Maria Paula Calderon – Solar Satellites Chapter Summaries

Maria Paula Calderon – Solar Satellites Chapter Summaries
Solar Satellites: Chapters 1, 2, and 8

Introduction

Considering our imminent depletion of natural resources and the increasing need of a steady and reliable clean energy source, the development and launch of solar satellites, specifically those of the Sunsat variety, is crucial to the conservation of our planet. The principal purpose of these satellites is to be positioned around Earth’s atmosphere in strategic positions to directly capture the Sun’s energy and then send it back to Earth. This alternative source of energy would be a vital source of “base load power”, as the electrical power generated as a result would be able to be accessed and delivered anywhere in the world. However, in order to reach such a prosperous outcome, there are still several factors that must be further developed.  Firstly, larger and more sophisticated space platforms, arrays, and power transmission systems must be developed. More robots and reliable transportation systems to deliver materials must also be done, along with more specialized large-scale receivers, converters, storage and distribution systems on Earth. In-orbit position allocations must also be granted, along with a radio frequency spectrum for the transmission of the energy from Earth’s atmosphere. Finally, an effective operational arrangement and management system would also be crucial for this project to be carried out, as it would ensure that all the components work in a safe and efficient manner.

Chapter 1: What is a Solar Power Satellite?

A solar power satellite is a vehicle located in space whose main function consists of collecting sunlight directly from the Sun and delivering it back to Earth in the form of electrical power through antennas on the ground, which would be plugged into electrical power grids. In order to provide such enormous amounts of energy, the Sun’s energy would be converted into low-density radio or light frequency waves, which would provide “many times more electrical power than we use today” (4). In order to do so, and increase efficiency, large-scale reflectors would be used to concentrate the Sun’s photons. This would result in the PV cells perceiving more energy from the Sun than would usually be the normal.

Currently, there are no solar powers operating yet, but the pressing need for clean, abundant, and instant energy is paving way for the development of such satellites. These satellites would also have functions such as communication (to broadcast audio and video, enable mobile telephony, broadband data, and Internet), remote sensing (to keep a check on weather, environmental surveillance, and mapping), navigation and geo-positioning. The difference between the newly envisioned Sunsats and the current in-orbit satellites pertains to their qualities in terms of the space segment, the Earth segment, and the transport segment.

The Space Segment

New solar power satellites would include several features that are already present in communications platforms, such as a satellite bus, solar arrays, onboard processing, telemetry control, and wireless transmission systems. However, solar power satellites would be specifically made for the purpose of relaying energy back to earth to be converted into electricity, unlike the current comsats that only gather smaller proportions of energy from the Sun simply to power their own spacecraft. With the current advances on thinner, lighter, and cheaper photovoltaic cells, Sunsats would benefit greatly as they would not only be more productive, but also less expensive. However, there is still a great need for bigger, more efficient solar panels in order for such an ambitious goal as that of using Sunsats to replace current energy resources to be achieved.

The Launch Segment

For the successful launching of vehicles or objects out of Earth’s atmosphere, launch systems are crucial. Various reusable launch vehicles (RLV) are used in order to do so, which are of various types, including the “vertical takeoff vertical landing”, and even “single stage to orbit” or “two-stage to orbit” types. At first, Sunsats would use private, commercial, government rockets to get into space, similar to normal communications satellites. Another future possibility is to assemble the solar satellites from components lifted by rockets into a low-Earth orbit. A final alternative would also be to use more powerful thrusters to have the same effect. In terms of its maintenance, the Sunsat would be constructed and maintained tele-robotically by operators on the ground.

The Ground Segment

Similar to radio and TV receivers, rectifying antennas would receive the signals sent by the solar satellites and convert them into electricity. However, these receivers would be larger and would be more spread out to enable a lower density of energy, as passing radio frequency beams with highly concentrated transmissions could potentially harm airline passengers passing by and could even interfere with other communication satellites. These rectifying antennas would also be networked into power distribution centers. Another advantage of these sites is that they could potentially hold agricultural crops or fish farms.

