This circuit belongs to the ‘car modding’ category. This is similar to the popular case modding in the computer world and has found its way into a substantial proportion of cars. The modifications vary from light effects to complete movie playback systems. This circuit is much more modest, but certainly still worth the effort. It provides a high quality interior light delay. This is a feature that is included as standard with most modern cars, although the version with an automatic dimmer is generally only found in the more expensive models. With this circuit it is possible to upgrade second hand and mid-range models with an interior light delay that slowly dims after the door has been closed.