The call button relay has one unused terminal, this terminal becomes hot (track voltage) when the track call is made and track power goes off. If you are using yellow caution lights with a flasher built in, they can be hooked directly to this terminal. since the relay will be carrying the load, the interface board will only be used for signal power to the relay.
If you are using lights without a flasher built in, a common automotive flasher can hooked to this terminal first, then to your lights. If using LED Bulbs, there may not be enough draw from them to activate a common flasher, so an electronic auto flasher can be substituted. the ground can be hooked to your track power source.
