How to connect a tachometer to a diesel engine. Homemade tachometer for a car Tachometer automobile general view drawing

The car market today provides a choice, like budget foreign cars good quality and more expensive premium cars. Available on the market electronic tachometers designed for domestic cars, four-cylinder, in-line engines. An electronic tachometer can be easily connected to any VAZ car model. The concept of a four-cylinder engine is currently the most common on the market, but there are also 3-cylinder or 6-8-12-cylinder engines. In this case, it is impossible to qualitatively connect the electronic tachometer to the car, the readings of the device will not accurately reflect the actual parameters.

Figure 2 shows the electrical circuit of the quasi-analogue electronic tachometer. The principle of operation of this device is as follows. The engine crankshaft speed corresponds to the linear scale of the LEDs, which are located on the tachometer panel. Certainly digital tachometers that were produced in the factory are more accurate in their readings, but they cost money. We propose to create such a device with our own hands, and with a small set of base components.

The electronic tachometer scale consists of 9 LEDs. Each LED illuminated must correspond to 600 rpm of the engine. Only one LED should be on when the engine is idling. The tachometer is adjusted by selecting the value of the resistor R6. Depending on the resistance of the resistor, you can set the indicators for the required number of cylinders. You can also change the division price.

The source of impulses for the full operation of the electric tachometer, depending on the vehicle configuration, can be a Hall sensor, which is included in the electronic ignition system, a shaft position sensor and other versions. The operation of these devices sends pulses to our electrical circuit, which change the resistances R1.

The tachometer indicator works as a simplified frequency meter. The pulses, which are constantly received from the sensor of the car engine, go to the counting input of the decimal counter. The pulses from the clock generator are fed to the "zeroing" input. The counter status depends on the input pulse frequency. The higher the frequency, the larger the number will change the state of the counter.

The LEDs will light up depending on the input frequency of the indicator. A decimal decoder is connected at the output of the counter. During the process of counting the input pulses, none of the LEDs will turn on. The inertia of human vision creates, as it were, the impression of a simultaneous glow of LEDs.

Power for the operation of the device circuit can be connected from any source, bypassing the ignition. A cigarette lighter or a car radio connector can serve as a connection point.

In some cases, the circuit can be powered from the ignition switch. There is no big difference when the motor does not work, the electrical circuit is disconnected, and accordingly, no current is supplied to the LEDs, they stop shining after the engine stops working.

Diode VD1 is designed to protect electrical circuit from the incorrect polarity of the power supply, which is supplied to the input of the circuit. Since there is no voltage stabilizer, the K561 microcircuit operates at a standard voltage of up to 15 V. All auto electricians and car owners know that the car power grid should not supply more than 14 volts of voltage, as this badly affects the operation of on-board electrical devices.

The crankshaft speed sensor sends pulses in real time to the base of the transistor VT1. The KT3102 transistor can be replaced with an analogue of KT315. A transistor is used at the input to protect the input of the CMOS microcircuit from various voltage surges that occur in the vehicle's electrical network. Also, the transistor VT1 works as a converter.

The value of the resistor R1 is selected depending on the source of the pulses. The diagram shows the resistance corresponding to the pulse width from the output of the crankshaft position sensor in the injection engine or the Hall sensor in the contactless ignition circuit of the carburetor engine.

The pulses, which are already consistent with each other in terms of level, are removed from the VT1 collector and fed to the Schmitt trigger, which is built on the elements D1.1-D1.2. The trigger is responsible for converting the pulses into the form necessary for the operation of the counter. Capacitor C2 suppresses interference that can cause meter malfunctions. Paired with resistor R4, capacitor C2 forms a kind of filter that does not pass pulses relative to high frequency.

Output D1.2 sends pulses to the counter input D2. The multivibrator is assembled on two other elements of the D1 microcircuit. The multivibrator generates clock pulses of a certain frequency. The clock frequency, in turn, depends on the selected resistance R6. These impulses go to the part electrical circuit C3-R7, which contributes to the formation of a pulse to reset the counter D2.

