Assuming the devices you are controlling require minimal current to drive them (likely), a simple 3 component circuit can invert the control signal - this will give close to 12v output when the input is low, close to 0v when it is high. The transistor BC337 is a widely available European transistor, it should be easy to find a US equivalent.

It requires a 12v power supply which you can probably pick up from one of the Meridian comms sockets, otherwise from a simple wall-wart.

[Linked Image from i47.tinypic.com]


Mark
MC200, AC200, M6, 557, G91