New to Arduino and electrical circuitry in general. I want to design a remote control for my car's radio which can be hard-wired. I have found a tutorial which describes how to send the different commands by changing the resistance on the line. Can an Arduino be used to simulate this resistance changes without the need for multiple resistors and switches? Below is a circuit design which has multiple switches with resistors of differing resistance each one controlling a different function of the radio. Any help or suggestions would be appreciated.