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Le guide de Make Magasine : Pas de batterie tampon.

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Le guide de Make Magasine : Pas de batterie tampon.

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Weekend Projects - Pedal Power Phone Charger

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Complete instructions for this episode of Weekend Projects can be found at http://makezine.com/projects/pedal-power-phone-charger/ Convert AC electricity from an alternator into a steady stream of 5VDC to charge your phone or power other mobile devices while bicycling. Attach a bicycle generator to your bike frame so that as you pedal you produce alternating current.

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Rectifieur de courant ET chargeur de batterie.

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Rectifieur de courant ET chargeur de batterie.

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For a while now I've been obsessed with bicycle hub dynamos. Two of my three bikes are equipped with them. I ride quite a lot at night around the streets of Toronto, and for almost half of my year-round commute I ride home from work in the dark. A well designed dynamo-powered bicycle lighting system can provide a surprising amount of light with very little load on the rider and almost no extra drag while riding during the day with the lights off.

I bought my wife a very dilapidated 1966 Raleigh Superbe from a friendly street bike peddler with an enthusiasm for old English 3 speeds. The Superbe was the high-end model of the Raleigh 3 speed family and came equipped with a Sturmey-Archer GH6 6V 2W (some sources say 3W) Dynohub and a shiny chrome light set (unfortunately missing from this example).

I overhauled the Dynohub and was excited to find out that it still worked. After some hunting around on ebay I got lucky and managed to track down a NOS Sturmey Archer chrome light set for a reasonable price (some folks are willing to pay over $100 for a used set!).

Brand new out of the box (hand courtesy of the gentlemen who got far less than 100 bux for his shiny wares).

The original configuration did not throw out much light at low speeds and, of course, the lights went out completely when the bicycle came to a stop. A few modern dynamo lights have a supercapacitor that can power a small auxiliary LED while the bike is stationary (called a standlight). Busch & Muller even make a nice chrome retro-styled headlight with this feature but offer no matching rear light. I have one of these for my bike equipped with a modern 3W Shimano hub, but the old GH6 doesn't quite put out enough juice to satisfactorily light up the 2.4W halogen bulb. Being an obsessive weirdo this just wouldn't do, so I thought I'd try to build a modern dynamo lighting system with a standlight into the original Sturmey Archer lamps for my wife's Raleigh.

Step One: Finding Suitable LEDs

The GH6 has a lower output than modern dynamos, so using LEDs as the main lamps instead of the original incandescent bulbs makes good sense to get high brightness at low speeds. With a total power output of about 2W, I figured 1W front and rear should do. Bicycle dynamos put out AC, so an AC to DC conversion needs to be worked out as well - more on that later...

Scrounging around google, I found that there are several manufacturers that make drop-in LED replacements for flashlight bulbs. The TLE-1S is a 1W white LED with a screw base that fits the Sturmey Archer head lamp. $15.99 for a flashlight bulb? Only a crazy person would want this. They do brag about a 'power push' circuit which is supposed to suck every last drop of juice out of the batteries that are meant to power it without dimming. Most importantly, it accepts a fairly wide input voltage (3-9V) and presumably has some way of limiting the current going into the LED.

Finding an appropriate taillight proved more difficult. The Sturmey Archer tail lamp uses a bulb with an old fashioned automotive wedge base. There are LED replacement bulbs available in a rainbow of colours, but they all seem to be 12V only. I experimented with a mini maglight replacement bulb that used pin contacts and soldered them to the filament terminals of a broken wedge bulb base and then encased the whole thing in silicone, but unlike the TLE-1S the TLE-20 didn't seem to have suitable current limiting circuitry. Unfortunately it took blowing two $12 bulbs to learn this. bummer. :(

I finally settled on a 2V 350mA 1W jumbo red LED from digikey, but it's a bit steep at $5.17. This is just a LED so it will need a current limiting resistor.

Step Two: Designing a standlight

Many modern dynamo bicycle lights use a supercapacitor to power auxiliary low power LEDs, which provide some light while the bicycle is stationary. I only wanted to work with the main bulbs in the front and rear lamps and keeping 2W worth of LEDs lit for more than a few seconds would require some hefty supercapacitors. I originally tried to work out a design using a 120F supercapacitor, which is slightly shorter and fatter than an AA battery. The supercapacitor solution seems the most elegant, but with a typical supercapacitor rating of only 2.3V and the dynamo's output ranging from 3-20 VDC (after running it through a bridge rectifier) the design requirements quickly exceeded my ability.

