Intellijel VCO 1U User manual

VCO 1U
Syncable, Multi-Waveform Analog Oscillator & LFO
Manual (English)
Revision: 2021.07.18

TABLE OF CONTENTS 
COMPLIANCE 2
INSTALLATION 3
Before You Start 3
Installing Your Module 4
FRONT PANEL 6
TECHNICAL SPECIFICATIONS 8
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VCO 1U Manual 1

COMPLIANCE 
VCO 1U Manual 2
This device complies with Part 15 of the FCC Rules. Operation is subject to the
following two conditions: (1) this device may not cause harmful interference, and
(2) this device must accept any interference received, including interference that
may cause undesired operation.
Changes or modifications not expressly approved by Intellijel Designs, Inc. could
void the user’s authority to operate the equipment.
Any digital equipment has been tested and found to comply with the limits for a
Class A digital device, pursuant to part 15 of the FCC Rules. These limits are
designed to provide reasonable protection against harmful interference when the
equipment is operated in a commercial environment. This equipment generates,
uses, and can radiate radio frequency energy and, if not installed and used in
accordance with the instruction manual, may cause harmful interference to radio
communications.
This device meets the requirements of the following standards and directives:
EMC: 2014/30/EU
EN55032:2015 ; EN55103-2:2009 (EN55024) ; EN61000-3-2 ; EN61000-3-3
Low Voltage: 2014/35/EU
EN 60065:2002+A1:2006+A11:2008+A2:2010+A12:2011
RoHS2: 2011/65/EU
WEEE: 2012/19/EU

INSTALLATION 
This module is designed for use within
an Intellijel-standard 1U row, such as
contained within the Intellijel 4U, 7U and
Palette Eurorack cases. Intellijel’s 1U
specification is derived from the
Eurorack mechanical specification set
by Doepfer that is designed to support
the use of lipped rails within industry
standard rack heights.
Before You Start 
Intellijel Eurorack modules are designed to be used with a Eurorack-compatible case and power
supply. We recommend you use Intellijel cases and power supplies.
Before installing a new module in your case, you must ensure your power supply has a free power
header and sufficient available capacity to power the module:
● Sum up the specified +12V current draw for all modules, including the new one. Do the same for
the -12 V and +5V current draw. The current draw will be specified in the manufacturer's
technical specifications for each module.
● Compare each of the sums to specifications for your case’s power supply.
● Only proceed with installation if none of the values exceeds the power supply’s specifications.
Otherwise you must remove modules to free up capacity or upgrade your power supply.
You will also need to ensure your case has enough free space (hp) to fit the new module. To
prevent screws or other debris from falling into the case and shorting any electrical contacts, do not
leave gaps between adjacent modules, and cover all unused areas with blank panels. Similarly, do
not use open frames or any other enclosure that exposes the backside of any module or the power
distribution board.
VCO 1U Manual 3

You can use a tool like ModularGrid to assist in your planning. Failure to adequately power your
modules may result in damage to your modules or power supply. If you are unsure, please contact
us before proceeding.
Installing Your Module
When installing or removing a module from your case
always turn off the power to the case and disconnect the
power cable. Failure to do so may result in serious injury
or equipment damage.
Ensure the 10-pin connector on the power cable is
connected correctly to the module before proceeding.
The red stripe on the cable must line up with the -12V
pins on the module’s power connector. The pins are
indicated with the label -12V, a white stripe next to the
connector, the words “red stripe”, or some combination of
those indicators. On Intellijel power supplies the pins are
labelled with the label “-12V” and a thick white stripe.
Sometimes the connectors are shrouded, ensuring the cable can only be oriented in one direction.
Most modules will come with the cable already connected but it is good to double check the
orientation. Be aware that some modules may have headers that serve other purposes so ensure
the cable is connected to the right one.
The other end of the cable, with a 16-pin connector,
connects to the power bus board of your Eurorack
case. Ensure the red stripe on the cable lines up with
the -12V pins on the bus board. On Intellijel power
supplies the pins are labelled with the label “-12V” and
a thick white stripe. Sometimes the connectors are
shrouded, ensuring the cable can only be oriented in
one direction.
If you are using another manufacturer’s power supply,
check their documentation for instructions.
VCO 1U Manual 4

Once connected, the cabling between the module and power supply should resemble the picture
below:
Before reconnecting power and
turning on your modular system,
double check that the ribbon cable
is fully seated on both ends and
that all the pins are correctly
aligned. If the pins are misaligned
in any direction or the ribbon is
backwards you can cause damage
to your module, power supply, or
other modules.
After you have confirmed all the
connections, you can reconnect
the power cable and turn on your
modular system. You should
immediately check that all your modules have powered on and are functioning correctly. If you
notice any anomalies, turn your system off right away and check your cabling again for mistakes.
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VCO 1U Manual 5

