Car lock defroster - open that door!

car lock defroster You"re cold and in a hurry, and your car door won"t unlock .. . a well- known hazard to drivers in winter! "Forewarned is forearmed", of course, and you may have one of those handy little de-icing sprays. In our experience, however, they conform strictly to Murphy"s Law and tend to be empty at the crucial moment. An electronic solution is shown here. In essence, it consists of a plug that fits into the cigarette lighter socket on the dashboard and a heavy-duty current source, connected to the car key. When this is inserted into the lock, a heavy current (approximately 10 A) flows through the entire lock mechanism. Since the resistance will normally be highest at the various joints, it is precisely at these points that heat is developed! A few practical points should be noted. Heavy-gauge wire should be used for all connections (2.5 mm 0, at least), and the power transistors must be provided with an adequate heat- sink. For improved thermal stability, they can be moun