Challenges That Sunsat Face

In order for the Sunsats to be launched, there are still several challenges that are to be faced. Such a project faces challenges in terms of their orbital registration, position, frequency allocations, and levels of power transmission, which would be a further struggle in current times as there are scarce orbital slots. The nation-by-nation approval process that would have to be passed would also be an enduring constraint. The lack of commitment from the government is also a hindrance to the project in general, which is mostly being carried out by the private sector. Finally, some of the technical challenges that this project faces include increasing the efficiency and capacity of solar cells, enabling wireless power transmission and receiver networks, developing energy conversion mechanisms, and further developing the storage and distribution systems.

 

Chapter 2: What are the principal Sunsat services and markets?

Overall, solar power satellites are crucial solutions to our need for a clean energy resource as they can be strategically placed in orbital sectors where the greatest amount of solar energy can be collected, supply power at all times due to this, and their land receivers can be used for multiple purposes.

As listed by the National Space Society, other advantages of solar powered satellites include:

  • No emission of greenhouse gases
  • No production of hazardous waste
  • High quantity availability at all times
  • No requirement of environmentally problematic mining operations
  • No potential target for terrorists (unlike nuclear power plants)

Other main uses for the solar satellites pertain to the production of baseload electrical power to support agriculture, desalinate water, disaster relief, military operations, and other uses.

  • Power utilities: will provide on-demand electric power that can be repurposed and reutilized and could also potentially replace other, polluting sources of energy.
  • Agriculture: could pave way for the creation of a multipurpose greenhouse that would have constant temperatures and light all year round. Not only allows farmers to farm their cash crops but also serves as a supply of electricity.
  • Terrestrial purposes: Rectennas would be placed along with other solar power plants, and can be designed to let light pass through, so the same area could be used for the production of electricity through normal solar plants, or could be even used for agriculture.
  • Fresh water: the satellite could also provide the power needed to desalinate seawater, a process that would provide freshwater at all times every day.
  • Cities: the continuous and non-depleting supply of energy would be crucial in meeting the growing energy needs of cities. As there is no atmospheric nor cloud interference and no night nor seasons, this continuous baseloud resource is vital.
  • Disaster sites: these solar powered satellites could also not only provide illumination and a communication means during power outages in disaster sites, but could also provide an alternative means to recover from a power outage through its readily available energy. An extension of this possibility is to create a navigable airship that hovers around the stratosphere to provide help when needed. It would be able to relay up to one billion watts of energy to any surface on Earth that would need it, which could power a million homes during a crisis. It could even potentially run generators and power up an electrical grid, and could contain passive electro-optical and active radar sensors to find people trapped in debris.

 

Chapter 8: How is Sunsat Development Faring Internationally? *Focusing only on section on China

Given the rapid growth of China accompanied by a growing need of electricity and energy, the country is currently developing space-based solar satellites in its attempt to provide an alternative clean means of meeting the energy demand. Given that by 2050, 85% of the growth in energy demands would feed from fossil fuels, nuclear power, and hydropower, and only 30% of the remaining 15% would be met by alternative renewable energy resources, the situation calls for a pressing, and early, development of solar power satellites. To make matters worse, the Chinese Academy of Engineering reported that oil, coal, and natural gas would be depleted in the next 15, 82, and 46 years respectively. In response, the Chinese Academy of Space Technology (CAST) has stated in its report on “Solar Power Satellites Research in China” the following timeline in terms of its goals related to the development of SPS.

  • 2010: finish concept design
  • 2020: finish industrial level testing of in-orbit construction and wireless transmissions
  • 2025: complete first 100kw SPS demonstration
  • 2035: 100mw SPS will have electric generating capacity
  • 2050: first commercial level SPS system will be in operation

Amongst the CAST’s priorities in the development process of SPS, sustainable development, a skilled workforce, and a means of disaster prevention and mitigation are included. Four other important areas of development include the launching approach and mechanisms, the in-orbit construction mechanisms, high efficiency solar conversion, and wireless transmission.

