The tachometer is a device that is actively used on gasoline and diesel vehicles. This device is used to measure the speed of rotation (revolutions) of the crankshaft or generator. Most modern vehicles are equipped with a standard tachometer directly from the factory.
The need to independently install a tachometer on a diesel engine can arise for various reasons. It should be noted that the connection diagram for a tachometer on a diesel engine is somewhat different from a similar solution for gasoline internal combustion engines. In the process of choosing a tachometer for a diesel engine, this feature must be taken into account, since a tachometer for gasoline engines will not work on a diesel engine.
Read in this article
Where does the tachometer signal to the diesel engine come from?
Today, electronic, digital and analog tachometers are on sale for diesel engines, the connection diagram of which assumes a number of features. The fact is that, in the overwhelming majority of cases, the generator acts as the connection point for a tachometer for a diesel engine.
To implement the connection to the generator, you must have the tachometer itself, an insulated wire and accompanying instructions for installing and operating a car tachometer.
Device connection
The principle of operation of the electronic tachometer is based on the reading of electrical impulses. In gasoline units, pulses are read, which in a certain amount are fed to the ignition coil. As for the diesel engine, the reading is carried out from a special terminal located in the generator housing.
Read also
Why doesn't a diesel engine need to be turned like a gasoline engine. Features and differences of diesel internal combustion engines in comparison with gasoline. Optimal RPM.
Many car enthusiasts know perfectly well why and for what purpose engineers came up with a tachometer in cars. Some do not look at it at all, and on some cars its presence is not provided. Is an electronic tachometer provided for such cars?
What is it?
Before we talk about electronics, let's see what this device is for in general.
So, this is a special device that is installed on cars to control the crankshaft speed. So, this device shows the driver with what frequency the motor is rotating. This is necessary so that the driver does not exceed the permissible speed.
Main function
The tachometer helps inexperienced drivers who cannot yet determine the rpm by the sound of the unit's operation to select the correct gear. Driving in the correct gear allows not only to significantly increase the resources of the power unit components, but also to save fuel. When the arrow of the device enters the red zone, it is recommended to shift a higher gear. Also, this device is used to adjust the carburetors both at idle and while driving.
Operating principle
The tachometer registers the number of pulses that are supplied from the sensors. The pauses between pulses and the order in which they arrive are also taken into account. The counting process can be carried out using both forward and backward directions. Indicators are often converted to a certain value. This value can be any indicator. Most of these devices can be reset. As for the accuracy of the readings, it is rather arbitrary. The electronic tachometer of the best quality has an accuracy of about 100 rpm.
Digital tachometer device
If we consider this device, then this device consists of:
- central processor;
- 8 or more bit ADC;
- coolant temperature sensor;
- display;
- an optocoupler used for diagnostics;
- reset block.
Electronic pointer devices
Electronic tachometer in most cases is made in display format. Readings are displayed on this screen.
These are the revolutions of the crankshaft. These devices are especially convenient in the arrow version. Pointer equipment is most commonly seen on dashboards. Drivers find it very convenient, as the signals from the sensors are transmitted to the switch. Scientists have proven that the brain perceives information from the arrow better than the numbers on the display.
We assemble an electronic tachometer with our own hands
Why buy when you can assemble everything yourself? It is not that expensive and interesting enough. There are several device options for assembly. These devices are assembled on the basis of contact or non-contact sensors. In non-contact systems of the optical type, it uses laser or infrared beams to register pulses. The time of one revolution is calculated. Let's see how to build your own optical registration device using an Arduino microcontroller.
Arduino electronic tachometer circuit
To assemble the device, you will need, of course, an Arduino microcontroller. If it is not there, then any other controller with similar characteristics will do, but then you will need to additionally assemble the programmer. Also for this circuit you need 33k ohm, 270 ohm, 10k ohm resistors in the form of a potentiometer. You can also purchase blue LED, infrared LED and photodiode. Next, find the DSV display and shift register chip labeled 74HC595. It uses an optical sensor and the principle of ray reflection. With this system, you don't have to worry about how thick the rotor should be, and the number of its blades cannot change the performance. The sensor will be able to accurately read rpm.
Assembling the sensor
The first thing to create a sensor is an infrared diode and our photodiode. In the first step, sand the diodes until they are flat. Then it is recommended to fold a strip of paper in the form of a rectangular tube.
