Constructing short pole for tarp

Continuing construction of an ultralight tarp, this is the previous post:

https://bkhome.org/news/202105/tarp-glueing-reinforcing.html

The tarp has a ridgeline, with a high head-end and a low tail-end. The head-end can be tied directly to a tree-trunk, branch or can sit on a trekking-pole or a 125.5cm carbon-fibre pole.

The pole for the tail-end is to be 48.5cm, and I want  it foldable, no longer than 25cm so as to be able to lay flat in my backpack or lumbar pack.

The tarp is intended to have in inner mesh tent permanently sewn in, and the tail-end pole will also be sewn-in. The 2 pieces of the tail-end pole could have bungee cord to keep them together -- that is the usual method -- however, being sewn into the tent, think will be able to avoid a bungee cord.

I have carbon fibre tube, 4x6mm (IDxOD) and 6x8mm (IDxOD), the latter to be used as the joining sleeve. Here is a picture:

Those 4x6 tubes are 24.8cm long each (without the end-caps), and I cut 3cm length of the 6x8 for the joining-sleeve. There are rubber end-caps, that add a couple of millimeters on each end.

When pulled apart, the two pieces will fold to be the same length, close to 25cm. To achieve this, one of the 4x6 poles had to be cut short, to 23.5cm (including the end-cap) -- this is the piece that will have the 3cm sleeve glued onto it -- inserted 1.5cm onto the 4x6 pole, thus giving a total length of 25cm.

For the 23.5cm pole, I wrapped electrical tape around it, then sandpapered the surface so that the glue will adhere better. The photo shows this, and in the middle is the 1.5cm piece that I cut off the pole:

I discussed on the Aussie bushwalking forum what glue to use:

http://bushwalk.com/forum/viewtopic.php?f=53&t=35123

...decided on epoxy adhesive. It turned out well.

Here is where I bought 4x6 and 6x8 carbon fibre tube:

https://www.aliexpress.com/item/1005002341116771.html

The silicone rubber end caps:

https://www.aliexpress.com/item/1005001609758449.html

Just a little detail, the 4x6 does fit inside the 6x8 tube, but is a tight fit, and I used some 4x6 that had purchased earlier from another vendor on Aliexpress (here), as it is a slightly looser fit inside the 6x8 sleeve.

The epoxy adhesive is a very cheap brand from Bunnings:

https://www.bunnings.com.au/utility-25ml-slow-setting-epoxy-adhesive_p1662637

Getting closer to the weekend, when I will have waited long enough for the silicone sealant to cure, and will be able to sew the tie-outs.  

Tags: light

Tarp glueing reinforcing

Continuing with contructing TreeHugger 1P Mark-1 tarp. Here is the previous post:

https://bkhome.org/news/202105/tarp-glueing-hems-and-ridgeline.html

Reinforcing is to be at the tie-out points. I used the same 10D silnylon, and two plates from the kitchen to cut circles. I cut out two sets of circles, 15.5cm and 21cm diameter -- nothing special about those sizes, they were what I had in the kitchen that seemed about the right size.

Here is a sketch showing where the reinforcing is to be applied:

"A" is glued on top of "B" on the ridgeline, for extra strength.

Here is one of the bottom corners:

The reinforcing on the ridgeline were larger pieces, more of a challenge to glue down. You can see the ripples, somewhat less than a perfect job:

One good thing: it will be very easy to sew. If I decide to reinforce with some sewing later on, won't have to grapple with two pieces of thin slippery fabric trying to go off on every direction.

I was reading a post from someone, can't recall the link, who glues-on reinforcing, and he said to wait several days before sewing. The reason is, the silicone will cure quickly at the edges, but underneath the two layers of silnylon, it will take many days to cure. He said, if you do it too soon, it will gunk up your sewing machine -- especially around the bobbin.

Next, I will sew on the webbing tie-outs. But, oh no, I will have to wait several days! Hmmm, maybe work on EasyOS or something.

Now the really interesting bit: I have been weighing this tarp as construction progressed, and the weight is now 158g. This is so good. I estimate the webbing and a bit of hardware, such as cord-tensioners, will add another 15g, bringing the estimated total up to 173g. That is just the basic tarp, but I do plan to add more features, such as rain-baffles on each end, plus an inner mesh tent, but I do now expect the total tent weight to be well under my original goal of around 500g.     

