Panneau Solaire USB

Irritation de puissance

Panneau Solaire USB

Je vois régulièrement passer sur les réseaux sociaux un objet, ou plutôt un concept, qui m’irrite. Il s’agit d’une prise électrique 230V qui comporte au dos un petit panneau solaire circulaire d’environ 6cm de diamètre que l’on fixe avec une ventouse à une vitre et qui permet d’avoir du courant en tout temps.

Les commentaires sont en général très enthousiastes, c’est un design fort élégant, la solution aux problèmes d’énergie. Rares sont les personnes à réfléchir à la quantité d’énergie que peut produire un tel objet, quel genre d’appareil pourraient s’alimenter sur cette prise.

La manière la plus intuitive d’expliquer la quantité d’énergie que produire un panneau solaire, c’est qu’au mieux, il peut produire autant de lumière que la vitre qu’il obscurcit bloque. Ce n’est pas complètement vrai : le panneau pourrait convertir des rayonnements invisibles en lumière visible, et c’est assez vague. L’énergie maximale du soleil sur terre est de l’ordre de 1000 Watt / m2, soit 0.1 Watt par cm2. Un disque de 6 cm de diamètre a une surface de 6 × π, ce qui nous 18.34 cm2, soit une puissance maximale théorique de 1.834 Watt, cela correspond à un ensoleillement maximal dans des conditions idéales.

La lumière doit d’abord traverser la vitre, qui typiquement absorbe les rayons ultra-violets, et la ventouse qui n’est pas complètement transparente. Pour simplifier, je vais ignorer ces deux facteurs. Le taux de conversion de panneau solaires actuels tournent autour de 20%, ce qui donne donc une puissance maximale de 0.3668 Watts. Si cela vous semble peu, c’est normal, c’est peu. L’énergie d’un pet est de 6.2 Joules. Il faudra à ce panneau près de 17 secondes pour produire autant d’énergie.

À présent il faut convertir l’énergie en courant électrique 230V, la bonne nouvelle c’est qu’on a des convertisseurs très efficaces : ≈95%, la mauvaise nouvelle c’est que je doute qu’ils tiennent dans l’objet, mais bon. Nous avons à présent environ 3.5 Watts de courant 230V dans le meilleur des cas. Quel appareil peut-on connecter sur cette prise? Aucune idée. Un chargeur USB de 5W a généralement une efficacité de 75%, il lui faut donc 6.67 Watts. Un aspirateur ou un fer à repasser consomment facilement 1000 Watts. Pour avoir un sens, cet objet devrait produire 10 fois plus d’énergie.

La première absurdité est qu’il comporte une prise 230V, or il ne peut physiquement pas fournir assez d’énergie pour alimenter un appareil qui fonctionne à ce voltage. S’il comportait directement une prise USB, on éviterait les pertes dues à la conversion vers le 230V et retours. La plupart des appareils qui consomment peu de courant utilisent cette prise à bas voltage. Ensuite, il faudrait sensiblement augmenter la surface.

Je possède un chargeur USB solaire : il comporte 4 panneaux d’une capacité théorique de 1.8 Watts (soit 7.2 Watts). Avec un beau soleil de mars en Suisse vers neuf heures du matin, le tout produit environ 2.5 Watts. Ici le panneau est exposé directement à la lumière, pas de vitre ni de ventouse sur le chemin. Cela permet de charger (lentement) un téléphone mobile. Évidemment, cet objet est beaucoup moins ambitieux que le précédent, mais il a l’avantage d’exister et de fonctionner en accord avec les règles de la physique.