Indication LEDs HL1-HL9 are connected to the counter outputs D2. The K561IE8 microcircuit has a relatively weak current at its outputs, therefore, it is recommended to use super-bright LEDs as indicators (with a low incoming current, they glow like ordinary indicator ones). We replace the K561LE5 microcircuit, if necessary, with an analog K561LA7 or CD4001, CD4011. Chip K561IE8 can be replaced with CD4017. The circuit has a brightness regulator R9, with which we can regulate the incoming current, and, accordingly, the brightness of the indication. This allows you to dim the LEDs at night so that they do not blind the driver's eyes.

Figure 2 depicts a simple printed circuit board on which the indicator is assembled. In order not to complicate the wiring more expensive than the board, it was decided to connect the HL1-HL4 LEDs to the meter outputs through jumpers from the mounting wire. The LEDs are connected to the printed circuit board in one line.

In the event that the design of the car dashboard does not allow compactly placing the entire module with the circuit and diodes, then the LEDs can be taken out of the board by installing them on a separate section of the dashboard.

There is another option for installing the tachometer on the dashboard. This is to assemble the indicator into a stand-alone plastic case... Use double-sided tape to stick it in a convenient place.

It is better to buy LEDs super bright. Preferably rectangular.

After installing the complete instrument in its place, you need to adjust correct work devices. The adjustment should be started by calculating the resistance R1 based on the fact that the resistance indicated on the diagram corresponds to the amplitude of the incoming pulses. Then you need to replace the resistor R6 with series-connected variable resistors of 1 Ohm and a constant one of 10 kOhm. Next, we adjust variable resistor for maximum resistance. It needs to be adjusted so that only two LEDs are on when the engine is idling. Note this position of the resistor. Then you still need to reduce the resistance so that only one LED is lit. Now that the resistance plug is installed, you need to adjust the resistor to the middle position. Next, we measure the resulting resistance and find out the necessary resistance R8.

Using a special device at a service station, you can measure the frequency of the car's crankshaft. Thus, having the necessary data on the number of revolutions of the crankshaft, you can more accurately adjust the indicators, with the readings of an exemplary device. This device is only an indicator, it does not need to be treated as a measuring device.

Good afternoon, dear radio amateurs! As we know, a tachometer is a measuring device that measures the rotational speed of the shafts of mechanisms. In cars for measuring the speed of the engine crankshaft, mechanical tachometers were previously installed, modern cars are equipped with electric or electronic ones. Recently I found in my folder with diagrams a simple tachometer straight from the 90s. I did not collect it myself, but my uncle did, he says, it works well. Unfortunately, the photo is gone. The principle of operation is based on transformation alternating voltage removed from the windings of the car generator, into a constant voltage proportional to the crankshaft speed and changing the length of the luminous strip in the indicator gas-discharge lamp IN-13. Here is a diagram of this device:

A 6.3 volt transformer, a 6.3 volt winding was used as a primary winding, and a 220 volt winding as a secondary. The diode bridge is designed for 400-500 volts, the amperage is not important. Resistors R1-R2, 2 watts each (5 watts are also possible). Capacitors C1-C2 must be non-polar.

Tachometer setting

The device is configured as follows: by selecting capacitors C1, C2 and resistor R4, make sure that the luminous strip of the indicator lamp is about 10 mm long at idle (for a shorter length, increase the capacitance of capacitors C1, C2 or reduce the resistance R4). Then achieve a uniform change in the length of the luminous strip with an increase in the crankshaft speed (by selecting resistors R4, R5, capacitors C1, C2, C3) and calibrate the scale using a reference tachometer. The scheme was sent Vasily R.

Most modern cars are equipped with tachometers facilitating right choice transmission, which prolongs the life of the engine. If your car does not have such a device, then it can be made according to the proposed description.

Tachometer circuit is shown in Fig. 1. Its main feature is the use of the K1003PP1 microcircuit, designed to control a linear scale of 12 LEDs. V standard version of the version described in, the microcircuit provides the formation of a column of luminous LEDs, the length of which is proportional to the input voltage.