Tags: light

Tarp glueing hems and ridgeline

Continuing the project constructing TreeHugger 1P mark-1 tarp, a simpler design than originally conceived. Previous post:

https://bkhome.org/news/202105/th1p-mark-1-simple-tarp.html

I decided to glue the entire tarp, and only sew the tie-out webbing. Really want to find out if an almost-totally glued tarp will be strong enough. Of course, it very much depends on the weather conditions in which it is going to be used. I am in Western Australia, Mediterranean climate, but there will be some high winds on the South Coast. Unlikely to ever use it in "gale force" winds.

The tarp consists of two pieces, that will be glued together at the ridgeline. This stage of the project started with getting together support items:

The idea of the roller is to run it over the seam, to ensure both surfaces are pressed into the adhesive. I purchased this 30mm Seam Roller from Bunnings:

https://www.bunnings.com.au/uni-pro-30mm-seam-roller_p1662302

The Parfix All Purpose Silicone Sealant is also from Bunnings, a small 40g tube:

https://www.bunnings.com.au/parfix-40g-clear-all-purpose-silicone_p1230047

I reckoned that it would be easier to handle a small tube, rather than a large 300g tube with dispenser.

The roller is in a cup with mineral turpentine, the idea being to clean any silicone off it. The gloves are vinyl disposable.

The sides and bottoms of the tarp are just simple folded-over hems. What I did was lay the fabric over a dressed-pine plank, with some weights to keep it in place:

And used the marking pencil to draw two lines, 1.5cm apart:

...oh, you can see my awful cutting of the edge! That was a particularly bad spot, lack of concentration. Probably a roller-cutter would do a straight line, or a soldering iron.

What is to happen here, is first adhesive is spread between the two lines, then the edge is folded over. Seems simple enough in theory, and in practice wasn't that difficult.

I am left-handed, so it seemed most natural for me to start from the right side, and use the left hand to apply the adhesive, then spread it with a thumb or finger of the left hand. I dribbled a very thin line of adhesive between the two lines, then with one sweep of the thumb, held sideways, spread the adhesive into a thin film, hopefully filling the entire space between the two lines.

I did it a section at a time, using the newspaper edges as convenient stopping-points.

This spreading operation has to be done in one go. Going back and trying to spread it around can end up in a mess. As I was very miserly with applying the adhesive, it didn't always spread out to 1.5cm. But for the hem, I think that is non-critical.

I waited several hours between doing each hem, then finally got to doing the ridgeline...

I first spread cling-wrap over the wood plank. Reason is, cling-wrap is made with polyethylene, which silicone does not stick to. I have cheap Woolworths brand cling-wrap, and it doesn't say on the packet what it is made with, but I tested, and confirmed silicone sealant doesn't stick.

I marked a line 3cm from the edge, then lay the other ridgeline on top. So, 3cm overlap.

Now for the tricky bit, how to glue this without the two pieces moving all over the place...

With the two pieces of fabric in place, I put a lot more weights here and there, so that if the edge of the top fabric is lifted, when let go, it will naturally fall back into the same place.

A problem with silnylon is that it is stretchy, particularly this thin stuff. So you can't pull it. It really has to be as much as possible placed so that the upper edge will just fall down in the correct place. You can lower it with some encouragement to meet the edge with the chalk-line, but do not pull the fabric longitudinally -- we do not want the top piece stretched when the bottom piece isn't.

Due to the 3cm width, I applied the adhesive in a zigzag pattern, then used the side of my index finger (finger closest to the thumb) to spread it. As with the hem, I did a small section at a time.

The ridgeline turned out OK, except that I was too miserly in administering the adhesive. Wasn't quite getting 3cm spread in some places. I measured afterward, only use 4g adhesive in the ridgeline, much less than anticipated. What I will do later on. is go back over the edges that are not fully stuck down, apply more adhesive.

Here is what the ridgeline looks like:

Now for measuring the weight...

The two pieces of silnylon weigh 128g. After glueing the hems and ridgeline, total weight is 144g. Oh man, that is light!

What is going to be very interesting is how much weight the tie-outs will add. Plus a bit of remedial glueing on the ridgeline -- but that will probably only be a few grams.

