Vernier BTA and BTD sensors all work based on 5-volts. Most Arduino models work based on 5-volts. A few, mostly newer, Arduino models are based on 3.3 volts. We do not recommend using the 3.3-volt Arduinos with our sensors for the following reasons:
– You might damage the 3.3-volt Arduino using our sensor. There is a slight risk the sensor could provide an output of greater than 3.3 volts. Here is the warning message on the Arduino Due web site: Warning: Unlike most Arduino boards, the Arduino Due board runs at 3.3V. The maximum voltage that the I/O pins can tolerate is 3.3V. Applying voltages higher than 3.3V to any I/O pin could damage the board.
– The Arduino’s A-to-D converter cannot read the sensor output properly. On most (5-volt) Arduinos, the A-to-D converter reads a count of 0 to 1023 representing voltages from 0 to 5 volts. On the 3.3 volt based Arduinos, the A-to-D converter reads a count of 0 to 1023 representing voltages from 0 to 3.3 volts.

Here is a list of Arduino Models that are based on 5-volts, which we have used successfully:
Arduino RedBoard (the one we sell)
Arduino Uno (similar form to Redboard)
Arduino Mega 5V
Arduino Leonardo
Arduino Micro (5-volt version)

Here is a list of other 5-volt Arduinos, which should work fine, but we have not tested:
Arduino Pro 5V/16MHz
Arduino Mini 05
Arduino Pro Mini 5V/16MHz
Arduino Ethernet
Arduino Pro Micro 5V/16MHz
Arduino Mega Pro 5V
Arduino Yun

Here is a list of 3.3-volt Arduinos, which you should not use with our sensors:
Arduino 101
Arduino Genuino
Arduino Due
Arduino Gemma
Arduino Zero
Arduino Pro 3.3V/8MHz
Arduino Fio
Arduino LilyPad
Arduino Pro Micro 3.3V/8MHz
Arduino Mega Pro 3.3V
Arduino Mega Pro Mini 3.3V

Arduino and SparkFun RedBoard Troubleshooting and FAQs