DOEPFER A-100CGK Betriebsanweisung PDF herunterladen (Seite 17)

User's Guide page 17 DIY Synth Kit

VCA OUT VCA Output Usually connected to a socket labelled

"VCA Out", which is normally the final

output of the synthesizer and connected

to the audio mixer

JP10: Tempo-Option

If the tempo option is used IC1 has to be removed and replaced by the tempco option. That’s

nothing but the former IC1 expanded by a small temperature controlled oven that is glued to

the circuit. The oven heats up the the circuit IC1 to a fixed temperature which is cleary above

the usual room temperature (sorry - the tempo option will probably not work in the Death

Valley or in the Sahara desert ☺).

The tempo option is connected to JP10.

Auxiliary terminals

Near the power supply connector JP1 some auxiliary terminals are available (please refer to

the picture on page 9 for the corresponding positionss):

• +5V / GND (JP8): output of an +5V voltage regulator (derived from +12V)

• –5V / GND (JP9): output of an –5V voltage regulator (derived from –12V)

• +12V (JP11): nothing but a terminal connected to +12V

• -12V (JP12): nothing but a terminal connected to –12V

These terminals can be used whenever a fixed voltage is required (e.g. for potentiometers

that are used to generate manually controlled voltages e.g. for VCO tuning, VCF frequency,

VCA loudness or others). If a higher voltage range is required (e.g. for manual VCF

frequency control) the "high voltage" terminal +12V can be used. If a smaller voltage range is

required the "small voltage" terminal +5V can be used (same applies to –12V and –5V). The

voltages appearing at the +5V and –5V terminal have the advantage that they are nearly

independent of possible voltage changes of the +/-12V supply. Consequently they should be

used for VCO control applications.

Trimming potentiometers

Trimming potentiometer P1 is used to adjust the 1V/octave scaling of the CV inputs of the

VCO (CV1…CV4 of JP2). If the tempo option is used the board should be powered at least

20 minutes before this parameter is adjusted. For example a control voltage with the values

0.0 V / 1.0V / 2.0V / 3.0V / 4.0V /5.0V is applied to one of the 1V/oct CV inputs of the VCO.

The CV can be supplied e.g. from a Midi-to-CV interface (e.g. A-190-2) or a CV keyboard

(e.g. A-100CGK). P1 is adjusted so that the 1V intervals of the CV correspond exactly to

octave intervals. If a frequency counter is available the frequencies can be measured, e.g.

32 / 64 / 128 / 256 / 512 / 1024 / 2048 Hz. But usually the human ear is the best frequency

counter.

Trimming potentiometer P2 is used to adjust the frequency offset of the VCO (i.e. the lowest

frequency if all VCO CV inputs are 0V). It' up to the user which frequency is chosen. Usually

a "C" is chosen when all frequency controls (e.g. coarse and fine tuning) are in the center

positions. The corresponding "C" frequencies are ~ 65 Hz or ~33Hz (one octave less).

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DOEPFER A-100CGK Betriebsanweisung Seite 17