Diy pinewood derby timer

Introduction to pinewood derby timers

The Pinewood Derby is a beloved tradition in Cub Scouting, where participants design, build, and race small wooden cars. While the focus is often on the craftsmanship and design of the cars, accurate timing is crucial for fair and exciting races. A DIY pinewood derby timer offers an affordable and rewarding alternative to expensive commercial timers. This guide will walk you through the process of creating your own timer, using readily available components and basic electronics principles.

Understanding the basic components

A DIY pinewood derby timer typically relies on a microcontroller (such as an Arduino), sensors to detect the cars crossing the finish line, and a display to show the race times. Here's a breakdown of the key components:

• Microcontroller (Arduino Uno): The brains of the operation. It receives signals from the sensors, calculates the race times, and sends the information to the display.
• Sensors (Light Sensors or Infrared Break-Beam Sensors): These detect when a car crosses the finish line. Light sensors are simple but can be susceptible to ambient light interference. Infrared break-beam sensors are more accurate and reliable.
• Display (LCD Screen or LED Matrix): Shows the race times for each lane. An LCD screen offers clear readability, while an LED matrix can display more complex information.
• Power Supply (9V Battery or USB Connection): Provides power to the microcontroller and other components.
• Wiring and Connecting Components: Jumper wires, breadboard, or PCB to connect everything together.

For instance, a common setup involves using photoresistors as light sensors. When a car blocks the light, the photoresistor's resistance changes, which the Arduino detects as a finish line crossing.

Building the timer circuit

The construction process involves connecting the components according to a schematic diagram. Start with the power supply and connect it to the Arduino. Then, connect the sensors to the Arduino's analog input pins. Finally, connect the display to the Arduino's digital output pins.

1. Connect the Power: Attach the positive and negative wires from the power supply to the Arduino's Vin and GND pins, respectively.
2. Connect the Sensors: Wire each sensor to an analog input pin on the Arduino. A typical setup involves a voltage divider circuit, where the sensor's resistance changes when it detects a car crossing the finish line.
3. Connect the Display: Connect the display's data and control pins to the Arduino's digital output pins. Consult the display's datasheet for the correct pin assignments.

Example: Using an LCD screen, you might connect pins like RS, EN, D4, D5, D6, and D7 to specific digital pins on the Arduino, such as pins 12, 11, 5, 4, 3, and 2, respectively. The exact pin assignments will depend on your chosen components and the code you write.

Programming the arduino

The Arduino code is responsible for reading the sensor data, calculating the race times, and displaying the results. The code typically follows these steps:

1. Initialization: Set up the pins for the sensors and the display.
2. Sensor Reading: Continuously read the analog values from the sensors.
3. Time Calculation: When a sensor detects a car crossing the finish line, record the time using the `millis()` function.
4. Display Output: Format the race times and display them on the LCD screen or LED matrix.
5. Reset Functionality: Add a button or switch to reset the timer for the next race.

A simple Arduino sketch might look like this (simplified example):

 
 // Define sensor pins
 const int sensorPin1 = A0;
 const int sensorPin2 = A1;

 // Variables to store start times
 unsigned long startTime1 = 0;
 unsigned long startTime2 = 0;

 // Variables to store finish times
 unsigned long finishTime1 = 0;
 unsigned long finishTime2 = 0;

 void setup() {
 Serial.begin(9600); // Initialize serial communication
 }

 void loop() {
 // Read sensor values
 int sensorValue1 = analogRead(sensorPin1);
 int sensorValue2 = analogRead(sensorPin2);

 // Detect car crossing the finish line
 if (sensorValue1 < 500 && finishTime1 == 0) { // Adjust threshold as needed
 finishTime1 = millis();
 Serial.print("Lane 1 Finish Time: ");
 Serial.println(finishTime1);
 }

 if (sensorValue2 < 500 && finishTime2 == 0) { // Adjust threshold as needed
 finishTime2 = millis();
 Serial.print("Lane 2 Finish Time: ");
 Serial.println(finishTime2);
 }
 }
 
 

This is a very basic example; a complete implementation would include more robust error handling, display output, and reset functionality. Many online resources offer complete Arduino sketches for pinewood derby timers.

Calibration and testing

Once the timer is built and programmed, it's essential to calibrate and test it thoroughly. This involves adjusting the sensor thresholds to ensure accurate detection of the cars crossing the finish line. You can use a sample car to test the sensors and fine-tune the thresholds. Also, verify that the display shows the correct race times.

• Sensor Threshold Adjustment: Experiment with different threshold values in the Arduino code to find the optimal setting for your sensors and track conditions.
• Timing Accuracy Verification: Compare the timer's results with a stopwatch or another timer to ensure accuracy.
• Track Consistency: Make sure the track is level and free of obstructions that could affect the car's speed or trajectory.

A good practice is to run several test races with the same car in each lane to identify any systematic errors. This can help you pinpoint issues with the sensors, track, or Arduino code.

Advanced features and enhancements

After building a basic timer, you can add advanced features to enhance its functionality. These include:

• Multiple Lane Support: Expand the timer to support more than two lanes.
• Race Data Logging: Store the race times in a file or database for analysis.
• Wireless Communication: Use Bluetooth or Wi-Fi to transmit the race data to a computer or mobile device.
• Automatic Reset: Implement a mechanism to automatically reset the timer after each race.
• False Start Detection: Add sensors at the starting line to detect false starts.

For example, you could use an SD card module to log the race times, along with the date and time of each race. This data could then be analyzed to track the performance of different cars and racers.