Adafruit USB Isolator - 100mA Isolated Low/Full Speed USB Category_Linux Embedded/OLinuXino A13 SIM7000C Arduino NB-IoT/LTE/GPRS expansion shield

SIM7000C Arduino NB-IoT/LTE/GPRS expansion shield is the best solution to applications of low power consumption

A full datasheet for the relays used on the RLY02 is here: RM85 datasheet

a magnetic rotor will rotate and the rate of rotation will vary with the rate of flow

see the 3pi+ 32U4 Robot Kit with 30:1 MP Motors (Standard Edition Kit)

We recommend the extended mounting bracket for wheels with recessed hubs

Adafruit USB Isolator - 100mA Isolated Low/Full Speed USB Category_Linux Embedded/OLinuXino A13 SIM7000C Arduino NB-IoT/LTE/GPRS expansion shieldHave some USB logic analyzer, multimeter or oscilloscope and bumping up against the frustration of a shared earth ground? The Offspring (known for being electrical engineers) wisely sang "Ya gotta keep'em isolated!" Power and signal isolation improves common mode voltage, enhances noise rejection, and permits two circuits to operate at different voltage levels. This handy little low cost USB Isolator is exactly what you need to provide protection