Question regarding +/- power

[shawn]

Suppose I have an effects pedal that I want to build but in order to power it I would need two 9v batteries to supply + AND - 9v with a common ground. How would I go about using a walmart instead?

[Unbeliever]

Dunno, but it sure as hell isn't going to be portable. 

[d95err]

If you use an AC Wallwart, you can use a voltage doubler to get a bipolar supply. Take a look at Aron Nelson's "Shaka Tube".

[Floyd Pepper]

Here's how to get +9v, command ground and -9v from two 9v batteries.


The above is linked to Music From Outerspace DIY synth site.
http://www.musicfromouterspace.com/analogsynth/SOUNDLABMINISYNTH/soundlab.html#LFO
I'm currently in the process of building one of their SoundLabs.

This is also worth a look if you like crazy oscillating beeping noises
http://www.musicfromouterspace.com/analogsynth/YOUR_FIRST_SYNTH/YOUR_FIRST_SYNTH.html

[Paul Perry (Frostwave)]

For my boxes that use + 15 and -15, I use a 14v AC plugpack. One of the outputs goes to ground, the other goes to two diodes, arranged to give a + and a - half wave rectified supply.
The raw + goes to a +15 regulator chip, LM7815.
The raw - goes to a -15 reulatr, LM7915. And that's it.
For +-9, use a 10 or 12v AC plugpack  and + and-9v regulators.
You might get lucky in a thrift & find 10V AC plugpacks used on old modems!
***using regulators? Try reading the data sheet first! I wish I had!***

[R.G.]

A fair fraction of the questions here in this forum can be answered by "Go read the tutorials at GEO - http://www.geofex.com."

In this case, it's spot on. Go read "Power Supplies Basics" at http://geofex.com/Article_Folders/Power-supplies/powersup.htm. You'll not only get your question answered, you'll know a whole lot more about power supplies.

Then rip through all of the "Technology of..." articles, the Circuit Sweepings, and look through all of the New At GEO page for things that hit your fancy. You'll get a lot of questions that you haven't thought of yet answered.

[shawn]

awesome, thanks guys.

battery isn't an option. i hate using batteries. time to read.