A-151 Quad Sequential Switch

Doepfer A-151 v2 Quad Sequential Switch Eurorack Switch Module

Compact simple 4 to 1 sequential switch module!

Sequential switches have multiple I/O on one side to a single I/O on the other (they are called I/O because they are bi directional. either side can be inputs or outputs). This module has 4 on one side and 1 on the other, and when triggered will re route or "switch" the next of the four I/O to the single common I/O. This is perfect for stuff like switching between channels on a multi-row sequencer to make longer sequences. Other fun tricks include feeding an offset to an input to create a simple clock divider, sequential clock, or sub oscillator (when clocked at audio rate.) Or for rerouting a single set of triggers to switch between going to four different destinations.

A physical "switch" on the panel allows for reducing channel count to 2 or 3 channels, and a reset input brings the selection back to channel 1.

Per Doepfer:

Module A-151 (Quad Sequential Switch) is like an electronic four-position rotary switch.

It includes trigger and reset inputs, four in / outputs, and a common out / input. Each time a pulse is received at the trigger input socket, the common out / input is connected to the next in / output. After the fourth in / output, the next trigger makes it step back to the first again, and so on. A positive pulse at the reset input switches the out / input immediately back to the first in / output.

Voltages in the range -12V...+12V at the O/I resp. I/O sockets can be processed by the module (not only control voltages but also gate, trigger or clock signals provided that they are in the -12V...+12V range).
By means of a toggle switch the number of steps can be limited to 2, 3 or 4.

Four LEDs indicate the active in / output (ie. the on that is connected to the out / input at any particular time).