The goal of this experiment was to generate light via human movement and I will describe the steps that we took to reach this goal.
Apparently, I skipped the physics class in which professor explained how the interaction between a magnet and a coil can induct electricity promoting the movement of electrons. This two elements (magnet and coil) can be found in any DC or Stepper Motor because that's the way they work. In a motor you are using electricity to create a magnetic field which guide the movement, converting electric energy in mechanical energy. A motor is a converter and fortunately for our purpose it can be use in all the way around to convert mechanical energy in electric energy.
This is my first experiment with induction and I encourage anyone who haven tried to give it a chance because it feels pretty magical to induct electricity (even a little amount), being something that we take for granted every time we push switches from our homes. What about if they just stop turning off someday?.
We decide to choose a movement which allow us to explain how easy its induct electricity (the difficult part its to maintain it), so we choose the act of swinging in a hammock, an easy and almost intuitive pattern you follow being in a hammock. We noticed that we're facing two problems:
1. Need to convert arc movement to circular mechanic.
2. Insufficient RPM or Swinging frequency (pendular movement its too slow).
The swinging of the hammock implies an arc which has X and Y components. This can describe a circle allowing us to attach the hammock to an unfixed point of our gear to allow rotation
The motors come with many features including torque, RPM, relation, gearboxes and more. This caracteristics describe what you can expect from the motor once is connected to electricity. In the same way you can expect that if you apply the same amount of revolutions at the same rate you will get the electricity the motor were designed for. In our case we wanted to use a motor easy to get (you may find it in the trash) which corresponds to an stepper motor of 12 volts. These motor usually come with a high RPM which means it rotates many times quickly with a given power supply, which means we need to rotate it really fast to get some significant voltage and current. In our case we decided to build a gear system to exchange size and weight for a higher RPM. We decided to calculate the teeth needed in the gear system but this has to be too accurate to make it work properly otherwise it will stuck as happened to us, so we decide to go with a belt system. The relation we use was almost 1:6.
The circuit included a rectifier to transform the AC generated by the motor to DC and a couple of 250uf capacitors to retain electricity and normalize peaks.
Once in experimentation, our motor was generating 9V and 150 mAmps. We built a base to entire system in order to fixed to the floor (being pushed and pulled by the weight of the person in the hammock all the time). The movement of the hammock transmit Kinect energy and our gear systems amplifies the speed, but unfortunately the points in which the hammock is at its highest altitude the speed goes to 0 (as in any pendular movement) given us a gap between induction, so our light was fading in and out. After we change the light for a LED strip, the strip was flickering so we decided to remove the capacitors to use the peaks of current because we were having gaps anyway.
In this experiment we are wasting so much energy (with the mechanics, circuit, etc) but we are still able to induct electricity from it which make us ask ourselves how many other daily actions can be turned into usable energy in a so much more efficient way. We gain a better understanding of kinetic and electric energy and how it is easy to induct an transform but how difficult is to make it durable and wasteless.
This project was produced by Daniel Castano, Sam Chasan and Roland Arnoldt