ZMPT101B AC Single-Phase Voltage Sensor Module

The ZMPT101B module gives a microcontroller project a safe, isolated way to measure AC mains-level voltage, using a precision onboard voltage transformer to step the measured voltage down to a safe, scaled analog signal rather than exposing the microcontroller's low-voltage circuitry to mains voltage directly. That onboard transformer is the module's core safety feature, providing genuine electrical isolation between the high-voltage side being measured and the low-voltage side feeding into a microcontroller's ADC pin.

An onboard op-amp circuit handles signal sampling and compensation, cleaning up and scaling the transformer's output into a usable analog signal, and the module includes an adjustable analog output, letting the scaling be tuned to match a specific microcontroller's ADC reference voltage and measurement range. It's rated to measure AC voltage up to 250V, covering standard mains voltage in most regions directly without needing an external voltage divider or additional scaling circuitry.

It's designed to work with Arduino, ESP8266 and Raspberry Pi platforms, and supply voltage for the module itself runs from 5V to 30V, giving flexibility in how it's powered within a larger project. At just 49.5mm by 19.4mm, the board is small enough to fit into a compact enclosure alongside other monitoring electronics, and operating temperature is rated from -40C to 70C, giving it reasonable tolerance for installation in an unconditioned utility space.

Builders adding mains voltage monitoring to a home energy monitor, a smart plug project, or any system that needs to know the actual AC voltage level rather than just assuming nominal mains voltage, will find the ZMPT101B's isolated transformer design a genuinely safer approach than trying to sample mains voltage through a resistor divider alone.