lights in' warning - protects your car battery

protects your car battery Who has not at one time or another forgotten to switch off his car"s lights on a murky morning? That is not much of a problem when col- leagues or passers-by are kind enough to draw your attention to it. But if there are no such friendly souls about, you may at the end of the day find that your battery is as flat as a pancake. Some modern cars have a factory-fitted warning unit, others have their wiring arranged such that when the ignition is switched off only parking lights can be left on. The majority of cars, however, are not protected against such an oversight and it is for those that we have developed the present warning circuit. This has an advan- tage over other similar circuits in that you can switch on your headlights when the ignition is switched off. The circuit is based on two astable multivibrators (AMVs) of which the first is formed by NAND gates N1/N2 and associated components. It operates as a clock with a fre- quency of about 20 Hz. The s...