please help me decide if this will work:
Primary objective: Amplify 0~3v input signal to 0~12V output signal.
I understand that this whole setup is a bit unusual, since I can simply connect the +input of opamp to 12VDC, and with my resistors' values, 3v input could be amplified to 12V (I'm 80% sure). But nevertheless I want to know if this odd scheme will work? I think I'll have to be very careful with my OpAmp output, which dictates the 3904?
Edit: My most sincere apologies there SHOULD BE a pullup resister between the collector and the 12V, for some reason this slipped through my double check, incredible, I'm new to eagle and the copy paste in it isn't that intuitive.
The resistor has a value of 2K.
Sorry for the delay but a few things to clarify, apologize again if I overlooked your question, there are too many and I'm kind of really busy:
200mA is supposed to be the current drawing in. This whole setup is kind of to sink current from lower-tier components that will be connected to this interface, so 12v/2K = 6ma isn't what I'm talking about.
The resistor should be 90k/30k, as some of yous suggested, my mistake.
Oscillation: I believe your concerns are quite legit but please be advised that the input will be mostly "static" voltage signals, meaning it rarely changes more frequently than 5 times per second, so I'm skeptical that it will be that huge of a problem, I could very well be very, very wrong.