Instructions
Table Of Contents
- Introduction
- Parts
- Using Alligator Clips
- Solar Board Reference
- Project 1 – Sun Finder
- Project 2 – Garden Light
- Project 3 – Self Charging Cooling Fan
- The BBC micro:bit
- Getting Code to Run on the micro:bit
- Project 4 – Adding an Energy Meter
- Project 5 – Energy Logger
- Connecting Up
- Code for the Energy Logger (MakeCode)
- How it works
- Connecting to Your PC
- Pairing Your micro:bit With MakeCode
- Showing the Device Console Graph
- Capturing Data From a Charge and Discharge Cycle
- Downloading Data
- Getting Data into a Spreadsheet Program
- Analysing the Data
- Graphing the Data
- Results
- Understanding the Data
- Understanding Duty Cycle
- How the Solar Store Works
- Project 6 – Intelligent Cooling Fan
- Troubleshooting
- About the Author
- Learning
- Monk Makes Kits
How it Works
This project is similar to project 2, but by using the two alligator clips, you have
made a simple switch that allows you to decide when you want the fan on. If there is
enough energy stored in the Solar Store when you connect the alligator clips
together, the fan will spin.
By separating the charging phase and the discharging phase into two separate
phases, you can harvest and store energy when light is available without the fan
using some of that energy to power it, so your Solar Store will charge faster.
Because the energy is stored in the Solar Store, when the sun goes down and there
is not enough light to charge any more, you have enough stored energy to spin the
fan when you want to, by joining and breaking the alligator clip connection to turn
the fan on and off on whenever you need it.
All practical energy harvesting systems are designed to separate the charging and
discharging phases. If you do the right measurements and calculations you can
then design a well-balanced system so that it always has enough energy when you
need it (even though the energy source, the sun, is not always available).
Experiments
1. Connect the two alligator clips at the top to enable the board, and disconnect the
fan. How long is it before LED D3 lights up to indicate some stored charge?
2. When LED D3 lights up, connect your fan to the Solar Store and time how long
your fan runs for before it stops.
3. If you leave the board charging for longer, does it then allow the fan to run for
longer?
4. What is the longest time you can make the fan run for before the Solar Store runs
out of energy, and how long does it take with your chosen light source to charge it
up to that level?
Results
1
2
3
4
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