The thing you're looking for is a 555 timer (or something similar)
A 555 timer (http://www.instructables.com/id/555-Timer/) takes in a DC signal and oscillates at a frequency determined by a capacitor and resistor attached to specific pins. You can do all sorts of fun things (http://www.555-timer-circuits.com/) if you want.
Monitor manufacturers use similar technology. After the power supply converts the AC wall signal into a DC signal, they have a timer circuit that tells the monitor to refresh every 1/10 of a second (or 1/144 of a second if your monitor runs that fast). There's no sense of "amplifying" the frequency of the wall signal - the monitor uses a completely separate signal that it generates itself.
Hope that helps clear things up!