 

Solar Contraptions: Long Term Assignment – Maya Wang, Professor Mikesell

A Summary of Low-Cost Solar Electric Power: The Solar PV Market Today and the Need for Non-polluting Solar Energy

Maya Wang

Abstract

Solar energy has become a more affordable way to generate electricity, but it still is a low priority compared to conventional fuel electric power sources. Conventional fuel sources have unintended costs, from costs and depletion of natural resources to the harmful environmental and moral impacts. As a result, we need to prioritize solar energy in order to prevent these problems.

Introduction

Solar photovoltaic systems prices are around $4 per watt in the US. However, compared with the costs of other ways of generating electricity, solar photovoltaic costs are higher according to a table published by the US Department of Energy’s Energy Information Agency, which lists the projected costs for electricity from various fuel sources for 2017.

Table of projected costs for electricity from various fuel sources for 2017

The table is in US dollars/megawatt hour, which can be simplified to USD cents/kilowatt hour. From the chart, it can be seen that the average cost of conventional coal (boxed in red) would be around 10 cents/kwh, much less than the cost of solar photovoltaics (also boxed in red) of 25 cents/kwh.

The Age of Hydrocarbon Fuels & Peak Oil

Hydrocarbon fuels, including natural gas, coal, and oil, are still the major sources of energy in our lives, mostly because of transportation. Oil is so important given that the cost is immense, one barrel of oil (158.987 liters) costs 25,000 hours of human labor. While it has revolutionized transportation, economically recoverable oil reserves are finite. Peak oil was projected for 2008, which coincided with the great recession. Although the recession was a general worldwide economic decline, higher gasoline prices may have contributed to some of the stress on the main crisis – mortgage payments.

Table of EIA’s projection for liquid fuels supply

This table shows that there is a visible decline in known production sources starting from 2015. New liquid fuel sources are unlikely to fill the gap of demand versus production (red arrow). According to Olivier Rech at the International Energy Agency, the production of oil has already been on a plateau since 2005. Solar photovoltaics may not immediately replace oil for transportation, however, they could provide electricity for electric car batteries, shifting the demand of energy sources. According to Jeremy Leggett, author of Energy of Nations, argues that when there is an obvious decline in liquid fuel supply, there will be a shift in context or mindset, and money will then start to flow to solar power and the renewable energy sector. Oil is a declining and non-renewable source of energy, and increased funding for solar photovoltaics and other renewables is logical, so that we do not run out of energy sources.

Global Warming

Global warming and climate change is another large driving force in favor of renewable energy and solar photovoltaics. This is less visibly urgent than the declining oil sources, yet it is also worsening as a result of the oil industry. The burning of hydrocarbon fuels is generating carbon dioxide in the atmosphere, contributing to the greenhouse effect, which slowly increases the earth’s average temperature. The main fuel burned for electricity generation in both the US and China is coal, and we live in the negative consequences of this process every day, as smog and pollution are at an all time high in Shanghai. Health and environmental issues arise from this increasingly unsustainable source. An increase in natural disasters is also a visible warning of global warming. Superstorm Sandy that hit the New York in 2012, caused $62 billion in damages and led to the flooding of the New York subway system. In order to prevent future global warming-caused disasters, decrease pollution, and the continuous decrease in oil supply, there must be a shift to renewable energy. Despite all of these warnings, hydrocarbon energy still remains dominant. Natural gas, especially shale gas, is the least polluting of the hydrocarbon fuels, yet it was also predicted to peak around 2015 and decline thereafter.

The Arguments for Solar Energy

Solar energy is currently unfavorable by any industry to be commercialized, as American oil companies can obtain low-cost oil from the Middle East, the defense industry’s charter is to develop weapon systems, electric utilities don’t benefit from homeowners generating their own power, and small businesses don’t have the finances to participate in the energy industry. China provided the billions of dollars to manufacture silicon PV modules, so in the US, solar energy can become a mainstream source of energy over the next 10 years, if the US re-establishes a serious national program to develop alternative energy. There are even opportunities in photovoltaics for innovations leading to lower costs.