Les gens s’offusquent lorsqu’un politicien ne sait pas le prix d’un pain au chocolat, considéreraient un revenu universel de 2€ mensuel ridicule pour un pays européen, pourtant quand on parle d’énergie, les gens ne valent pas mieux. L’énergie est pourtant un sujet important : le réchauffement climatique, le nucléaire sont avant tout des problèmes d’énergie. Les calculs que je fais ici ne sont pas compliqués, des multiplications et des divisions…

Un projet de la confédération helvétique est la société à 2000W, comme le titre l’indique, le but est d’avoir une société où chaque personne ne requiert que 2000W, ce qui correspond à 600 fois ce que cette prise pourrait fournir. La consommation annuelle moyenne de courant électrique par habitant en France en 2015 était de 4763 kW/heure, ce qui nous fait: 4763000 × 4763 ÷ (365.25 × 24) ≈3260 Watts. Environ 1000 fois plus que ce que pourrait produire cette prise, c’est un peu comme un RMI à 45 centimes d’euro…

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USB Type C connector

The C in USB C stands for Confusion

The industry is slowly moving to the USB C connector, while this might sound like just an incremental change, yet another standard, I think this has the potential to change many things, but also to confuse users a lot.

The USB C connector has the following features:

  • Symmetrical: USB-C cables have the same connector at both ends
  • Alternate Mode: the USB-C connector can carry USB signals, but also other protocols like , , and MHL.
  • High power delivery, up to 60W which is enough to charge a laptop.
  • Reversible, no longer will you have to flip the connector five times until you got it right

How standards proliferate – situation there are 14 competing standards – ridiculous we need to develop one universal standard that covers everyone's use cases. Yeah!  Soon 
situation there are 15 competing standards.

These features mean that a laptop can just have one type of port, and the same port can be used to charge it, connect it to a screen or to a hub where keyboard and mouse will be connected. The fact that there is the same connector at both ends means that you can use the same cables for everything. This is cool. Of course this means yet another type of cable and connector, this is less cool.

Things get confusing when you consider power delivery. Up until now, USB cables had a direction, when you connected a device to another one, power went from the A connector (the flat one which everyone plugs the wrong way) to the other one – this is consistent with the way main power plugs work. With USB-C, what happens when you connect your phone to your laptop? When you connect your laptop to your screen? The behaviour will be software defined, which means bugs, confusing interfaces.

Alternate mode can also make things confusing, up until now when you connected a device into a USB port, it was a USB device, with a USB driver. Let’s consider a screen with an ethernet connector connected to a laptop using a USB-C cable. It could be the following:

  • A USB hub with two devices, for instance a DisplayLink screen and a USB ethernet adapter.
  • A HDMI device, with the ethernet port run using HEC (HDMI Ethernet Channel).
  • A DisplayPort device, with the ethernet port implemented on top of USB run using DockPort (USB over DisplayPort).
  • A Thunderbolt device, with the screen driven by DisplayPort over Thunderbolt, and the ethernet card on a PCI/Thunderbolt device (this might be a PCI/Thunderbolt USB controller with a USB ethernet adapter).

There is no way to physically distinguish these cases, maybe there will be some icons, or maybe port colours to act as hints, maybe not. Each of these cases could be supported by the laptop’s operating system, or not.

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Car Display – The Understanding – Röyksopp – What else is there?

Matthias et les automobiles

Car Display – The Understanding – Röyksopp  – What else is there?

Cela ferra bientôt huit ans que je vis à Zürich, sans voiture. Si j’en possédais une au Japon, ce n’était de loin pas un modèle récent: une vieille Toyota Starlet. Depuis, j’utilise surtout des voitures de location, aux États-Unis notamment, où les transport publics sont simplement insuffisants.

J’avais déjà loué une voiture hybride il y a cinq ans, cela a de nouveau été le cas cette fois-ci. Le hasard a voulu que la voiture que j’ai loué cette fois-ci avait un problème, heureusement détecté au moment de partir, j’ai donc fini avec une Hyundai Sonata Hybrid, une voiture plus grosse que ce que j’ai l’habitude de louer.

