When the train reaches the activator, the relay should close. Once this is done it's time to wire the lights. The relay will have a normally open contact and a normally closed contact as well as ...

Normally-Closed Single Pole Single Throw SPST relay In figure 1 no DC voltage is applied to points A and B therefore no current flows through the coil of the relay, the contact stays in the close ...

Industry-standard ISO mini relays are common and affordable. A 12-volt, NO/NC, SPDT version like this one (Hella PN 007794301, $6.38 at Summit) can control both normally open and normally closed ...