Reason #1: Lower-Cost Solar Electricity

Solar cells actually can generate electricity at low cost rates compared other sources of electricity.  Current commercial solar cells produce electricity in sunny locations at rates of about 15 cents per kilowatt/hour, and advanced solar cells have been demonstrated to be twice as efficient as today’s commercial cells. Besides efficiency improvements, other cost reductions are also possible, as glass, plastic lenses, or aluminum mirrors can be used to concentrate sunlight onto efficient solar cells. These collector materials are cheaper than single crystal semiconductor materials. Cost reductions can also come by tracking the sun, which can produce more kilowatt/hours per kilowatt installed, therefore bringing solar electric costs down below 10 cents per kWh compared to the average of 25 cents seen in the first table. However, huge investments are required for manufacturing these cells and systems in quantities large enough to bring down prices. The problem is not the actual cost of photovoltaic cells, but the lack of investment for widespread implementation that can actually create an equal payback.

Reason #2: Rising Oil and Natural Gas Prices

Oil and natural gas resources are being depleted, as seen previously in the second table. The consequence of this “Impending World Oil Shortage” is that electricity prices are going to be rising abruptly within the next 5–10 years. Weather disasters caused by global warming caused by burning hydrocarbons will increase the cost of the energy source that causes these disasters in the first place. The economics of solar electricity are not mainstream, as solar modules based on semiconductor devices will last for 25 years or longer, and today’s cost competition assumptions for solar energy assumes a short-term payback and non-escalating energy prices, which is why there is a disparity in projected costs.

Reason #3: War, Weapons of Mass Destruction, and the Moral Argument for Solar

Economic and environmental consequences of conventional energy sources have been accounted for, but another unintended impact of these systems are the moral implications of the current non-renewable energy sources. Firstly, nuclear energy and nuclear fuels lead to nuclear waste management and nuclear weapons. In turn, nuclear waste and nuclear weapons impact the cost homeland security and America’s fear of weapons of mass destruction, so by prioritizing nuclear energy, we add to the hidden cost of preventing nuclear terrorism.

Another argument against a different non-renewable energy source, oil, is that American dependency on oil from the Middle East has inevitably linked America with terrorism problems from the Middle East. America has already fought two wars in the Middle East to secure their oil supply. The US energy policy and political interests has only been to guarantee the oil supply from the Middle East using the military as necessary.

Solar energy is inherently benign, with the sun naturally being available in nearly every part of the globe, and it will benefit the entire world, not just industrialized nations. As non-renewable energy sources deplete, there will most likely be wars in the future over these scarce resources. US government funding for solar energy has only gone into solar cells used for spy satellites and weapon systems, showing that there is little interest in peaceful applications of solar energy.

Major government commitment and cooperation with the energy industry is needed to bring solar electricity into the mainstream in the US, but the costs are still small compared to the cost of war and terrorism. To put the costs in perspective, in 2013, the subsidies to Chinese solar companies only cost the Chinese government $2.1 billion & a new 1 gigawatt electric power plant costs $1 billion, compared to the American government’s endeavors: the $4 – $6 trillion of the Iraq & Afghanistan, the $20 billion of the Manhattan Atomic Bomb Project, and the $5.5 trillion of the U.S. nuclear weapons enterprise.

Solar PV Cells and Markets

There is a large variety of photovoltaic cell types and markets, but the markets for the silicon solar cell planar module represents 80 % of the terrestrial market for solar photovoltaic cells.
Today’s terrestrial solar market is divided into three sectors: residential PV systems that are less than 10 kW in size, commercial systems in the 100 kW to 2 MW range, and utility systems over 2–500 MW in size. In the future, there may be a solar market sector for systems of 1 GW and larger.

Table of PV development by region

According to this table, the terrestrial solar PV market at the end of 2013 of worldwide installed power reached 134 gigawatts. However, the US only contributed to 10% of this total, showing that they still have not expanded their terrestrial photovoltaic market.

