DOD Fx86 Death Metal question

[gaddargaddar]

Hi I've made a PCB for this effect...I'm pretty sure that everything was connected as seen in this schematic



this the PCB that I've drawn at EAGLE  for it



and this is EAGLE's schematic



I'm confused about how to connect battery and INPUT OUTPUT jacks...
I think -4.5V is the ground of the battery and +4.5V is the "+" pole of the battery and the ground in the original schematic is probably Vbias...So I'd like to know what are the resistor values in the voltage divider between the + pole and the ground of the battery ...  any suggestions ... I tried a 100K pot between + pole and the ground of the battery but it starts to oscillate  ...

I've got a dual supply for +-12V's...but I'm afraid of  frying op-amp's:D
   
I made the whole project but I don't know how to connect the power supply ...

please help me....

[ambulancevoice]

the dod death metal is powered by 9volts

btw, can i get a ready to transfer version of that pcb
to build one of those would help me alot

[meric]

That is correct...-4.5 V is the negative of the battery...100k resistor is too much...try 10k for those...more importantly
there should be about 47 to 100 uF capacitor from center (shown as ground in your schematic) to the negative terminal of the battery.
(AC wise that center point should show zero impedance with respect to the negative terminal of the battery).

It is also good idea to put another 100 uF or so on the circuit from plus battery terminal connection to the negative battery
terminal connection (This is a good practice and it could be important if you are gonna use the circuit with an external supply).

On the output jack there is  -10 V connection but I guess it is typo...

Hope this helps...

meric

[ambulancevoice]

why does it say 4.5 volts? the death metal is powered by 9

[gaddargaddar]

Here it is


two 3k  and a 100microfarad with a 47 microfarad sounds great but still while playing with the pots at some point oscillation starts...I'm not sure if  it's becouse of the layout...
anyway probably the best solution is  using  dual linear 10k pot instead of 3k's...

Thanks for your help ...

[ANDYEFFECT]

post sound here!!!!

[ambulancevoice]

what the @#$%? a 4.5V - and + power supply for this thing? why is it powered by one 9v - tip adaptor then?

[MartyMart]

what the f*ck? a 4.5V - and + power supply for this thing? why is it powered by one 9v - tip adaptor then?

It's just another way to set up an opamp, rather than +9 and 0 volts the biasing is +4.5 and -4.5volts with "0" volts
as the VR amount, in much the same way as a TS-9 has 9v+ / Ground "0" volts and 4.5v as VR "bias" for the opamp
inputs.
It's more of an "old school" way and in some ways can give better headroom/performance.
I've only used this setup on one circuit, Alphonso Hermida's original "Mosferatu" from 2003, uses it.
MM

[ambulancevoice]

so how do i get the 4.5- out of a 9v

[ambulancevoice]

hello?

[allan_belt]

Hello from Peru, i have the same issue with my clon of the DOD FX86...it has oscillation  when i turn up the pain and Scream pots..any help? Tnx in advance...

[anchovie]

Have you tried using shielded wire?

[allan_belt]

Good idea ...i`m gonna put shielded cables on it and i`ll post the results ..thanx for the advice..