I have a power supply for a project I am working on and I am fairly new to Arduino and electronics.
My Arduino Uno R3 (non-SMD) controls a transistor that controls a 5v relay that triggers a electronic door strike which is powered by a 12VDC power supply.
I was hoping to also power my Arduino off the same power supply using the Vin. I read that it supports 7-12V input and that 12V is not recommended as it will make the voltage regulator on the Arduino very hot if not burn up overtime.
I tested my 12VDC 3A power supply on Vin in hopes of not releasing the magical smoke inside, and everything works fine but the voltage regular does get extremely hot; well enough to burn my finger.
How would I go about taking this 12VDC 3A input and reducing it down to around 9VDC for the Arduino Uno R3 to handle more comfortably?