A circuit arrangement for monitoring the state of signal systems, particularly traffic light systems monitors different signal states as to the admissability or inadmissibility thereof in a simple manner without the necessity of carrying out manual wiring manipulations given a change of the signal conditions...http://www.google.fr/patents/US4290136?utm_source=gb-gplus-shareBrevet US4290136 - Circuit arrangement for monitoring the state of signal systems, particularly traffic light signal systems
Circuit arrangement for monitoring the state of signal systems, particularly ...
