Well you could always use a IR circuit, so that if the reciever is broken, the transmitter emits high pulses of sound and starts up a high intensity strobe light :twisted: Those could be pretty easy to build, just use a 6000+ MCD LED, with a polished reflector, and possibly a small focusing lense. Definately not a condenser lense, don't want anyone to go blind, or have their eyes turn to a liquid here.