ABSTRACT
Introduction
This project began as two separate ideas by two individuals. Both of us; Dana Martin and Julian Klehr, are focused on pedal-power with similar goals, but are both admittedly novices in the field of electricity. We saw this as an opportunity to join forces, share knowledge, and create something even better and more efficient than we each would have accomplished individually.
The project we have chosen is creating a "kid zone" at Humboldt State University's CCAT with a demonstration where kids can see how appropriate technology works. This display will be hands-on where a child can use their own power to operate an electronic device. The importance of this project is to plant the seed in a child's mind of understanding how human power is simple, yet can be utilized in so many ways. The hands-on display will need to be durable and able to withstand regular abuse from kids.
We have chosen to use a pedal power exhibit where one child will ride a bike to produce power for another child to operate an electric keyboard or small transistor radio. This will give young people the opportunity to see how the energy they produce can be harnessed through an electrical pathway to power an electronic toy.
Criteria
| Criteria | Weight of Criteria |
|---|---|
| # of moving parts | 8 |
| Safety | 10 |
| Toxicity | 9 |
| Cost | 5 |
| Locality of Parts | 7 |
| Durability | 8 |
| Mobility | 6 |
| Size | 5 |
Design
Originally we intended to have a more electrical system and perhaps a battery. Once we realized that we were producing such little volts by pedaling, the next design was to go directly into the electronic device. This means we have a direct current going into the device from the motor. This can be dangerous to the system if producing too much voltage. Many devices if over powered will "short-out", meaning the device is ruined. With ours producing such little power and our device being able to run on less power than stated on the label, it was safe for our system.
Costs & Materials
| Qty | Material Needed | Source | Cost | Total cost |
|---|---|---|---|---|
| 1 | Keyboard | Thrift Store | Donated | Donated |
| 1 | Bike | Craigslist | $13 | $13 |
| 1 | Bike Stand | Campus Metal Shop | Donated | Donated |
| 1 | Generator (Motor) | Marin Electronics Store | $50 | $50 |
| 1 | Wiring (5ft) | Recycling Center | $1 | $1 |
| 1 | Belt | Car Quest | $20 | $20 |
| 1 | Wood Pieces | CCAT | $0 | $0 |
| 1 | Small wheel | Arcata Recycling Center | Donated | Donated |
| Total: | ~ $84.00 | |||
Discussion
Securing the bike to the stand
We were very fortunate to find an already assembled bike stand. This was built by an industrial technology student at HSU. The design is quite simple, you basically just need to be able to suspend the back wheel off the ground. The important thing is to make sure it is stable enough for kids to climb and knock it around without it falling. The stand is a little bulky, but definitely stable. With the emphasis also being on locality and recycling of parts we secured the bike to the stand by small pieces of scrap wood found at CCAT. All you would need is 2x4x8 inches pieces of wood. The metal stand already had holes drilled through it and we simply drilled holes through the wood. We then fastened this down with a screw and bolt. We then fastened the bike to the wood. The main reasons for this was to hold the bike in place and to prop it up and keep it level.
Hooking up the belt
The back wheel is suspended by the sprokets to spin freely when pedaling. The back tire is removed with only the metal wheel to allow the belt to be attached. The belt is connected to the back wheel which is then connected to a small wheel. The small wheel is connected to the shaft of the motor. A mold was created to perfectly fit around the metal piece that comes out of the motor which fits in the middle of the small wheel. The motor is mounted on to the bike stand by screws and wood. The belt is now connected to back wheel and to the pully on the motor.
Testing the power
Next, its time to hook up the motor to the voltage meter. This is to test the amount of electricity the pedaling can produce. First, we hooked the motor to an ampmeter (measuring the amps), to a Rheostat (stores the electricity, acts as the end use device), to a voltmeter (measuring the volts), and to the motor. We then pedal the bike to get it up to speed to test the amount of electricity the system could produce. We were only producing 2.5 volts, when the originally intended device, a keyboard, needed 6 volts. To increase the amount of volts we would need a smaller wheel. After obtaining this small wheel/pully, it was clear that our design would not allow for this modification. This limitation is just fine, as we can still produce enough electricity to power a variety of small devices that would be vastly entertaining to children.
Final Product
We finish this project with a fully functional mounted bicycle, attached with a belt to a motor. This motor is wired to the cigarette lighter plug from out of my car. Into this, we plugged in a cigarette-lighter size cell phone charger piece with the appropriate wiring coming out. This can be attached to any low-voltage electronic device to supply it with around 3 volts of electricity.
Conclusions
Through the process of designing and building a pedal power project, it was exciting to see how simple it is to generate electricity. Although we can only generate a small bit using our little motor, it is still a significant amount in regards to how simple of a process it is. Now that I have conducted a pedal power project, I am excited to experiment more in the field of electricity generation using small motors. What is so significant about these motors and their appropriateness is that they exist in a vast number of household devices. As things stop working, the parts can be harvested and recycled appropriate technology projects can be conducted. While these small motors are limiting and can create only a couple volts, a slightly bigger motor with a rating of 24v would create an impressive amount of power.
Literature Review
- Dean, Tamara. "The Human-Powered Home". New Society Publishers 2008.
- This book goes into a description about several different human powered household items. This book also has tables to show how much human power can produce and how much electricity household appliances use. This will help give a comparison when applying kid toys.
Proposed Timeline
- 3/07/09 Shop for generators at Coope, purchase some parts from ACE (wiring, fuses, bike, and other parts that can be found at thrift stores)
- 3/12/09 Have most parts purchased, begin constructing
- 3/27/09 Continue constructing and test first design of the project
- 3/31/09 Work out any kinks in project and continue building
- 4/11/09 Update webpage