Using a battery to power the LEDs and using the dynohub to recharge the battery seemed like a less elegant but more practical solution to keeping the lights on when stopped. There are a few resources for dynamo-powered battery chargers out there, but they were too complicated and bulky for my requirements. I needed a small charging circuit and a small battery that would fit together into the housing of the headlamp. High capacity 3.6V lithium ion CR123A camera batteries are a good fit and are available for only a few bucks complete with a built-in circuit to prevent over-charging, over-discharging and over-heating. I went with the Ultrafire Li-Ion from DealExtreme ($5.08 for two!)

Here's the 880mAh Ultrafire with its cover peeled off to reveal the protection circuitry.

Step 3: Design a regulated battery charging circuit

Single cell lithium ion batteries have very specific charging requirements. Just connecting the rectified output of the hub wasn't going to cut it. For starters, 3.6V Li-Ion cells need exactly 4.1 or 4.2V and carefully controlled current regulation during charging, but the GH6 throws out anywhere from 3V at low speeds to over 20V at higher speeds (based on my measurements of the rectified output).

Fortunately, there are several integrated circuits available that are designed specifically to monitor the charging of Li-Ion cells. I went with the simplest one I could fine: the National Semiconductor LM3622, available from Digikey for $3 (or you can ask National for samples). The LM3622AM-4.1-ND takes anything from 4.5V up to 24V and puts out exactly 4.1V. It controls the current going into the cell by monitoring the cell's charge status and in its most basic configuration requires only 5 external components. National even has a handy application note about it, which suggests exactly what components and values to use for the highest efficiency.

Perfect! There's only one problem:

It only comes in a tiny 4.9mm x 3.9mm SOIC8 surface mount package. Having only ever soldered through hole components, I thought I'd hit a wall. But, it turns out that the SOIC8 is one of the larger SMD packages out there and that soldering with conventional techniques is not that bad (although I remained skeptical until I actually did it).

So, I designed the charging circuit, including a bridge rectifier, based on the design in National's application note. To make the schematic and layout the circuit board I used EagleCAD, a difficult to learn but ultimately useful FREE (for my needs at least) software package that can run on Mac OS 10. To make things even easier, Lady Ada has EagleCAD files on her site that include an LM3622 device used in her Wave Bubble, saving me the trouble of having to figure out how to configure custom devices in already hard-to-learn software.

I bought all the parts from Digikey, including an SOIC-8 to DIP-8 adapter (virtual robbery at $6.43 a piece) to facilitate the use of a prototyping breadboard.

Soldering the SOIC8 package to the DIP adapter proved to be easier than I thought. I was even drunk and shaky from too much coffee.

Using a regulated DC power source, I was able to get 4.09V over a range of input voltages and when connected to a discharged Li-Ion cell, the charging circuit drew about 180mA and took about 2 hours to drop the current to a couple hundred µA, indicating that the charge was complete. I tested a rectified AC source from the motor-crank assembly of a wind-up flashlight to roughly mimic the output of the dynohub (albeit with a much higher frequency) and the circuit worked fine. Success!

Now to see if the GH6 Dynohub could power the charger:

Even at low to moderate speeds, the GH6's output was good enough to power the circuit. Spinning the wheel as fast as I could made the voltage across the rectifier peak close to 20V, a little over 4V shy of the LM3622's maximum rated input. I doubt my wife will ever go that fast, even downhill in relatively flat Toronto.

Here is the complete parts list for the charger:

1 LM3622 IC
1 D45H8 transistor
1 MBRS130L diode
2 10 µF capacitor
1 0.22ohm resistor
1 1000 µF electrolytic capacitor
1 W02M 1.5A 200V bridge rectifier
1 CR123A 880mAh 3.6V Li-Ion battery

Step 5: Make a PCB

The charging circuit needs to be assembled into as small a package as possible to fit into the housing of the headlamp. Here's what I came up with:

With no mad PCB-routing skills, this is the best I could do for a single-sided design with large traces and pads suitable for DIY etching. Q1 is a large 10A power transistor and probably could have been swapped for a smaller SMD component such as the STN479 used in the design of the Wave Bubble. I decided to stick with the D45H8 suggested in National's application note, even if it was overkill. The final footprint of the PCB is a little less than 1.3" square. Download the EagleCAD project here.

