BugBrand ENV1 User manual

ENV1 – Attack Decay
Rev1 – June09
Overview
The ENV1 is a voltage-controlled Envelope Generator offering
Attac (Sustain) Decay type events plus a looping oscillator
mode.
The module uses Vactrols to control the speed of operation.
Controls
1. Range Switch – 3 position switch to select envelope
speed.
- Fast (Up) is designed primarily for audio-rate
oscillation in loop mode.
- Mid provides typical control envelope speeds and
mid-range oscillations from LFO to low audio range.
-Slow (Down) offers an overall slower response for low
modulation rates.
2. Attack CV Modulation nput – typical 10V pea to
pea modulation signal.
3. Status LED
4. Decay CV Modulation nput – typical 10V pea to
pea modulation signal.
5. Gate nput – a 0 – 5v gate signal is typically applied
here to trigger the envelope.
The input is protected against negative voltages and
can accept higher input signals too. This allows, for
example, a VCO waveform centred around 0V to be
applied – by using the A/S/D mode in Fast range tonal
divisions can be achieved. Other external signals can
be used to varying effect.
6. Attack Rate Control – Manual control for envelope
Attac . Note that cloc wise corresponds to a rising
frequency (ie. Shorter time). At low settings the
control may ta e a short moment to stabilize due to
the nature of the Vactrol control elements.
7. Attack Modulation Control – a bipolar modulation depth control to modify the envelope Attac rate.
Audio-rate modulation can be applied, but may not always produce a strong effect due to the nature of
the Vatrols.
8. Decay Rate Control – Manual control for envelope Decay – similar to Attac .
9. Decay Modulation Control – a bipolar modulation depth control to modify the envelope Decay rate –
similar to Attac .
10. Mode Switch – 3 way switch to select the mode of operation (see diagram overleaf)
- A/S/D (Gated): An Attac stage is initiated by a Gate signal. Once the pea is reached, this level is
sustained until the Gate signal is released, at which point the Decay stage occurs (Fig.1). If the Gate
signal finishes before the Attac stage has completed then the Attac stage will still continue to pea
with the Decay stage occuring immediately afterwards (similar to A/D mode)
- A / D (Triggered): The positive going edge of a Gate signal begins the Attac stage. The output rises to
pea 10V before entering the Decay stage (Fig.2). The length of Gate has no effect in this mode.
- Loop: In this mode the envelope continually cycles between Attac and Decay. A Gate signal may still
be applied to reset the envelope in loop mode, but the behaviour is somewhat unpredictable as it
depends on the envelope's current status.
11. Envelope Output – typical 0 – 10V output signal. Note that the envelope has a roughly exponential
shape.
Specifications
Current Draw: +ve 35mA, -ve 35mA (max.)
Module Width: 1 Frac-width (1.5”)

Adjustment Procedure
There is one multi-turn trimmer in the circuit, but this should not need to be altered in general use. Please read
the notes carefully performing any adjustments. The trimmer adjusts the triggering bias and incorrect setting
can mean the envelope either does not trigger or stays permanently on.
To test correct setting (without oscilloscope) – set Range to Mid and Mode to Loop, Attac and Decay to around 2
o'cloc with no modulation or gate input. In this setting the Indicator LED should pulse On / Off at a relatively
quic rate.
If the LED stays permanently lit then the trimmer should be slowly turned anti-cloc wise until pulsing begins.
If the LED stays permanently unlit then the trimmer should be slowly turned cloc wise.