Buchla 200e series, User Manual

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Model 281e Quad Function Generator
281090825
The 281 has four function generators organized in 2 pairs. The following
describes the top pair (A&B), but applies to the bottom pair as well (C&D).
The two topmost generators, A and B, normally function independently, but
can be paired to operate in a quadrature mode.
Independent operation
A momentary switch selects one of four modes: transient, sustained, cyclic or
none. On receipt of a pulse, output voltage A ramps up to 10 volts at a rate
determined by the sum of an applied control voltage and the setting of the
attack time knob. If in the sustained mode, the voltage will stay high as long
as the input pulse is maintained. If not in the sustained mode, or when the
input pulse terminates, the output ramps down to zero at a rate determined by
the sum of the decay voltage and the setting of the decay knob. If no mode is
selected, incoming pulses will have no effect – envelopes will be initiated by
internal MIDI signals.
At the end of the decay, a pulse is generated and applied to pulse out A. If in
the cyclic mode, the cycle now repeats.
Same for section B.
The time range for both attack and decay is from .001 to 10 seconds. The
scale is linear from .001 to .03 seconds (input value from 0 to 3/8), and
exponential from .03 to 10 seconds (input value of 3/8 to 1).
Outputs may be OR’d together, with one scaled and one at full value. The OR
outputs may be used to establish and initial attack transient followed by a
sustain at some lower value. Other applications will occur to you, but keep in
mind that the OR levels are not stored as part of a preset.
The Quadrature mode:
Generators A and B operate in tandem to provide more complex envelopes.
The quadrature mode is toggled by a push switch and indicated by LED's near
the outputs.
As before, a pulse applied to the A input triggers the attack phase of A. When
A's attack is completed, B begins its attack while A stays high. When B's
attack is complete, A begins its decay while B stays high. And finally, when A's
decay is completed, B begins its decay.
The trigger logic for the quadrature mode is derived from section A. If set to
the sustain mode, A will stay high until the end of the initiating pulse. If A is in
the cycle mode, the cycle repeats when B's decay ends.