A note for those who haven't been following my "traveling light" posts, I am trying to reduce the weight carried in my Mountainsmith Daylight lumbar pack, from 4.5kg to 3.5kg (including weight of the lumbar pack). So the tarp, and planned inner mesh tent, are mostly being designed for light weight and compactness, rather than for durability.    

Tags: light

TH1P mark-1 simple tarp

I have posted about interesting ideas for a tent, that I named "TreeHugger 1P":

https://bkhome.org/news/202105/th1p-tent-design-using-solvespace.html

However, as I am a neophyte at tent construction, and indeed anything to do with sewing and fabrics, I decided that baby-steps are in order...

So have modified the outer skin of the tent to not have the spreader-pole, and just be a simple tarpaulin. I made the foot-end a bit higher -- want poles that fold to no more than 25cm long, but can have two poles at the foot-end, that lock together, achieving about 49cm length.

This simple tarp can still be tied up as a "tree hugger", and later could add an inner mesh tent. Just want to create this tarp first, to learn how to do it.

So, from SolveSpace, figured out the required dimensions of the tarp. Here they are, and sequence of marking the fabric shown in green:

I marked it with a clay fabric pencil, this one, which marks OK on the silicone surface:

https://www.spotlightstores.com/sewing-fabrics/scissors-dyes-accessories/sewing-tools-accessories/fabric-markers/semco-fabric-pencils/BP80401344

Used normal general-purpose scissors, new and sharp, to cut out. It isn't easy, this stuff is so slippery, can't cut very straight. It doesn't have to be a perfect straight line, as all edges will be folded.

I bought new scissors, as they have to be sharp. Scissors get blunted when used to cut paper. These ones:

https://www.bunnings.com.au/trojan-240mm-general-purpose-scissors_p0191105

The fabric is 10D silnylon, silicone-coated on both sides. In fact, it is impregnated right through with silicone. So it is not only incredibly thin, but also incredibly slippery. I wasn't able to source it in Australia, so bought it from these guys (7 metres):

https://www.adventurexpert.com/product/10d-silnylon-fabric/

I then used the first one as a template for the second:

Marked out with fabric pencil and cut the second. Very difficult, as my lounge room is too small. A large floor area is required, so can walk all around the sides.

Next step will probably be to sew or glue the side and bottom hems. After that, join the two pieces together along the ridgeline. Note, the reason that the ridgeline has to be cut along the side of the fabric, is that ripstop fabric is more stretchy when pulled diagonally. We want minimum stretch along the ridgeline.  

Tags: light

5V linear regulator with L4940V5

I built a little 5V linear regulator for a "5W" solar panel in 2016:

https://bkhome.org/light/solar/panels-small-2016.htm

Fast forward to 2021, and I am building another, using a low-dropout linear regulator with higher current rating, 1.5A compared to 1.0A previously. This new regulator is the ST-Microelectronics L4940V5, that I posted about recently:

https://bkhome.org/news/202104/some-considerations-for-5v-solar-charging.html

I used the same circuit as in 2016, with 0.47 microfarad and 22 microfarad capacitors on input and output.

This time though, I have placed the USB Type-A female socket inside the toothbrush-head holder, and twin wires coming out to directly solder onto the solar panel. This is to reduce weight.

I constructed it in the same manner as in 2016, just soldering wires together, no circuit-board, and construction was well underway when I realised that the USB socket is not sufficiently anchored.

Considerable force is required to insert and remove a USB male plug. I fixed it by firstly shaping a small piece of plastic that the USB socket can grip onto. This is to prevent the socket from being pulled out of the housing when the plug is extracted:

Another problem is that is is very fiddly soldering the wires directly together, without a circuit board substrate, particularly the pins of the USB socket.

The other thing I did to hold the USB socket in place, and also to anchor the twin flex, was to inject some potting adhesive into the bottom of the housing, after it was closed up. I used K-705, which is clear adhesive:

https://www.aliexpress.com/item/4000959632758.html

The clear one is quite runny, and stays runny for an hour or so after pouring. It doesn't skin quickly like silicone sealant that we buy in hardware stores. Has to be left overnight.

From the photo, it looks like the black and white ones are less runny. Interesting.

