I use three beehive lamps, a single clear one to indicate that I have power to my 1A2 system (taken from the lamp power terminals) and a double with one red and one green to indicate the status of the two CO lines. They work really well, I only wish that they had a bit more 'umph' in the way that the outer shell attaches to the base. A slight bump will dislodge the outer shells. I guess that is why I mounted them at the top of the board!

Joe

Real comms took 200lb teletypes, hand keys, sounders, operators and cranked phones!