noob having voltage problems

[diblit]

hi,
i have 2 questions.
first: i am attempting to redesign a schematic for an amp and make it into a pedal.  the voltage going into the overdrive portion says its   +15v   and -15v     but i want to be able to use it with my regular 9v power supply.   so how would i convert it from +15v/-15v to  +9v/-9v  ?     
or does it matter at all because the schematic is set up for 15v+/- so if i only ever use 9v would it work fine and not blow anything up?


second which maybe should be the first question:
how do i take the 9v power supply and change it into +9v  & -9v?
what kinds of resistors/capacitors would i need and how should i lay them out?


thanks for your time  =)
-Noob

[mgwhit]

The way to get  +9v/-9v from your regular 9v power supply is to use a charge pump like the TC1044SCPA.  Check out the MadBean Road Rage board for an example of how to do this.  Or better yet, look at the MadBean Boneyard circuit for an example of how to do exactly what you're trying to do.  It uses a 1044 to feed an op amp +9v and -9v.

Once you do this, you're essentially working 18v peak-to-peak.  I wouldn't use any components that aren't at least rated for 25v, and you'd probably be safer with 35v ratings.

[Jack Deville]

Voltage is defined as a [electrical/charge] potential between two conductors/sources.
Thus, a voltage cannot exist when referenced from a single source.

Expanding upon this definition, a +/- 15VDC supply can be considered a +30VDC supply, with respect to low potential or a dual +/- 15VDC supply with respected to +15VDC.

Creating a +/- 9VDC supply can accomplished equally in the following two examples:

- A single +18VDC (when referenced to ground or low potential) referenced at 9VDC
- A single +9VDC with respect to ground potential and an additional single -9VDC with respect to ground potential.

Both examples express identical conditions, highlighting different reference points.

Capacitive charge pump circuits have their own host of limitations which may or may not become apparent or be hazardous to the specific circuit in question.  Determining whether or not hazards are present is a case by case situation and must be evaluated after analysis of the circuit in question.

I would highly recommend disregarding "carpet bomb" solutions as they often have a tendency to do more harm than good.  A potentially successful solution is to study capacitive charge pump theory of operation (sounds much more daunting than it actually is) and consider why you are even pursuing the use of a charge pump circuit to begin with.

As far as canned solutions go, look at the LT1054.  It is a far superior IC than the MAX1044 and its clones.