Anyway, next day it was ready for testing. It doesn't look pretty with the holes I burnt into it with a soldering iron, but it functions, and the USB socket stays in place:

Weight is 14g. It would probably have turned out lighter if I had used a piece of veroboard. Like this one from Altronics, could just cut a tiny piece off it:

https://www.altronics.com.au/p/h0714-75-x-100mm-0.1-inch-pitch-vero-board-pcb/

...hmmm, will do it that way next time.

The test was conducted yesterday, and we are mid-winter here. Sky was cloudy, but was thinning out briefly, and I took readings as quickly as possible. The panel is the CLAITE "10W", and plugged into a small lithium battery bank, via a voltage & current monitor.

The sunlight kept changing, but averaging, managed to get a reasonable reading. Got a 0.2V drop, from input to output, 4.5V into the battery bank, at 0.5A.

What that means, is the regulator is dissipating 0.1W (watts) as heat. It feels slightly warm to the finger, after running for several minutes.

The power coming from the panel is 4.7V times 0.5A, which is 2.35W.

That means the regulator is running at a percentage loss of (0.1 / 2.35) * 100, which is 4.2%. That means the regulator is running at 95.8% efficiency, which rivals the switching regulators.

Another thing I mentioned in a previous post, if you are hiking and carrying this on your backpack, near your head, the linear regulator will not be radiating RF (Radio Frequency) waves into your head.  

Tags: light

TH1P tent design using SolveSpace

The first post about the new project, "TreeHugger 1P" tent, was about short carbon-fibre poles:

https://bkhome.org/news/202105/poles-for-treehugger-1p-tent.html

Now, I have used SolveSpace to create 2-dimensional and 3-dimensional views. I must preface this post by stating that this is very exploratory, and I do not know if this design will become an actual physical tent. I know nothing about tent design, and can barely use a sewing machine, so it will be "venturing into unexplored territory" if I do actually have a go at sewing it.

Here are the SolveSpace files. This is using SolveSpace version 3.0. Some OS distributions only package 2.x, and these files cannot be opened in 2.x. EasyOS 2.7.3 has 3.0. Here they are, gzipped. You will have to un-gzip them:

tent6-4.slvs.gz

tent6-3d-6.slvs.gz

Another thing that I want to state up-front: if, in the unlikely event that someone sees something in this design that they think is patentable, I claim that every aspect of this design, and features of this design that I will reveal in later blog posts, is free, open-source, public-domain, no restrictions whatsoever in copying, modifying, or using.

I have made this statement because in some countries, the USA in particular, just about anything can be patented. The original concept of patents was to protect new inventions, however, that (in my opinion) got corrupted, and now even just the tiniest twist of an existing concept, the most trivial idea, can be patented. This is a massive money-earner for some companies, such as Microsoft. Anyway, onward ho...

Here is the first SolveSpace file, 2-d views:

And now I can reveal why I have named it "tree hugger". The head-end can be tied directly against a tree trunk, as the head-end has a vertical wall.

Yes, it could be away from a tree, with cord to tie the head-end to a branch, or it could sit on a trekking-pole or any other pole, with cord to a stake in the ground.

However, I love the idea of being tied right against a tree trunk. I have previously posted about how to sit comfortably inside a tent, with various ideas such as sitting cross-legged with bracing to hold the lumbar-region of the spine erect.
A tree trunk gives you an instant backrest! Inside the tent, lean back against the tree, maybe with something rolled-up to support the lumbar region, and hey, comfy!

I have posted previously about the difficulty I have with crawling in and out of a tent. One issue I have is a degenerated lower-back vertebrae. The TH1P design has side-entry that has step-in and step-out. You can see the label "flap", that is the outer fly. It can unhook from the corner stake and fold back over the ridge-line, exposing a zippered entry to the inner tent.

The angle of the zippered entry is such that you can just step-in and step-out.

In summary so far, the design has these great features:

1. Spreader-bar at the top for head-space.
2. Vertical wall at head-end to lean against a tree trunk.
3. Fold-back fly and inner mesh zipper opening angled for step-in and step-out.
   

The other side of the fly can also unhook and fold back, if extra ventilation is required.

The 3-d view shows that there are two ridge-lines, and I have highlighted the surface formed by these in yellow:

However, to improve water runoff, I plan to join the two ridgelines into one, about halfway down. This is incredibly complicated to calculate, how to cut the fabric. This is where the "dressmaker's dummy" that I constructed should come in handy.

