How to Charge Any USB Device by Riding Your Bike

8/2/2019 How to Charge Any USB Device by Riding Your Bike

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http://www.instructables.com/id/How-to-Charge-Any-USB-Device-by-Riding-Your-Bike/

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How to Charge Any USB Device by Riding Your Bikeby JeffB on July 1, 2007

Table of Contents

How to Charge Any USB Device by Riding Your Bike ...................................................................................

Intro: How to Charge Any USB Device by Riding Your Bike ...........................................................................

Step 1: Our original intention... ................................................................................................

Step 2: Our Invention Statement and Concept Evolution .............................................................................

Step 3: Design a circuit ......................................................................................................

Step 4: Getting Power .......................................................................................................

Step 5: Wiring .............................................................................................................

Step 6: The Actual Circuit! ....................................................................................................

Step 7: The Enclosure. ......................................................................................................Step 8: Testing! ............................................................................................................

Step 9: Future Plans ........................................................................................................

Step 10: Finish! ............................................................................................................

Related Instructables ........................................................................................................

Comments ................................................................................................................
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Intro: How to Charge Any USB Device by Riding Your BikeTo start off, this project was started when we received a grant from the Lemelson-MIT Program. (Josh, i f you're reading this, we love you.)A team of 6 students and one teacher put this project together, and we have decided to put it on Instructables in hopes of winning a laser cutter, or at least a t-shirt .

What follows, is a compilation of our presentation and my own personal notes. I hope you enjoy this Instructable as much as we did.

I'd also like to thank Limor Fried, creator of the MintyBoost circuit. It played an key role in our project.

Jeff BrookinsDivine Child InvenTeam Member

Image Notes1. Voltage Regulator2. The 140F Ultracapacitor3. 2200uF Capacitor

Image Notes1. The Students2. The sweet banner Lemelson-MIT gave us.

Step 1: Our original intention...Our original project was to develop a product that used the Faraday Principle to allow runners to charge their iPods while they run. This concept would generate electricitythe same way those Faraday flashlights do.However, we had a problem. To quote my team mate Nick Ciarelli,

"At first we considered using a design similar to one of those shake-up flashlights and converting it so that a runner could strap it on for a run and have energy to chargetheir iPod or whatever device they use. The shake-up flashlight gets its energy from the interaction of the moving magnetic field of the magnet in the f lashlight and the coilof wire wrapped around the tube the magnet slides through. The moving magnetic field causes electrons in the coil to move along the wire, creating an electric current.This current is then stored in a battery, which is then available to use for the flashlight bulb/LED. However, when we calculated how much energy we would be able to getfrom a run, we determined that it would take a 50-mile run to get enough energy to charge one AA battery. This was unreasonable so we changed our project to the bikesystem."

We then decided to use a bike-mounted system instead.


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Step 2: Our Invention Statement and Concept EvolutionWe initially theorized the development and feasibility of a regenerative braking system for use on bicycles. This system would create a mobile power source to extend thebattery life of portable electronic devices carried by the rider.

During the experimentation phase, the regenerative braking system was found to be incapable of fulfilling it s dual functions simultaneously. It could neither produceenough torque to stop the bike, nor generate enough power to recharge the batteries. The team therefore chose to abandon the braking aspect of the system, to focussolely on the development of a continuous charging system. This system, once constructed and researched, proved fully capable of achieving the desired objectives.

Image Notes1. The Bike, on loan from Josh Schuler.

Step 3: Design a circuitTo start off, we had to design a circuit that could take the ~6 volts from the motor, store it, and then convert it to the 5 volts that we needed for the USB device.

The circuit we designed complements the function of the MintyBoost USB charger, originally developed by Limor Fried, of Adafruit Industries. The MintyBoost uses AAbatteries to charge portable electronic devices. Our independently constructed circuit replaces the AA batteries and supplies power to the MintyBoost. This circuit reducesthe ~6 volts from the motor to 2.5 volts. This allows the motor to charge the BoostCap (140 F), which in turn supplies power to the MintyBoost circuitry. The ultracapacitorstores energy to continuously charge the USB device even while the bike is not in motion.

