"Vintage" Version of the A-151. 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. 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