The signal, the frequency of which is proportional to the engine crankshaft speed, is taken from the contacts of the breaker or from the amplifier-shaper of the Hall sensor and is fed through the voltage divider R1R2 to the input of the Schmitt trigger DD1.1. The purpose of the trigger and capacitor SZ is to suppress bounce pulses at the output of the chopper, high-voltage surges on the winding of the ignition coil and bring the signal to standard levels of CMOS logic with a normal steepness of the edges.

click on the diagram to enlarge
Rice. 1 Tachometer diagram

The Schmitt trigger output triggers a waiting multivibrator on the DD2 chip. In the main position of the switch SA1 “6000” the duration of the pulses generated by the waiting multivibrator is 2.5 ms. At a rotation speed of 6000 rpm, the pulse frequency for a four-cylinder engine is 200 Hz, the repetition period is 5 ms, the duty cycle is 2. The R12C6 integrating circuit averages these pulses, and the average voltage across the capacitor C6 is about 3 V. This voltage is fed to the pin ... 17 (UBX) DD2. At a voltage of 3 V applied to the pin. 3 (UB) of this microcircuit and determining the display scale, all 12 LEDs HL1 ... HL12 are turned on, forming a luminous column.

At lower engine speeds, the duty cycle of the pulses at the DD1 output increases, the average voltage across the capacitor C6 decreases in proportion to the revolutions, and the column height becomes smaller. When the engine is stopped, none of the LEDs are on. The “scale division” of the LED scale is 500 rpm.

It is advisable to install LEDs of different glow colors. For example, if the optimal engine operation corresponds to 2000 ... 4000 rpm, the LEDs HL1 ... HL3 can be yellow or orange (“downshift”), HL4… HL8 - green (“normal”), HL9… HL12 - red ("change to a higher gear").

To adjust the idle speed, the switch should be set to the “1200” position. In this case, the duration of the generated pulses will increase by 5 times and will be 12.5 ms, and the “scale division” is 100 rpm.

Chips DD1 and DD2 of the tachometer are powered through an integral voltage regulator DA1. Capacitors C1 and C2 ensure the stability of the stabilizer.

The current through the LEDs connected to the DA2 microcircuit is determined by the voltage at its pin. 2. In the daytime, when the instrument panel illumination lamps are turned off, a log is present at the inputs of the DD1.2 element. 0, at the output - voltage 6 V, at the pin. 2 DA2 - about 0.85 V, which sets the current to 25 mA through each LED. In the evening, when the backlight is turned on, the voltage on the pin. 2 decreases to 0.4 V, which reduces the current through the LEDs to 8 mA and, accordingly, their brightness.

A drawing of the tachometer printed circuit board is shown in Fig. 2. The design uses constant resistors MLT, trimmer SPZ-19a. Capacitor C5 of type K73-17 for a voltage of 250 V, C6 - K50-16, the rest - KM-5 and KM-6. Microcircuit DA1 - any voltage regulator for 6 V, for example, KR1157EN6 with any letter index, KR142EN5B (G), KR1180EN6, 78L06, 7806. Chip K561TL1 can be replaced with KR1561TL1, CD4093, CD4093B, and K1003PP1 - with UAA180 or A277.

Orange LEDs - AL307MM (yellow ones usually shine weaker than others), green ones with increased brightness - AL307NM6, red - AL307BM. The LED pins are bent at 90 ° with their axes parallel to the PCB. The size of the LEDs has been reduced to 5 mm with a file.

Switch SA1 is any small toggle switch, it should be installed in close proximity to the printed circuit board.

The unused inputs of the DD1 and DD2 microcircuits are connected either to the common wire or to the +6 V circuit.

Setting up the tachometer is pretty straightforward. First, switch SA1 is set to the “6000” position, pulses of positive polarity with an amplitude of 12 V with a frequency of 200 Hz and a duty cycle close to 2 are applied to the tachometer input to simulate a connection to a chopper. If necessary, select the resistance of the resistor R8. Then the same operation is performed for position SA1 “1200” at an input pulse frequency of 40 Hz.

