Im about to tackle the obsidian but readin gJoes site I came across something my newbie brain just couldnt wrap around-

"The circuit runs on a -9v supply, so hook it up just like you would a normal circuit but reverse the polarities of the battery and electrolytic capacitors."

Can someone lend a hand and translate this to monkey speak for me?

Thanks!

Audioguy

Well... I think that's perhaps a little misleading.

Basically, electrolytic caps need to be oriented correctly in order to work properly. They normally have an indication as to which is the negative terminal. In all effects, the negative terminal must be at a lower potential (voltage) than the positive terminal. Fairly obvious.

So, the positive terminals in your case will be connected to the ground of the circuit. Also, the POSITIVE terminal of the battery is connected to the ground. The NEGATIVE terminal is the one that connects to the other parts of the circuit.

Interesting... do you happen to know if the same holds true for both Joes and Gringo's PCB layouts?

The layouts don't really matter. The easy way to understand this is that the transistors are "negative", meaning the operate on a negative voltage. Just flip the battery around, and pretend the + and - are reversed when wiring it up. The electrolytic caps are also reversed. That's it!

Fuzz-Faces and most other germanium pedals are the same way, FWIW. A battery should be used on this unless you have a dual-polarity supply, like +9 / 0 / -9, so that the grounds are all on the same line. Otherwise something might short out.

-Joe

QuoteInteresting... do you happen to know if the same holds true for both Joes and Gringo's PCB layouts?

You should use joe's layout if you are in a hurry, as i'm revamping all the layouts i made for joe's designs. Will be up soon (i hope).

I like the layout that you did for the vulcan- I also like the LOOK of Joes layouts... so either way Im cool.
Im not in a big hurry I was kicking around the idea of a late night build (as most of mine are done in the wee hours) for the coming weekend.


Audioguy