Image Notes1. Her Circuit.2. Our Circuit.


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Step 4: Getting PowerSelecting a motor proved a more challenging task.Expensive motors provided the proper torque needed to create the braking source, however the cost was prohibitive. To make an affordable and effective device anothersolution was necessary. The project was redesigned as a continuous charging system, out of all possibilities the Maxon motor would be a better choice due to its smallerdiameter.The Maxon motor also provided 6 volts where as previous motors gave us upwards of 20 volts. For the latter motor over-heating would be a huge issue.

We decided to stick with our Maxon 90, which was a beautiful motor, even though its cost was $275.(For those wishing to build this project, a cheaper motor will suffice.)

We attached this motor close to the rear brake mounts directly on the bike frame using a piece of a meter stick between the motor and frame to act as a spacer, thentightened 2 hose-clamps around it.

Image Notes1. The Maxon 90, with attached wheel.

Step 5: WiringFor the wiring from the motor to the circuit several options were considered: alligator clips for mock up, telephone cord, and speaker wire.The alligator clips proved to work well for the mock up design and testing purposes but they were not stable enough for the final design.The telephone wire proved fragile, and difficult to work with.Speaker wire was tested due to its durability therefore becoming the conductor of choice. Although i t was stranded wire, it was much more durable due to its largerdiameter.

We then just attached the wire to the frame using zip-ties.

Image Notes1. The Wiring Job.


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Step 6: The Actual Circuit!Tackling the circuitry was the most difficult challenge of the process. Electricity from the motor first travels through a voltage regulator which will allow up to a continuousfive amp current; a larger current than other regulators would pass. From there the voltage is stepped down to 2.5 volts which is the maximum the BOOSTCAP can storeand safely handle. Once the BOOSTCAP attains 1.2 volts, it has enough power to allow the MintyBoost to provide a 5 volt source for the device being charged.

On the input wires we attached a 5A diode so that we don't get an "assisted-start effect," where the motor would start to spin by using the stored electricity.

We used the 2200uF capacitor to even out the power flow to the voltage regulator.

The voltage regulator that we used, an LM338, is adjustable depending on how you set it, as seen in our circuit diagram. For our purposes, the comparison of tworesistors, 120ohm and 135 ohm, connected to the regulator determines the output voltage. We use it to reduce the voltage from ~6 volts to 2.5 volts.

We then take the 2.5 volts and use it to charge our ultracapacitor, a 140 farad, 2.5 volt BOOSTCAP made by Maxwell Technologies. We chose the BOOSTCAP becauseits high capacitance will allow us to hold a charge even if the bike is stopped at a red light.

The next part of this circuit is something I'm sure you are all familiar with, the Adafruit MintyBoost. We used it to take the 2.5 volts from the ultracapacitor and step it up toa stable 5 volts, the USB standard. It uses a MAX756, 5 volt boost converter coupled with a 22uH inductor. Once we get 1.2 volts across the ultracapacitor, theMintyBoost will begin to output the 5 volts.

Our circuit complements the function of the MintyBoost USB charger, originally developed by Limor Fried, of Adafruit Industries. The MintyBoost uses AA batteries tocharge portable electronic devices. Our independently constructed circuit replaces the AA batter ies and supplies power to the MintyBoost. This circuit reduces the ~6volts from the motor to 2.5 volts. This allows the motor to charge the BoostCap (140 F), which in turn supplies power to the MintyBoost circuitry. The ultracapacitor storesenergy to continuously charge the USB device even while the bike is not in motion.

Image Notes

1. Voltage Regulator2. The 140F Ultracapacitor3. 2200uF Capacitor

Image Notes1. Her Circuit.

2. Our Circuit.

Image Notes1. A beautiful thing


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Step 7: The Enclosure.In order to protect the circuit from external elements, an enclosure was necessary. A "pill" of PVC tubing and end caps was chosen, with a diameter of 6cm and a lengthof 18cm. While these dimensions are large when compared to the circuit, this made construction more convenient. A production model would be much smaller. The PVCwas selected based on durability, nearly perfect weather-proofing, aerodynamic shape, and low cost. Experiments were also performed on containers crafted from rawcarbon fiber soaked in epoxy. This structure proved to be both strong and light weight. However, the construction process was extremely time consuming and difficult tomaster.

