For several years now, a rear fog lamp has been mandatory for
trailers and caravans in order to improve visibility under foggy
conditions.When this fog lamp is switched on, the fog lamp of the
pulling vehicle must be switched off to avoid irritating reflections.
For
this purpose, a mechanical switch is now built into the 13-way female
connector in order to switch off the fog lamp of the pulling vehicle and
switch on the fog lamp of the trailer or caravan.Here a type P521 optocoupler detects whether the fog lamp of the caravan or trailer is connected.
If the fog lamp is switched on in the car, a current LED in the optocoupler
to light up,with the result that the phototransis tor conducts and
energises the via transistor T1. The relay switches off the fog lamp of
the car. For anyone who’s not all thumbs, this small circuit can easily
be built on a small piece of perforated circuit board and then fitted
somewhere close to the rear lamp fitting of the pulling vehicle.
No comments:
Post a Comment