Ce que j’ai trouvé intéressant, c’est la quantité d’électronique embarquée. L’auto-radio est fondamentalement un écran tactile qui affiche en marche arrière la vue de la caméra arrière, avec une projection de la trajectoire, sinon, il affiche les informations sur la musique, téléchargées depuis mon téléphone via la prise USB. La fonctionnalité ne m’a tant étonné que le fait que cela a fonctionné automatiquement, du premier coup.

Silicon Valley regorge de voiture spéciales : celles qui mesurent les routes pour Street View ou des projets analogues, petites automobiles auto-guidées, sans oublier les Tesla, voiture de sport du geek par excellence. Ces voitures me font penser au hoverboard du film back to the future, un objet associé à une époque projeté dans une autre. Le tissus sub-urbain peu dense que forme la région de la baie est l’écosystème idéal pour les voitures, mais est-ce réellement l’avenir ? Peut-être que la maison de banlieue avec son jardin est l’équivalent du ⅩⅩe siècle du château fort…

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Vodafone 802SE

My phone, ten years ago

Vodafone 802SE

Ten years ago, I was settling in Kanazawa. This involved getting a Japanese phone, and more importantly getting it work for me. At the time, I wrote a blog post with some observations on what worked and what did not.

Looking back at the problems I faced at that time is a pretty good indication on why Apple managed to storm that market:

  • Contact synchronisation only worked partially
  • Todo synchronisation only worked partially
  • Music playback was crippled by DRM
  • GPRS modem function (tethering) was broken

The Vodaphone 800 had pretty good specifications for that time: it was built by Ericsson in collaboration with Sony. Yet most of the features I wanted did not work. I was using Mac OS X, which certainly did not help: there were Windows, Japanese only drivers available, but even then, integration with computers was an afterthought.

Like many phones at that time, the phone had very different connectors: there was a USB connector, but it was only used for data exchange, not charging. There was not standard jack headphone port, but instead the wide Ericsson connector, for which I had a charging dock and a special headset. I never used it because of the crippled audio playback. The phone had a Sony Memory stick slot and an infrared port (which I never used).

One aspect of the phone I liked was that it supported many Bluetooth profiles:

  • Hands-Free Profile (HFP)
  • Headset Profile (HSP)
  • Object Push Profile (OPP)
  • Serial Port Profile (SPP)
  • Dial-up Networking Profile (DUN)
  • Synchronization Profile (SYNC)
  • Generic Access Profile (GAP)
  • Object Exchange (OBEX)
  • File Transfer Profile (FTP)
  • Basic Imaging Profile (BIP)
  • Human Interface Device Profile (HID)

For comparison my iPhone only supports the following profiles:

  • Hands-Free Profile (HFP)
  • Advanced Audio Distribution Profile Source (A2DP)
  • Audio/Video Remote Control Profile target and controller (AVRCP)
  • Personal Area Network (PAN)
  • Serial Port (SPP)
  • Device Identification (DID)
  • Generic Access Profile (GAP) – Low Energy
  • Battery Service – Low Energy
  • Current Time Service – Low Energy

While some profiles have replaced others, for instance Personal Area Network (PAN) replaces Dial-up Networking Profile (DUN), with the added advantage that PAN actually works, I miss some of the old profiles, in particular Object Exchange (OBEX) which let me push a file from my laptop to my phone and vice-versa and Human Interface Device (HID) which let me use my phone as a mouse, very convenient for presentations.

Having left Japan, I never managed to sim-unlock the device, so it rotted away in a drawer…

Vodafone 802SE (Sony Ericsson V800) mobile phone © Episteme – Public Domain

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DC62 LED Display USB Power Charger Data Transmit Current Voltage Tester and Apple A1205 Power Supply

USB Power – Apple

DC62 LED Display USB Power Charger Data Transmit Current Voltage Tester and Apple A1205 Power Supply

One comment I got about my previous blog post about USB power supplies is that it depends on the manufacturer of the power-supply, that Apple supplies would work better with Apple devices. This makes sense, so I did another quick run of tests. The set of power supplies I tested is a bit smaller, mostly because I stored some of them into boxes which are now in the attic.

