I'm wanting to convert 3 battery operated marquee signs to AC power by following one of the many tutorials out there on sites like instructables.com. I'm more than capable of doing each one on its own and having 3 wall warts for each sign. My question is can I power all 3 signs off 1 AC power supply? Each sign takes 3 C batteries so I know to do each one would require a 4.5v power supply on its own. Could I do 1 13.5v power supply and wire it to all 3 signs?