Using a PDF (derived from the EPS output of EagleCAD's CAM processor), I made the etch-resist mask using the toner transfer method. This was considerably harder to master than advertised. After several attempts, I had a reasonable looking etch-resist pattern that still required a bit of touching up with a black Sharpie pen. I etched the board using ammonium persulphate (220g/L) which we have in the biochemistry lab where I work. Using a magnetic stirring hot plate to keep the the temperature at 60ºC and the solution in constant motion the board was nicely etched in less than 10 minutes.

A few minutes of soldering later, the circuit was complete!

I got a little too excited after finishing it and soldered in test pins, making the connection of the battery and dynohub leads a little sloppy.

Step 6: Connect to the dynamo

Now the whole thing needs to be connected to the dynamo and stuffed into the headlamp.

Here's the bottom of the board with the surface mount LM3622 and diode. This time I was sober and coffee-free.

All connected. On the upper right you can see a 6.8ohm 2W current limiting resistor connected in series with the rear light.
Wrap it all up in electrical tape and stuff it in there. Plenty of room left over.

Now for the rear light. The LED won't fit into the wedge socket by itself so I cut out a small piece of PCB and soldered it to the leads to approximate a wedge base bulb.

Fits snuggly in the socket. The bulb looks like it's a bit too long.
But the lens fits!

The rear light is super bright. Blinding, actually. Even brighter than the front, but using about half the current.

Final thoughts Everything seems to work. The only problem I've had so far is that the battery wasn't fully charged when I installed it. The two lights discharge the battery faster than the dynamo can charge it, so on the first night out I wound up draining the battery completely, preventing the lights from staying on when stopped (the charging circuit seems to provide enough current to power both lights while the bike is in motion when the battery is dead). I expect a long ride during the day with the lights off should get it charged up sufficiently. That said, for long night rides this design is somewhat lacking. Under the conditions my wife is likely to ride, I suspect it will rarely be a problem.

Another potential design flaw is excessive battery charging time. Other charging circuits incorporate a timer so that after the battery is held at full-charge for a determined amount of time the circuit shuts off completely (I think). The LM3622 doesn't incorporate at timer; as long as the wheel is spinning the charging circuit is on. I think this is probably OK for the long term health of the battery because the LM3622 monitors the charge state and drops the current to a few µA when the battery is fully charged . If the bike was ridden for hours and hours with the lights off then there could be an issue with battery lifespan, but my wife's bike will never be taken out for more than an hour or so once or twice a week so I don't think it will be problem.

Finally, there is the issue of the dynamo's output exceeding the 24V maximum rating of the LM3622. This is an unlikely but not impossible scenario. I don't doubt that flying down a steep hill at top speed would probably blow the chip. A better design would incorporate voltage regulation.

Back to the drawing board...

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For a while now I've been obsessed with bicycle hub dynamos. Two of my three bikes are equipped with them. I ride quite a lot at night around the streets of Toronto, and for almost half of my year-round commute I ride home from work in the dark.

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These days there's a wide array of dynamo USB chargers available on the market. While most of them do an adequate job of keeping your electronics charged, different chargers are better optimised for different tasks. The things you will be trading off include charging potential with hub drag, the size and practicality of the charging unit, and of course, the price and overall build quality.
This article will be discussing everything from power at certain speeds, to hub drag, right through to the general practicalities of dynamo USB chargers.
Firstly, let's quickly cover a few basic electricity units of measurement. Sorry, it'll take a moment to get your head around this, but the knowledge will help, promise!

Today we will be discussing voltage (in volts or 'V') and current (in amps, or 'A' or 'mA', where 1A = 1000mA). A common analogy for these units of measurement is in terms of a water pipe. Voltage is the water pressure and current is the flow rate. By increasing the water pressure in a pipe, you will increase the flow rate too. It's the same with electrical systems; increasing the voltage increases the current.

Watts (W) are the total electrical system power, equal to the current (A) multiplied by the voltage. The equation is therefore:
Watts (W) = Volts (V) x Amps (A).

A 3-watt dynamo hub will put out 6 volts at 500mA (3W = 5V x 0.5A) in AC power. Once the power is converted to DC it's more like 5V and 500mA; the power required for USB 2.0 charging. While some USB chargers will start charging at lower rates, most devices like to charge above 2-watts to ensure the charging level is stable.

