Electrical signaling devices have been introduced in Europe as part of standard equipment only in the 1960s of the last century. Prior to that time, the direction indicators were blinking by mechanical detectors attached to the upper edges of the front side doors. It is not surprising that drivers tended to use the turn signals without a heart turn them off even if it was already mandatory in the event of a change of direction. Until now, the direction indicators are placed laterally in the mudguard and are included in the headlamp housing.
According to legal requirements, the indicator light must be yellow, while the flashing rate would be approximately 90 flashes per minute. From a purely technical point of view, the indicator is usually connected to a flasher relay, which can be replaced by an electronic device in combination with a control unit. In addition, the emergency lights are on, making it unnecessary to use additional lighting devices. As far as intermittently concerned, different methods have been used to implement it over the years.