Further according to the scheme
Resistors and their ratings may vary slightly. It depends on the diodes. A variable resistor makes it possible to change the sensitivity level of the received sensor. So, "ground" is connected to a 33 kΩ resistor and a variable resistor, and that, in turn, is connected to the wire to be installed in front of the potentiometer. The minus of the LED is connected through the remaining resistor to ground, and the plus goes to the "Arduino". So, we got three leads - ground, plus and a signal wire. This circuit uses an 8-bit shift register and display. In the case, it is advisable to think over the indentations for the indicator. Now the 270 Ohm resistor is soldered to the LED and then installed in the 12th pin of the microcontroller. Now the electronic tachometer is ready. You can start programming and calibrating it. The program for "Arduino" can be found on automotive resources.
Another homemade tachometer
In order to measure the number of revolutions, as we already know, the counting of the breaker pulses or the voltage from the spark plugs is used. The frequency of these pulses is linearly related to the speed of the motor. You can also try to organize inductive coupling with such a circuit, which will be demonstrated in this device. As a basis for this option, a one-shot with the marking LM 555 is used.
The element is triggered due to impulses from the candles that are guided in the coil. The input contact is used for either setting or signaling from the breaker. For an ordinary four-cylinder unit, the speed of which is 3000 rpm, the frequency is 100 Hz. For 1500 rpm - 50 Hz. This enables simple frequency calibration of the device. The pulses received from the third output of the microcircuit are fed to the dial indicator. In this circuit, the author uses a milliammeter. The indicator will show the voltage in this network. Since the duration of the pulses at the output of the microcircuit is approximately the same, the voltage is proportional to the frequency with which sparks are formed. So, the scale of the measuring device can be redrawn by calibration. A head from an old cassette recorder is an excellent coil. It should be located near the high voltage coil. To protect the microcircuit, you can use a 12 V diode.
Tachometer for motor vehicles
How do I fit an electronic tachometer to a motorcycle? Here the owners of motor vehicles have a choice: either to purchase ready-made equipment, or to make them on their own. Suppose there is a motorcycle, there is a device for monitoring the revolutions. But how do you connect an electronic tachometer? For these purposes, the TX-193 apparatus from the six is \u200b\u200bbest suited for mounting on domestic brands of motorcycles.
The device is extremely accurate, lightweight, energy efficient, and stable under vibration. I must say that this model does not even compare with any tachometers for motorcycles. The process of connecting the device to two-cylinder motorcycles with a starter and a battery, as well as single-channel ignition, is no different from the process of connecting the same device to a VAZ. The input of the device is connected to the output of the primary winding of the ignition coil. The device can be powered from the battery. For this, the unit has appropriate wires. It is then recommended to integrate a switch into the positive cable. This is useful when the technique is at a standstill. This saves battery power.
If the motorcycle is not domestic and there is still the same electronic tachometer, the connection diagram will change slightly. In this case, you will have to power it through the ignition switch. There are special contacts there for these purposes. If the motorcycle does not have a starter, then the battery should be connected to the output of the rectifier. And from the battery it is already possible through the switch to supply power directly to the tachometer. If there is no rectifier, you need to buy one. If there is no battery, you can put it in. The easiest option is to supply power from a UPS or an old flashlight. If you connect the measuring device directly to the generator coil, then it will burn out. To avoid this, you can ask your neighbor radio amateur to make a voltage regulator on thyristors.
If the engine has three cylinders, then signals from two coils are input here. There are also technical possibilities for installing a tachometer on six-cylinder motorcycles, but this already requires purchasing proprietary equipment.
Installing a tachometer on VAZ cars
You can purchase a freelance electronic tachometer (VAZ 2109 is not equipped with these necessary devices regularly) and enjoy life. Modern devices are also multifunctional. On many of them, the car enthusiast will find an additional clock with an alarm clock and much more useful.
It should be noted that these devices differ in the type of motor power supply. For gasoline engines, the principle of operation is the same, for diesel engines it is completely different.
Gasoline devices also have differences in the number of cylinders
So, everything is bought. Now decide where you will install the electronics. Many put it on the dashboard, others mount it near the ignition switch. However, it is best if the electronic tachometer is installed in a place where it will not spoil the appearance of the panel.
The best friend of the motorist will help to fix it - double-sided tape. This versatile remedy can help you in a variety of situations.
