DIY balcony/terrace/garden lantern

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Bra Ljus
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DIY balcony/terrace/garden lantern

Hej,

nice to see there’s not only flashlighters around, but also lanternists; a small but growing minority, I hope ; )

I am about to build three small, lightweight and minimalist lanterns. For each I bought…

1. Cree® XLamp® XP-L LED – XPLAWT-00-0000-000UU30E7 – 3000K, 320lm, CRI 90, 1050mA, 2.95V & matching MCPCB & matching Fischer fcool heat-sink

2. OLIMEX Li-Ion rechargeable battery – 1s, 3.7V, 3000mAh / 1s, 3.7V, 7000mAh

3. TP4056 USB 3.7V Li-Ion single cell charger with micro-USB / Adafruit USB DC Solar Lithium Ion/Polymer charger v2

…but now I need a constant current driver.

I’ve seen in the flashlight section that the AMC7135 seems to be a popular choice for those like me who can’t design their own circuitry with TI or Analog Devices ICs that only come in DFN-packages or similar. My question is should I buy one of these ready-made drivers, a better made and/or more reliable version of that if that exists, or if it is better making my own and learning something in the process?

All I need is four slider switch or momentary tactile switch button settings/modes like off, low, medium and high; ideally logarithmically spaced, because of human brightness perception; if that’s too tricky, linear will do for starters.

Any suggestions much appreciated!

PS: Once this works, I like to build a brighter 9V version of it, with based on the CITIZEN – CLU701-0303C4-303H5K2 – 3000K, 505lm, CRI 90, 525mA, 9.4V, 4.7W powered from an EnerPower 3s2p – 11.1V, 5500mAh with a MEAN WELL LDB-500LW – 500mA, Vin 6-30V, logarithmically PWM dimmable via an Adafruit Trinket most likely.

Edited by: Bra Ljus on 02/04/2019 - 18:49
Lightbringer
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I got a few of those “hurricane lamp” type LED lanterns, which I have yet to gut and turn into something more useful with 2700K-3000K LEDs. Gutting the space for 2 D cells and transplanting a 3×18650 block from a powerbank, and using a USB charger (with protection FET).

The voltage seems “compatible” enough to use the front potentiometer to control the brightness. If it pops, well, I’ll throw something else in there. An emitter-follower is easy enough to throw in there to regulate current.

Yeah, if I ever get around to it… Facepalm

09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0

Rdubya18
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I hope some of the knowledgeable people chime in for you . I too have begun a ( sort of ) lantern project . I’m not as far along as you as I haven’t decided on body size of my build. I have been wondering what driver to use . I was thinking along the lines of the ready made one you posted , as I lack the knowledge at this point to do much else. I’ll be following your thread. Looking forward to seeing your build . Randy

By the way , welcome to BLF !
Bra Ljus
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Thanks!

Well, there seem to be maybe a hundred different vendors offering a 1050mA matching ready-made PCB (intended for flashlights) with four modes (unfortunately not logarithmically dimmed), but for the novice, a ready-made PCB might be the best way to go.

The best Citizen, Bridgelux or Nichia LEDs, with a CRI higher than 90 at 2700K and 3000K, are all requiring around 35V forward voltage, so I can’t drive them from a 1s Li-Ion battery/USB-charger combo : (

I think I buy a ready-made 1050mA driver from Aliexpress or Ebay, and first see how that goes before trying a 9V solution, and then maybe something else. The battery size and charger PCB is always the biggest issue it seems.

Rdubya18
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Yeah I’m leaning toward easier so I don’t frustrate myself . I hadn’t been considering a charger , but now you got me thinking .

Bra Ljus
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Yeah, easier is what I like to begin with.

First a 3V solution with over 300lm. Second a 9V solution with over 500lm. And from there to see how to balance high-CRI requirement, colour temperature and running time, whilst keeping the product minimal. At the minimum, I like to “beat” this well-known product that is very popular in “design stores”:

Ingo Maurer KOYOO – LED (unknown brand) with 2700K, CRI 90 minimum, 240lm, 3000mAh LiPo battery, USB fast recharger and 5/10/36 hours of use (three modes plus off).