Solar PV Economics

The leveled cost of electricity (LCOE) is the standard for calculating the cost of solar cell electricity systems. The equation for calculating the LCOE contains 9 important input variables required in order to calculate a numerical value. This equation is more precise than the simple qualitative intuitive example seen in the first table of the costs of all energy sources because it takes into account the fact that vertical integration (combination of two or more stages of production in one firm) and cooperation is required amongst a large number of diverse groups in order to bring down the price of solar electricity.

The LCOE Equation

  1. η2 =  The amount of energy in the form of sunlight that can be converted via photovoltaics into electricity.
  2. Cm = Module cost which emphasizes low-cost modules.
  3. Cb = Balance of system which includes module supports, field wiring, and installation costs. This can be higher when the module efficiency is low, since more modules would need to be installed.
  4. S = Sunlight available at the location.
  5. ha = Solar hours for tracking, following the sun by tracking the modules will increase the number of hours per year of operation.
  6. Ci = Inverter cost, increasing the annual hours of operation will reduce the impact of the inverter cost, note that the cost of the hardware and installation are not the only costs.
  7. F = Finance, the projects have to be financed by the banks.
  8. r : Government permission is required, which can cause delays and an increase in costs.
  9. O&M = Operations and maintenance, as the system will need some maintenance over time.

Table of total US PV system price by sector and system size in 2012

The various sections in this table are opportunities for photovoltaic cost improvements. Note that the system cost is double, relative to the hardware cost as a result of the permitting and financing variables, r & F. The cost can be halved if these penalties (soft costs) caused by current government funding of the incumbency shifts away from non-renewables.

Module prices declined as a result of global market factors, mainly due to the rapid buildup of supply in China and strong feed-in tariff (FIT) incentives ensuring demand in Europe. Reducing soft costs in the US will require public policy changes aimed at removing market barriers and accelerating the deployment of photovoltaics. To compare, Germany’s median installed small residential system’s price at $2.60/watt was half the U.S. price of $5.20/watt as a result of national policies.

Cost reduction can be achieved with five factors.

  1. A national feed-in tariff (implemented in Germany), a premium rate paid for electricity that is fed back into the electricity grid.
  2. Standardization of building and planning requirements to reduce permission and inspection costs. There are many unnecessary permit packages to satisfy the varying requirements of building and planning authorities.
  3. Removal of jurisdictional requirements. Cost and time are doubled when installing the roof-penetrating mounting systems that are required in U.S. building codes.
  4. Exemption from revenue, sales, or value-added taxes. State sales taxes accounted for $0.21/watt of the cost of solar systems in the U.S. in 2011.
  5. Liberalization of installation rules, as requirements to use union labor or specially licensed electrical contractors inhibit competition in installation labor.

The US solar industry needs policymakers, regulators, code jockeys (electrical, building, and planning), and elected officials to make solar energy more accessible.

Future Opportunities for PV Technology Improvements

As of now, solar photovoltaics consist mostly of planar silicon PV modules. However, there are more PV developments in the near future. CPVs, or concentrator photovoltaics, are highly-efficient solar cells with lens technology to increase the efficiency of photovoltaic systems. TPVs, or ThermoPhotoVoltaics, solve the problem of a lack of sunlight during the night. It is a nonsolar option where man-made heat sources can be used to generate infrared radiation, which are used by infrared sensitive PV to generate electricity day and night. It is also used for generating heat and electricity in smaller residential systems and furnaces for the night and in the winter. The concept of Space Power Satellites, which has not been implemented yet, collects energy 24/7. A more economic variation is to deploy a mirror in space to deflect sun beams down to gigawatt sized solar farms, distributed in sunny locations around the world. While this option does not provide solar energy 24/7, it can extend the sunlight hours at the gigawatt sites into the early morning and evening hours, which would reduce the cost of solar electricity to below 6 cents per kWh.