I connected my iPhone 5 using a lighting cable to the power meter and the various supplies. The results are interesting: basically all the power supplies I tested output more power when connected to the iPhone, the only exception is the Mac Book Pro and that was expected. The iPhone seems to more aggressively draw power regardless of the manufacturer of the power supply. I really need to try with another Android device…

Power Supply Volts Ampères Watts
Apple A1400 5.07 0.93 4.72
Apple A1205 5.04 0.87 4.38
Apple Mac Book Pro (laptop) 5.07 0.52 2.64
Asus PSM06A 5.09 0.87 4.41
HTC TC-E250 5.00 0.8 4.00
Jet AC Adapter 4.92 0.83 4.08
Kensington Absolute Power 4.2 4.99 0.89 4.44
LG MCS-02ER 4.95 0.51 2.52
Steffen Swing Steko 5.07 0.89 4.51

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Internal board of a Protek PAC - 1200 WH Power Supply

USB Power

Internal board of a Protek PAC - 1200 WH Power Supply

One of the annoyances of electronic devices in the past used to be the myriad of power supplies, each with their own connector, voltages. They were all black and you would always mix them up or misplace them so that the relevant device would become useless.

USB solved this problem, which is kind of surprising because USB was first a data connector that happened to carry some power. The upshot is that you can use any USB power supply to charge any device with a USB connector.

These power-supplies typically have a longer life span than the device they came with, so they tend to accumulate. I was wondering what the difference is, so I ran a simple test on all of them: charge the same device, a Nexus 5, and measure the output of the various power supplies.

I only measured the supplies that have a USB A female connector – many power supplies have either a male micro or a male mini connector. I also tested various devices with such a connector for comparison.

Power Supply Volts Ampères Watts
Apple A1400 5.07 0.63 3.19
Apple A1205 5.04 0.61 3.01
Apple Mac Book Pro (laptop) 5.06 0.47 2.38
Asus PSM06A 5.08 0.57 2.90
Brother 4040 (printer) 4.84 0.34 1.65
Denon AVR-3310 (amplifier) 5.02 0.45 2.26
Google MSTK3K-US 5.08 0.43 2.18
HTC TC-E250 5.03 0.56 2.82
HTC MCS-01ED 4.99 0.76 3.79
Jet AC Adapter 4.99 0.47 2.35
Kensington Absolute Power 4.2 5.04 0.54 2.72
LG MCS-02ER 4.75 0.21 1.00
Model SM-600B 4.97 0.34 1.69
Steffen Swing Steko 5.18 0.67 3.47
Tylt UPPLANT (battery) 4.94 0.43 2.12

The first thing to notice is that the LG power supply barely meets the USB specification, which requires a 5 volt output ± 0.25 volts. The second is that while many power-supplies have similar sizes, their output changes quite a lot. The relatively low output of the Google power supply was expected, as it is meant to be used with a Chromecast, which consumes 2 Watts at peak.

Similarly the output of the Apple A1205 power supply was expected, as it was originally meant to recharge an iPad. The output of the Steffen Swing Steko power plug was a surprise, with nearly 3.5 Watts of output, officially it can output 500 Milliampères per connector (there are two).

So while there is a standard, it is pretty undefined what actual power you get from a USB plug, the actual USB spec only mandates 500 millampères, which is what the Denon amplifier provided. As often, it was nearly impossible to know beforehand how the various plugs would perform: LG is a pretty well know brand and the Jet AC Adapter I got from some small shop in Akihabara. Testing seems to be the only real way of figuring out; I also figured out that one adapter I had, a Protek PAC – 1200 WH was dead. I opened it up and used the board for the image of this blog post.

What would be interesting would be to measure the efficiency of these power-plugs, sadly the device I have to measure power-consumption is not that precise, so it does not see their consumption.