Rdubya18
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It’s good to have goals ! Smile

Bra Ljus
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It sure is… Until the MCPCBs arrive and I can solder the LEDs, I mocked up one of the 9V solutions, the 400mA Cree LED driven at 500mA, so that’s a few more lumens than the nominal 366. The heat sink is too large, but I had no matching one around; 41°C is ok here. It’ll be interesting to see how long this lantern setup emits without dimming…


Edit 1: Finally reached steady 51°C after two hours
Edit 2: Now, after 7 hours, the output appears dimmed. Although the Cree used here is 3000K and CRI 90, there is a bit of a cool tint to it, probably because it’s driven at 500mA instead of the nominal 400mA

Rdubya18
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Yeah Stupid Imgur . I was having quite a problem posting pics for awhile . Their help thing didn’t help me too well. Here’s my idea . I’m gonna use an old glass & brass door knob . I’ve drilled the brass part to the glass . I keep going back and forth on the tube diameter. This is the largest diameter I think will look good . I have a convoy triple inside the tube just to light the glass so you can see what it’s supposed to look like.

Bra Ljus
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Your image is embedded like this img src=“https://i.imgur.com/hS23jGZ.jpg” style=“height:200px; width:300px;” alt=”“ so it looks like it’s that “i” from an imgur shared link that does the trick.

Rdubya18
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Yeah your pics are up now. Lookin good . Actually the bigger heat sink you can use , the better , right . Course , that one is pretty big. Silly

Bra Ljus
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Yes, it really is. I will use the same model, but half the height is sufficient.

Wired up the Citizen LED 9V version using a CCS with built in dimming via momentary switch. It also works with a potentiometer. Although it is a 3000K CRI 90 LED like the Cree before, the visual quality of the light is more pleasant. Will be interesting to see how long this one will illuminate at 100% and 50% setting. It’s rated for 505 lumens (the Cree was 366).

Can’t wait for the Cree XP-L and the MCPCB to arrive from the U.S.; the 3.7V battery is so much smaller (but only half capacity).

After Euroluce Milan, Citizen should have the new CRI 97 Natural COB series commercially available. I hope there’s also a 9V version available, would be great for 2700K lanterns.

Bra Ljus
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The problem with lanterns and all LED lighting is the balance of illumination strength vs. illumination duration vs. illumination diffusion. The Citizen above has been good for 9 hours at the medium setting so far. Have to try out full setting at 500lm, better for a small terrace or garden setting; maybe even sufficient for a caravan?

A sheet of Covestro Makrofol® LM 309 held at around 50mm distance to the LED. Transmission 81%. Half-value angle 28°. Thickness 500µm. This special LED diffusor film is used in the automotive and aircraft industry. Looks ok considering the size of the COB. Have to try 300µm at a slightly larger distance, spec sheet says 85% at that thickness, but only 21° half-value angle. Well, I can’t have everything. The magic full diffusor with 100% transmission has to be invented still ; )

This stuff can be rolled into a tube of 40mm Ø before it cracks; the problem there is the seam, so vacuum-forming would be better.

If one of you fellow lanternists knows a material with higher transmission at around the same half-value angle, even if I have to get it from the U.S., please link to it here; I’d really appreciate that!

Edit 1: Rolled into a tube, quite sweet…

Edit 2: Turned it off after 24 hours at the medium setting with around 300 of the full 500 lumens. Enough for a good lantern, but 2700K version might be better still. On full setting now…

Ilumenati
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Hi Bra Ljus,

Do you have a source for small amounts of Covestro Makrofol, I can’t locate one.

If money was no object I would enjoy buying this sample kit of different diffuser films from Corbell Plastics. Different thickness, color temp and textures. Looks very fun to play with.

Diffuser Sample Kit

Bra Ljus
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I got many samples from this source (use Bing translator), in the framework of a product development research project.

But I saw Corbell also trades in these wares, so maybe you can obtain single sheets from them?

