You do not have to strip an old battery for the 9 volt battery connctor. You can buy the battery connector at Radio Shack. This is for those who build a layout and then find out there is a short, "somewhere".
Unfortunately there are a few who who could use the circuit who will never click on the subject heading for the message.
http://model-railroad-hobbyist.com/magazine/mrh-2012-03-mar/audible_short_detector
Rich