My new Guardline Security Alarm can send a 12 volt output signal to an accessory device. I would like to send that signal to my Rashberry pi and have it send an email to my iphone. I bought a SMAKN Dc/dc converter to step down the 12v to 3.3v Can I just direct wire them together? Any help would be appreciated. Don’t want to blow up a $100 alarm. Thanks.
If you know the voltage (is it always 12V or is it sometimes 14V) you could have used a pair of suitable resistors as a voltage divider.
As long a your DC converter or whatever circuit you end up using constrains the voltage at the Pi to 3V3 or less you will be fine.
In any case I don’t see how you could damage your alarm by tapping its 12V output (unless you chose to be deliberately inept).