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20. Project development

The motivation and idea of my final project is energy and health. To be medically fit and healthy, you need to be physically energetic. Consistent physical activity can help protect you from serious diseases such as obesity, heart disease, cancer, mental illness, diabetes and arthritis. Riding your bicycle regularly is one of the best ways to reduce your risk of health problems associated with a sedentary lifestyle. Cycling is a healthy, low-impact exercise that can be enjoyed by people of all ages, from young children to older adults. It is also fun, cheap and good for the environment. Another aspect of my project is Energy. Energy is an essential part of our daily lives. We use energy to heat and cool our homes, schools and businesses. We use energy for lights and appliances. Energy makes our vehicles go, planes fly, boats sail, and machines run. All living things need energy too. Plants use light from the sun to grow. Animals and people eat the plants and use the energy that was stored. Food is fuel for our bodies’ energy needs like muscle power. We also use our bodies to make heat energy. When you have been running or working hard, your body produces heat energy. When you wear clothing like a jacket in the winter, it holds in that heat energy and keeps you warm. Also, the increasing population of low power electronic gadgets demands more and more energy. I want to club these all ideas to make a unique and easy solution which can afford to everyone. In my project, I integrate bicycling energy to store it for low power electronic gadgets. In addition to this, I will display the speed of the bicycle in the LCD panel. Hall sensor based magnetic switch used for the detection of the speed of the bicycle. Worldwide, the number of bicycle lists are increased tremendously as health seek, eco-friendly and cost-effective mode of transportation. I am cycling every day around 5-10 km by pedalling force is applied approximately 21.68 N for achieving 30.4 kph or more. Finland has a wide bicycle route nearly 72 marked national cycle routes and many bicycle riders. My idea is an effective way to harvest energy from bicycle dynamo to a power bank. The project describes developing an energy harvesting from bicycle riding for our day today smart devices. The present plan is an attempt to establish an energy harvester module for smart devices power sources. Below figure present a brief idea about my final project,

List of requirements

  • Bicycle
  • Commercial bicycle dynamo generator
  • Electronic parts (PCB, Power supply, Microcontroller, LCD display, USB charging port)
  • Acrylic press fit box for project packing
  • 3D printed package for electronics
  • Power bank
  • Connectors (USB)

Current and Previous Work in Bicycle Projects

I have found there are several bicycle energy project during google search, I have made a detailed project survey on bicycle based energy projects. I gather most of the information from all the projects in google search, fab lab projects and made a list which is listed below, -Commercial Energy Harvester KIT -JAY_2019 Solar Powered Bike -Bike Battery tracker_2019FAB LAB -Pressure Sensing Pedals -Haptic Navigation Bicycle Handlebars -48V Electric Flat Tracker -Speedometer_2017 Fablab

Electronic Circuit Design and Fabrication

My project electronic circuit fabrication done with Eagle (schematic and board). I used Roland PCB milling machine for both hall sensor and LCD board. I also develop AC to DC voltage converter by conventional bridge rectifier and voltage regulations for 5 V with minimum voltage dropout. Also made a separate PCB for hall sensor. My final project electronic boards were already done in my Week 11 and week 12 assignments. Both LCD and Hall Sensor working perfectly. For the power supply circuit fabrication, I take long time trial and error methods. I have made conventional way to connect shorkey diode () based bridge rectifier with filter capacitor and regulator available in the Fablab Oulu. Some of the initial testing are shown below, that is AC dynamo output with oscilloscope, its shows the expected voltage level of 6V (AC) and 3 Watts power average.

I used RB-See-266 Bicycle Dynamo. It has output rating based on constant-resistance load (18 ohms) are

  • 5 km/h-output power of 0.45 W-output voltage of 2.45 V, output current of 0.115 A

  • 15 km/h-output power of 1.89 W-output voltage of 5.78 V, output current of 0.325 A

  • 30 km/h-output power of 3.21 W-output voltage of 7.23 V, output current of 0.435 A

Hence, I decided to use low voltage drop regulator for my bicycle project. See the fabricated regulator board for my final project. I compare the conventional shorkey diode based bridge rectifier and bridge rectifier pack with difference voltage regulator based on its low voltage dropout. Finally, I optimized bridge package with voltage regulator (L4940V5]( See the board with two type of rectifier for the optimization.


Hall Sensor

Program done in [week 11] ( For the final project, I used one board for LCD and Hall Sensor. I used Attiny 44A microcontroller for both input and output devices


Program done in [week 12] ( For the final project, I used one board for LCD and Hall Sensor. I used Attiny 44A microcontroller for both input and output devices


In my final project, one part is harvested energy is used for speedometer. Initially, I faced several issued when both the codes are combined. The major problem is limited memory of Attiny44. I have discussed with our local instructor and finally we made a code for both hall sensor and LCD in a single board that developed in output week. Final code is shown below with explanations in the sting

  Attiny44 Speedometer
  by Cesare Brizio | CC by-sa-nc// Modified by Jobin Varghese
  this sketch is in the public domain

  Version 2.0 - 17 jun 2019
  The implementation is relatively rough: 
  - wheel circumference has to be hard-coded
  - an attempt at debouncing has been made both at ohysical and software
    level - to no avail. Will be revised soon.
  A few more details here: 

  Modified from an original by John Boxall
  Example 37.3 – Basic speedometer using millis(); > chapter 37
  John Boxall | CC by-sa-nc

  Hardware – you will need a sensor. For example – a reed switch and magnet. 
  Consider the reed switch to be a normally-open button, and connect as usual 
  with a pull-down resistor.