2-watts can be reached by dynamo USB chargers at speeds between 12-16km/h. Travelling at speeds below this, and you'll need to use a cache battery (topped up with power) to make sure your devices can make up the power difference for a stable charge.

Most dynamo USB chargers use chipsets with a current limit to prevent overheating (eg. Sinewave Revolution is 1A, therefore the maximum power is about 5W (5V x 1A)). It can be said that any USB charger that puts out high watts will also be putting out a high current.

The Fahrrad Zukunft crew have conducted some really extensive testing to determine the amount of power (in watts) that can be produced by various dynamo USB chargers. The two below charts compare eight different models, some with different cache batteries or capacitors wired in.

What you're looking at is the maximum output power at the USB charger at various cycling speeds. You'll notice that most power curves are rather linear from 5km/h until they plateau somewhere between 20-40km/h depending on the model. The exception is the Forumslader V5 and Dynamo Harvester Plus. These chargers use special series capacitors to boost the power potential of a dynamo hub.

Power at different speeds:
1 Watt -Most chargers will achieve 1w between 9-11km/h.
2 Watts - At 12km/h the highest performing charger hits 2w. Most other chargers will hit 2w between 14-16km/h.
3 Watts - At 15km/h the highest performing charger hits 3w. Other chargers hit 3w between 20-30km/h.
4 Watts - At 18km/h the highest performing charger hits 4w. Three other chargers hit 4w between 27-28km/h.
5 Watts - At 20km/h the highest performing charger hits 5w. Three other chargers hit 5w above 35km/h.

You'll notice The Plug III has an odd curve. This is because it's hooked up to a current-limited cache battery on two different current settings (400mA and 900mA). With a current limit and a dynamo hub that produces 5V, that's why it's limited to either 2-watts or 3-watts power. If you were to plug it directly into a device you can expect a more linear curve like the rest. In fact, according to the chart by Cinq5 found in my review, The Plug III should hit 2.5-watts at around the same time as the Forumslader V5 thanks to its power amplifier.

A smartphone consumes around 3-4 watts in navigation mode with full-screen brightness. Therefore, just to keep the battery at the same level will require cycling speeds between 15-30km/h. Even then, there's only a handful of products that can achieve that kind of power. If you're a heavy smartphone user for your navigation you'll want a charger with series capacitors. But powerful chargers like these have their downsides too...

Sorry, but there's no such thing as free energy. Do you want a powerful charging system? That's fine, but you're going to have to pedal a bit harder for it! Let's take a look at dynamo hub 'drag' from using different charging systems.

The charts above show the power at the USB charger (via a full buffer battery). The efficiency of a high-quality dynamo hub at low power (eg. cycling at 10-20km/h) is typically 50-60%. This means that when the charger is making between 1-3 watts you can probably double that figure to work out the drag at the hub.

Therefore, when making 2.5 watts for USB charging you're probably taking about 5 watts of your pedalling power. That drag equates to ~0.4km/h slower riding speeds than if you weren't charging at USB specification (80kg rider / 15kg bike and gear / 150 watts / flat road). Or a ~3-minute time penalty over a 100km ride.

The efficiency increases to 70-80% at high power (ie. cycling at 30km/h). This means that a charger like the Forumslader V5 will be taking 15-watts from your pedalling power while charging at 10.5 watts. That drag equates to ~1.1km/h slower riding speeds than if you weren't charging at 10.5 watts (80kg rider / 15kg bike and gear / 150 watts / flat road). Or a ~9-minute time penalty over a 100km ride.

While efficiency increases with rates of power, the more power developed, the more drag at the dynamo hub.

Once a 3-watt dynamo hub has been converted from AC to DC the output will translate to roughly 5V and 500mA (the USB 2.0 charging standard), which for an hour of riding is 500mAh. Charging a 5000mAh battery will, therefore, equate to 10 hours of riding. However, there are also small losses in the charging circuitry, perhaps around 20% of the total generated power. Adding the 20% extra ride time (10 hours + (10 hours x 0.2)) and we're looking at 12 hours of riding to fill the battery from scratch.

