π‘ New project! An USB powered LED desk lamp made of wood, ceramic, and aluminum. It will be called "Portuaria", which in Spanish means "related to the port", because its shape reminds me of the cranes and sailboats at the port.
𧡠#PortuariaLamp #lamp #prototype #LED #USB #lampdesign #woodenlamp #woodworking #electronics
I wanted the base of the lamp to be a 16 x 2 cm disc, but I only had 7 x 2 cm boards around here, so I ended up glueing a few cuts.
Then I cut a circle with the hand router using the guide as a compass, and sanded it with the orbital sander and sanding sponge.
Recycling ceramics to build a lampshade. I found that these mini bowls I made to test ceramic glazes roughly fit what I need for the lampshade of the prototype, so I drilled one to accommodate the LED and two screws.
The screws pass between the heatsink fins and will attach both the lampshade and heatsink to the wooden rod.
First attempt to mount the lamp head on the rod π€. What seemed easy in the drawing turned out not to be so easy when transferring it to materials.
The difficult thing was making the 3 mm slot in the 10 mm rod, and getting it to align with tolerances of less than 1 mm.
Next time I'm going to try with a router and templates, we'll see how it goes with that.
𧡠#PortuariaLamp #lamp #prototype #woodenlamp #woodworking
Stripping a cable to dress another π€¦ββοΈ. The cable with a cotton textile sheath that I got is very thick compared to the diameter of the rods. The rods are 10 mm in diameter and the cable is 6.5 mm, so when drilling holes in the rods to pass the cable through there would only be 1.75 mm of wood left on each side.
So, I made a customized cable using the sheath of the original cable and an AWG 24 cable. The new one is 2.5 x 4 mm and fits perfectly in 4 mm holes π.
Assembling the head of the lamp. Despite the chamfered slot, it turned out pretty well. The yellow thing at the tip of the cotton sheath is a heat-shrink with glue, which is then inserted under pressure into the slot. It's the first thing that occurred to me to fix the sheath to the rod so that it can withstand the tension. Perhaps in the next iteration I will replace that with a screw, although the limited space is a challenge.
𧡠#PortuariaLamp #lamp #prototype #woodenlamp #woodworking
The LED I am using for the prototype lamps is one from the Bridgelux's Thrive series, which has a CRI of 98. The CRI is a color rendering index, which says how similar is the color rendering with the light from a LED compared to the rendering with natural light (which has a CRI of 100).
After using CRI 98 LEDs for a while, the CRI 90 ones look depressing, it's a one-way street π.
After a lot of experimenting with various models of the height-adjusting disc that holds the cable near the base, I decided that it would be better to make the height fixed instead of adjustable π€·ββοΈ
The main problem is that it is very difficult to make the adjustment fluid enough to adjust the height without the lamp jumping, which does not look good as a user experience.
This is the light spectrum emitted by the Bridgelux Thrive LED series compared to other ones that have a lower CRI.
You can see that the one from Bridgelux does not have the blue peak at about 450 nm that is present in the other LEDs in the chart.
That is why I chose it for this lamp prototype. If you were seeing a greenish tint in your "high" CRI 90 LEDs, now you know why π‘π.
𧡠#PortuariaLamp #lamp #prototype #LED #CRI #lighting #spectrum #electronics
Carving the lamp base with a router to mount the USB voltage booster, resistors and switch.
The router is not quite tamed yet, doing this I learned that turning it off and on again in the middle of a slot is not a good idea π¬. I finished it with a chisel, slow but more predictable π€·ββοΈ.
𧡠#PortuariaLamp #lamp #prototype #woodenlamp #woodworking
The holes are for the switch, the cable, and the vertical rod. The one for the rod ended a bit loose; drilling it with a 10 mm bit to fit a 10 mm rod was too optimistic. Next time, I'm going to use a 3/8" drill bit and sand the end of the rod until it fits just right.
This is the circuit diagram for the lamp, which will be powered from a USB charger.
The LED is a Bridgelux BXRE-30S0801-D-7X with a CRI of 98 and 3000 K. It is a 6 watt LED, but I'm going to use it at 4.85 watt to extend its lifetime.
The power on the USB port is 5 volts, which is not enough to turn on this LED that needs 17.15 volts. That's why I use a voltage booster (the green board), which converts 5 volts to 18 volts.