DIY device connection
Not everyone understands electronics, but it is still desirable to be able to connect a measuring device. This will not cause difficulties, because there are only three wires. The first thing to do is take the wire from the tachometer to the engine compartment. The easiest way to do this is through the hole in the speedometer cable. Next, you need a piece of wire. It should be about one meter long, thin and tough. At one end, use electrical tape to secure the wire from the device. Try to work neatly. Carefully insert the other end of the wire into the holes in the cable and push. Connecting an electronic tachometer can be done as follows. The positive wire is connected to the ignition coil (contact B). Connect the signal wire to contact K of the same coil. Connect the minus to the mass. Work as carefully as possible, the wires are very thin and very unreliable.
Now it remains to start the car and test everything. That's all. Now you know how to connect an electronic tachometer, and you can even assemble the device yourself if you want. It will not take you much time and effort.
The main function of the tachometer in the car is to determine the correct gear, which positively affects the life of the engine. Most cars have an analog tachometer built in during assembly. The driver looks at the arrow approaching the red line and knows when to shift up. Not all cars have a type of device that satisfies the owner, so you just need to figure out which ones are and how to connect a tachometer.
Did you know? The term "tachometer" comes from the Greekτάχος - speed and μέτρον - measure.
Types of tachometers
There are two types of tachometers: digitaland analog. The first looks like a small screen where the driver can see all the data he needs while driving. The second is simpler and looks like a board with arrows and values.
Remote
The remote tachometer is installed on the front panel of the car. For greater ease of placement, such a device has a leg for fixing on the panel. Remote digital tachometers are good for monitoring idle speed. Their readings have fewer errors, therefore, using such a device, you can check the operation of a standard tachometer. In addition, their stylish appearance gives the car an elegance.
Staffed
The standard tachometer is built into the car dashboard. This device is more convenient, since it is easier for the driver to perceive the movement of one arrow, and not several indicators while driving. A standard tachometer is more often used in cars, and manufacturers of electronic devices produce kits for self-assembly of cars.
Important!Measuring instruments are produced according to the car brand. The readings of a non-native mechanism will not be correct.
How to connect a tachometer via an ECU
If your car does not have a carburetor engine, and the tachometer injector is not connected to the ignition.In this case, you need to connect to the ECU controller. The tachometer connection diagram is simple: take the mass to the body (ground), plus from the device, bring it to the ignition plus. The tachometer has two inputs: the first goes to the control unit, the second to the crankshaft position sensor. The device connected to the ECU will read pulses directly from the controller of the control unit.
Connection diagram of a tachometer to a gasoline engine
Before installing the tachometer on the carburetor engine, read the instructions supplied with the device. If not, proceed with the installation according to the following steps:
- Secure the mechanism in its place (the location is determined by the type of device).
- Connect the black wire to the ground (body) of the vehicle.
- Connect the red wire to the ignition switch terminal that supplies 12 W when the ignition system is operating.
- The third wire can be of any color. Since the ignition system is contact and non-contact, we will consider where to connect the tachometer in both. With a contact system - the device is connected to the distributor breaker. In the second system - to the voltage switch.
If the car has a display backlight, the tachometer is connected to the terminal available for this in the ignition switch. How to connect a tachometer to a diesel engine
Before connecting, let's figure out what the diesel tachometer works from. The principle of operation of the electronic device is to read the readings of the pulses sent by the terminal, which is located in the generator.
Since the process is time consuming, it must be carried out in an inspection pit.The first point of work is to dismantle the protective casing of the generator, try to avoid getting dirt. The second stage is the connection of the tachometer to the diesel generator. To do this, find the terminal marked with the letter "W" on the generator body and connect the device output to it.
Attention! It is imperative to close the contact extending from the oil pump. If this is not done, the tachometer may "lie".
It happens that the above indicated terminal cannot be found. In this case, disassemble the generator.Connect one of the wires connecting the winding and the rectifier to the tachometer cable. Insulate the wires and reassemble the generator in the reverse order. The installation of a measuring device is not very difficult, but without any knowledge of how a diesel engine works, how a tachometer works on a diesel engine, without the slightest idea about car repair, it is better to turn to professionals.
