madbeanpedals::forum

Projects => General Questions => Topic started by: Bret608 on April 26, 2013, 03:12:54 PM

Title: Positive ground fuzz question
Post by: Bret608 on April 26, 2013, 03:12:54 PM
Hi everyone,

Now that I'm off and running with my GE tranny testers, I've managed to put together a decent set for a MKII-type circuit. I'm thinking of building this:

http://tagboardeffects.blogspot.com/2012/02/marshall-supa-fuzz.html

A couple of questions as I've never built or tested a positive-ground circuit.

1) Is there a safe way to test the board on my jkokura-style testing rig? Needless to say, I'd use a battery rather than the rig's wall wart powered leads. Just wondering if there is anything else to consider.

2) On the vero layout, lug 1 of the attack pot goes to ground. When I box it, what would be the best place to attach that?

Thanks,

Bret
Title: Re: Positive ground fuzz question
Post by: midwayfair on April 26, 2013, 03:43:34 PM
1) You can use the power leads -- just swap them from how they're normally hooked up and don't daisychain the power supply. No sense draining a battery in the test phase.

2) Star ground, usually the input jack tip.
Title: Re: Positive ground fuzz question
Post by: Bret608 on April 26, 2013, 03:51:32 PM
Perfect! I'm all set then. My test rig is indeed not daisy chained; I just run it off a decent Ibanez AC adaptor. Thanks as always.
Title: Re: Positive ground fuzz question
Post by: lincolnic on April 26, 2013, 11:11:11 PM
Quote from: midwayfair on April 26, 2013, 03:43:34 PM
2) Star ground, usually the input jack tip.

Shouldn't that be the input jack sleeve?
Title: Re: Positive ground fuzz question
Post by: midwayfair on April 27, 2013, 04:32:29 AM
Quote from: lincolnic on April 26, 2013, 11:11:11 PM
Quote from: midwayfair on April 26, 2013, 03:43:34 PM
2) Star ground, usually the input jack tip.

Shouldn't that be the input jack sleeve?

Eep! Yes!  :-X
Title: Re: Positive ground fuzz question
Post by: juansolo on April 27, 2013, 07:33:05 AM
This is your friend and finds it's way into all my -9v builds that use a PSU.

(http://juansolo.demon.co.uk/stompage/schematics/Tonebenders/positive%20ground%20fuzz%20adapter%20vero%20verified%20v1_0.gif)

You don't need the sag trimmer or the LED resistor, omit those and the two cuts outside the IC. Connect -9v to the track above ground on the right. A seriously tiny board when it's done, easy to hide ;)