Most people with USB chargers like to save their power for use later. But this is not the most efficient way to charge because there are energy losses through the additional circuitry. When power is stored in a battery, it experiences a storage loss of 15-20%. In order to minimise this loss, it is best to try to charge your electronics either straight from the USB charger or using the pass-through feature of a battery. It's nice to have that power on tap, but when it means you lose 1-hour of power per 5-hour ride... it adds up!

You can read my detailed resource on external batteries HERE.

I don't know about you, but I really appreciate a neat and integrated charging solution. The steerer tube mounted systems have got to be the neatest option - I personally use the Cinq5 The Plug III. But this dynamo USB charger has downsides too - the USB plug is exposed and can deteriorate over time. That said, my Plug III is a little rusty, but still operates as normal a few years on. The Sinewave Reactor uses gold-plated USB contacts and has been designed with a path for water to drain away. Look at it this way: if these products both didn't work, they wouldn't still be on the market.

Ortlieb has a handlebar bag called the Ultimate 6 Pro E which has connectors built into handlebar bag mount. This allows you to keep your USB charger and devices inside your waterproof bag, and take the handlebar bag off without unplugging anything. That just leaves a few wires on your bike - very neat!

There's another neat charger design. A few dynamo lights actually incorporate a switch which directs power away from the light to charge your USB devices. This creates a nice integrated and cost-effective light/charging system with less cabling. That said, some light/chargers are less efficient than standalone units because they are not optimised around charging. The Sinewave Beacon should technically operate similarly as it uses the same charging internals as their other units.

If you're having issues with charging, a cheap USB LCD Voltmeter can help diagnose whether your USB charger is making the right amount of power. If you've determined you're getting the right voltage and current for your device, you may be having issues with the particular cache battery you're using.

Take a look at my list of the hub dynamo USB chargers options HERE.

Dynamo USB chargers are almost all excellent these days. You'll be able to generate USB specification or over 3-watts of power at 20km/h with all of the chargers mentioned above. Many are waterproof, some are super neatly mounted on the bike, some are integrated into a dynamo headlight.

If you're happy with an increase in dynamo hub drag, you can generate additional power using USB chargers with integrated series capacitors. This is going to be the best option for heavy electronics users. That said, if you just want to keep on top of your phone or GPS, any of the regular USB chargers should work absolutely fine.

Alee
Alee LOVES bikes and travel. So much so he once sold everything he owned to ride through 30 countries to learn a bit about himself and the world. Check out his book Bicycle Touring in One Hour to do the same: http://cyclingabout.com/bicycle-touring-book/

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All About The Best Dynamo USB Chargers For Bicycle Touring and Bikepacking - CyclingAbout

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These days there's a wide array of dynamo USB chargers available on the market. While most of them do an adequate job of keeping your electronics charged, different chargers are better optimised for different tasks. The things you will be trading off include charging potential with hub drag, the size and practicality of the charging unit, and of course, the price and overall build quality.

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[Electricité][Fini] Le chargeur solaire (Page 9) / L'Atelier des Bricoleurs / Le forum de la randonnée légère ou ultra-légère !

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Très simplement, lorsque une batterie complètement chargée reste connectée à son chargeur, lent ou rapide, après la fin de charge, elle reçoit un courant d'entretien qui est sensé compenser l'auto décharge. Malheureusement au bout d'un certain temps ce courant d'entretien engendre une transformation graduelle de la structure cristalline du couple Ni-Cd, en une nouvelle structure dégradée.

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Compat v3 | Minty Boost | Adafruit Learning System

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We are pretty sure that every device that worked with the MintyBoost v2 will work with the v3 in addition to all the Apple devices. However, we don't own every gadget in the world (that would be neat but expensive!)

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×Ce projet est un travail en cours, les informations qu'il présente doivent être vérifiées, corrigées. Mais toute aide est utile alors n'hésitez-pas à écrire un commentaire en bas de page.

EDIT 4.10.2015 : J'ai perdu la moitié de mes graphes à cause d'une mise à jour de la base de donnée qui a flanché....

Le projet est mis en pause faute de temps disponible... Mais je reste intéressé par tout commentaire dessus !

Depuis quelques jours, je souhaite réaliser un chargeur USB depuis la dynamo moyeu de mon vélo.

Il existe déjà de nombreux systèmes qui existent sur le marché pour réaliser cela. Voici une liste de ceux que j'ai retenu :

Ces systèmes sont déjà bien conçus mais très cher et ne remplissent pas toutes les fonctionnalités qui m'intéressent. Ce projet me tient à coeur car il me permet de mettre en pratique de la théorie et en plus de réaliser quelque chose qui me sera vraiment utile ! Double motivation.

