Detector Building is a Division C event for the 2020 season. It was a featured trial event at the 2019 National Tournament, and was also run at various 2019 state tournaments including North Carolina, Texas, and Florida. In this event, students are required to build a sensor or detector that fits the parameters outlined in the rules.
In the 2019 season, participants are required to build a temperature sensing device that accurately measures and displays temperatures from 0 C to 100 C using a microcontroller board such as an Arduino or a Raspberry Pi. Teams are also required to submit a Design Log including a picture or schematic, a practice log with a minimum of 10 trials, an equation modeling the data, and an explanation of the device's programming. All items must be impounded, with the exception of tools. The sensing device is tested at four different stations, where it must measure the temperature of the water and display the temperature zone using colored LED indicators. The device may be connected to a laptop, but it must withstand the temperatures it could possibly be subjected to.
A test is also given at the event over the theories behind it. The test has 10-15 questions, and is used as a tiebreaker. Questions can be about electricity (voltage, resistance, etc.), how an LED works, calibration, or construction parameters. The test questions can be answered at any time during the event.
A light-emitting diode (LED) is a semiconductor light source that emits light when current flows through it. When a current flows through the diode, electrons are able to recombine with electron holes within the device, releasing energy in the form of photons. This effect/process is called electroluminescence. The color of the light (corresponding to the energy of the photons) is determined by the energy band gap of the semiconductor. White light is obtained by using multiple semiconductors or a layer of light-emitting phosphor on the semiconductor device.
Appearing as practical electronic components in 1962, the earliest LEDs emitted low-intensity infrared light. Infrared LEDs are still frequently used as transmitting elements in remote-control circuits, such as those used with a wide variety of consumer electronics. The first visible-light LEDs were of low intensity and limited to red. Modern LEDs are available across the visible, ultraviolet, and infrared wavelengths, with high light output. Early LEDs were often used as indicator lamps, replacing small incandescent bulbs, and in seven-segment displays. Recent developments have produced white-light LEDs suitable for room lighting. LEDs have led to new displays and sensors, while their high switching rates are useful in advanced communications technology. LEDs have many advantages over incandescent light sources, including lower energy consumption, longer lifetime, improved physical robustness, smaller size, and faster switching. Light-emitting diodes are used in applications as diverse as aviation lighting, automotive headlamps, advertising, general lighting, traffic signals, camera flashes, lighted wallpaper and medical devices. Unlike a laser, the color of light emitted from an LED is neither coherent nor monochromatic, but the spectrum is narrow with respect to human vision, a.nd functionally monochromatic.
Resistors and thermistors
Microcontrollers are small computers that run a specified program on an integrated circuit. Manufacturers have the option of mounting microcontrollers onto a circuit board connecting to an ordinary computer, which can read data from the microcontroller and write a program to the microcontroller. This lets users control the microcontroller from their laptop or desktop computer, allowing ease of coding. Some examples of microcontroller boards are TI Innovator, Raspberry Pi, and Arduino.
- See also: Amazing Mechatronics § Arduino
Arduino is a family of microcontroller boards that run open source Arduino software and are approved by the Arduino S.r.l. company. Arduino code is written in syntax based on the C language.
The Arduino can transmit data to an output on your computer known as the serial monitor. You'll be able to use the serial monitor to read data from the Arduino, and this may help at debugging code in the early stages of the process.
The Arduino has both digital pins and analog pins, as well as pins that are neither. Analog and digital pins may be input (to read data) or output (acting as a source of current). Digital pins are all-or-nothing pins: they may be
HIGH, where they have an output of 5 volts (3.3 volts on some Arduino models), or
LOW, where they serve as ground (0 volts). However, they cannot be set to intermediate voltage values between
LOW. Analog pins too can also be used to source current, but unlike digital pins, analog pins can acquire a range of voltage values between 0 V and 5 V.
Pins that are neither digital nor analog include the 5 V and ground pins. The Arduino references its voltage measurements relative to the ground pin, which acts as 0 V.
Electricity can break an Arduino. If more than 40 milliamps of current travel through a pin, the Arduino may reboot or the pin may "burnt out," leaving it permanently disabled.
Serial.begin(9600) - initializes the serial monitor, with data transferred from the Arduino to your laptop at a rate of 9600 bits per second
Serial.println("Hello world!") - prints
Hello world! onto the serial monitor
Raspberry Pi is a microcomputer that runs the Raspbian operating system, which is derived from Linux. In this way, it is more versatile than many other microcontroller systems. For instance, Raspberry Pi can link directly to an HDMI-enabled monitor as well as keyboard and mouse. However, the Raspberry Pi must be fed large amounts of electricity to sustain its powerful processing, and it is therefore susceptible to overheating. A fan may be installed to cool the Pi down. (Because the Pi processors overheat rather than the wires, overheating and fanning have negligible impact on temperature sensing.)
Raspberry Pi requires socket-type wires in order for you to connect it to other electrical components.
The team with the highest Total Score wins. A team's score is based off of how accurate their device is and whether or not they have a complete design log, as well as a test about a team's knowledge of electricity and detector construction. A complete Design Log gives 28 points. 60 points total are possible based on how accurate the sensor is when displaying the temperature at all four stations (15 points per station). If the detector turns on LEDs of the correct color at a station, 5 more points are awarded, or at most 20 points for all four stations. A 10-15 question test is worth 30 points. Prior to the 2019-20 season, the written test was only used to break ties.