Control circuit for vehicle turn-signal flasher systems

摘要

A control circuit for the turn-signal flasher system of an automotive vehicle. The flasher system includes a relay having switch contacts which are serially connected, together with a direction indicator switch, between the vehicle battery and the turn-signal lamps. A measuring or sampling resistor is connected between the battery and the relay contacts. First and second pulse generators are connected between a first voltage indicator and the relay coil, and are selectively gated to interrupt the relay during normal lamp load conditions. The first pulse generator provides a normal mark-to-space ratio whereas the second pulse generator provides a reduced mark-to-space ratio for use during night driving conditions. Third and fourth pulse generators are responsive to corresponding voltage indicators connected to the measuring resistor. The third and fourth generators function to respectively provide different mark-to-space ratios in response to, and indicative of, lamp outage or current-overload conditions.