Image Notes1. Our PVC "pill" in the water bottle holder of a bike.

Image Notes1. Our carbon fiber experiment didn't go as well as we hoped.

Step 8: Testing!For the capacitors, we test two different types, the BOOSTCAP and a super capacitor.

The first graph depicts the use of the supercapacitor, which is integrated with the circuit so that when the motor is active, the capacitor will charge. We did not use thiscomponent because, while the supercapacitor charged with extreme speed, it discharged too quickly for our purposes. The red line represents the voltage of the motor,the blue line represents the voltage of the supercapacitor, and the green line represents voltage of the USB port.

The second graph is the data collected with the BOOSTCAP ultracapacitor. The red line represents the motor's voltage, the blue is the ult racapacitor's voltage, and thegreen line represents the USB port's voltage. We chose to use the ultracapacitor because, as this test indicates, the ultracapacitor will continue to hold its charge evenafter the rider has stopped moving. The reason for the jump in USB voltage is because the ultracapacitor reached the voltage threshold necessary to activate theMintyBoost.

Both of these tests were conducted over a period of 10 minutes. The rider pedaled for the first 5, then we observed how the voltages would react for the final 5 minutes.

The last picture is a Google Earth shot of where we did our testing. This picture shows that we started at our school, and then did two laps at Levagood Park for a totalapproximate distance of 1 mile. The colors of this map correspond to the speed of the rider. The purple line is approximately 28.9 mph, the blue line 21.7 mph, the greenline 14.5 mph, and the yellow l ine 7.4 mph.

Image Notes1. Supercapacitor Graph

Image Notes1. Ultracapacitor graph2. Approximately 45 seconds


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Image Notes1. Our testing grounds

Step 9: Future PlansIn order to make the device more economically viable as a consumer product, several improvements must be made in the areas of weather-proofing, circuit streamlining,and cost reduction. Weather-proofing is critical to the long term operation of the unit. One technique considered for the motor was to encase it in a Nalgene container.These containers are known for being waterproof and nearly indestructible. (Yes, we ran over one with a car to no ill effect.) Additional protection was sought against theforces of nature. Expansion foam would seal the unit, however the material has limitations. Not only is it difficult to position properly, but it would also prevent ventilationessential to the overall operation of the device.As to the streamlining of the circuit, possibilities include a multitasking voltage regulator chip and a custom printed circuit board (PCB). The chip could replace multiplevoltage regulators, this would decrease both the product's size and heat output. Using a PCB will provide a more stable base because the connections will be directly onthe board and not floating beneath it. To a limited extent it will act as a heat sink because of the copper tracing in the board. This change would decrease the need forexcessive ventilation and increase component life.Cost reduction is by far the most important, and difficult, change that must be made to the design. The circuit itself is extremely inexpensive, however the motor costs$275. A search is underway for a more cost efficient motor that will still meet our power needs.

Step 10: Finish!Thanks for reading our Instructable, if you have any questions feel free to ask.

Here are some of the pictures from our presentation at MIT.


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Image Notes1. Nick Ciarelli2. Jeff Brookins (Me)3. Charles Demmer4. Kelcie Ebbitt5. Jeff Cain6. Laura Veldhuis

Image Notes1. Our presentation board

Image Notes1. C.J. Demmer riding the bike for our live demonstration

Image Notes1. Our table


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Image Notes1. Me and Professor Merton Flemings, faculty director of the Lemelson-MITProgram.

Image Notes1. Me and Josh Schuler, executive director of the Lemelson-MIT Program and agreat guy.

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Comments

50 comments Add Comment view all 172 comments

griteck says: Jan 28, 2011. 4:51 PM REPthat is cool would you be able to power a bike light

lovetoride says: Nov 2, 2010. 7:56 AM REPI always wondered about charging my devices (I have a lot of them) while riding my bike.

