The Foldiplier is a 4hp odd/even harmonics generator with 2 different oscillating feedback paths. The folding core of the design originates from the odd harmonics (middle)section of the Serge Wave Multiplier. But the Foldiplier adds voltage control over the symmetry and offset as well as a switch for feedback featuring a transistor based oscillating fuzz inspired by the Hemmo Bazz Fuss. When these feedback oscillations mix with an incoming waveform some unpredictable and unique nonlinear timbres can be achieved. The module can also be used as a no-input experimental oscillator with the feedback switch engaged. All diodes in the module are silicon.
The Fold knob controls the amount of times the waveform is folded in on its self (indicated by the red led window below the knob). The C.V. knob below is an attenuator for incoming control voltage corresponding to the Fold jack(indicated by the red led window above the jack, it only responds to positive voltage). So, the Fold knob acts like an initial amount of folding depending on its position. For example, with the Fold knob fully clockwise you can get even more folds with a control voltage in at the Fold jack. The Offset knob controls how much positive DC voltage(0 to 5v, clockwise) or negative(0 to -5v counter clockwise) DC voltage(indicated by the led window above the Offset jack, red for positive, yellow for negative) injected into the waveform via the Symmetry knob. With the Offset knob position at noon(0v) there will be little effect from the Symmetry knob. The Offset jack is expecting +5v to -5v, with knob position at noon, to scan through the positive and negative voltage. The Symmetry knob controls the amount of negative or positive offset voltage(dependent on the Offset knob) mixed with the waveform(indicated by the yellow led window above the Symmetry jack). If positive voltage is mixed with incoming waveform more folds will occur on the positive troughs of the waveform, likewise, when negative voltage is introduced more folds happen on the negative troughs. This part of the circuit can also be broken down by thinking of the Offset as a voltage controlled crossfader swinging between positive and negative voltages into a VCA controlled by the Symmetry knob and jack. When a voltage is present at the Symmetry jack the Symmetry knob becomes an attenuator. The Symmetry jack only responds to positive voltage.