I have a device that runs on -5v DC but I only have 120V AC. I need to build a power supply that can convert 120v AC to -5v DC. I need to draw the best power supple and indicate the wave form at each stage.
The first is likely a specific point of the assignment.
The second is, by far, the worst offense.
Close on it's heels is no indication of what constitutes "best possible" -- I hate assignments that pull that crap.
I'd be tempted to offer up something that is a 5.1 V zener, a resistor that brings the zener to 5 V at the peak voltage, and a large, low-leakage capacitor. So what if it takes it minutes to build up to -5 V -- the specs say nothing about that. So what if it can only deliver a few microamps of current before the voltage is pulled way off -- the specs say nothing about that.