I bought the Cycle Charger from www.econvergence.net/cyclech.htm because it has a USB port. It works well and starts charging at pretty slow speeds -around 8 mph.

I use it primarily to charge my Blackberry for work.

zoltzerino says: Jul 31, 2010. 6:00 AM REPWhy not use a smaller, cheaper, lower power motor and use a gearing system to increase it's RPM from the wheel rim? Similar to those wind-up torches withthe handles. :-) Nice one anyway, but pricey.

zoltzerino says: Jul 31, 2010. 6:04 AM REPThe torch in question (one that I've dismantled) has a simple 4 diode AC-DC rectifier with a smoothing cap, this is somehow rut through a t ransistor, thisseems to be enough to charge a little 3v button cell. With something a little more flashy, could this be notched up to 5v directly? With or without a MintyBoost.

rapidprototyping says: Jul 16, 2010. 5:16 PM REPhey look at what was done in the early seventies in this work on the pancake motor i'm trying to clean up the images but new to that line work

rapidprototyping says: Jul 16, 2010. 5:08 PM REPhere is gimp photo of a pancake motor
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dirty_valentine says: May 14, 2009. 7:29 AM REPI really like this instructable, but the circuit is not optimal. Stepping down from 6V to 2.5V with a linear regulator such as the LM338 is inefficient. In this caseonly about 42% of the power from the generator will make it to the Minty Boost circuit. The Boost circuit will have further losses lowering the efficiency downeven more. The circuit will no doubt work but it is not optimal.

If the generator really puts out 6V, then a simple 5V output Low Drop-Out (LDO) regulator such as the Linear Technology LT1963A (http://www.linear.com/pc/productDetail.jsp?navId=H0,C1,C1003,C1040,C1055,P1879 ) could be used to drive pin 1 of the USB directly. In this case about83% of the generator power would make it to USB device. The USB device would charge twice as fast, and the circuit cost and complexity is significantlyreduced.

If the generator typically puts out less than 5V under load, a 5V output Buck-Boost converter could be used. This would provide for further efficiencyimprovement. I don't feel the added complexity and cost is justified if the generator can put out more than 5V under load though.

rpvanpatt says: Feb 11, 2010. 8:27 PM REPI actually was thinking the same type of thing, but i am a newbie with all this stuff, I was wondering if a capacitor would be good tho, so that if the bike

comes to a stop, the charging wont stop, i feel like that may hurt the battery to stop and go, is it?

dirty_valentine says: Feb 12, 2010. 6:15 AM REPI=C*dV/dt is the equation for a capacitor where I=current, C=capacitance and dV/dt is the change in voltage with time. rearranging the equation youget: C=I*dt/dV. If you are riding along and getting 6V out of the generator then suddenly stop, your capacitor will be charged to 6V. If a linearregulator is used as I suggested above It will start dropping out around 5V, and most LiIon chargers will stop charging around 4V. Thus best case youcan only discharge the input capacitor from 6V to 4V (dV=2V). As for dt, that depends on how long you plan to be stopped. Lets assume you want tostop for 10seconds (dt=10s). Most LiIon chargers charge at 100mA or 500mA. I'll assume the best case (I=100mA). With this information we canfigure out what size cap we need: C=100mA*10s/2V=0.5F. 0.5F is a REALLY big cap and would only buy you a best case stopping time of10seconds.

Most likely any hand held electronics you buy today (cell phone, media player, etc) will have a LiIon type battery. LiIon batteries do not like to beovercharged. If overcharged they will start to loose capacity (best case) or can even burst into flames (worst case). The good news is that mostquality electronics have built in protection circuitry that keep from overcharging the battery. I have not heard of any issues with starting and

stopping charging. In fact some quality chargers do just that to measure the Equivelant Series Resistance (ESR) of the battery during the chargingprocess. Hope that helps.