  The circuit for LCD board
  (HD4770 compatible display)
  4-wire dialogue
 * LCD RS pin to digital pin 5
 * LCD Enable pin to digital pin 4
 * LCD D11 pin to digital pin 3
 * LCD D12 pin to digital pin 2
 * LCD D13 pin to digital pin 1
 * LCD D14 pin to digital pin 0
 * LCD R/W pin to ground
 * LCD VSS pin to ground
 * LCD VCC pin to 5V
 * 10K resistor:
 * ends to +5V and ground
 * wiper to LCD VO pin (pin 3)

// include the library code:
#include <LiquidCrystal.h>
// initialize the library with the numbers of the interface pins
const int rs = 5, en = 4, d11 = 3, d12 = 2, d13 = 1, d14 = 0;
LiquidCrystal lcd(rs, en, d11, d12, d13, d14);
 float start, finished;
float elapsed, time;
float circMetric=2.093; // wheel circumference (in meters)
float circImperial; // using 1 kilometer = 0.621371192 miles
float speedk, speedm;    // holds calculated speed vales in metric and imperial

void setup()
  // convert metric to imperial for MPH calculations
  // the syntax with digitalPinToInterrupt should allow portability
  //among different Arduino models - see
  attachInterrupt(digitalPinToInterrupt(8), speedCalc, RISING); // interrupt called when sensors sends digital 2 high (every wheel rotation)
  //attachInterrupt(0, speedCalc, RISING); // interrupt called when sensors sends digital 2 high (every wheel rotation)

  //start now (it will be reset by the interrupt after calculating revolution time)

  // set up the LCD's number of columns and rows:
  lcd.begin(16, 2);

  // Print a transitory message to the LCD.
  lcd.print("  Bi_SPEED");
 // delay(5000); //just to allow you to read the initialization message


void speedCalc()
  //Function called by the interrupt

  if((millis()-start)>100) // 100 millisec debounce
    //calculate elapsed

    //reset start

    //calculate speed in km/h

    //calculate speed in mph
 void loop()
  // The loop will be interrupted by the sensor each time the 
  // magnet passes near the sensor, in other words once per revolution

  // Top line in the 16 char, 2 lines display - speed data
  lcd.print(" km/h ");
 lcd.print(" MPH ");


I have done several trial before reaching the final projects, test trials images are shown below, Power bank charging test using breadboard measurement as shown below, after several trials for changing the filter capacitor, regulator, finally I chosen bridge package with L4940 regulator which has low dropout voltage,

The final program after burning the code, LCD output with Hall Effect sensor as shown in below figure,

Project Cost

An approximate estimation of my final project is shown in below table, which is excluded from 3D printing, Laser cutting and PCB milling and final assembly. Overall cost of the final project is less than 30 euro

What tasks have been completed, and what tasks are remining?

The tasks completed till today is 3D printing case for hall sensor using ABS and PCB seperating sheets using PLA material, laser cutting and engraved final project box in a 3 mm acrylic board. microcontroller board is ready and its functioning. Task remaining are voltage regulation, tuning, output power checking and assembly of final project.

What has worked, what hasn’t?

  • LCD board
  • Speedometer program
  • Hall Sensor
  • AC to DC conversion working initially with voltage drop of 1V, then i changes the regulator with 0.2-0.4 V voltage drop regulator.
  • The bicycle output power is enough for microcontroller board and Power bank energy storage
  • Future plan to upgrade the packages and study the efficency with variable dynamos and hub dynamo.

What questions need to be resolved?

  • Bicycle speed and output power efficency
  • Time and energy storage efficiency
  • Comparison with commercial products

What will happen when?

  • My project idea is almost done, after completion of this project, i would like to give advertise my project through social media as well as fab academy to promote people to use bicycle
  • I also created deadline for each task based on the priority.
  • I have 2 weeks to complete my project, Last week, I am planing to do all the documentations. My input and output weeks works well so the amount of time, used for AC to DC conversion and efficent output power for Power bank, LCD and hall sensor.
  • The main concern is output voltage and current which is needed for complete working of my project without any energy sources. If, my output power management doesnt work, I have alternate plans to use extenal baterries to power the boards initially.
  • Also checking the minimum dropout voltage regulator 0.2 to 0.4 V. So that everything works fine.

What have you learned?

  • During my final project, I learned mainly, how effectively one can produce a complete module which is useful to day to day life. Also, it is a refreshment for my 10 year back academic studies of electronics and upgradation of my current research in laser cutting, 3D printing and so on.