La dynamo

Il s'agit de la dynamo (ou plutôt alternateur) Shimano DH-T780 qui possède les caractéristiques standards 6V AC / 3W.

Cahier des charges

Ajout d'un switch pour basculer entre mode "lumières" (qui sont directement connectées sur la dynamos et déjà régulées à l'intérieur) et chargeur.

Ajout d'une batterie tampon d'une capacité moyenne (une demi-charge de l'iPhone par exemple) pour que le système charge continuellement l'iPhone et ne s'arrête pas au moindre ralentissement du vélo.

Faire attention à la polarisation de l'USB. (l'iPhone n'est pas reconnu sinon)

Ajout d'une source d'alimentation ponctuelle par panneau solaire. (Comment gérer le panneau solaire ?)

Ajout d'un système automatique qui coupe le boitier quand l'iphone et la batterie est chargée

To do list
Liste des choses à faire dans l'immédiat

Test de tension en fonction de la vitesse

Test de courant en fonction de la vitesse

Monter un premier circuit sur plaque de test

Commander des composants si nécessaire

A faire plus tard

Relier le prototype au vélo et le tester

Implémenter les fonctionnalités du cahier de charges

Trouver un boitier étanche

Monter sur le vélo

Questions

Est-ce qu'il vaut mieux recharger la batterie qui va simultanément se décharger dans l'iPhone ou bien une charge directe de l'iPhone par la dynamo ?

Dimanche 12 avril - Le circuit de base, première idée

Un iPhone a besoin d'une tension de 5V DC (avec au minimum 500mA et 1A max).

Il faut donc convertir le signal en DC et le réguler à 5V. Pour cela, nous allons utiliser :

Un pont de diodes (Pont de Graetz)

Un régulateur 5V (LM2940)

Les diodes devront supporter une tension maximale d'environ 40V (valeur réelle à mesurer lors de tests ultérieurs) et un courant maximal de 500mA.

Le régulateur choisi doit avoir la caractéristique "Low dropout 0,5V - 1V" qui permet de réguler la tension à 5V même si on est presque à 5V à l'entrée (cas critique). On pensera à rajouter un heat-sink sur le régulateur pour dissiper la chaleur produite :

*C1 is required if regulator is located far from power supply filter

**COUT must be at least 22 μF to maintain stability. May be increased without bound to maintain regulation during transients. Locate as close as possible to the regulator.

Lundi 13 avril - Expérience : Caractéristique tension/vitesse

J'ai réalisé une petite expérience pour mesure la caractéristique de tension en fonction de la vitesse.
Résultats
On remarque que la tension suit la vitesse selon une caractéristique linéaire qu'on peut corréler à V = 0,76v - 0,86. (V tension et v vitesse)

Cette caractéristique me servira pour dimensionner les composants à utiliser. Sachant que la vitesse maximale à vélo doit se situer aux alentours de 60km/h, on aura une tension max de 44V environ.

Edit jeudi 16 avril : mon montage ne permet pas de me donner réellement la tension alternative que va me donner la dynamo car je n'ai pas branché de charge...A refaire plus sérieusement donc !

Mardi 14 avril - Expérience : Test d'un régulateur

J'ai pu récupérer un 7805 que j'ai pu tester sur une plaque de test avec une alimentation DC qui peut aller à 30V max.

J'ai pris comme charge une résistance de 10Ω pour avoir un courant de 50mA (I=U/R), soit 10X moins que ce que demande un iPhone.

Remarques

Vout se fixe vers 5V quand Vin est plus grand que 6,7V

La tension de sortie baisse de Vout=5,04V quand Vin=25 V jusqu'à Vout=4,93V quand Vin=30V -> vérifier si cela n'est pas un effet de la température qui monte trop fortement (on a déjà presque 1,5W à dissiper quand Vin=25V). Pour vérifier cette théorie, je testerais le circuit avec une résistance plus grande (1kΩ au lieu de 100Ω) pour diminuer le courant qui passe dans le circuit.

Questions

La tension de sortie se stabilise à 5,04V, d'où viennent ces 0,04V supplémentaires et est-il possible de régler plus finement ce régulateur ?