Evonik USA also sells thicker similar materials and a flavor of Plexiglas that transmits the light at a 90° angle when fed into the edge of a block, rod or sheet, which is great for use in luminaires, quite unlike the classic edge-lighting plastics that primarily transport the light.

Ilumenati
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Thanks Bra Ljus,

I may contact Corbell directly for sample sheets. I am really glad you mentioned Evonik’s product, I will look into it.

Bra Ljus
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Right, good luck with Corbell!

While waiting for the parts for the 3V Cree variant, and the two 9V versions working very well, particularly with over 12 hours on full setting, I thought why not go one step further and make these solar powered, so that the battery is charged during daytime and the LED comes on at dusk and then illuminates for as long as the battery can power it.

There is a timer breakout-board at Adafruit that lets one add low-power/timed-use to a circuit quite easily.

Existing balcony/terrace/garden solar lanterns look awful, their light output is visually garish and too low. Would be great to see more solar powered lanterns here!

Rdubya18
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Hey BraLjus , there are some threads on here on lantern talk . One is the BLF ultimate lantern project , by DBSAR . He is pretty knowledgeable about lanterns . It’s a long thread , but you may get a feel for some members or ideas that can help . That Coventry sheet is pretty cool . I had never seen that before .

BLF Ultimate Lantern Project*~updates:Sofirn working on design, to produce prototype!

Sorry , can’t get the link Facepalm
Bra Ljus
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Yeah, that’s the only high transmission high half-value angle diffusor material on the market that works. I saw it at the Light + Building and Euroluce fair several years ago. Engineering these plastics is an art. Good to see that it is also available in the U.S. I’m always puzzled how some put a high-lumen LED in a luminaire – only to then kill 50% of the photons by using matt opalescent glass or frosted Polycarbonate or worse.

I clicked around in that lantern thread for a bit, it’s uuultra long, but I happened to come across an image and that looked rather as if a Kenwood blender had gone to bed with an SWAT-issue flashlight ; )

It’s a matter of taste and, as Oscar Wilde said, taste is a matter of taste : )

PS: Instead of a flat bottom, bouncing light right back onto the LED and surrounding heat-sink area, I would have made the internal reflector conical/hyperbolic/asymptotic… just like in good omnidirectional loudspeakers.

Barry Lyndon
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I’m not really a lantern-tard, but throw in solar [and LiFePo4], and my enthusiasm grows.

I got one of these recently as a lightning deal (sale price) for $9.99 … https://www.amazon.com/gp/product/B013UCC65G/ref=ppx_yo_dt_b_asin_title_...

I’d suggest bumping the total circuit up to 12V (if possible), using [4] LiFePo4 in series, and some kind of jack readily comptabile with:

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Expounding on my idea a bit, throw one of these into the body with its own on/off switch (to avoid parasitic drain) :

Then you could measure charging / discharging currents and have some idea of the state of the battery charge.

If you were car camping at night, and the battery circuit dipped below 12V, you could plug it into the car’s cigarette lighter, and the car’s battery would run the light and charge its batteries (assuming car battery had voltage >12.0V).

Bra Ljus
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Thanks, Barry, I already bought 6V solar panels, chargers, batteries and 3V LEDs with matching MCPCBs (see first post).

The Cree XPLAWT-00-0000-000UU30E7, 3000K, 320lm, CRI 90, Vtyp: 2,95V DC, Ityp: 1050mA is just at the sweet spot for a single LED 3V lantern.

If USPS weren’t so slow, I would have tested that set-up already and posted some pictures and running times : (

Edit 1: That looks like a practical little meter… The idea expanding the lantern to solar would mean to use the solar panel itself as the darkness trigger, meaning that once the solar panel delivers 0V, a MOSFET switches the charger/battery <-> LED driver path on.

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What do you think about, as a next project, a 4S LiFePo4 12V setup with on-board voltmeter/ammeter and 12V jack to connect solar panel or cigarette lighter lead?

And if you want it to be really boss , have it accept:

(Enough juice to start your car with appropriate cabling)

Bra Ljus
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Ha, next project… I have not even finished the first three (9V, 3V and 3V + solar)… I also would need a car to begin with ; )