Inside, an Arduino Nano is hooked up to a series of WS2812b LEDs. The LEDs are flashed in time with the heartbeat of the person holding the heart, thanks to a MAX30102 heartbeat sensor.

In this particular project, I contemplated a shield for Arduino Nano, which can gather weather-related information by a built-in BMP280 Temperature and Pressure Sensor, a photoresistor, and a ...

This was helped further thanks to the use of transistors to run the LEDs directly from battery voltage, rather than obeying the current limits of the Arduino Nano’s output pins.