Overview & Conclusion

Solar energy is becoming an increasingly favorable and logical source for electricity generation due to many factors encompassing various environmental, economic, and moral issues. However, the United States and other industrialized countries must implement new policies, improve current systems, and invest in renewable solar energy on a national level in order to make an impact on the impending energy crisis. Global solar energy will benefit the entire world as a result of its affordances and accessibility, as long as there is a shift from the current incumbent energy sources to the optimistic future of renewables.

Source: Fraas L.M. (2014) The Solar PV Market Today and the Need for Non-polluting Solar Energy. In: Low-Cost Solar Electric Power. Springer, Cham

Class #9 Lab: Making a Magnet pendulum and Miller solar engine

For Lab #5, we made two circuits, the Miller solar engine and the magnet pendulum.

The Miller Solar Engine

The first consisted of making a breadboard version of the Miller solar engine, which consisted of using a diode, a 1391 and 2N3904 transistor, a polar capacitor, a motor, the solar cell, breadboard, and some wires.

Miller SE schematic

Schematic of the Miller Solar Engine obtained from: http://solarbotics.net/library/circuits/se_t1_mse.html

This solar engine uses a 1381 voltage detector IC, which, as the capacitor is being charged and the voltage reaches its trip point, applies voltage to the 2N3904. Being an NPN transistor, the 2N3904 then applies current to the motor.

In regards to the previous pummer lab, this Miller SE lab was comparatively more straightforward and simpler. As such, I was able to complete it in a fairly quick and stress-free manner, which enabled me to try two different motors and also left enough time for us to proceed with the making of the magnet pendulum.

Google drive link: https://drive.google.com/open?id=1oy3UJHyJCJUN1g0RujEVBiVPQ0dEBlWa

Google drive link: https://drive.google.com/open?id=1m-zAvmE5AiUtS1g_LoWrc2XesHM-fLn4

The Magnet Pendulum 

The magnet pendulum consisted of using a coil of wire and a magnet to essentially lead the magnet to sway indefinitely. The materials used included 1 solar cell, coils, 1 supermagnet, 1 4700uF capacitor, 1 1000uF capacitor, 1 2N3904 transistor, 1 2N3906 transistor, 2 100k resistors, 1 diode, 1 LED, and a base or suspension point.

Schematic from Junkbots, Bugbots, and Bots on Wheels

The circuit works as follows: first, the solar engine charges and pulses electricity. If a current is put through a coil of wire, a magnetic charge is created. As such, the magnet can be pushed or pulled by the coil to produce motion due to its exposure to the created magnetic field. As mentioned in Junkbots, Bugbots, and Bots on Wheels, this circuit “is a simple arrangement of parts that waits until the coil comes near, then pulses power to the coil to give the swinging magnet a bit of a pull. As the magnet swings past, it stops pulling, letting the magnet swing a bit higher each time”. For the sake of time, we made our circuit in a breadboard and simply used a lamp as our source of light and as our base for the pendulum. I was able to get the circuit to work successfully, but it still did not have the “sleek” movement that usually accompanies well-made pendulums. A such, a possible improvement would be to do a better base with a good balance between the distance of the magnet and the coil.

Setup of the pendulum.

Google drive link: https://drive.google.com/file/d/16Yy0nWdLx8bdQoC3RUGbBC3veDW80osO/view?usp=sharing

 

Solar Contraptions: Class 9 Lab – Maya Wang, Professor Mikesell

In this class’s lab, I made a Miller solar engine and a magnet pendulum, both powered by solar energy. I started with the Miller solar engine, and gathered the parts. I followed the diagram given to us and put everything in place without any problems. This was much easier than the pummer circuit from last class, and it worked immediately when I completed the circuit. Below are pictures and videos of the Miller solar engine I created.

