10/28/19

Solenoid Control

Because our solenoids require 1 A of current at 12 V each and the Arduino is only capable of transferring 200 mA at 5 V max, we need to use semiconducting switches to remove the Arduino from the direct current flow. We do this by using a 60V 3A NPN (Negative, Positive, Negative) MOSFET (metal–oxide–semiconductor field-effect transistor) and using the Arduino to control the gate rather than the entire current flow. This circuit also requires a diode between the positive and negative rails of the solenoid to prevent back-EMF from damaging the MOSFET chip. We also included a 200 Ohm resistor to protect the Arduino from the potentially harmful currents in case something goes wrong.