𧡠#PortuariaLamp #lamp #prototype #LED #USB #electronics #DIY
And the 4.85 watts that the LED will be working at come from this calculation:
led_voltage * current = led_power
17.15 volts * 0.283 amps = 4.85 watts
This way of connecting an LED is fairly simple, but it is not used much because the excess voltage from the supply to the LED is wasted as heat in the resistors. The trick to minimizing this loss of efficiency is to not have the supply voltage be much higher than the voltage to the LED, as in this circuit.
𧡠#PortuariaLamp
The energy wasted as heat in this circuit would be:
(supply_voltage - led_voltage) * current = power_in_the_resistor
(18 volts - 17.15 volts) * 0.283 amps = 0.24 watts
That is, between LED and resistor we have a total of:
4.85 watts + 0.24 watts = 5.09 watts
And of which the energy wasted in the resistor is 0.24 watts / 5.09 watts * 100 = 4.7%, more than acceptable for such a "primitive" circuit π€·ββοΈ.
𧡠#PortuariaLamp
One issue with this shameless display of the heatsink is that it should at least be left more or less presentable for that. Normally the heatsinks are hidden inside the luminaire because they are considered ugly and not very aesthetic, but that is an idea I do not share, as you can see in my other prototypes π.
This is how the heatsink comes from the manufacturer, and sometimes they come worse than that with steps from the sawing.
f it is going to be hidden, it is enough to level only the part where the LED will make contact so that it has good thermal transfer. But here it is part of the visual of the product, so I proposed to leave it as mirrored as possible.
The steps were 220 grit sandpaper, fine sanding sponge, superfine sanding sponge, and rubber abrasive block (I have no idea what grit these last three are).
Putting the heatsink so exposed also has a technical reason; doing that maximizes the air flow through the heatsink, which reduces the working temperature of the LED and extends its useful life.
It would need one more step with some finer grit, because the scratching is still a bit visible, but it turned out pretty mirror-like compared to how it was initially πͺ.
Shellac is my favorite finish for wood. Some reasons for this are:
- It is of biological origin, since it is obtained from the secretion of an insect from Southeast Asia.
- It can be diluted in ethyl alcohol, a relatively safe solvent also of biological origin.
- It is not toxic, it is even an authorized food additive under code E904.
- Easy to apply and repair locally if it gets scratched.
- Biodegradable in reasonable times.
Shellac is sold in flakes to dissolve or in a ready-made solution with alcohol. In both cases it has a limited storage time of one to two years. In the case of flakes, what happens is that it polymerizes and then no longer dissolves in alcohol.
It already happened to me with a batch of flakes that were left unused for two years. With the next batch I bought, I set out to prevent the same thing from happening to me again.
I read that you can extend the shelf life by lowering the temperature and humidity the flakes are exposed to, so the plan was to seal portions with silica gel in vacuum-sealed packs, store the packets in an airtight glass jar, and store the jar in the refrigerator.
Two years have passed and the flakes from that batch still completely dissolve in alcohol in just two hours, as if they were freshly harvested π₯³.
The time has come to assemble the base. The idea is to have a printed circuit board with the voltage booster, resistors, and connectors for the LED and the switch, and at the same time to act as a cover for all the wiring.
Sending the printed circuit board to be manufactured in China as usual implies a delay of at least a month in the mail, so I decided to improvise something with a blank board. It didn't turn out so bad π.
First working prototype of the Portuaria Lamp! πͺ
Although it is a desk lamp, I will be using it as a bedside lamp to test the mechanical stability against being hit in the dark.
There are still several things to improve:
- The cotton-covered cable gets very linty and stains very easily.
- The ceramic screen also needs modifications. I can see the screws π±.
- Making the vertical axis of the lamp perfectly square is hard π€―.
𧡠#PortuariaLamp #lamp #woodenlamp #woodworking #LED #productdesign
Trying other cable colors. I got some colored polyester cords (plastic π±) to cover the lamp cable. The idea is to solve two problems that the white cotton cord has: it gets very linty and stains very easily.
Of the four, I chose the orange one because I thought it was the one that best matched the wood of the base. I took the whole lamp apart, reassembled the LED cable with the orange cord, put the orange cable in the lamp... and I didn't like how it turned out π€ͺπ€¦ββοΈ.
𧡠#PortuariaLamp #lamp
What I didn't like is how the contrast between the orange cable and the wood of the rods looks. I had only compared it with the wood of the base before putting it on and it looked good, but the wood of the rods being lighter and with less grain is totally overshadowed by the striking orange cable.