Working Miller solar engine

The magnet pendulum required a some different components but I re-used many of the parts from the Miller solar engine. I followed the diagram found in the Junkbots textbook, minus the optional LED. After putting the circuit together and making sure the coil was facing the right direction, I created the actual magnet pendulum using some wires, tape and a magnet. I suspended the pendulum from the lamp that was providing the solar panel with energy, and tried to get it as level to the table as possible. Once I placed the coil under the magnet, I tested to see if it was working by moving the coil to see if the magnet reacted. It did, so the pendulum was working. I gave the magnet some momentum and the coil kept the pendulum in motion.

Working magnet pendulum

Solar Contraptions: Class 8 Lab – Maya Wang, Professor Mikesell

For this lab, I created a solar powered pummer that would go off when it was charged enough using solar power. I began with my materials (pictured in the gallery) and followed the circuit diagram to wire it. This circuit diagram was pretty difficult to follow since the chip had 20 pins. I spent most of my time wiring making sure that each component was in the right place. The diagram I used was from https://www.bertnase.de/beam/pummer.pdf. I double checked the position of each part of the circuit so I wouldn’t have to go back and troubleshoot. Once I added the solar panel and the batteries to the circuit, the LED started to blink or “pumm.” Since I had more time after completing the LED pummer, I moved on to adding a buzzer to the circuit, experimenting with putting it in serial and parallel. I found that connecting the buzzer in parallel made the buzzer very loud, and series made the sound softer and cuter. I also experimented with adding a different size capacitor to the circuit, which resulted in the buzzer just making a clicking noise. The final change to the circuit was to replace the resistor with a potentiometer to change the volume of the buzzer and strength of the LED flash.The process and all of the working circuits are documented in the gallery and videos below.

Class 8 Lab – Making a Pummer

For this lab, we created a pummer in a breadboard. A pummer is essentially a “robot plant”, as it absorbs solar energy during the day and releases it at night in the form of a pulsing LED or a Piezo speaker. Its solar cell captures light energy, converts it to electrical energy and sends it to the capacitors and rechargeable batteries, and then triggers the pulsing of the LED.

For this circuit, we used 2 rechargeable batteries, 1 small solar panel, a 74AC240 chip, 2 220nF capacitors, 1 polar capacitor, 1 diode, 1 4.7ohm resistor, 1 1Kohm resistor, 1 100k resistor, 1 LED, and some wires.

 

Image result for pummer circuit diagram

Overall, finishing this circuit took some time and guidance, but was very gratifying once it was working properly, triggering the LEDs and the Piezo speaker with each energy release. Although it was painstaking to make sure that each of the components were placed correctly and the debugging did take some time, I’m looking forward to playing around with different capacitors and different LEDs to create different pummers. I am also excited to get more comfortable with making different shaped pummers, as they are the main components of my final project.

Google drive link of the video in case it has issues loading: https://drive.google.com/file/d/135vNb42xlTUXTSTh0QBPW-DJBLcO0pqy/view?usp=sharing

Class 7 Lab: Building a Symet

For this lab, we created our first, “symmetrical robot”, or Symet. According to Junkbots, Bugbots, and Bots on Wheels”, the creation of a Symet includes two steps: first, storing the energy by attaching a capacitor or a rechargeable battery, and then deciding when to “dump the energy, and then dump it” through a solarengine. For this lab, we used a voltage-based activation circuit. In other words, the circuit monitors the volts stored in the capacitor to know when to activate, and, when high enough, releases the energy into the motor. We also used a breadboard to recreate the circuit and used solar panels with a higher voltage than needed, which caused a few complications in the process. In terms of materials, we used three 1000uH capacitors,one 2.2k ohm resistor, one 2N3904 and one 2N3906 transistors, one flashing LED, a breadboard, a 5V solar panel, and a motor.

This is the circuit diagram we followed. It was relatively simple overall, but making sure that the circuitry for both transistors was correct was a bit painstaking.

