I am currently trying to use Arduino to control a device that requires 3V of power supply (DC powered). I know the arduino has a pin that provides 3.3V and a pin that provides 5.0V. I'm unsure as to whether these pins can be used to power a device that requires lower voltage like the one I am using. I also want to be able to control when the current is passing through to the device (like when you use a relay). I initially bought a 5V relay that I had planned to use to help control when the current was passing through to the device, but I realized that this may not be suitable since the device requires 3V.
Please advise as to how I can achieve this. Thanks!
A relay controlled by a 5V signal is not limited to controlling a 5V device. It can switch any combination of voltage and current within its specification. I think that you may have misunderstood how a relay works
Rule #1 A Power Supply the Arduino is NOT! Post annotated schematic of what you are trying to do. It should be very easy with the selection of appropriate parts. Part of that selection is what are you trying to power, how much current does it require, just as important then voltage. Is this device switched On/Off, PWM, ???