My circuit has a microcontroller, it uses power from a DC transformer (120V to 12V DC). My circuit also control an pneumatic valve which also use 12V DC. Almost every time when the pneumatic valve opens, the current becomes unstable. This makes the microcontroller restart.
Some guy suggested me to use two power sources. In my case, it is very rare for a microcontroller and a pneumatic valve to use two DC transformers. How can I build "two power sources" in a microntroller circuit?