Easiest way to get positive and negative 6 volts??

Appliancide*

So I breadboarded the Forrest Mims percussion synthesizer and I think this simple circuit is worthy of a box! Is there an easy way to get -and+ 6 volts using batteries? Wall wart would be ok, but I would prefer the device be portable.

Also, would it be necessary to use a transformer to wire a line out in place of, or in addition to, the speaker to match line-in impedance?

Sorry for the basic questions.

scriptstyle · Joined: Jan 22, 2008 Posts: 250 Location: nj

i have never seen the forset mims drum circuit? i have read some of his material and i thought he was strictly a logic guy? any way you could use the old 2 9volts back to back if 9volts isn't to much? post the schemo im interested...

guitarfool

Appliancide* · Posted: Sun Jan 18, 2009 9:31 pm Post subject:

Thanks for the info!

I haven't seen the schematic online. I'll see if can scan it at school. It's from the book "Timer, Op Amp & Optoelectric Circuits and Projects". Definitely worth checking out.

As far as the audio out goes, I just want a line level signal. I will be running it into an amp or a mixer.

Appliancide* · Posted: Mon Jan 19, 2009 6:19 pm Post subject:

Here's the circuit:

Posted Image, might have been reduced in size. Click Image to view fullscreen.

There is also another Forrest Mims percussion synthesizer in the electronics learning lab manual which can be downloaded for free here

scriptstyle · Joined: Jan 22, 2008 Posts: 250 Location: nj

thanks for sharing!!

guitarfool · Posted: Mon Jan 19, 2009 9:40 pm Post subject:

Well, there ya go. I thought you were trying to use a line out type of signal to drive a speaker, but it's the other way around. Embarassed

Mr. Mims is using the 386 here, so you're set. To get that line level signal out of it, try tapping where C5 joins R5. You'll probably need to add an attenuator for it, but no need for transformers (unless you're going into balanced XLR or something).

Forrest Mims wrote quite a few books on analog and digital electronics - like the Engineer's Notebook and the Circuit Scrapbook. He's also done a lot of stuff with sensors (did you know you can use a regular LED as a detector?). He was also editor for the Amateur Scientist column in Scientific American magazine. He has a website: http://www.forrestmims.org