A-154 Seq. Controller

Module A-154 is a supplement to the A-155 Analog/Trigger Sequencer module. It offers a lot of new features that are not available in the basic control unit of the A-155. The A-154 is used to replace the control unit of one or more A-155, i.e. the section marked "Control" with Start / Stop / Step / Reset buttons and inputs in the upper left corner of the A-155 front panel. If the A-154 is used to control the A-155 the control section of the A-155 is put out of action.
The 10 pin ribbon cable, that was used to connect the A-155 control section with the rest of the A-155 module has to be removed and plugged to the new A-154 sequencer controller. Therefore the A-154 has to be assembled next to the A-155 (right side). In case that more than one A-155 have to be controlled longer ribbon cables between A-154 and the remote A-155 have to be used.
If two A-155 are used they can work in parallel (8 steps) or serial (16 steps). The 8/16 steps switch determines if the 8 step mode (one A-155 or two A-155 in parallel) or the 16 step mode (two A-155 serial) is chosen. Both modes work with CV controlled step addressing too (see below). In 8 step mode only the steps 1...8 are addressed, in 16 step mode the steps 1...16.
For serial operation an additional VC switch (A-150) is required to switch between the CV/trigger/gates of the two A-155. In this case the VC switch is controlled by the "9-16/A4" output of the A-154.

The expected features of the A-154 will be:

• Several running modes: forward, backward, pendulum, random, CV controlled step adressing. All modes are available as loop or one-shot.
   
• LED display of the 5 different current modes and one LED for loop/one-shot display.
  
  
• Manual and voltage controlled selection (with attenuator) of the running mode. If no external control voltage is applied one of the 10 modes (5 modes x 2 loop/one-shot) is simply selected with a rotary knob. The CV input with attenuator is used to modulate the running mode with an external control voltage (digital high/low CV to switch between two modes or continuous analog CV to sweep through different modes). With the combination of manual control and CV with attenuator it is possible e.g. to use only two neighbouring modes (e.g. forward/backward) or sweep through all possible running modes.
  
  
• If the running mode "CV Controlled Step Address" is selected the active sequencer step is determined by the Step Address section. Manual and voltage controlled selection (with attenuator) of the active step are possible: the active step can be set by hand with the manual control and then modulated by an external control voltage (e.g. LFO, Random, S&H, Theremin, Light CV source, Joy Stick) with attenuator.
  
  
• An internal voltage controlled clock generator with manual and CV control with attenuator is available. The output of the clock generator is displayed with a LED and is used as sequencer clock provided that no external clock signal is connected to the Clock In socket (normalled socket). If the CV input of the Clock section is connected to one of the analog outputs of the sequencer the time for each step can be set separately. Even jumps (or skipping) will be possible as we will introduce the feature that a very short clock pulse will be generated if the control voltage exceeds a certain value. For example the gate row of the A-155 can be used to obtain skipping of steps: the gate output simply has to be conneted to the CV input of the A-154 clock generator. If the corresponding switch of the A-155 is set correspondingly in the gate row the step will be skipped.
  
  
• Manual and voltage controlled (with attenuator) pulse width (PW) of the clock signal. This features can be used to obtain a different gate length for each step: one of the CV outputs of the A-155 has to be connected to the PW CV input of the A-154. With a PW control voltage coming from a LFO/random/S&H the gate length will change automatically.

• 8/16 step mode selected by a switch: the "16 step" mode requires two A-155 and an VC switch A-150. The A-150 is controlled by the "9...16/A4" output of the A-154 that tells the A-150 to select the CV/trigger/gates of the first A-155 (step 1...8) or second A-155 (step 9...16).
  
  
• The functions of the Start/Stop/Step/Reset buttons and inputs are the same as for the "old" control unit of the A-155:
  
  
• A high level at the Start input or operating the Start button starts the sequence from the momentarily addressed step
  
  
• A high level at the Stop input or operating the Stop button stops the sequence (the last active step remains addressed)
  
  
• A high level at the Reset input or operating the Reset button resets the sequence to step 1. The sequence remains at step 1 as long as the Reset input level is high (function is activated by high level, not by low/high transition)
  
  
• A positive transition (low -> high) at the Step input or operating the Step button causes an advance to the next step. The step input is connected to the clock output of the internal clock generator provided that no plug is inserted to the step input socket