So I took it all apart again and put the grey cord on, which doesn't conflict with the wood of the rods... but now the lamp is very sober and boring! π.
Keep trying π€·ββοΈ.
𧡠#PortuariaLamp #lamp
I'm working on a new screen for the prototype. This time custom made instead of recycling what was lying around from previous projects.
The things this new screen design aims to improve are:
- Ease of assembly. Placing the LED in place while tightening the screws was no fun at all π€―.
- Mounting the LED with connectors instead of soldering it, to make it easier to repair π .
- Avoiding the cable and screws being visible through the gap between the heatsink and the screen.
- Improving the airflow through the heatsink by creating a chimney effect.
𧡠#PortuariaLamp #lamp #prototype #productdesign #ceramics #lampdesign
This task is kind of delayed because the clay is sabotaging the perfect circularity of my pieces π.
Because of the unorthodox shape for a ceramic piece, the circle dries unevenly and ends up becoming an ellipse π€¨.
Slow drying over several days didn't work either. So I turned to the wisdom of r/Ceramics on Reddit to see how I could fix it and they threw out a few ideas that I need to try.
To be continued...
𧡠#PortuariaLamp #lamp #prototype #ceramics #lampdesign #productdesign
I made a USB cable that matches the cable I put in the lamp π.
It only has two conductors because it will be used to send power and does not need the data pins, if someone wants to use it to transfer data they will be in for a disappointment π (probably the me of the future π€¦ββοΈ).
The white tubes are heat shrinkable tubes that come coated with glue inside. I have not grey heat-shrink in stock, so I used a white one that was around here π€·ββοΈ.
The heat shrink on the USB-A side turned out pretty good because the metal USB plug gives it shape, but on the USB-C side it turned out kind of a mess because there is nothing uniform underneath. I am still quite happy with the results of this improvised technique to assemble USB plugs.
Working on the second prototype, now with more angles for greater pleasure π.
In the previous prototype, making the cutouts in the round rods and aligning the holes turned out to be quite complicated. And the result didn't convince me much either, because it had a more crafty style than a designer lamp one π€¨.
So to change the look and simplify the manufacturing, I tried using square and rectangular rods.
𧡠#PortuariaLamp
I made them different on purpose, to add contrast between the rods. Making the vertical rod rectangular also helps prevent the wood from bending due to the weight of the lamp head.
And look who's back, the orange cable! Because I like how it matches the eucalyptus wood rods.
Another reason to use eucalyptus wood instead of "palo blanco" wood for the rods is that, as with all other native woods in Argentina, everyone cuts them down and no one replants them π.
𧡠#PortuariaLamp
The LED is running at 48.6 C. Pretty good considering the maximum operating temperature is 105 C π₯³.
What's not so good is the voltage regulator temperature, which is at 50 C. We're in winter now and the room was at 19 C, so it's running at 31 C above ambient. In the summer heatwaves it could reach 35 C + 31 C = 66 C.
While the recommended maximum is 85 C, those 66 C won't help achieve the goal of a lifespan that is counted in decades π€.
One way to reduce the regulator temperature is to use a more efficient one.
The regulator PCB I'm using is based on Aerosemi's MT3608. Measuring the incoming and outgoing current and voltage gives an efficiency of 86%, which is a very decent number for a switching regulator boosting from 5V to 18V.
Maybe by using some of the latest ICs the efficiency can be increased to ~92%, but I don't think this will be enough to solve the temperature problem π€.
New ceramic lampshade design. Apart from the fact that the piece deformed when drying and that I sawed and sanded it after firing, it turned out "acceptable".
I like the fit between the wooden rod and the ceramic. The thermal design got a little worse; it now works at 1 or 2 degrees warmer than before.
And what I liked least is that now the lamp head is very large in relation to the base π€¨. So I have to think about how to fix this π€.
There are days when you wake up feeling a bit like Jony Ive, except for the tolerances ππ.
This is the base of the second prototype of the Portuaria I'm working on now. The change in shape is to give more visual weight to the base with respect to the ceramic screen, because in the previous prototype I didn't like how that relationship turned out.
Another change is that instead of the printed circuit board it has an aluminum plate to better dissipate the heat from the regulator. The goal is to create a product that lasts several decades in regular use, and the rule of thumb is that for every additional 10 C the useful life is reduced by half.
