Tycobrahe Octavia. Because I Like This Sort of Thing. No really, what is it?. It is an Octave/Fuzz pedal for electric guitar. It uses three BJTs along the way. It was first made in the early ‘70s. The Circuit. Things To Consider.
Because I Like This Sort of Thing
The first transistor utilizes the collector voltage off the third transistor for its emitter voltage. The input signal goes into the base.
The First Transistor
For 1k resistance due to potentiometer.
For .1k resistance due to potentiometer.
The result of the third transistor is that the output current is clipped. It makes fuzz. Fuzz is good in this case, as this pedal is supposed to provide fuzz.
The following is the –1 x the current from the collector of Q3 when the potentiometer caused .5k ohms of resistance:
This is the resulting voltage on the primary side of the transformer for a .5k potentiometer value:
Transistor Output Result
Now that all is said and done with the transistors, we have most of the ac component being able to pass the capacitor and go to the transformer.
And Now For The Rectification...
That last, clipped signal will now go through this transformer setup:
The transformer steps it down 1:3, and the diodes then rectify the signal, taking off the .7V off the voltages.
The following is the resulting voltage of the rectification with the .5k ohm pot resistance:
This is after going through a little volume control. There is actually a potentiometer instead of the two resistors in series, but it doesn’t affect the circuit other than amplitude.
The fourier analysis shows that there is actually more of the second harmonic (the octave) present than the first.
For 1k Ohms
Here are the resulting output graphs for two other values of the pot:
For .1k Ohms
That Is All