FRONT PANEL 
[1] PITCH knob : Adjusts either the pitch of the VCO, or the rate of the LFO — depending on the
position of the VCO/LFO [2]
switch. Specifically:
VCO : The PITCH knob
controls pitch over a 3-octave
range, which can be extended
to 7-octaves using the
OCTAVE [3] switch.
LFO : The PITCH knob
controls the LFO rate over a
larger (approx 7-octave range),
which can be extended to over
11-octaves using the
OCTAVE [3] switch.
[2] VCO/LFO switch : Sets whether the oscillator runs at audio (VCO) or low frequency (LFO) rates.
With nothing patched into the PITCH [A] input, the VCO and LFO ranges are as follows:
VCO range:
● Minimum pitch = 16 Hz
(when OCTAVE [3] = ‘ -2 OCT ’ and PITCH [1] knob is fully counterclockwise)
● Maximum pitch = 2.048 kHz
(when OCTAVE [3] = ‘ +2 OCT ’ and PITCH [1] knob is fully clockwise)
LFO range:
● Minimum LFO rate = 23 seconds
(when OCTAVE [3] = ‘ -2 OCT ’ and PITCH [1] knob is fully counterclockwise)
● Maximum LFO rate = 52 Hz
(when OCTAVE [3] = ‘ +2 OCT ’ and PITCH [1] knob is fully clockwise)
Patching a voltage into the PITCH [A] input extends these ranges further.
NOTE: These are the frequency ranges as set at the factory. If you’re comfortable with your
tweaking skills and would prefer a slower LFO rate (at the expense of maximum pitch), or a
higher maximum pitch (at the cost of increasing the minimum LFO rate), you can use the back
panel’s OFFSET trimmer to do this — but you’ll want to keep your trim tool away from the
SCALE trimmer. Proceed at your own risk.
[3] OCTAVE switch : This three-position switch raises (in the top position) or lowers (in the bottom
position) the oscillator’s pitch (or LFO rate) by two octaves.
VCO 1U Manual 6

[4] OUTPUT VOLTAGE LED : Displays the TRIANGLE [D] wave’s output voltage. Positive
voltages are indicated by a green LED, and negative voltages by a red LED. The intensity of the
LED represents the relative voltage level. This is particularly useful when using the module in
LFO mode, since it gives visual indication of the LFO rate. Obviously, at VCO rates, the LED
modulates too quickly for the naked eye to discern the voltage changes.
[A] PITCH IN : 1V/OCT pitch input for controlling the pitch of the oscillator with a sequencer or
voltage source.
[B] SYNC IN : The periodicity of a waveform patched into SYNC IN will force the VCO to cycle at
some whole number multiplier of the input signal.
Different timbres are produced when the VCO’s oscillator runs at a different pitch than the one
patched into SYNC IN. That’s because, in order to synchronize to the SYNC IN waveform, the
VCO must restart its wavecycle every time the input waveform crosses zero in the positive
direction (“hard” sync). This causes abrupt changes to the oscillator’s waveform, which results in
a harmonically rich sound. Further harmonic complexity is achieved by modulating the pitch of
the VCO, which causes its harmonic structure to constantly change as each cycle resets at a
different location. This alters the VCO’s harmonic complexity over time while its pitch continues
to be governed by that of the SYNC IN signal.
[C] SINE OUT : Sine wave output. Pure waveform that outputs only the fundamental frequency with
no harmonics. Good for adding bottom end to a sound, since no higher harmonics come into
play. Used as an LFO, it allows for smooth transitions between peaks, though hovers around
those peaks for a longer period of time than the linear Triangle wave.
[D] TRIANGLE OUT : Triangle wave output. This waveform has a lot of energy in its fundamental
frequency and a bit of additional energy in its first few odd harmonics. This makes a Triangle
wave still sound relatively pure (like a sine wave), only brighter — but not nearly as bright as a
square wave (which also has odd harmonics). Triangle waves are excellent for LFO use, since
they ramp smoothly and linearly between maximum and minimum values.
[E] SQUARE OUT : Square wave output. Like triangle waves, square waves have only odd
harmonics. But unlike triangle waves, the energy in the higher harmonics does not dissipate as
quickly, meaning they have more (and louder) upper harmonics, and therefore sound much
brighter than Triangle waves. Square waves are also good for LFOs, since they switch back and
forth between two discrete levels, without ramping between them.
[F] SAWTOOTH OUT : Sawtooth wave output. This waveform has both even and odd harmonics,
which makes this the brightest and buzziest sounding output. Sawtooth waves are ideal for use
in subtractive synthesis, where they’re run through a filter which removes (and helps shape) the
harmonic content.
VCO 1U Manual 7

TECHNICAL SPECIFICATIONS 
VCO 1U Manual 8
Width
14 hp
Maximum Depth
37.5 mm
Current Draw
19 mA @ +12V
16 mA @ -12V