How to check the tachometer for performance
We figured out how to connect a tachometer to a diesel and carburetor engine. Now let's consider the causes of device breakdowns. You have noticed problems with the meter, such as an arrow jumping in different directions. There may be several reasons for the breakdown. When the engine is running for a long time, vibration occurs, which can damage the display. The next reason may be oxidation of the contact group of electrical wiring, damage to its insulation or disconnection from the terminals. All these are visible reasons that must be eliminated immediately. If the sensor itself is broken, a replacement is needed. In the event that self-diagnosis has not identified the reasons, it is worth contacting a car repair shop.
Interesting! The tachometer was designed by American Curtis Widder in 1903.
Automotive tachometer - a measuring device installed on a car and showing the frequency of revolution of the crankshaft in the engine. The unit of measurement is the number of revolutions per minute. The main function of the device is to monitor the level of the crankshaft speed. This is to prevent it from exceeding the maximum permissible value for optimal motor performance.
Stable engagement of the tachometer while the engine is running will help reduce engine wear. Each time the arrow on the tachometer approaches the limit zone, the driver shifts into a high gear. Tachometers - regulators of engine idling and driving. As practice shows, a tachometer can be installed on a car of any brand, regardless of whether it was included in its equipment or not. It doesn't matter what engine is installed on the car - gasoline or diesel. In case of failure, it can always be replaced with a new one.
On a car equipped with a standard ignition system, remote tachometers are installed in a clear location, most conveniently near the dashboard. The black negative wire is connected to the car body. The red lead serves as a power transmission line for the tachometer, it is connected to the terminal of the ignition switch, showing at the moment of ignition itself 12V. The third wire is attached to the coil terminal, to which the ignition distributor is also connected (if the ignition system is contact, if contactless, then a switch is connected to the terminal). This wire is responsible for measuring readings on the tachometer. If the tachometer system provides a scale illumination at night, it can be operated from the side light switch.
The diesel system for installing a remote tachometer is also not a problem. In this case, the measuring output of the tachometer is connected on the generator to the terminal with the "W" sign. If this terminal is missing, you can remove it yourself using a tightly insulated wire. First you have to remove the generator, and then also disassemble. Thus, three wires will be visible, extending from the winding and going to the built-in rectifier. You can connect a tachometer to any of them, having previously insulated and lengthened to output it outside the generator. At the end, the generator should be assembled in the reverse order. It is imperative to make sure that the withdrawn wire does not touch the moving parts.
Connecting a tachometer to the specified system does not mean that it will accurately show the speed. Many of the latest tachometers count the pulses from the engine in different ways. For gasoline generators one value is obtained, for diesel generators another. Therefore, before you buy a tachometer for your car, you should find out if the device you have chosen is suitable for your model. But there are universal tachometers with a built-in switch that allows you to connect it without damage to different types of engine (from 2 to 8-cylinder petrol and diesel).
Everyone knows that a tachometer is included in almost every dashboard in modern vehicles. However, not all drivers know exactly why this device is needed. In this article we will tell you what a tachometer is, what they are, and we will analyze the main causes of its technical malfunctions.
A tachometer is a device that measures and shows in real time the number of revolutions of the crankshaft of the power unit. It can track changes in engine speed in order to avoid too low or, conversely, high crankshaft speeds.
During the movement of a car or other vehicle, the device helps the driver to increase the gear in a timely manner, based on its readings. Even the most inexperienced motorist will be able to switch the speed in time when the needle of this device approaches the red zone or, conversely, goes down to the minimum. Also, it should be said that using the tachometer, the desired engine operating mode is selected.
Tachometers are both digital and analog, they can reset the received data, and the accuracy of their readings is rather arbitrary and can vary.
Digital tachometers have an electronic display that displays all the necessary information about the speed of the power unit. Such devices are used to tune and adjust the economizer, electronic ignition, as well as the entire engine as a whole.
The analog tachometer is more popular and used more often than the digital one. And all because of the convenience in its use. When driving, no special accuracy is required, the speed is shown by an arrow moving along a calibrated dial. If the sensors are not working correctly, then the needle twitches and it becomes impossible to control the speed. The design of this device has been created and changed over the years, so it is easy and reliable to use it.
If, when starting the engine and when driving the vehicle, the tachometer needle jumps or points to the zero mark, this means that the device is out of order. There may be several reasons for this. However, the most common cause of failure is replacement of high voltage ignition wires. Poor wiring conditions can also cause the tachometer to malfunction.