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USB Power Meter – 5.12 v

USB Power measurement

USB Power Meter – 5.12 v

It is really strange that a data-connector would manage to become a standard power plug, but USB achieved just that: most devices which can work or charge using 5 volts nowadays come with a USB connector. I think this is generally a good thing, one standards means less redundant incompatible hardware, and people don’t need to have N power adapters around. Of course there are compatibility issues, and we already have reached the point where determining the power draw of a device connected over USB is black magic: this can be determined by software nobody implements (original spec), or by putting some magic resistors between pins, with each manufacturer using his own secret sequences.

This leads to the second interesting question: how much power do these various devices use? I just bought a small device that is pretty useful to answer that question: a short USB plug that measures both the voltage and the power consumption on a USB connector. This device only gives you half of the story, how much power goes into the device, not how much was consumed by the power supply (which might be a computer, a printer, or a TV), it still gives some insights into the electrical power consumption of various gizmos – as a good charger typically has 75% efficiency.

For instance, a Qi wireless charger uses 0.04 Amperes when empty, that is 0.2 Watts for doing basically nothing. Charging my Fitbit Charge draws 0.03 Amperes out of my laptop (0.15 Watts). When docked and charged, my iPhone 5 consumes 0.3- 0.4 Amperes (1.5 – 2 Watts).

I’ll need to try more devices around the house. I also would like to measure how efficient the various chargers in the house are.

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Foldable array of solar cell, portable auxiliary battery with solar cell and iPhone 5 charging

Of energy estimations…

Foldable array of solar cell, portable auxiliary battery with solar cell and iPhone 5 charging

I have a vision for solving world hunger: each person just needs to have a small pot in their appartement and grow salad in them. So they will have food. Problem fixed, hand-over the Nobel price please. Thank you very much!

Of course, this is a silly idea – the numbers just don’t add up. It takes many days to grow a single salad, and you need more than a salad every other week to feed a human, not to mention this winter thing. People realise this, because they somehow understand what quantity of food they eat, how fast salads grow. This does not mean that having every person grow her own salad is bad idea, just that it won’t solve world hunger.

When the topic turns to energy, all the common sense flies out of the window: people don’t understand the quantities, so everything seems possible. A typical example is this solar powered window socket. Looks neat no? Just stick the thing to a window, it uses solar energy to recharge itself and acts as a power plug. Cool, no?

This device would contain a 1000mA/h battery that is charged in 10 hours. First problem the voltage is not specified, but if the battery charges in 10 hours, we need a 100mA solar panel. With the current technology, a panel a tad larger that the one in that device would output 100mA at 5V, so let take that as a baseline.

So we have 1A/h at 5V, which gives us 5 W/h (18 KJ) So what can you do with this amount of energy?

  • Run a 1000W hair-drier for 18 seconds.
  • Run a 100W LCD television set for 3 minutes.
  • Run a 40W incandescence light-bulb for 4½ minutes.
  • Run a 10W LCD light-bulb for half an hour.
  • Charge an iPhone 4 (5.254 W/h) to 95%.
  • Charge an iPhone 5s (5.966 W/h) to 84%.
  • Charge a Nexus 7 (16 W/h) to 31%
  • Boil 7 ml of water.

All this is assuming no conversion loss, which would be hard, as the battery would be 5V DC but the plug is 230V AC.

Now I have a solar charger, but it is much larger, and by experience, it produces just enough power to charge an auxiliary battery with an USB plug, which in turn can charge my phone (see picture). All this is done using USB cabling at 5V. This is convenient when travelling, but again, not a solution for energy problems and certainly does not look as stylish as the clean vision of the small plug stuck onto the window.

If you want to have solar power, you need a large surface, for the same reason that if you want to feed people, you need a field… You also might want to do that outside of the house’s windows, which tend to reflect ultra-violet lights.

