Doepfer A-151 Quad Sequential Switch

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 (see Fig. 1). Voltages in the range -8V...+8V at the O/I resp. I/O sockets can be processed by the module.
Four LEDs indicate the active in / output (ie. the on that is connected to the out / input at any particular time).

From spring 2005 a revised version of the module is available. With an additional switch the number of steps can be set to 2, 3 or 4 (thanks to Peter Grenader for this idea). Moreover the revised module allows to process voltages in the full A-100 voltage range (i.e. -12V...+12V). The limitation to -8V...+8V is no longer valid. While stocks last the user can choose between version 1 and 2. Version 1 will be no longer manufactured in the future. The A-100 DIY page describes how to install this additional switch for the old version of A-151..

Width: 4 HP
Depth: 35 mm (measured from the rear side of the front panel)
Current: +20mA (+12V) / -10mA (-12V)