Calibrating the State Machine
If you bought PCBs or a kit, you should only need to calibrate the unit once. If you bought a pre-built
and tested unit, you can skip this section.
There are two calibrations. For both calibrations, start with the following:
1.
Power up the module.
2.
Attach -ve probe of multimeter set to the 20V range (or an oscilloscope) to the GND of a patch
cord or other accessible signal ground.
3.
Attach the +Ve probe of the multimeter (or an oscilloscope) to the signal pin of a patch cord
plugged into the CV out jack of the State Machine.
4.
Set pots ATTACK to between 50% and maximum, DECAY, RELEASE and SUSTAIN to minimum.
5.
Plug a GATE signal (from a keyboard or other gate source) into the GATE input.
Attack Peak
1.
R32 (ATTACK PEAK) determines the maximum voltage that the ATTACK will reach before
beginning the DECAY time.
2.
Turn the trimmer R32 fully counterclockwise by turning up to 25 times or until you hear the click
of the end stop, then turn it 10 turns clockwise. The following steps will then need to be
repeated until the CV output rises to the desired ATTACK PEAK level and then immediately starts
to decay:-
a.
generate and maintain a GATE signal by pressing and holding a key on the keyboard,
b.
measure the CV OUT signal. It should rise (ATTACK) to a maximum value and may start
to decay. The objective here is to get the signal to decay immediately the attack
reaches 10V.
c.
while holding the key down, adjust R32 until the CV OUT signal switches to decay mode
when it reaches 10V, maybe 3 or 4 turns either way.
d.
If the voltage is high, turn the trimmer clockwise until the voltage gets to around 10v
and then fine tune it. If it is too low, attack will not reach maximum before decay starts,
too high and the attack wil be slow to turn around to the decay or it will not turn around
at all but remain high.
e.
release the GATE signal (key) and allow CV OUT to reach 0, and repeat the exercise