I'm searching for a shield (or a separate board) I can use to drive a (big) set of relays' coils with the output pins of the Arduino. I'm searching for something easy to deploy frequently for hundreds of relays on dozens of Arduinos.
I've got these relay boards that are really nice, compact and economical (you can see a small manual at http://formula9.net/files/8relaycard_manual.pdf);
they have the electronics (simple transistor/diode circuit) to drive the coils of 8 relays (230V, 10A), so I can just connect the pins to the board and go.
What I'd like to find is a shield or board that takes the role of that amplifier circuit (for each pin), so that I can use external, heterogeneous relays (more powerful or less powerful).