It's probably not the final shape of the base, I'm already thinking of a third prototype that needs less sanding! π€§.
New LED holder design, now with connector so you can change the LED without having to use a soldering iron π.
I did it to be able to mount the Bridgelux V8s I'm using, with 3mm polycarbonate scraps I had around here.
The future plan is to migrate to the Bridgelux V6s, which have more standard measurements and can be used with TE's Z35 holders.
𧡠#PortuariaLamp #lamp #prototype #LED #holder #lighting #DIY
Portuaria 0.3!
- More angles! Square and rectangular rods add contrast; it's easier to align the holes and slots when making them; and they use the same eucalyptus wood as the base instead of Palo Blanco.
- Larger base surface. The idea was to give the base more visual weight in relation to the ceramic screen, turning the circle into a rounded square without modifying the width and length. But I think I went overboard and now it's too big π.
- Aluminum heatsink for the voltage regulator. This worked quite well, the temperature of the circuits dropped 10 C compared to the previous version.
- New LED holder with connector. This allows changing the LED without needing a soldering iron, increasing repairability πͺ. Made of polycarbonate for now, but perhaps ceramic in future versions to reduce plastic parts to the minimum necessary.
Recalculating! I've been doing measurements of various parameters on the last prototype, and I'm less and less convinced that it's a good idea to run a 5 watt lamp from a 5 volt USB π€¨.
Here's the list of problematic issues:
- Crappy USB cables π. Unless they're of very good quality, they use very thin conductors and connectors with dubious plating. This produces a significant voltage loss of up to 0.4 volts with the currents that the circuit handles.
𧡠#PortuariaLamp
- USB chargers. Usually you can only use up to half of the maximum current without the output voltage dropping too much.
- The voltage regulator I'm using loses efficiency if the voltage drops below 5 volts, and it gets too hot π₯΅.
- The total efficiency is terrible, it only reaches 63% due to all the power losses from the previous points π±. The Huanacus I built before with a simpler circuit that was only an 18 volt transformer, an LED and resistors reached 80% efficiency π.
𧡠#PortuariaLamp
But don't panic! π I have a plan: Use a step-down LED driver like the one in the photo, with a switching transformer from 18 to 30 volts... or 20 volts from an USB-PD π.
The first tests gave a total efficiency of 87%, an amazing improvement π€©. There are still some issues with the flickering produced by the LED driver (a whole topic, it's for another post), but they are being resolved πͺ.
𧡠#PortuariaLamp #LED #driver #efficiency #flicker #electronics #USB
The design of the dimmable version of the Portuaria is progressing, slowly but it is progressing π₯³.
Organizing the wiring of the components inside the base was quite a challenge because there are things with fixed positions (potentiometer, LED cable, vertical rod and power plug) and the circuits have to fit into the gaps between those things π€―. I think it could be simplified more, but for now everything fits into its place.
𧡠#PortuariaLamp #lamp #prototype #LED #driver #dimmer #electronics
I also managed to stabilize the driver circuit to reduce the oscillations of the light intensity to less than 0.2% (2 mV, 0.84 lumens), from 72% that the original circuit had π±. The trick was to add four 22 uF ceramic capacitors in parallel to the LED, and another 10 uF at the potentiometer input.
The goal remains to simulate natural lighting as best as possible, and after all, the sun does not flicker π€.
𧡠#PortuariaLamp #lamp #prototype #LED #driver #dimmer #flicker #electronics
New electronics design that improves energy efficiency from 63% in the previous USB version to 79% with a new circuit that uses USB PD at 20V π.
𧡠#PortuariaLamp #lamp #prototype #LED #driver #USB #PD #electronics #efficiency
The problem with the previous circuit, which worked with the 5V of the common USB, is that it had a lot of power losses due to the inefficiency of working at such a low voltage. The charger got very hot due to the low conversion efficiency from 220V to 5V, power was lost in the cable due to the 1.4A current, and the step-up worked hard if the voltage dropped much below 5V due to using a charger or cable of dubious quality π.
The solution? Use the new USB PD chargers, which can deliver different voltages if we ask them nicely π. I'm using a board with the HUSB238 to ask the charger to give me 20V, which is enough to turn on the 17V LED and makes everything work more efficient and cooler because the current in the cable is only 0.25A, converting from 220V to 20V is more efficient, and the step-down to regulate the LED current is more efficient than the step-up of the previous version.