rpvanpatt says: Feb 12, 2010. 11:29 AM REPthanks for the help...another idea... if you havent already seen the 'contactless dynamo' bike light instructable, I was wondering if it would be

possible to use that idea and your info to create a USB charger instead of with a motor...im not sure how much output voltage the contactlessma ent enerator creates thou h, but I think this would be a better idea

dirty_valentine says: Feb 12, 2010. 1:47 PM REPContactless induction can certainly be made to work. There are a lot of variables and I do not have much experience with this type ofgenerator so I am not sure if the 'contactless dynamo' instructable will work in this application. My feeling is that the magnets turning at therate of the wheel will be too slow and too far away from the coils to generate enough power. FYI - it is really power that you are interested inand not voltage. My guess is that the peak voltage is probably high enough open circuit, but as soon as a load is applied (i.e. while charging)the voltage will collapse and charging will stop. To really make this work you will probably need an inductorless motor geared up off the wheelor chain to roduce enou h ower to sustain char in .

rpvanpatt says: Feb 12, 2010. 5:58 PM REPotcha...would the be ood with ust led li hts tho? and ma be a ste er motor to char e?

dirty_valentine says: Feb 15, 2010. 9:30 AM REPNot sure, as I said I do not have much experience with generators, just a basic understanding of how they work. You would have toexperiment or seek out knowledge elsewhere. Good luck.

Ohnanka says: May 15, 2009. 2:51 AM REPYey, constructive criticism! : ) would've been nice to have some from ac-dc.

Water Child says: Feb 12, 2010. 9:24 AM REPI love this instructable, most likely ill be using it for life, anyway would it be illegal if i could use this fro my science fair project? there are no winners and noprizes its an elementary science fair for energy and i really lik this idea, i am a polite kid os i have to ask for your permission

advante says: Nov 14, 2009. 6:15 AM REPIt's hard to find the materials in this country which is one of ASEAN countries.Cause I lived in Indonesia... If I go to an electronic markets where the items are in so many kinds, the electronic stores are traditional electronic stores (dirty,old building, simple). It sells LEDs, Voltage stabilizer, UPS, antenna, audio devices (not exclusive), transistors, transformator, etc.

advante says: Sep 24, 2009. 3:33 AM REPI need 4.9 volt for my Sony Ericsson phone. Does it matter if over-voltage 0.1 volt? Cause 0.1 volt is matter for computer's processor. Please give a reply [email protected]
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Jodex says: Nov 12, 2009. 10:14 AM REPYou CAN always charge with a lot higher voltage than your battery needs. BUT if you use enough big voltage your battery MAY explode. But couple ofvolts doesn't matter.. Except LiPos may be bit different.. Sorry for the words written with BIG letters : D

jules15 says: Nov 4, 2009. 12:49 PM REPno man, thats fine

ctonks says: Apr 3, 2009. 6:54 AM REPHow do ou handle sur lus ower?

name101 says: May 8, 2009. 4:45 AM REPThat's What the 140F capacitor was used for. In the graph explains that the surplus power is stored in the Ult ra capacitor ~Name101

ac-dc says: May 14, 2009. 9:52 AM REPSuch a capacitor would store power, but will not "handle" surplus. When the load current drops the input voltage will rise and the linear regulator willbe dropping more voltage, resulting in a higher heat level. You'd need far more than a capacitor to store the energy, something like a battery of acapacity high enough that it never reaches full charge, and yet this would be an additional drag on the bike, it should not be used because the wholecircuit is wron in the first lace.

PCfreak says: Aug 21, 2009. 9:50 PM REP7.2v RC Battery is Lightweight and ive used one in many applications

name101 says: May 16, 2009. 10:19 PM REPThe way I see this design, The Supercapacitor was not meant to store "Large" amounts of energy but enough to keep the power consistent if therider was to slow down or stop for a short period of time.. I agree a battery would be able to store a lot more energy than a Capacitor. but thecapacitor is short term. Correct me if I'm wrong. ~Name101

ac-dc says: May 17, 2009. 12:13 AM REPOf course, a supercap is short term. The problem is, a supercap doesn't have enough capacity to *buffer* for regular riding. That means thatonce the supercap is charged the voltage in the system r ises and creates even more heat and loss with the linear regulator.

Let me put it another way. I don't revel in wasting energy but it's not so much a concern when something is AC wall powered. When you arepeddling on the other hand, and a design has multiple forms of loss, energy conservation is really good, worth the time to do it right.

