Relay is a device controlling large current through small current. A relay system usually consists of small current circuit, large current circuit, and circuit conversion part. When the low current circuit reaches a certain condition, it will trigger the high current circuit through the conversion section. This method is more safe and flexible than direct control of large current circuits.
Common ways of circuit conversion are electromagnetic, solid state, magnetic spring, temperature, light, etc. Relay Card is a reed type. With the help of Relay Card and other sensors, it is easy to automatically turn on air conditioner when detected the temperature is high.
Relay Card allows you to control the circuit of high voltage with a low voltage, say 5V from the Carduino. The relay on the Relay Card is normally-opened. You can connect any high voltage appliance through the 2-pin terminal block connector on the front of the board. The maximum voltage ratings for the high voltage appliances are 3A@250V AC and 3A@30V DC. When you apply a 5V signal to the Relay Card, the relay gets close, and the connected device will turn ON.
CAUTION: Don't touch Relay Card while connected to the mains electricity or high voltage DC.
Longan Cards is a unique open source development platform designed by Longan Labs. As a plug and play development platform, Longan Cards allows you to quicky build wide array of prototypes and applications in no time. A full set of Arduino libraries and plenty of example codes are available to play with Longan Cards platform.
↑ Longan Cards system consists of Cards and Boards. There are many gold finger antennas on Card and several gold finger sockets on Board. They are combined together through sockets interpolation, which is intuitive and easy to use. With this unified and flexible interface, you can realize a variety of ideas. Many more Boards with different themes would luanch to help people explore more fun.
↑ Longan Cards modules are classified into many types. Firstly, the main control cards which are the heart of Cards system, run the code and take charge of the exchange of data between modules. Besides Carduino, you can also use MicroBit, Arduino and other development board through connection board. The sensor cards can detect data of surrounding such as temperature and air pressure, etc. The inputs cards allows you to do some operations, such as buttons, knobs, etc. The output cards give feedback in various forms, such as buzzers, motor drives, etc. The communication cards can transmit data in many ways, such as Bluetooth and 4G network. The power cards supply power for electronic projects, including batteries, DC, etc. And other cards, mainly do some auxiliary work, such as expansion, code downloading, etc.
↑ STEM is an acronym for science, technology, engineering, and math. STEM education began in the United States in the 1990s. It is an interdisciplinary teaching method that combines STEM content and real life situations, which helps stimulate students’ original curiosity and thirst for knowledge and novelty. Longan Cards contains dozens of modules, involving a wide range of knowledge in the process of use, including electronic circuit, mechanical structurenature, programming, science of nature, daily wisdom, and humanities, etc. It is a powerful tool for STEM education at fields of electronic prototyping, science experimentation and DIY project.