Introduction: Bicycle USB Output
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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.
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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.
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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.!!
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parts needed;
- dc motor
- female usb port
- boost/buck adjustable voltage regulator
- mini voltmeter (optional)
- frame (3D printed, DIY case)
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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...
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or you can easily get creative with pipe holder clamps, nuts & bolts. any round object with some hot glue can be your wheel disk..
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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.
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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
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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.
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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.
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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.
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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.
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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.!!
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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..
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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.
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