I have the code for this project completed. Basically I have a scenario in which when a particular device sounds and alarm, it will also create a voltage to go to a GPIO input and register as a high, or registering as 1. I must first state that my understanding of circuitry is limited. I understand basic circuit analysis up to transformers, but not board logic. My first question is in the event that my input voltage cannot be lowered to at or under 3.3 volts, what would be the best method of dropping that voltage? I know that DC-DC converters exist, but they are expensive. I also know that either a voltage division setup using resistors can be used to drop the voltage as well as a zener diode or even a voltage regulator.
Second, I have the button motor, but it requires about a 300 milliamp source. I know that to stay in safe operation, the Pi should not output more than 16 milliamps. What is the best way to amplify this value? I am also curious as the best way to include an external power source, such as a battery. Any aid in this matter is greatly appreciated. I understand that many try to use transistors to increase the voltage.