DIY rain detector for clothes

A Japanese-language social post on May 21 drew attention to a simple rain detector project built to protect clothes left out to dry. The post, from the howtofunda account, showed a small working model that detects water and triggers a mechanism to move or cover clothes when rain starts. A related howtofunda project page and YouTube video describe the build as a school-exhibition or hobby project made with low-cost parts and no Arduino. ### How does the device say it works without Arduino? The howtofunda project page says the model works on the electrical conductivity of water. When rainwater touches the sensor, the circuit is completed, and the motor activates; when the sensor is dry, the circuit remains open and the motor does not run. The YouTube description says the setup uses “basic electronics” and a rain-sensing mechanism rather than programming. (howtofunda.com) It describes a miniature house, a rotating mechanism and a covered area that the clothes move under when water is detected. ### What parts are included in the build? The howtofunda page lists a water level sensor, DC motor, battery, connecting wires, switch, cardboard house model, optional relay and a cloth-stand model as required materials. (howtofunda.com) The same page says the parts are intended to be easy to find and low cost. The howtofunda video listing also points to craft and hobby materials used in the display model, including paper, glue and electronic hobby components. (youtube.com) The emphasis in both the page and the video description is on a demonstration model rather than a full-scale household installation. ### What exactly happens when rain hits the sensor? (howtofunda.com) The howtofunda page says water droplets falling on the sensor send a signal through the circuit and activate the DC motor instantly. It says the motor then either pulls the clothes inside or closes a protective roof over them. The YouTube description frames the same action as an automatic cloth collector designed to keep clothes from getting wet during unexpected rain. (howtofunda.com) It says the model is meant to demonstrate a practical home-automation idea with a visible mechanical response when water is sensed. ### Why did commenters and hobby accounts focus on school use? The howtofunda page says the model is “ideal” for school science exhibitions, Inspire Award projects and classroom demonstrations of circuits, conductivity and automation. (howtofunda.com) It also says the project is meant to help students learn practical problem-solving and basic electronics through a real-world example. (youtube.com) That framing matches the presentation in the video listing, which labels the build as a science-exhibition working model. The project is presented as a teaching aid and hobby demonstration, not as a commercial product. ### What are the limits of the design shown? The howtofunda page says the system depends on proper sensor placement and battery power. It also presents the build as a model made from cardboard and simple components, which indicates the demonstration is suited to exhibitions and prototypes rather than direct outdoor deployment in the form shown. (howtofunda.com) That assessment is an inference based on the listed materials and the miniature setup shown by howtofunda. (youtube.com) The howtofunda materials remain available on its website and YouTube channel, where the project page and demonstration video were published in March and April 2026, respectively, and were still accessible on May 21. (howtofunda.com)