Pourquoi le courant monte t-il à 54,36 mA au lieu des 50 prévus ? (Je n'ai pas vérifié la résistance mais en faisant le calcul inverse, j'obtiens une résistance de 90-91Ω)

Conclusion
Le problème de ces régulateurs...c'est qu'avec un ΔV entrée-sortie élevé, ce sont de vrais fours... Par exemple si je vais à 60km/h (cas extrême), ce ne sera pas moins de 17W qui devront être dissipés par le régulateur !!

Du coup, je recherche en parallèle d'autres alternatives. On m'a conseillé une alimentation à découpage, je vais faire des recherches dessus prochainement.

Mercredi 15 avril - Recherches : Alimentation à découpage

Après quelques recherches sur le sujet, j'ai trouvé une référence d'IC qui me correspondrait plutot bien pour l'utilisation que je veux faire. Il s'agit du LM2575. (Le PDF donné en lien est très complet et permet même de dimensionner chaque composant pour le régulateur).

Une autre partie interessante : un circuit qui coupe le régulateur quand la tension d'entrée n'est pas assez haute.

Dans le même genre, j'ai trouvé une autre référence : MAX5035

Mercredi 29 avril - Quelques informations et nouvelles avancées

15 jours se sont écoulés depuis la dernière update... Entre temps je n'ai pas fait beaucoup d'avancées hormis quelques points que je vais énoncer ici.

Test à nouveau des caractéristiques courant/tension/vitesse mais cette fois avec une charge

Montage d'un pont de diodes et explications concernant le montage de celui-ci

Nouvelles références de composants à garder en tête

J'ai pu mesurer la résistance de la dynamo : 3,9Ω

En changeant la charge et on me mettant à une vitesse suffisante pour atteindre 0,5A, j'ai pu observer ces caractéristiques :

13Ω - 6,5V - 16km/h

15Ω - 7,6V - 20km/h

20Ω - 10V - 25km/h

On peut observer que la vitesse est proportionnelle à la tension (ou la charge).

Mesures sur un pont de diodes
Pour mesurer à l'oscilloscope un pont de diodes, il faut faire preuve de précaution au niveau de la masse.

La tension aux bornes de la charge après le pont de diodes est :
Uout = S2-S3
comme indiqué sur le schéma suivant (Les masses des trois sondes sont M1, M2, M3).

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[DIY] Chargeur USB 5V dynamo vélo - Robin Megret

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×Ce projet est un travail en cours, les informations qu'il présente doivent être vérifiées, corrigées. Mais toute aide est utile alors n'hésitez-pas à écrire un commentaire en bas de page. EDIT 4.10.2015 : J'ai perdu la moitié de mes graphes à cause d'une mise à jour de la base de donnée qui a flanché....

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Overview | Minty Boost | Adafruit Learning System

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New from the fine people who have brought us the Beagle Board, we now have a smaller, lighter, but powerful single board linux computer, Beagle Bone! We like this move to a more compact and integrated SBC. For example, there is onboard Ethernet and USB host, as well as a USB client interface (a FTDI chip for shell access).

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Schéma du circuit, pas de batterie tampon

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Schéma du circuit, pas de batterie tampon

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Un voyageur qui devait se rendre au Japon et y circuler à vélo souhaitait pouvoir recharger son iPhone lors de ses trajets, l'homme, adepte du " Do It Yourself " (Fais le par toi même) a donc relevé le défi de produire un circuit relié à une dynamo qui permettrait de recharger son iPhone.

Je ne vais pas vous refaire un cours d'électronique, mais sachez que pour produire une tension constante il a utilisé un pont de diodes et des condensateurs pour ainsi avoir une tension continue de 5 volts à 1 ampère. Le dispositif n'est pas encore intégré au vélo, mais comme vous pouvez le voir dans la vidéo il est pleinement fonctionnel, pour ceux que ça intéresse le créateur a mis à disposition le schéma de montage :

Source

Bons Plans JDG via WhatsApp

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Recharger son iPhone avec un vélo et une dynamo, c'est possible !

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Un voyageur qui devait se rendre au Japon et y circuler à vélo souhaitait pouvoir recharger son iPhone lors de ses trajets, l'homme, adepte du Do It Yourself (Fais le par toi même) a donc relevé le défi de produire un circuit relié à une dynamo qui permettrait de recharger son iPhone.