The problem was they didn't look at how to get from point A to point B, point A being a human being producing linear movement of a wheel,and point B, producing the desired charge, then f inding the best way to get there.

Instead, they reused a design not just suboptimal for the purpose but contraindicated for the input and output.

The way this is set up it would be far better to just strap a battery pack onto a bike to recharge something, or of course to use a proper bikegenerator, a switching supply circuit that accepts (uses) input over the voltage variations that result from a bike generator, and and output withcurrent regulation and the associated charge control chip complimentary to the battery type being recharged.

I appreciate this is beyond the ability of someone starting out, but at the same time this is what is great about technology today that we haveready-made ICs to do things difficult or lengthly to do with discrete parts. It is good to experiment but it is also good to see when it isredundant work, that each part of the problem can be seen modularly as how to get from point A to point B and that today we have greatcustom ICs to do these jobs (since when broken down into units, none of the things being done are new electronically).

I think it's great if they had no hands-on experience, to learn from building something like this, BUT to put it out there for others as an exampleof how to get something done, it is a poor one.

name101 says: May 17, 2009. 2:08 AM REPWell Personally am new to electronics.

I see that stepping down then stepping the voltage up again is a waste of energy. but when the power supply is so close to a LDO linearregulator I thought Providing consistent energy would be a problem.

You said "supercap is charged the voltage in the system r ises and creates even more heat and loss with the linear regulator."

How is this so? I would like to learn from this experience.

I would like to learn how to make this as efficient as possible.

(I'm sorry about the short comment I wrote a big one but pressed cancel instead of post =( )

~RegardsName101
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ac-dc says: May 17, 2009. 2:02 PM REPTo make it as efficient as possible, to start you would approximate an efficiency, perhaps 80% pulling numbers out of air. Nextdetermine the required charge current for the device, and divide that by 80% or 0.8. Next determine the minimum dropout voltage forthe regulation stage, some working familiarity with switching regulator designs helps a lot here, but just to pick a number a run with ituntil something more is known experimentally let's say 3V dropout across regulation stage. With this much info we know the minimumoutput voltage a generator will need, and can begin testing generators loaded to the desired output power (current times pre-dropoutvoltage) to see if they are sufficient. Once one at least capable of this output power is selected, the max and minimum voltage duringriding with it powering the same load level will tell us the voltage range the switching subcircuit will have to accept. Next go to awebsite like Digikey if you don't have a regulation controller in mind yet. Browse through their offerings for a regulation chip capable ofthe input voltage variations and either fixed output for the device charging, or variable output with components you add to select thetarget voltage. Study the regulators example datasheet circuits as they provide the basic topology as well as reading any datasheetnotes about precautions and requirements for it's rated functionality. Then you are ready to convert a rough sketch of circuit logicblocks into a schematic of electronic component values, and generate a PCB layout. Prior to that you probably also want to have

selected a chassis for the circuit board, a vibration resistant mounting, and have therefore determined the dimensions of the PCB andkeep-out zones for mounting hardware so you can plan the circuit layout around these dimensions. Obviously there's a bit more to itthan described, but it is a start.

ac-dc says: May 17, 2009. 1:52 PM REPWith a variable input voltage (6V is not constant) an LDO will be a problem, but even if kept above the LDO regulated voltage it's still avery lossy circuit. With the supercap you are improving charging, but putting more drag on the rider to generate that charge, and bykeeping the voltage higher it is continual drag instead of the voltage being allowed to drop below the critical level needed to power therest of the circuit so the rider has no moments of relief. So it does improve the circuit but it does not meet a different goal in use on abicycle, plus it adds a lot of weight. With a battery on the other hand, or really I mean a pack of series cells, they serve as a crude buteffective enough form of regulation to keep the voltage at roughly the sum of the cells. There is some loss in doing this too, but not asmuch as use of an LDO. One thing that is not really clear is why either would be needed, charging doesn't have to continue at allmoments necessarily. It could be good to even tweak the circuit such that applying the brakes bypasses a current l imiter right after themotor so that during braking a higher % of power is produced and more motor drag, then less when not, but it would be a secondaryissue, the primary one being that the better solution is none of these supercaps or batteries, to just use a wide input voltage, regulatedoutput switching circuit. I'm not suggesting no capacitors are needed for that, but rather less capacitance, a smaller design with onlythe parts the regulation stage needs, also built more rugged (leaded parts like capactors don't like vibration much as you'd see on abike, you can cement/glue/etc them in place or you can pick parts more immune to the environment).

