The Rattlesnake Audio Probe is a great tool for you DIY effect builders and modders. It allows you to probe the circuit establishing break points that let you know what the circuit is doing audibly. This is a great way to identify bad components or where there circuit is failing.
You simply connect a cable from the amp's input to the 1/4" jack on the probe. Connect a cable from guitar or signal generating device into the input of the pedal. Insert the black (ground) probe somewhere in the circuit (usually a screw hole to ground) then touch the red probe to the circuit. I usually tend to start at the input which should give you a clean, un-effected tone, then work down the trace until you identify a problem.
The probe is not meant for high voltage devices.... it was designed to test simple 9V circuits like pedals.
Check out some videos talking about Rattlesnake Cables - unboxing, demos, etc.
