I think maybe you are being too consumed with voltage and ignoring current requirements.
I think maybe I don't know the difference between voltage and current. :)
Don't capacitors supply current? Now that I think about it, I'm not sure. I guess when I see a pic of noise on an oscilliscope, that's probably plotting voltage over time, and if the cap is supposed to smooth that out, then it's smoothing out the voltage, not the current. Then again maybe it is plotting the current. I don't know. :/
How many servos are you trying to drive and what is the maximum current demand for the servos? Only then can you determine what size batteries and voltage regulator is proper for your application.
I'm trying to drive two sub-micro servos. I don't know how much current they require, because servos don't come with datasheets, and the current varies depending on the load. Also, I cannot be sure the same servos will be used by everyone. So I have to make a guess as to the current requirements.
If you take a look at this you can see the stall current of a number of servos plotted on an oscilliscope:
The ones at the top are smaller servos, the ones at the bottom are larger ones. The servos I'm using are even smaller than the smallest servos shown here, and the peak current is when the servo arm is being prevented from moving. Based on these numbers, I'm assuming that the sub-micro servos I'll be dealing with probably won't ever draw more than 500mA each. Also, based on other sources, I believe I can expect the servos to draw less than 200mA each when active normally.
So the current draw I'm looking at for the two servos together is anywhere from say 400mA to 1A. And the voltage regulator I have is supposedly good to 1.5A, though I have yet to check the datasheet to see exactly how much current it can handle without a heat sink as I have it set up now.
(When I get the boards made, I may leave some bare copper there as a heat sink if I have the space. But I'm not sure yet if I'll have space in the prop for a real heat sink. The voltage regulator gets hot to the touch when I use the servos for a whiile, but not too hot.)
Are you sure about that? Most r/c servos I have seen will operate between 4.5v - 6.0v - you typically want to operate them at 6.0v in order for them to develop maximum torque...
Well, the truth is the servos I'm using CAN handle 6v, but I'm designing the circuit with 4.5v in mind because many sub-micro servos can't handle more than 4.5v, and I may need to use different servos.
Also, torque isn't a huge issue here because the servos will just need to move a couple arms with leds on them back and forth. I can tell just by trying to prevent the servo horn fron turning with my fingers that it's got plenty of torque for the job.