name101 says: May 17, 2009. 7:27 PM REPPersonally. I want to charge my device a constant as possible(GPS device). Once the Supercap is fully charged the Circuit willonly draw the current needed to maintain the charge on the device. Correct? When I was doing the Research with my basicknowledge Something similar to this was perfect. I was aware of the energy loss through heat and converting the voltages 2 timesis excess but the way I saw it was the voltages(form power source to USB device) are too close to use the LDO linear regulator. IFthe hub generator produced 12v for example having a single Linear regulator would be perfect. Simplifying the circuit drastically. Ifthe supercap was replaced with a battery pack for example would the circuit charge the batteries and would the batteries act like acapacitor? From my understanding capacitors have the advantage of being able to charge or discharge incredibly fast while if abattery had the same current draw the battery it self would be damaged. I completely forgot about the environment with myresearch. I must thank you so much with helping me here. ~Name101

ac-dc says: May 18, 2009. 5:00 PM REPThe generator voltage is not "close" to the LDO regulator necessarily, it depends on the load on it and of course gearing orfriction wheel diameter, how fast it is spinning. A genuine 6V bike dynamo goes quite a bit above and below 6V even beingdesigned for the task. That's why it's normally it's normally rated for wattage like 6W or 12W. I'm not saying it's terribly bad tohave the supercap except it puts more drag on the bike at the worst possible t ime, getting started from a dead stop afterhaving discharged. A constant charge isn't really needed, you only need to limit the max voltage and current within what thebattery will accept. For example, suppose 20% of the time it wasn't charging, but the rest of the time it was charging at a highenough rate to compensate. The point that I'm attempting to keep drifting back towards i s this needs to be seen as anaccessory to bicycling, not the primary detail that matters so much as what factors are present while riding. Yes the batterieswould charge like a capacitor, the point would mainly be that you can either: A) Have already charged them before the bikeride so they are a renewable portable power pack. B) Shut off the charging circuit before it drains them too much, then turn onagain after having gotten up to speed so they aren't putting a high early drag on acceleration. You really don't want a linearregulator, not even an LDO. The voltage f rom a motor varies quite a lot, to always have it charging you will have to usesomething larger and create a great deal of heat as well as extra drag riding. The only way to have a small drop before thelinear regulator is if you already had a wide input range switching regulator, but if you did then you wouldn't need the linearregulation stage at all. I have already outlined a much better way to do it, for good reason, that it should not be done a differentway for bike powered use.

name101 says: May 18, 2009. 7:59 PM REPOh. I'm starting to understand. Haha. I suppose I'll keep this in mind when I'm designing future circuits. I did throw myselfinto the deep end by starting with this projects with very little prior knowledge. Ill Look into what I can do.

Seriously, Thank you so much. =]

~RegardsName101

PCfreak says: Aug 21, 2009. 9:42 PM REPyour "PVC Pill" Just Gave me an Idea for a bike project Thx Ps. its not a pipe bomb either, to those that were probably thinking
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kd0afk says: Jul 27, 2009. 6:42 AM REPHow about a parts list for the electronic components. And many of us can't afford a charging motor that costs more than our iPod, how about discussingusing a bicycle generator.

3xpl0dingR4pt0r says: Jul 12, 2009. 4:57 PM REPNow please design one for my unicycle. Then ill be happier, still, good job.

Alexbretherton says: Jun 20, 2009. 12:07 AM REPcom licated

Shut Up Now says: May 14, 2009. 6:38 PM REPall this electrical work i s way over my head..when do people typically learn how to read schematics and work out big circuits...im just starting high school sothats why i am wondering..

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