VC SEQUENCER 54B

Like most 'analogue', or more correctly, discrete or integrated logic circuit sequencers, the 54B employs a logic counter that is
incremented sequentially from 1-16 steps using a low frequency pulse or clock input.
The additional VC step selection circuitry allows the user to go beyond the standard incremental mode, selecting the steps
in any order desired using an input voltage.
Some examples: A sawtooth wave increment steps 1 thru 16, a triangle 1 thru 8 and then decrement 8 thru 1,
a random wave would select 1,5,2,7,9,... etc. The CV offset and CV amount panel controls scale and offset the input voltage.
All of the above synchronous examples have step selection tied to the clock. In other words the sequencer won't advance,
regardless of the VC input, till the clock pulse occurs.
In VC mode 1 the sequence will step as normal until a 0.2V threshold is crossed at the CV input jack.
At the 0.2V threshold the input voltage will override the step selection.
Example: sequencer is clocked normally till reaching the 5th step at which time an envelope generator patched
to the CV input is fired. Now the sequencer jumps to the 16th step and then gradually counts backwards to the 1 step.
In VC mode 2 the cv input selects the step and the threshold voltage is ignored.
Example: sequence is clocked as normal but step won't advance till a voltage selects the step.
Async mode permits step selection to be made using the input VC only.
An example: patch a Joystick Controller, LFO or any DC voltage source to the VC input and
use it to select the sequencer step without being synchronized to a clock.
In Async mode step transition generates its own gate pulses suitable for triggering envelopes etc.

A companion module to the sequencer is the Clock 53B
Click on the image for larger picture.

The Clock module is used to drive the sequencer with a pulse signal.
What sets this module apart from a typical LFO or oscillator is the
ability to divide the clock into typical note values.

The clock module uses ROM data tables which are programmed
to divide the clock pulse by 1/16th, 1/8th, 1/4 notes etc.
There are 8 tables to choose from. Some are simple divide by 2 and 4
And some have triplets and syncopated values.
It works very much like a pulse divider or divide by N module
but with the added ability to select the range of divisions available.
A typical divide by N module will divide from 1 to 60.
Dividing by 19 or 41 etc. are fun but sometimes you just want to
divide by standard note values. The Clock 53B makes this an easier task
by connecting an output row from the sequencer to voltage control the
step duration of the clock.
Example: step one can be a 1/4 note, step 2 an 1/8th, step
three a 1/16th etc. Odd number divisions are also available in
some of the tables for dividing by 5,7,9 etc.
Being able to select or filter the range of division values is
unique as it makes it possible to 'play' the sequencer, changing
step durations on the fly.
In some of the simpler division tables like table 4 with only 4 choices,
it is very easy to position the controlling step sliders as only 4 positions are
needed to cover the range, effectively reducing the resolution of the slider to
4 steps.
A typical divide by N would have a resolution of 60 steps which makes it difficult to select the desired note durations in real time.
It is also possible to change tables using voltage control, increasing the number of options available.
See the details for more info.

Sequencer Features:

• 16 steps with three rows
• Sliders used for better visual feedback
• LED indicators for steps and rows
• Clocked Logic Run/Stop push button with Trig1&2 for pulse run and stop. Sequence won't advance till clock transition
• Switch selectable Synchronous and Asynchronous operation
• Manual and pulse Reset (resets sequence to step 1)
• Skip Step function. Pulsing Clock jack skips the step
• Row Clock input selects Row out for up to 48 step sequence (using summed output 1-3)
• Clock out with voltage controlled variable width gate (enables having variable gate duration per step)
• Gate Width panel control and voltage controlled gate width input
• CV Mode selection switch
• Built in CV amount attenuator and CV offset
• Sequence Hold voltage input
• Sequence Up/Down voltage input
• Two gate buses with separate outputs
• Bus Disable switch and disable pulse input.
• Three Row outputs with 1-3 out used with row clock to switch rows
• Gate outputs for each step
• 16 gate bus selector switches route gates to one of the two busses. In center position switch is off acting like a rest in the sequence