A long, long time ago there was a great Design Idea for a simple gadget to find a bad bulb in a series-connected string of Christmas lights: This is really simple and works great, but it exposes the ...

All it takes is one bad bulb to keep all of the other Christmas lights from lighting up. The trouble is, how do you find that one bad bulb? This gadget is supposed to help you find it. A bad bulb ...

Why is that you always test 48 bulbs before you find the bad one in a 50-light string? This simple circuit allows you to divide and conquer, greatly reducing the time it takes to find the bad bulb.