Vernier Software and Technology
Vernier Software & Technology
Arduino and Vernier Sensors

Calibrating Voltage Probes

There are two standard Vernier analog (BTA) sensors that use a different input line than the rest of the analog sensors. These are the Voltage Probe and the 30-Volt Voltage Probe. These two sensors use the +/-10 volt input line (SIG2) on the BTA connector.

The Arduino A/D converter can only handle voltages in the range of 0 to 5 volts. The Vernier Arduino Interface Shield has the necessary circuitry built in to change the sensor output from +/-10 volts to 0 to 5 volts. If you connect a sensor to the Analog 2 port on the shield, you can read voltage values with the sample sketch, VernierTutorialLinearCalibration. Substitute the following slope and intercept values:

For the Vernier Voltage Probe used with the Vernier Arduino Interface Shield:

  • slope: 4
  • intercept: -10

For the Vernier 30-Volt Voltage Probe used with the Vernier Arduino Interface Shield:

  • slope: 15.41
  • intercept: -40.35

If you are connecting the sensor to a Analog Protoboard Adapter wired to Arduino pin A2, you will need to build a voltage-divider circuit on a breadboard with two resistors and a diode to change the sensor output from +/-10 volts to 0 to 5 volts. A simple circuit is shown below:

Simplified Circuit for Use with +/-10 Volt Sensors

Note that this circuit will not work with negative voltages; you need to keep the signal into the voltage probe positive. If you try to measure negative voltages the Arduino will read an incorrect voltage (0 V), but nothing will be damaged. You can read voltages with the VernierTutorialLinearCalibration sketch after substituting the following slope and intercept values:

For the Vernier Voltage Probe used with the Vernier Analog Protoboard Adapter:

  • slope: 2
  • intercept: 0

For the Vernier 30-Volt Voltage Probe used with the Vernier Analog Protoboard Adapter:

  • slope: 6.356
  • intercept: 0

Contents

Introduction

Vernier Engineering Contest

Vernier recognizes instructors for creative uses of Vernier sensors to introduce engineering concepts and/or practices. Vernier Engineering Award »

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