An automobile tachometer is a device that is used to determine the number of revolutions of the rotating parts of a running engine. The measurement is made per unit of time or according to the speed of linear motion. An automobile tachometer helps in choosing the right gear and, as a result, helps to extend the life of the power unit. This means that at the moment when the arrow of the device approaches the red zone, you should immediately switch to overdrive. Automotive tachometer often used for adjustment work: at idle and for the purpose of operational control of the speed of rotation of the motor shaft when the machine is moving. The principle of operation of such a device is to register pulses from the sensors. In addition to counting their number, the automobile tachometer fixes the order of their arrival, as well as the pauses between the counted pulses. At the same time, the calculation itself can be carried out either in the direct way or in the opposite, and if necessary, mixed, that is, in both directions.
As a result, the obtained indicators are transformed into various values, such as seconds, minutes, hours, meters, etc. If necessary, the automobile tachometer can be reset, thereby resetting all collected values. However, when using such devices, it must be remembered that the accuracy of the measured data is very arbitrary and amounts to about 500 rpm; in the best electronic devices, it reaches 100 rpm.
Automotive tachometers come in two forms: analog and digital.
Digital devices are made in the form of an electronic scoreboard that displays all the counted information, namely the number of revolutions of the engine and shaft. Such a tachometer is very useful when carrying out adjustment work with the electronic ignition unit of car engines, as well as when setting thresholds in the economizer, etc.
Analog devices are very popular in the automotive industry. They show the number of revolutions of the power unit by means of a dial. The operation of such a device is carried out electronically. This means that the signal from the sensor located on the motor shaft is transmitted to the microcircuit. The latter sets the movement of the pointer (arrow) on the graduated scale. Any analog car instrument and tachometer for an outboard motor work on the same principle. The first is an elementary impulse counter of the electrical system of the engine. It directly depends on the speed of the crankshaft. Outboard boat engine tachometers also count electrical pulses, but they receive “information” directly from the magdino lighting coil, which acts as a generator.
In any car, it makes sense to additionally have a digital tachometer. It is useful for regulating idling and checking the operability of the economizer control unit, as well as the correctness of a standard analog device. This is due to the high accuracy of measurement with digital devices. However, when driving a car, it is better to use a dial gauge, since it is more visual for the driver.