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i use portable usb powerbanks for most of my projects (usb heated clothing, smart plant pot). and i also bike a lot. so i decided to create a very cheap, "clip on" power source to charge these batteries. it can then be used to charge a smartphone, tablet basically anything that needs a usb plug to recharge.

the goal is to reach 5V-500mA to charge these batteries. our design is using a dc motor found inside of an old all-in-one paper printer. the biggest one in there.. you could easily add another motor in parallel to boost the current. at 1-2amps we are now able to charge all new smartphones and tablets directly from the handle bar. but remember, we can easily, with a single motor, still charge a powerbank which then can charge any electronic device you may have.

when you apply power to a dc motor it starts to spin. and if you spin the shaft manually either by pedaling, gravity, water, wind etc. then your motor starts giving out electricity from the wires. i can easily generate upto 10-13V constantly while biking. you can implement the same idea in a different scenario such as a wind powered generator.!!

parts needed;

- dc motor

- female usb port

- boost/buck adjustable voltage regulator

- mini voltmeter (optional)

- powerbank

- frame (3D printed, DIY case)

let's get started..>

Step 1: Frame

i needed to design a clip on piece based off the dimensions of my bicycle. i used sketchup, a free VERY easy to use 3D design software. you can download and use the 3D printed frame i have designed - https://drive.google.com/folderview?id=0B8bvYGugxv...

or you can easily get creative with pipe holder clamps, nuts & bolts. any round object with some hot glue can be your wheel disk..

find a place on the front fork where you think it is safe to install the dc motor, and imagine a disk rubbing against the wheel attached on top.

also another housing was designed for the handle bars. this will house the voltage regulator, voltmeter and usb. you can easily use any tiny plastic container as housing.

Step 2: Adjust, Test, Wire

before we solder, let's do some tests

using a voltmeter check the polarity of the dc motor pins while the bicycle wheel is turning the forward moving direction. on your voltmeter screen a "- minus" will appear telling you that your polarity is reversed, simply change the wires around and now you will have the correct polarity.

find a 9V battery or any dc adapter that is higher than 5V. we now must set the output of the voltage meter as 5.1V. to do this simple attach a higher voltage power source as input and turning the little screw to see the voltmeter as 5.1V as output.

now we know the correct polarity of the dc motor with the correct direction, we are able to get a reading of voltage generated and our regulator is set at 5.1V. once you are sure everything is figured out, go ahead and solder all the wires for a permanent connection.

this step may be a bit confusing for beginners. ask questions in comments.
read; basic electronics, how to solder

Step 3: Conclusion

we are simply generating electricity from the motion of the bicycle moving. it is a very simple dc circuit.

the voltage regulator is pretty much taking care of all the work. keeping our unstable input voltage at a constantly set voltage output of 5.1V - which equals to enough power for charging a usb powerbank.!!

similar products are sold online for upto $50. you can make your own for under $5 and learn basic electronics, intro to 3D printing and design. go ahead give it a try..

second version will include a better motor mount, possibly by the back wheel and house 2 in parallel DC motors to be able to directly charge a smartphone. remember to like, share and follow.