I have a project where I need multiple voltages onboard - 10v, 5v, and 3.3v. The supply to the circuit will be assumed to be an unregulated wall wart with a voltage high enough for the 10v reg. Assume these are all "standard" linear 78xx regulators. Are there any rules of thumb for designing such a power circuit?
For instance, would it be conventional to supply the wall wart voltage to the 10v reg, then supply the regulated 10v to the "in" pin on the 5v reg, then the regulated 5v to the "in" pin on the 3.3v reg? Or, would you design based on current requirements at each voltage?
What about capacitance? When using a single regulator on it's own, I'd just follow the datasheet or other convention for input and output caps. But, if I have three regs tied together like this, do I really need all the caps called for with each regulator?
For instance, assume (hypothetically!) that the 10v and 5v regs both call for a 10uF electrolytic and a .1uF ceramic on the inputs and outputs. Assume I'm feeding the output from the 10v reg directly to the input on the 5v reg (as well as to the portion of the circuit that requires 10v, of course). Do I need TWO 10uF electrolytics, and TWO .1uF ceramics, right there next to each other, "between" the two regulators?