Malfunction in the tachometer
If there are signs of malfunction, first, you should pay attention to the general condition of the wiring. Very often, damage to the wires or lack of contact in them can cause a breakdown of the tachometer. Various minor defects, in the form of traces of corrosion, minor cracks or loosening of the fastener, are easy to eliminate, but if the damage is serious, the wiring will need to be replaced.
An equally important reason for the breakdown is the installation of silicone ignition wires instead of the standard ones. This is because the linear resistance of silicone wiring is very different from the resistance of factory wires. As a consequence, the shape of the current pulse changes. If you reduce the value of the resistor on the KP board, then the malfunction is eliminated by itself.
As for digital tachometers, a popular cause of device malfunction is often the breakdown of a special digital screen that shows the current parameters of the car. To resume the operation of the device, you will have to change the LED display.
It is also not necessary to exclude the breakdown of other parts, it is necessary to identify which element is broken and replace it with a new one.
Why does the tachometer needle jump
To find out why the tachometer needle twitches, it is necessary to perform the following manipulations:
1. On the dashboard, find the "Check" lamp and check if it lights up. If not, then, most likely, system diagnostics will not be able to determine the malfunction.
2. Check the wiring by testing the voltage level on the wiring plus and minus, and also, check the condition of the connections.
3. If other equipment or devices are not working correctly, it is imperative to check the mass, because this part is often overlooked.
4. Check the condition of the distributor contacts and the capacitor on its cover, as it could be punctured during operation.
5. Also, you need to check the circuits in the ignition system.
6. If you have recently repaired the device or replaced it, then it just needs to be configured. To do this, you need to adjust the zero position and the device itself, adjust the quality of the connection and adjust the toggle switch on the back of the unit.
7. If the arrow jumps when the engine reaches high rpm, the commutator is broken and needs to be replaced.
Buy a tachometer for a car
The digital tachometer looks like a display with luminous numbers that show the frequency of movement of the engine parts.
It is useful when performing operations on tuning electronic ignition units, setting the saturation state of combustible material, when the engine is running at full power, or when it is necessary to perform a gradual acceleration. It is considered the most accurate and, most often, is chosen, if necessary, to adjust the idle speed or check other devices similar to it.
As for the analog tachometer, they are presented as a dial with an arrow. Such a device is considered more modern, popular and convenient, since the dial is more easily perceived by drivers and allows them to analyze the situation much faster than in the case of numbers. Therefore, when choosing a tachometer, you need to decide which characteristics are preferable and more important for you. However, one way or another, the presence of this important sensor is very necessary on the road, if only because it will allow you to determine in time about the presence of various problems in the engine of your car.
Do-it-yourself installation of a new tachometer, step-by-step work progress
You can install a tachometer on any car; this procedure is not complicated and does not require contacting a workshop. However, the installation process itself depends on which engine is under the hood - diesel or gasoline. I propose to consider the methods of connecting the tachometer in more detail.
Installing a tachometer on a car with a gasoline engine
If your car is equipped with an ignition system, then first you need to mount the device itself. Very often, drivers use a remote tachometer.
Directly the device mounting scheme looks like this:
1. Wiring “minus”, which often has black insulation, is connected to the vehicle ground.
2. Power wiring is usually red in color and connected to the correct terminal on the ignition switch.
3. If the car's circuit is contact, then the wiring that is connected to the measuring input of the device is connected to the terminal of the ignition coil connected to the distributor breaker. When a contactless circuit is applied in the car, the third wire is connected to the switch.
If the tachometer is equipped with a backlight, then it is connected to the dimensions of the car, using a special terminal of the ignition lock.
Installation of a tachometer on a car with a diesel engine
1.When your car has a diesel engine, the test lead of the device must be connected to the generator terminal marked with the symbol "W".
2. If you cannot find it, you need to disassemble the generator and get to the wiring that connects the winding and the rectifier.
4. Ultimately, the generator must be reassembled.
As you can see for yourself, tachometers are different, so it is very important, before buying such a device, to ask the seller if this unit will work correctly on your car.
Surprisingly, until recently there were no tachometers at all and the drivers somehow coped with it. However, modern motorists are accustomed to the fact that everyone makes special settings for them. Rumor has it that the manufacturers of the Mazda brand want to bury the tachometer and exclude it from the instrument panel.