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J’ai acheté un chapeau USB

bonnet en fourrure polaire noire avec des bordure jaune fluo et une lumière rouge visible

Durant mon dernier séjour aux États-Unis, j’ai acheté un chapeau USB. Techniquement, il faudrait plutôt parler de bonnet USB mais la langue française ne semble pas avoir d’équivalent exact pour le terme beanie, je trouve que chapeau donne un meilleur titre (quelqu’un a proposé calotte, mais ça me semble trop formel).

Le standard USB est apparu en 1996, soit il y a 17 ans. À l’époque, si on m’avait dit que j’aurais un bonnet avec un câble de ce type, j’aurais été très perplexe, surtout que cette connectique n’est pas utilisée pour transmettre des données, le rôle premier du standard USB, à la place elle est utilisée comme source de courant 5 volts.

Durant ce laps de temps, deux choses se sont passées, d’une part USB est devenu un standard de-facto pour des prises à bas voltage, de l’autre les batteries rechargeables sont devenues suffisamment compacts pour être logées dans un bonnet, ce qui me donne un bon moyen d’avoir des phares de vélo sur la tête, et un objet qu’il m’était impossible de ne pas acheter.

L’avantage de ce système c’est que je peux à présent recharger mon bonnet sur n’importe quel appareil doté d’une prise USB, ordinateur, naturellement, mais aussi télévision, imprimante, ou simplement un transformateur doté de la prise idoine.

De fait, charger un bonnet sur un ordinateur peut-être quelque chose de risqué quand on ne sait pas d’où il sort. Il est parfaitement possible de mettre dans le bonnet une puce hostile qui tente de pirater l’ordinateur auquel on le connecte. L’idée qu’un chapeau USB puisse pirater mon ordinateur peut sembler saugrenue, mais nous vivons dans un monde où les bouilloires et les fers à repasser tentent de pirater votre réseau local.

Le XXe siècle nous a amené les objets anonymes, fabriqués dieu sait où, la distance nous affranchissant de la respectabilité morale de leur origine. Aujourd’hui, une question plus pragmatique se greffe sur la question morale: on ne sait pas d’où viennent ces objets, et à cause de cela, ils peuvent très bien être hostiles. Une personne responsable ne saurait porter un chapeau dont elle ne connaît l’origine…

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Technology Cycle

Technology Cycle for Devices

When people talk about technological progress, they often seem to have the vision of a unstoppable army going forward, knowing where it goes. For me it looks a lot like a large river, unstoppable, but meandering around in unpredictable ways. One by one, objects around me are crossing the barrier that separates analog from digital. This evolution seems to follow some recurring path, where usability first degrades to improve afterwards. Here are the steps I observed.

  1. Analog device. The object has one purpose and just works for that purpose.
  2. Digital device with a clock. The first thing that you notice when a device becomes digital is that it gets a clock. The objet has a limited amount of buttons, and the clock is difficult to program, so often the device stays at the blinking 12:00 state.
    My kitchen and bathroom scales are at this level.
  3. Digital device with battery. A battery has been added to the device, so it can keep it state in case of power-cut, lots of feature have been added, but the device is way to complicated to configure properly, so the majority of its feature are unused. It displays winter or summer daylight saving time all year around.
    My old stereo is at this level.
  4. Digital device with serial port. A serial port (or a hacked usb-port) has been added to the device. Hackers can now use the device for many purposes, for the available population there is no noticeable changes. The device has now more unused features.
    My Casio electronic dictionary is at this level (no serial port, but proprietary USB).
  5. Digital device with USB port. The device has an USB port with some working protocol. It can now be used with computers relatively easily. The digital device is now much more useful than the analog equivalent. Digital cameras and MP3 players are typically at this level.
  6. Digital device with network connection. The device now has a network connection (Wifi or wired ethernet). The device can now be used in conjunction with other devices. Hardware is not the limiting factor, but software.
    My phone, my TV, my amplifier and my gaming console have reached that level.

Note that I’m not convinced there is a strict causation between certain feature and usability, more of a correlation.

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