How to up 5 V to 9 V

Hi guys! I have some unexpected problem for our project, wherein one of the sensors need a 9 V supply voltage from the MCU which is Arduino Pro Mini in our case. :confused:

Based on the general diagram I attached to this post, how can I accomplish this with a few additional components? Thank you anyone. :slight_smile:

If there are any clarifications or questions regarding my post, please do comment them.

You can convert 3.7V or 5V to 9V with a step up or boost regulator, but it is a bad idea to use the Arduino 5V output for this, as it will introduce switching noise into the Arduino and possibly overload the Arduino voltage regulator.

Better to use a separate power supply for the gizmo and/or a step down regulator. Don’t forget to connect the grounds.

50mA seems rather high for a smoke alarm (HIS-07 datasheet). That could draw 150mA from the 3.7volt battery when stepped up from there. Leo..