How to Use Voltage sensor: Examples, Pinouts, and Specs

A voltage sensor is a device that measures the electrical potential difference between two points in a circuit. It provides real-time voltage readings, which are essential for monitoring and controlling electrical systems. Voltage sensors are widely used in applications such as battery monitoring, power supply regulation, renewable energy systems, and industrial automation. They are particularly useful in scenarios where precise voltage measurement is critical for system performance and safety.

Below are the general technical specifications for a typical voltage sensor module (e.g., a voltage divider-based sensor like the commonly used 0-25V sensor module):

• Input Voltage Range: 0V to 25V DC
• Output Voltage Range: 0V to 5V DC (scaled for microcontroller ADC input)
• Accuracy: ±1% (varies by model)
• Operating Voltage: 3.3V or 5V DC (compatible with most microcontrollers)
• Input Impedance: High (to minimize circuit loading)
• Dimensions: Typically small, e.g., 30mm x 15mm
• Interface: Analog output

The following table describes the pinout of a standard voltage sensor module:

1. Power the Sensor: Connect the VCC pin to the 5V or 3.3V output of your microcontroller and the GND pin to the ground.
2. Connect the Voltage Source: Attach the voltage source to be measured across the VIN+ and VIN- pins. Ensure the input voltage does not exceed the sensor's maximum rating (e.g., 25V).
3. Read the Output: Connect the OUT pin to an analog input pin on your microcontroller. The output voltage will be proportional to the input voltage, scaled down by the sensor's internal voltage divider.

• Scaling Factor: Most voltage sensors use a voltage divider to scale the input voltage. For example, a 0-25V sensor typically has a scaling factor of 5:1. This means the output voltage is 1/5th of the input voltage. Ensure you account for this factor in your calculations.
• Input Voltage Limits: Do not exceed the sensor's maximum input voltage, as this may damage the sensor or connected devices.
• Calibration: For precise measurements, calibrate the sensor by comparing its readings with a known reference voltage.
• Noise Reduction: Use decoupling capacitors or software filtering to reduce noise in the output signal.

Below is an example of how to use a voltage sensor with an Arduino UNO to measure a voltage and display the result on the Serial Monitor.

// Define the analog pin connected to the sensor's OUT pin
const int sensorPin = A0;

// Define the scaling factor (e.g., 5:1 for a 0-25V sensor)
const float scalingFactor = 5.0;

// Define the reference voltage of the Arduino (typically 5V)
const float referenceVoltage = 5.0;

void setup() {
  // Initialize the Serial Monitor for debugging
  Serial.begin(9600);
}

void loop() {
  // Read the analog value from the sensor
  int sensorValue = analogRead(sensorPin);

  // Convert the analog value to a voltage
  float voltage = (sensorValue * referenceVoltage / 1023.0) * scalingFactor;

  // Print the measured voltage to the Serial Monitor
  Serial.print("Measured Voltage: ");
  Serial.print(voltage);
  Serial.println(" V");

  // Wait for a short period before the next reading
  delay(1000);
}

1. No Output or Incorrect Readings:

   • Cause: Incorrect wiring or loose connections.
   • Solution: Double-check all connections, ensuring the VCC, GND, and OUT pins are properly connected.

2. Output Voltage Exceeds Expected Range:

   • Cause: Input voltage exceeds the sensor's maximum rating.
   • Solution: Verify the input voltage and ensure it is within the sensor's specified range.

3. Fluctuating or Noisy Readings:

   • Cause: Electrical noise or unstable power supply.
   • Solution: Add decoupling capacitors near the sensor or use software filtering techniques.

4. Arduino Displays Incorrect Voltage:

   • Cause: Incorrect scaling factor or reference voltage in the code.
   • Solution: Verify the scaling factor and reference voltage used in the calculations.

Q: Can I use this sensor to measure AC voltage?
A: No, this sensor is designed for DC voltage only. Measuring AC voltage requires additional circuitry, such as a rectifier and filter.

Q: What happens if I reverse the VIN+ and VIN- connections?
A: Reversing the connections may result in incorrect readings or damage to the sensor. Always connect the terminals as specified.

Q: Can I use this sensor with a 3.3V microcontroller?
A: Yes, most voltage sensors are compatible with 3.3V systems. However, ensure the output voltage does not exceed the microcontroller's ADC input range.

Q: How do I improve the accuracy of the sensor?
A: Calibrate the sensor using a known reference voltage and account for any offset or scaling errors in your calculations.