Since my circuit was not working properly on the day of the lab, I recreated it again on the weekend, and with the help of the professor was able to get the circuit to work. There were two aspects that were potentially deterring the circuit from working properly. The first one was human error, in the sense that regardless of how much I revised the circuit, I still found some pieces misplaced. The second was the high voltage of the 5V solar panel, which was not the most appropriate for our circuit. As such, w tried adding two resistors in series, which only caused the motor to pulse a bit while rotating. We finally ended up using a potentiometer (as seen on the video below) instead of the resistors to change the resistance as needed and directly affect the motor’s movement. While changing the potentiometer, there were a few minutes when the motor functioned correctly and did the full rotations. However, as it stopped before I could document it, the video below shows its movement afterwards, which was in long, rotating pulses (there’s one point where it makes a full rotation!)

Breadboard Symet

Top view of circuit

 

In case the video doesn’t load, here’s the google drive link: https://drive.google.com/open?id=1PjiV8nyJOAOVQuT5d_yEoqzRQ_l6nsVj

Solar Contraptions Homework #3: Final Project Mechanisms

As an extension for my previous post describing my initial idea for the final project, this post details the design and functionality of the structure that will encapsulate the “Pummer Ecosystem”.

I decided that the optimum shape for the ecosystem would be a cube, since it is the easiest structure that would allow the solar panels to sit on the top, with a sliding window/side that is able to be detached to look inside.

Box alignment:

  • Top: solar panels with small wedges on the corners of the surface (so the wall placed to cover the panels is not directly touching them)
  • Front: sliding or folding mechanism that allows it to be detached and placed on top of the solar panels
  • Bottom: box has an additional, smaller box on the bottom that contains the circuitry of the pummers
  • Side: the sides of the box would contain the wires connecting the solar panels with the circuitry at the bottom

As seen in the sketches below, the front side of the box slides open in one of two ways: either by sliding to the side and then manually placing it on the solar panels, or by folding it up to be placed on top of the panels.

BOX DESIGN: side of the box slides to a side and is then placed on the top of the box, covering the solar panels and triggering the pummers.

I am still unsure whether I want to include mechanics (such as clams, gears, levers, etc.) in this project, since I want to focus for now on the design of each pummer and their light. However, as the weeks progress, I might find a mechanic that would fit this project well and implement it.

 

Solar Contraptions Homework #3: Final Project Ideas

For my final project, I brainstormed a few different ideas that might or might not be executable.

The first idea is an oscillating fan that rotates on a motor, and plays music as well, perhaps from a pummer or another device. The idea would be something simple portable which operates on solar energy, somewhat along the lines of those lightning/micro-usb powered fans that people usually attach to their phones.

Another idea was to design a simple robot that can draw or create something on a canvas. It can either carry a brush or pen which is dragged across the ‘canvas’, or use another medium like charcoal to create a trail. I’m not very good at drawing, but I love creating things and see a lot of beauty in abstract art. I don’t think this robot would need to be heavily programmed, but I would love for it to stay within certain bounds while drawing/creating.

My third and final idea was to create a simple solar powered robot which can water small plants on a scheduled basis. It would harness energy to then pick up a small amount of water, which is then delivered to the plant. This idea might not be very plausible given the need to program the robot.

Solar Contraptions: Class 7 HW – Maya Wang, Professor Mikesell

The mechanism I chose was the Four Bar Mech from robives.com. Link: https://www.robives.com/product/four-bar-linkage-mech-to-download-and-make/

I chose this mechanism because I thought the way it moved was very interesting  and cute. If I were to attach a character to the end that protrudes from the top, I would definitely incorporate the swishing mechanism. To integrate solar energy into the mechanism, I would replace the crank handle and attach the rotating bar to a motor. Similar to the Symet we created in last class’ lab, there would be a motor that rotated in intervals or continuously depending on how much light the solar panel was exposed to. I would attach the solar panel and circuit to the top of the box where there is space, and only the motor would be suspended on the side to control the rotating bar.

Link to video of the mechanism in motion: https://www.instagram.com/p/oTuvwABxmU/

The character or object I’d place on the moving part would have some flowing parts, such as strings or loose fabric so that when the motor moved the mechanism, it wouldn’t be completely static and continue to sway side-to-side. Perhaps a girl in a dress or a cute animal would fit the cute swishing mechanism.