Arduino-based DIY TDS Meter | Code and Circuit

This intermediate-level system functions by measuring the electrical conductivity of a water sample to determine its Total Dissolved Solids (TDS) value. The core of the circuit relies on a TDS sensor, which is submerged into a water sample container. The sensor probe applies an alternating voltage to prevent polarization and oxidation of the probes, measuring the resulting current flow that varies in proportion to the concentration of dissolved ions (such as salts, minerals, and metals) present in the water. The analog output signal from the TDS sensor is routed to an analog input pin on the Arduino board, which converts the continuous voltage into a digital representation using its internal analog-to-digital converter (ADC). Inside the Arduino, custom software processes this raw ADC value, applies temperature compensation factors if applicable, and translates the electrical metrics into parts per million (PPM) units. Once calculated, the Arduino communicates with an SSD1306 OLED display using the I2C protocol, updating the screen dynamically to present real-time water quality data. The entire assembly is interconnected using standard connecting wires, allowing continuous monitoring of fluid characteristics in practical settings.