PURPOSE: To have anti-vibrative performance and dazzle protection in a signal lamp circuit using a cold cathode emission lamp by allowing the output of a flashing signal control circuit to twinkle the cold cathode emission lamp and making the illuminance variable with a switch.

CONSTITUTION: When a turn-on switch S is closed, transistors Tr1 and Tr2 operate alternately by the action of a diode D and through another transistor Tr3 an intermittent signal is generated for a certain period of time determined by resistances R1 and and R2. If now a switch SW lies on the resistance R6 side, the base current flows in only in the ON period, and a transistor Tr4 repeats switching through coils N1 and N2 to light up a cold cathode emission lamp FL with the aid of the output of coil N3, which will go out at the next OFF time. As resistance R6 is smaller than R7, turning the switch SW to the resistance R7 side will decrease the illuminance.