I need to make a game buzzer system, which includes 7 outputs: an electronic vibrating buzzer and 6 lights to indicate which player clicked first. I decided to manage the circuit with logic gates, then tested it. The circuit works fine (tested with a voltmeter) and so does the buzzer, but none of the lights ever turns on. When connected to anything but a logic gate output, the lights turn on. Both the buzzer and the light use 6V so I used 4xAA batteries as a source, resulting in aprox 5.5V high outputs from the logic gates, which I suppose couldn't be low enough to cause the malfunctioning lights. The lights are 6V miniature light bulbs on a socket. The gates are 74HC OR, NOR and AND gates (02,08,32). I'd like to know what I can change to the circuit or what lights I need to buy if I need to replace them, but first and foremost I'd like to understand what properties can make certain devices incompatible with the current of a logic output. Thanks!