One thing that I am uncertain about is sag. The ridgelines will sag, no matter how tight the cords at each end are pulled. I don't know whether to try and compensate for this when cutting the cloth. Once again, erecting it on the dummy frame should be helpful.

The above 3-d drawing also shows one side of the inner mesh tent.

The length of the inner mesh tent in the above drawings is 180cm, which I intend to increase a little bit. I am 177cm, about 5 feet 10 inches, but I think a bit more length is needed. The foot-end of the sleeping bag will extend a bit beyond my body-length. Though, I do usually sleep on my side, slightly curled. I think will add another 5cm (2 inches).

There are some more details, that are not apparent from these simple drawings. These details are in my head, and will be explained later.   

Tags: light

Miniwell water filter kit

I am continuing to iterate through the gear that will go into the Daylight Lumbar Pack, aiming to reduce the total weight from 4.5kg to 3.5kg. Earlier this year, I reconsidered the base load, without shelter and sleeping gear:

https://bkhome.org/news/202102/reconsidering-the-waist-pack-base-load-sans-shelter-and-sleeping.html

The water filter kit had a Sawyer Mini, a flat bottle, tube and syringe. I reckoned that the syringe could be left home, so the weight was 82g:

There are two serious problems with that kit...

Firstly, I have discussed in previous blogs about the bottle wanting to stay flat and being a pain to fill from a pond surface.

I found a foldable TPU bottle that has a natural tendency to stay open, and can be filled from a pond surface in a few seconds. So I am now using this one instead of the Sawyer bottle, and it even weighs less -- I am using a lid from a soft drink bottle and total weight of bottle is now 21g. This is what I purchased, 500ml dark green (so as to distinguish from my clean-water TPU bottles, that are all light blue):

https://www.aliexpress.com/item/33012014287.html

Secondly, The Sawyer Mini is very restricted in how it can be used, by not having threads on both ends. So, it has been retired, and I am now using a Miniwell filter:

https://www.aliexpress.com/item/32666647306.html

This has a 28mm thread on both ends, opening up lots of extra possible configurations. You could, for example, squeeze directly from one TPU bottle into another. As the clean-water bottle can be rolled up and most air expelled, there is no problem with screwing it onto the outlet of the Miniwell filter and filling it with filtered water.

Here is a photo of my new kit:

For minimalist hiking, only the filter and bottle are required. Weights:

Miniwell filter	44g
TPU bottle	21g
TOTAL:	65g

The "dirty" water bottle also has another use, with the bidet. If you haven't been following my blog posts, here is one about a portable bidet:

https://bkhome.org/news/202104/bottle-cap-glued-to-portable-bidet.html

However, those other parts in the above photo are very useful. One problem with filtering water is that it takes time. If you arrive at a campsite, or anywhere where there is a water supply, it could take some time to fill up the filtered-water bottles.

Of course, a way around that is to just put the "dirty" water into all the bottles, and always drink through the filter. But for now, I won't go that way.

What is really nice is to have a plastic bag filled with water and let gravity do the job of filtering. That way, you can be doing other things, setting up tent or whatever, while the filtering happens. Here is a photo showing those other parts in action:

...that little white thing is a hose clamp. Bottom-left, using a plastic single-use shopping bag, they weigh virtually nothing.

You see the guy drinking from it, but a rolled-up TPU bottle could be screwed-on and left to fill, while you are off doing other things.

Here are the weights:

Adaptor	9g
Silicone tube	26g
Hose clamp	5g
TOTAL	30g

The grand total then becomes 105g. I do not want to be going up in weight, though these extra items are very useful.

The silcone tube is very heavy. Measuring with my measuring tape, ID (inside diameter) is 5.5mm, and OD is 8.5mm. Quite thick walls. I could replace with thinner tube, and reckon knock the weight right down, to under 10g.

That clamp is not really needed, only have to crimp the tube to stop water flow, could do that with an elastic band. So could end up with a total weight around 84g, almost same as before. But much more versatile.

Note, that tube is required for gravity filtering, as there has to be a certain head of water to get enough pressure.

Oh, one more point about the Miniwell kit: a syringe is not required for back-flushing. Any old flexible plastic bottle with 28mm thread will do. Fill it with clean water, even tap water when you reach civilization, screw onto the filter outlet-end, and press very firmly. Another advantage with having threads both ends!

