Context: A digital phase-controlled light dimmer system.
- 120V AC mains
- I use an isolating transformer (and rectifying circuit) to generate +12V and +5V DC rails.
I want to use reverse phase control (I've read that this produces less EM noise), so I'm looking to switch the AC mains using 2 Power MOSFETS (e.g. FDB14N30) with the source pins connected together.
In order to put the MOSFETs into the "on" state, I need to raise Vgs to 10V-30V, but in order to do this, I think I need to hook up the MOSFET source pins to my isolated ground rail, and the gate pins to my +12V switching signal.
By doing this, have I defeated the whole purpose of an isolated power supply, in terms of danger of death and damage to components?