Different Voltages
Kevin-
You can easily run the 12V and 5V stuff right off the 24V battery pile by using some switching voltage regulators. National Semiconductor and others make some really nice switchers for just your purpose.
National even calls theirs the SimpleSwitcher series of switching regulators. When designed properly, these regulators are low-noise, compact, and VERY efficient. Speaking of efficiency, this is a MUST if you're dropping from 24V to 5V or even 12V.
In their simplest form, the Simple Switcher chips use only 2 caps (input & output), a coil and a diode. That's it!
For using two chips in close proximity to each other, you can choose models that are synchronizable to eliminate beat frequencies between the two chips' oscillators. A few more parts, but well worth it. You won't be dissappointed.
Try looking at the LM2670 (3A) or the LM2677 (5A) chips from National. They both run at 260kHz and can be synchronized up to 400kHz. They are pretty robust chips. Versions include 7-pin TO-220 and 7-pin SMT. Available outputs are Fixed at 3.3V, 5.0V, 12V. The adjustable version uses two resistors at the feedback pin to sense voltage. Anyway, check out the two links:
http://cache.national.com/ds/LM/LM2670.pdf
http://cache.national.com/ds/LM/LM2677.pdf
I have used the 5-Amp LM2677S (surface-mount) in several CPU applications before, with good results. The only time the chip got warm was when I touched it and it picked up the heat from my finger!
Hope this helps!
Steve
