The Voltage Sensor Detection Module is a simple and effective voltage divider circuit designed to allow microcontrollers with low-voltage ADC inputs (like Arduino, ESP32, or STM32) to measure much higher DC voltages. Based on a 5:1 voltage divider ratio, it steps down a high input voltage to a safe level that the microcontroller can process.

Specifications

• Voltage Input Range: DC 0V – 25V
• Voltage Detection Range: DC 0.02445V – 25V
• Analog Resolution: 0.00489V
• Internal Resistor Ratio: 30k / 7.5k (5:1 Ratio)
• Operating Voltage: Works with both 3.3V and 5V microcontrollers

Pin Configuration

• Input (Screw Terminals):
  • VCC: Positive terminal of the voltage source to be measured (0V – 25V).
  • GND: Negative terminal of the voltage source.
• Output (3-Pin Header):
  • S (Signal): Connects to the Analog Input (ADC) pin of your microcontroller.
  • + (VCC): Not strictly required for the divider, but can be connected to the MCU's 5V/3.3V.
  • - (GND): Common ground connection with the microcontroller.

Features

• Simple Passive Design: Uses high-precision resistors to divide input voltage, requiring no external power for the core sensing logic.
• Safety Step-Down: Reduces a 25V signal down to 5V (for Arduino Uno) or a 16.5V signal down to 3.3V (for ESP32/ARM), preventing damage to sensitive GPIO pins.
• Plug-and-Play Compatibility: Directly compatible with standard ADC pins on most development boards.
• Compact Footprint: Small enough to be integrated into battery monitoring systems, solar controllers, and DIY power supplies.

Calculations & Usage

• The 5:1 Ratio: The module divides the input voltage by 5. For example, if the input is 25V, the "S" pin outputs 5V.
• Arduino Code Logic: To get the actual voltage in your code, you must multiply the ADC reading by 5.
  • Formula: Actual Voltage = (ADC Value X Reference Voltage / 1024.0) X 5
• 3.3V Limit: If using a 3.3V microcontroller (like an ESP32), the maximum safe input voltage is restricted to 16.5V (3.3V X 5).

Common Applications

• Battery Level Monitoring: Real-time tracking of 12V or 24V battery banks (Lead-acid or Li-Po).
• Solar Panel Tracking: Monitoring the output voltage of solar arrays.
• Power Supply Projects: Adding a digital voltmeter display to a DIY bench power supply.
• Remote Telemetry: Sending voltage data via IoT for remote equipment monitoring.