Some of my customers had requested this device and it was first introduced for module groups. The first offering of such a device was from QSI with a much higher price tag with visual indicators. That item is no longer offered. Our surge protector may be thought of as simple, yet effective protection for expensive electronics in today’s model railroading market. Whenever there are sparks between a roller pickup or wheel and the tracks you will get a short spike in voltage. This is the basis of the spark you see. Depending on the magnitude of the surge, it may damage electronics such as QSI, DCS, or TMCC electronics in the trains. These surges are particularly troublesome when operating older post-war trains with the newer command-equipped trains on the same transformer. When a train jumps the track, the resulting short may also cause a troublesome spark. Our simple, low-cost surge protector is designed to limit the voltage spikes or surges to 35 Volts thus providing a greatly reduced problem for the expensive electronics. Each transformer output that feeds a track should have one surge protector. No reset required. The first picture shows two of the original surge protectors wired across the two track outputs from a Z-4000 transformer after the TIU and TMCC brick connection. This version is no longer in production due to rising costs. However, you may order just the TVS item below. Contact Us.