Using A "CPU Superviser"(Voltage detector) as a voltage regulator.

Ok tell me if this is old news or if it just plain nonsense:

Is there any reason you couldn't use one of those voltage level detectors like they use in BEAM robotics to make a Buck mode regulator?
as in set it up to monitor the voltage across a capacitor and add a bit more charge if the output got too low?

the dectector chips cost about a dollar fifty and have 20mv hysterysis with 1-200us response time. this might not be the best regulation ever but combined with a linear regulator or used for things like led driving it looks like a good idea if it works. i know they use them for basically relaxation oscillators to store charge and dump it in a motor for solar bots. this would basically be a relaxation oscillator in reverse, with the switch charging the cap and the load discharging it. because the voltage detector IC never(or should never) be exposed to inuput voltage the whole system should be rated to the voltage of the transistor you use to charge the cap through.
so whadaya think? would it work?

You need a compensated feedback loop to make a proper buck mode regulator. Since the chips to do the control with the feedback built-in are available at low cost, I don't see any point in trying to kludge one together using a chip not made for that purpose.

What you are planning to do is called a hysteretic regulator.
There are many details involved in switchmode regulators (current limit is one of them), and there are so many ICs specifically designed for this purpose, that I agree with Carl, the best solution is to actually build your regulator with the proper IC.

The chips used in beam robots are designed for use in regulated PSU's, their use in beam robots is the obscure use. They are used in most TV's, VCR's, DVD's etc.

Thank you all for your input! it is appreciated. after hearing all of your opinions i think maybe a PIC Chip would do a lot better, especially since you don't need a current sense resistor if you know the filter capacitor value and your load has negligible capacitance like driving LEDs or such. If i do the project i was thinking about i might use a pic.