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 

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. 

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: 

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.

Week 3: 4/17/15 Discussion of Mechanical System

Week 3
4/17/15

An alternator was purchased on Ebay on 4/15.

Mechanical system was discussed. The Tire-riding wheel was decided to be solid rubber with a bearing in the center, which will be supported by a fixed shaft. The gear of the purchased alternator will be attached to the side of the rubber wheel concentrically. The body of the alternator will be fixed in place by supports made of steel strips, whose cross section is approximately 30 mm*4 mm and 2 strips needed for each side. Supporting strips will be attached to bike frame rods with U-bolts and the alternator will be bolted to the strips by utilizing the holes on the alternator housing. The fixed shaft that supports the wheel bearing will go through a hole in the strip on its side and be attached with a weld.

Week 3: 4/14/15 Decision of Alternator

Week 3
4/14/15

Considering the size and efficiency, it was decided to buy an alternator instead of building one. 

Looked for alternator online. The new alternator was decided to be as follow.

Alternator from Ebay

Week 3: 4/13/15 Generator Design and Calculation

Week 3
4/13/15

Generator design: Two generators in series, each including 4 magnets and one wire coil.
Each magnet size is 1in*3in. Coil size is 4cm*6.5cm. 18 gauge wire will be used, 96 turns needed for each coil and the cross section should be fit in 10mm*10mm square.

Possible idea:

• Epoxy might be used for supporting and connection.
• In order to stabilize the output voltage, a capacitor might be added to the electrical system.
• The material of coil core can be iron to increase the permeability.

Week 2: 4/10/15 Proposal Revised and Full Plan

Week 2
4/10/15

New design proposal was finished.

Details about current status and plans were discussed in the meeting. Possible idea would be testing the real cell phone charger to see the waveform and voltage produced.  

Full plan was finalized: generator -> (possible transformer) -> full-wave rectifier -> LM 7805 regulator -> USB socket.

Week 2: 4/8/15 Improvement of Generator

Week 2
4/8/15

Design proposal revision is ongoing.

New generator design: Copper wire coil will be placed inside of the magnets instead of surrounding them as in the initial design to make it easier to control and calculate. New design is like the figure below.

Figure 1: New Generator Design

Week 2: 4/7/15 New Generator Design

Week 2
4/7/15

Design proposal needs to be improved and more details as well as data should be included. Revised version should be finished on Friday(4/10).

Power takeup mechanism is changed from sprocket on chain to wheel against bike wheel, similar to the picture below.

Figure 1: Power takeup design 

Week 1: 4/6/15 Proposal Finished

Week 1
4/6/15

Design proposal is finished.

More research is done and general design is in progressing.

Instead of purchased, the generator is decided to be homemade. The mechanical energy will be collected from the sprocket on the bike chain.

Week 1: 4/3/15 Finalizing plans

Week 1
4/3/15

Plans were finalized and more details were discussed. The final product would definitely have the power output to a USB socket, for compatibility with more phone types.  User would need the charger cable from their phone, with the plug that fits in the phone on one end, and a USB plug on the other end. Background research is still ongoing, The proposal has been completed.

Week 1: 3/31/15 Brainstorming for ideas

Week 1
3/31/15

Through brainstorming, several possible ideas were brought out. After discussion and considering feasibility of various ideas, the design of the cell phone charger was chosen to be a mechanically powered device attached to a bicycle.

Possible idea: line wheel rim with magnets, put U-shaped coils of wire around the wheel.