Sin Phi - Miasma

Dual Sergesque Slope Generator with Logical Crossfading

The Miasma is an extremely versatile module. This design is based on the Befaco Rampage. At its core the Miasma is a pair of bi-directional slew integrators. The Miasma has a broad range of patch programibility from oscillators and envelopes to envelope followers and low pass filters.

The Miasma features inputs for rise, fall and exponential control voltages that change the shape of the wave-forms output. The rise and fall control voltages have attenuverters and offset potentiometers. The range switch selects between fast, mid and slow rates. Shape of the waveform can be set with a potentiometer from exponential rise and logarithmic fall, linear rise and linear fall, or logarithmic rise and exponential fall. Input for the trigger starts the cycle. The cycle can be reset while falling. The trigger momentary switch can trigger either side. The cycle input inverts the cycle switch which selects between looping or singular.

The Miasma outputs for each function generator are rising and falling gates, end of cycle trigger and bipolar output. The balance potentiometer sets the level going into the analog minimum, maximum, left greater than right comparator and an AD633 four quadrant multiplier.

Enhancements on the Rampage include the CV attenuverters, the four quadrant multiplier, pull down resistor on logic outputs and SMD layout for easy DIY construction. The AD633 can be optionally left off and jumpers used so that the 4QX output becomes an inverted sum of the left and right signals through the balance potentiometer.

CC BY-NC-SA 4.0

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