Project Overview

Problem Statement

The goal of this project is to design and build a capable mobile cell phone charger which utilizes clean energy as resource. Details of the generator need to be explored like the number and material of the components scientifically by using equations. Purchases are needed for the project. Associated circuitry is also supposed to be developed and DC is preferable.


Problem Solution

The basic design is a mechanically powered device which can be attached to a bicycle. The rotating mechanical energy originally generated by human will be collected and converted to electrical energy by the charger. The product will be consisted of two systems: electrical one and mechanical one. The mechanical system will include a mechanism to take power off of the drive train of the bicycle and transfer it to the generator. The generator will be included in the electrical system which will be associated with voltage regulation electronics. The design of it will be accomplished through manipulation of relevant electromagnetism equations and principles.
The final project will produce a physical prototype of the cell phone charger, consisting of the device to collect mechanical energy and the electronics necessary to convert it to electrical energy usable by the phone.

Week 8: 5/19/15 Adding Case

Week 8
5/19/15

A tin was obtained by Alexander on 5/17/15

The USB port was soldered on PC board and a metal case was decided to be used holding circuit can cell phone. The circuit was attached to the cover of the case using screws as pictures showing below: 

Figure 1: Case Cover with Circuit 
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Week 7: 5/15/15 Finalizing Construction Plans

Week 7
5/15/15
Alexander, Grayson, Ibukunoluwa 

 The construction plans were finalized. 

 Remaining work discussed: A case was needed for the circuit and cell phone. The alternator needed a shroud. 

Week 7: 5/12/15 Testing and Adjusting

Week 7
5/12/15

 A heat sink for the 7805 regulator along with thermally conductive grease was obtained on 5/10.

 Final report draft was finished on 5/11.

 In-class lab
The circuit output was tested by using an oscilloscope and the result showed that the AC generated by the alternator was converted to DC successfully. Also the output voltage plateaued at about 5 V as expected, even when the rotation speed was increased.  

 Idea for electrical system: get a plastic box attached to the bike frame to hold the electronics, cell phone and connector cable. 
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Week 6: 5/9/15 Assembling Mechanical System and Testing by Alexander

Week 6
5/9/15
The alternator and plate assembly were attached to the rubber wheel by using bolts. In order to make alternator shaft and wheel shaft close to paralleled, bolts were spaced with washers. Bolts also ensured that the whole setup was rotationally balanced. 
The alternator was tested and the result showed it generated about 20 V peak-to-peak.
A USB socket was took apart from a commercial cell phone charging adapter. It will be attached to the electrical system as the USB port. 

Week 6: 5/5/15 Soldering and Assemble

Week 6
5/5/15

 In-class lab
Wires were soldered to the circuit board to make the necessary interconnections. 

 Machine shop
Mechanical system were assembled and properly spaced with washers. The gear on the alternator was attached using epoxy to a small, round steel plate which will be bolted to the wheel. 

Week 5: 5/1/15 Work on Mechanical Support

Week 5
5/1/15

 Almost the whole mechanical support system was built: Steel flat stock was cut to length and holes were drilled for bolts, which then used to assemble the supports and attached them to the bike. The small wheel and alternator were also bolted to their supports, but not attached to each other. 

 Below are photos after construction: 

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Week 4: 4/24/15 Test of the Alternator by Alexander

Week 4
4/24/15

 All electrical components were gathered.

 The output of alternator was tested by using a dual-trace oscilloscope. The alternator had two outputs which were 90 degrees out of phase. Therefore, it needed adaption to avoid phase conflicts, but it could produce adequate voltage that agrees with the provided specifications. The idea of adaption was rectify each output separately, then combine them once the power is DC.

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