Fulltone 69 mod questions

[Luke]

Hi everyone,
I was hoping for a bit of help, if possible. I think I will number these questions to make it easier for me to articulate my quieres.

1.  I read somewhere that Duane Allman et al used to useonly 'almost      
    dead' batteries in their fuzzfaces to achieve a particular tone. I have
    heard that it is possible to simulate this 'effect' by wiring a pot into the
    circut to reduce the amount of battery power going into the circut
    board. How on earth can I do this?

2.  How can I make this pedal run off of a power adapter instead of a
    battery? Is this safe to do? (I am making the PNP- Positive ground
    version of this pedal)

3.  Can I use the millinium bypass with this pedal?

Thanks for your help!
take care,
Cheers,
Luke

[petemoore]

Yes you can do the batery sag thingy I think it''s a pot on the battery clip wire...check Joe Gagans Schematics, I think there's soemthing like this on one of those...
 NO you can't run a FF on a power supply, well not a wall wart without rediculous noise problems, I could be wrong but I do know these FF's typically don't like PS's and need batteries...
 YES I'm pretty sure the millinium bypass will work with about any efkt that has 9V, an input and an output...

[BD13UK]

http://www.generalguitargadgets.com/v2/diagrams/fuzzface_b_lo_pp.gif
This is a PNP 69 schem with a power supply that may be of use to you.

[Davefx]

I know you can do the millenium with pos. ground pedals. You'll need a p-channel mosfet instead of N and reverse the polarity of both the diodes and LED.  All the info is at GEO, of course.

[Davefx]

I meant that for the M2 with the mosfets.  Same thing with the M1, I believe, but with j-fets.

[Luke]

hi gang,
Is this right? The 'battery' pot, I mean. Will this do this job, or have I drawn it wrong?
[img

[Luke]

Sorry about the above- my mistake :oops:  I drew the pot into the schmatic EXACTLY as per the 50k 'BIAS' pot on the Skyripper schematic. (ie, Between the 'input' and +9v) I left the -9v side (and indeed, the rest of the circuit) completely unaltered. Is this how to simulate the 'dying battery' type sound? Have I drawn it in correctly?Will this work?
take care,
Cheers,
Luke

[Luke]

Guys?
Is this right- Plese help, I dont want to destroy my transistors
Cheers,
Luke

[Mike Burgundy]

it won't fry the trannies, but it's NOT a dying battery sim. It just screws with the input transistors bias.
when a battery dies, two things happen: it's voltage goes down, and it's internal resistance goes up. This means it has more and more problems of churning out volts when there's current draw: the supply will "sag" depending on how hard you play.
Adding a series resistor or pot of just 100-200 Ohms in the powersupply line is the easiest way to implement this. Just lift the - line (for PNP), and insert the resistor.
If you use an adapter, you can only use that adapter for positive ground pedals. If you mix positive and negative ground on the same adapter, you'll end up with unpowered pedals and a rapidly melting adapter...

[Luke]

Thanks very much Mike,
but sorry, I still dont quite follow you  :oops: . I am working off the PNP positive ground schem; the tip of the jack goes direct to +9v, then the -9v goes to bewteen R2  and R8 (JD Sleeps' Boutique Fuzz Face schematic). I HAD put the pot in as per the Skyripper (between the tip and +9v); should I have ACTUALLY put it between -9v and the junction between R2 and R8?
Sorry to be such a nusience, but I REALLY appreciate the help
thanks again,
Luke

[Luke]

thanks Mike
did you somehow change your above post? I could SWEAR it is different. Well, its pretty late here, I guess... But thanks man- I think I got it!
Cheers,
Luke