getting too faint.

 

There are high brightness IR leds on the market (so bright it's said to be able to hurt your eyes!) which may improve this range. Though they are in turn highly directional, meaning you can only detect it when standing right in front of it. That makes it quite hard, and in a way destroys a lot of the intended effect. Getting a wide angle LED will again have this range issue. LEDs used in RCs are also usually pretty directional.

 

Best way to see IR LEDs is by using a night vision camera, which is actually an IR mode. Some digital cameras have such a function, but most simply filter out IR light.

[+hobgoblinkiteflier]

There are lots of cool ideas in this thread

 

I have three night caches. My first was a trail of reflectors (pieces of tape from an old hi-viz jacket) which leads you along paths in the woods to the cache. It got muggled a couple of times, and I think it may have been someone with a torch/flashlight who found the trail by accident and followed it to see what was at the end of it.

 

So my next cache leads you to a fence made of wire mesh. I wrapped reflective tape around certain horizontal and vertical segments to write the coordinates of the final. That way, the cache is much harder to find by accident. In daylight the grey tape is almost invisible on the galvanised metal.

 

For my third night cache I used a variation of this idea. There were no fences nearby, so I made up a grid using thin steel wire. This time I used reflectors that are designed to clip onto the spokes of a bicycle wheel. When I had spelled out the necessary digits, I got my daughter to help me attach the wire grid to a branch of a tree, as high as we could climb. We recently followed some friends on this cache and it was funny when they eventually looked up and saw the numbers!

[Zerpersande]

If you don't have an open area like that, then you need to follow trails

I own four night caches. The shortest reflector string is just over a mile.

None are in open areas, and none are on trails.

Lots and lots of bushwhacking!

Is it true that you have been known to put reflectors on the tails of alligators?

No! That is an utter fabrication! A falsehood most foul!

(Besides, the buggers wouldn't hold still...)

 

Ahhh, but you tried. I knew it.