Hey all:
I'm working on adapting a simple FET boost from one of my favorite guitar amplifiers into stompbox form. While I have no problems with the actual FET booster, I'm at a loss about designing an elegant power supply. The original circuit ran on +/- 15VDC from a linear transformer. Most guitar players use a standard 9VDC plugpack. A linear transformer is obviously out of the question, as I am trying to keep this box as small as possible. While I know how to create +/- 15V from a single power supply, the only ways I can think of doing it are pretty ugly and expensive, requiring at least two ICs.
So far, I've come up with 2 pretty stupid ideas.
Option 1:
18v plugpack-> 78L15-> LT1054 to do the inversion:
This is the simplest way I can think of doing it, but it's messy. The LT1054 is a pretty expensive chip (compared to the ICL7660 I normally use), and you would lose the ability to use a common daisy chain power supply, which I would prefer.
Option 2:
9V plugpack-> 7805-> Murata 5v to +/- 15v DC-DC converter.
This is not only an obnoxiously expensive solution, it's extremely inefficient (estimates say the converter alone will draw 100mA, which is definitely overkill for a single FET circuit!)
I'm at a bit of a loss. Are there any single-chip solutions that can solve my problem? If not, what would be some simple ways to get the +/- 15V? I don't need a ton of current, or insane efficiency, just something practical and simple. Thanks!