Adding a DC jack socket to a positive ground pedal?

[fuzzmonger]

Hi guys,

I've got a job coming up on a Ge positive ground Fuzz Face RI; fella wants a DC socket added to it. I was thinking it wouldn't be a problem to add a negative centre DC socket to it and chuck it back on his pedalboard with his power brick but something tells me it's not going to be that easy. Can I do that, or will I need to flip the circuit to negative ground (a la Fuzz Factory) or will it require a seperate reverse polarity power supply?

Regards,
-Fuzzmonger

[slacker]

You'll have to either run it off its own power supply or convert it to negative ground. You can't run negative ground and positive ground pedals off the same supply, negative ground pedals have the negative pin (0 volts) of the DC jack as ground, positive ground pedals have the positive pin of the DC jack as ground (+9 volts). The grounds of the different pedals are connected together via the sleeves of the in/out jacks and the patch cable, so you're connecting the two pins of the DC jack together shorting out the power supply.

[rousejeremy]

There's a way to use MAX1044 to reverse polarity from the jack. I know there's a layout for a board here somewhere.

[fuzzmonger]

I see. Changing it to negative ground wouldn't be too hard. I read somewhere that it isn't recommended as it can cause freaky motorboating and oscillation. No reason why it would though, right?

-fuzzmonger

[kodiakklub]

the pumped up tone bender PDF from guitarPCB.com is an excellent source of info for exactly what youre doing. i would use the TC7660SCPA instead of the max1044. same pinout. everyone says they burn up very easily.