An audible warning tone and a flashing optical signal are generated by a personal portable signalling apparatus when it detects the approach of a lighted moving vehicle. The flashing optical signal also alerts the operator of the moving vehicle of the presence of the user of the personal portable signalling...http://www.google.fr/patents/US5005004?utm_source=gb-gplus-shareBrevet US5005004 - Light activated vehicle sensor with flashing light and pulsing sound alarm
Light activated vehicle sensor with flashing light and pulsing sound alarm
