diesel tachometer - connected to the alternator measures r.p.m. in virtually any (12V) diesel or petrol engined car

diesel tachometer Elektor February 1984 A tachometer is probably the single most important "meter" in a car"s dash- board (unless you"re in the habit of running out of fuel). It informs the driver how hard the engine is working and, when used correctly, it is an aid to economy, performance and engine longevity (to name but a few). These things are, of course, no less im- portant to the driver of a diesel car than to his petrol-powered counter- part, but most electronic tachometers cannot be used with diesel engines. The reason for this is that they take their "timing" from the ignition circuit, which diesel cars do not have. The engine speed of a diesel car can, however, be measured by "picking the brains" of another part of the electrical system, namely the alter- nator. the electronics easier. The ever-present alternator looks like a good possibility. Be- cause it is driven from the crankshaft via the fan belt it turns at a speed which is directly proportional to the engine spee...