EDIT 2021-05-24:
I have purchased silicone tube with 5mm ID (inside diameter) and 6mm OD (outside diameter), so the wall thickness is only 0.5mm. Very thin, so kinks easily, but it works. Although only 5mm ID, it still fits onto the Miniwell filter and to the gravity-bag adapter. The silicone tube supplied with the Miniwell kit is 60.5cm long. I purchased 100cm of this thin tube, and will use the entire length for gravity-feed, as the more water-head the better.

The new tube, 1 metre, weighs just 13g. Bought from here:

https://www.aliexpress.com/item/1005001986349236.html  

Tags: light

Poles for TreeHugger 1P tent

I have come up with a design for a tent, and tentatively given it the name "TreeHugger 1P". The "tree hugger" name will become apparent as the construction progresses. The "1P" means one person.

If you look back through my blog posts, under category "light", you will see some tents/tarps that I purchased that are held up by a pole. A single-pole tent may use either a trekking-pole or a carbon fibre pole -- I have a couple of the latter.

With a single pole holding it up, the inside walls and floor are going to be a triangle shape. At the top will be a ridge, and if you sit up inside the tent, the tent walls will be pressing both sides of your head.

My Six Moons carbon fibre pole is 117cm long, so if that is holding up the outer skin, the fly, of the tent, then the inner mesh tent will be lower. Not a good experience if you want to sit up.

Here is a photo of the inner mesh tent, single-pole design (not counting the short foot-pole), taken on a hike earlier this year:

...you can see the very constricted head room! The experience is worse than might be determined from looking at the photo.

Blog post about that hike, February 2021, experimenting with my Daylight lumbar pack:

https://bkhome.org/news/202102/waist-pack-hiking-test-2021.html

Tents that have two trekking poles have much more head room, for example the Dan Durston X-Mid, that I posted about recently:

https://bkhome.org/news/202104/the-best-double-wall-trekking-pole-tent.html

My TreeHugger is planned to stay with the single-pole design, except I will design it to tie up to a branch rather than sit on a pole. Though, I will make it optional, the 117cm carbon-fibre pole or tie to a branch.

So, I am going to have that problem of very squashed head-room. To alleviate this, the tent is going to have a "spreader", a 25cm long carbon fibre pole, held horizontally just above the head. I purchased these poles, 24.8cm long, 6cm OD, 4cm ID glossy:

https://www.aliexpress.com/item/33056914311.html

...however, looked online today, and that item is no longer sold. That is, I have them, purchased before they were withdrawn. If anyone wants to reproduce my tent design, there are other vendors, but they sell in 50cm lengths, for example:

https://www.aliexpress.com/item/1005002265467955.html

I don't know what this stuff is like to cut, presume that a hacksaw would do it.

As the tent is going to be draped over the horizontal spreader-pole, I also purchased plastic end caps, to help protect from tearing the tent, 6mm black:

https://www.aliexpress.com/item/33027991367.html

The weight of each 24.8cm pole is 5.5g, with the end caps, 6g. I plan to use two of these, one as a head-spreader, the other at the foot-end. At the foot-end, the pole will be vertical. Total weight added to tent: 12g. Having to count these grams very carefully, as one major goal is extreme light weight -- targeting putting this tent into my Mountainsmith Daylight lumbar pack. Photo with end caps attached:

And that is also why I wanted poles no longer than 25cm. The tent will roll up and fit into a stuff sack and lie flat inside the lumbar pack. same for any backpack, it will be short enough to lay horizontal.  

TreeHugger 1P, "th1p" for short, is a new project, and I plan to post as each step is completed. My sewing skills are minimal, but, we shall see. Also, having no prior tent-design experience, there is an element of uncertainty how the ideas in my head will turn out in the final product. How does that saying go? "...where angels fear to tread".

EDIT 2021-05-12:
I also purchased alternative end-caps. These are silicone, 5.7mm ID (inside diameter), black:

https://www.aliexpress.com/item/1005001609758449.html

They are more substantial, likely to stand up better to usage. Photo, showing the other type alongside:

These silicone end caps are probably the better choice for the vertical foot pole. Hmmm, probably for both poles. 

EDIT 2021-05-18:
Found a vendor on Aliexpress that sells the carbon fibre tube in 25cm lengths:

https://www.aliexpress.com/item/1005002341116771.html   

Tags: light