𧡠#PortuariaLamp #USB #USBPD
But not everything is pure pleasure in the world of USB PD. The USB PD charger I'm using is not a big deal, and has a standby power consumption of 0.125W when it's working at 5V (unpresentable for 2024 π), but when it's put to work at 20V the standby consumption goes to 1W! π±. A 5W lamp that consumes 1W when turned off?!?! π©
After a couple of days pondering this depressing result, I thought of trying something: Make the charger go back to 5V when the lamp is off!
𧡠#PortuariaLamp #USB #USBPD
The first attempt with the IP2721 chip didn't work because that chip can't renegotiate another voltage after power on, but I found another chip that can do it: the HUSB238! π₯³
The trick was to put a double switch and another cable to the HUSB238 so that when turning off the lamp it asks the charger to go down to 5V, and the result was quite interesting: 0.19W in standby, 80% less than before πͺ.
More efficient USB PD chargers with GaN chips are already on the way...
𧡠#PortuariaLamp
Experiments with an alternative wooden lampshade. The problem with the ceramic screen I was using is that it is very difficult to manufacture, because it deforms when it dries due to the cutouts it has. The only way to avoid that that I found is to make the cutouts after the piece is already baked... and that takes a looooong time with saws and diamond micro-files π€―.
Making the wooden screen is a more precise and predictable process, because it does not shrink between 5% and 9% like ceramic. It takes a lot of sanding work to get an acceptable finish, but eventually the rough cutting part of the piece could be sped up with CNC π€.
But the problem now is that everything looks very woody and very brown π. I liked the contrast of materials that the ceramic made. So, continuing with my materials hysteria, I now started trying to make the same shape of the wooden screen (held with screws from below) but in ceramic, which would need only two holes that are easier to make than the one with cutouts.
Sunlight has a notorious flicker at 11.5 ΞΌHz
@poleguy I have no idea π¬. I chose a regulator board without electrolytic capacitors, knowing the bad reputation they have, but I don't know enough about electronics to know if an IC will fail before a Schottky diode or a ceramic capacitor π€·ββοΈ. So I'm betting at making all them run cooler and hoping that will magically work.
The LEDs have a 5 year warranty from the manufacturer, but I can't guess what will happen after that. Same strategy here, make them run cooler and hope for the best πͺ.
@francc Long term behavior of electronics is a deep rabbit hole. :-) I love the longevity goal of your work though.
I
@bastelwombat I was thinking about that option too. Using USB-PD at 20V and stepping it down to 17V for the LED. PD chips for the lamp side are cheap and that would be a simple solution. But then I saw the prices of 20V USB-PD chargers and gave up on the idea, at least for now π.
The problem is that almost all USB-PD chargers I found here that support 20V are >60W, and too expensive to be used just as a 5W power supply at 20V π€·ββοΈ.
@francc Which "latest ICs" do you have in mind? Some of the GaN stuff can be very efficient, but it all seems to be targeting higher voltages. (e.g. epc-co.com) and GaN has now become a marketing term it seems. https://forum.level1techs.com/t/psa-on-gan-chargers/191532/14
You could do a custom PCB and/or parallel a few regulators to reduce heat as well. Sometimes efficiency is not worth the trade-off if longevity is a concern. Can you use an old school transformer based design that gets nice and warm and produces a comforting buzz?
Since my engagement in this thread, I watched a few more reviews about GaN chargers. One is by a hugely popular youtuber, sort of geek type. He teared down his GaN charger but was disappointed to find a discrete silicon MOSFET not GaN MOSFET. From my brief survey, discrete GaN MOSFET is expensive and perhaps way over specβed for consumer chargers which top out around 150W. Thatβs not considered high power application by any measure. What the industry adopts, as the current βstate of artβ, is a...
@poleguy After much research, I realized that there are no such "latest ICs" that can give me significantly better efficiency compared to what I already have π€·ββοΈ. I measured again the MT3608 based boost voltage regulator I'm using and it's working between 90% and 92% efficient, that is why I've focused my efforts on improving dissipation instead.
I'm not sure how I could convert 5 VDC to 18 VDC with a old school transformer π. It is an USB lamp.
Fran π¦π·
John Foley
Marius
poleguy looking for lost tools
Elan Feingold
Francis π΄ββ οΈ Gulotta
Bastelwombat