Biasing Network on OPAmp Circuits like TubeScreamer....

[Oliver]

Hi,

comparing some Overdrive Schematics with OP Amps. noticing,
that the Voodoo Lab Overdrive (old Version - 2Knob) dont using
a 4.5 Volt Biasing Network like  TS - SD-1 and so on.

Did someone tried to remove the BIAS Network and what will happen, if
you do that to a TS Circuit.... I know it sounds barmy, but i always question for everything i think about (just like a child?)

Thanks for some answeres

bye
Oliver

[spongebob]

This one?
http://www.geocities.com/CollegePark/Library/1355/voodoolabOD.gif

There are two 47K resistors (right in the middle) that form a voltage divider to create 4.5V, the non-inverting input is connected to it through the 470k resistor.

If you run your opamp on battery power you will always need some kind of biasing, otherwise the input signal would sit right at the bottom of the opamp's operating range. The bias voltage "elevates" the signal so it swings around 4.5 volt. At least that's how I think it works...

[Oliver]

This one?
http://www.geocities.com/CollegePark/Library/1355/voodoolabOD.gif

There are two 47K resistors (right in the middle) that form a voltage divider to create 4.5V, the non-inverting input is connected to it through the 470k resistor.

If you run your opamp on battery power you will always need some kind of biasing, otherwise the input signal would sit right at the bottom of the opamp's operating range. The bias voltage "elevates" the signal so it swings around 4.5 volt. At least that's how I think it works...

ahhhha - OK - thats the same kind in green, as we would say here  

Thans !!

bye
Oliver