The LEDs can be arranged in a circular arc. In this case, the glow of one LED from the chain may be more effective. To ensure such a mode of switching on the LEDs, their anodes should be disconnected from the outputs of the DA2 microcircuit and connected to the power output (pin 18).

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 a diesel engine come from?

Today, for diesel engines, electronic, digital and analog tachometers are on sale, 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 the installation and operation of the 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, which is 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.

Engine speed and service life. Disadvantages of driving at low and high rpms. What is the best number of engine revolutions to drive. Tips and tricks.

Tachometer consists of 4-digit LED indicator(for accurate determination of rpm) and group LEDs located in a circle (for a visual, more visual, determination of revolutions). The indicator shows with an accuracy of 1 rpm. The LED strip consists of 32 green LEDs and 5 red LEDs located at the end of the scale or any number of red LEDs at your discretion.

32-LED circular ruler

Point or continuous display

4-digit display

Gear shift indicator LED

Output signal limiter

Measuring 0-9999 or above 10000 rpm

Two display parameters above 9999 rpm

Options for 1 rpm, 10 rpm or 100 rpm display resolution

Automatic display of brightness in low light conditions

Adjustable for 1, 2, 3, 4, 5, 6, 8, 10 and 12-cylinder 4-stroke engines and 1, 2, 3, 4, 5 and 6-cylinder 2-stroke engines

Selecting the red line

Selection of turns of light shift

Choice of speed limiter

Selecting the number of red line LEDs

Selecting the refresh period of the image

Hysteresis selection for LED bar

Choice, minimum time limit

The device can be divided into two parts:

1) control board

2) display board

The control board contains the pic16F88 controller, LED power supply and control buttons. Perhaps the most interesting thing is the control buttons with which they adjust the tachometer. There are only three buttons:

S1 - installation

When configuring the device, the green LED34 (mode) and red LED35 (setting) indicate the status. 4-digit indicator with a common anode.

The device is connected to a low level or to a high signal level. A low level is understood as a connection to the car's ECU, and a high level to the ignition coil.

The MC34063 microcircuit is a DC-DC converter, which operates at a frequency of 40 kHz, commutes a transistor to supply LEDs with a stabilized current.

VR1 - allows you to adjust output voltage MC34063 within 1.25-4V.

Inductance L1 is wound on a 28mm ferite ring with a 0.5mm wire.

LM2940CT-5 voltage stabilizer for 5V, provides power to the control circuit. M5451 microcircuits, LED driver.

Automatic brightness is realized on the LDR1 element (photoresistor), which is located on the display board. The better the illumination, the lower the LDR1 resistance. The voltage across LDR1 at high illumination is about 1V. Depending on the resistance of LDR1, different voltages are applied to transistors Q2 and Q3, which in turn control the brightness of the LEDs through the drivers. To correct for automatic brightness, an element VR6 was introduced into the circuit, which is a 50K ohm variable resistor.

The tachometer has an electronic speed limiter, limit out.

Settings:

To switch to the settings mode, you need to hold down the button up and apply power, if the up button is not pressed, the device will go into normal operation. Release the button up and the unit should light up on the display, which means mode 1. The green "mode" LED will be on. It is necessary to select the mode from 1-13 with the buttons up and down.

In each mode, you need to make your own adjustments.

Mode	Possible settings	Note
1 Number of cylinders	1-12	selection of the number of cylinders
2 Red LEDs	0-10	allows you to change the length of the display of the red line
3 Red line	0-30,000	lighting up the first red LED
4 RPM per LED	automatically	automatically calculated from modes 2 and 3
5 Light shift	0-30,000	if you do not need to install further than the red line
6 Speed ​​limiter	0-30,000	install an electronic speed limiter (see 12)
7 Hysteresis	0-255	prevents LED flickering, see mode 4
8 Display updates	0-510ms in 2ms steps	the display refresh period is set
9 Display format	0,1,2	set the display format rpm 0) 9999 1) 9.999-10.00 2) 9.99-10.00
10 Resolution	0,1,10	set resolution 0) 1 rpm 1) 10 rpm 10) 100 rpm
11 Visualization	0 or 1	0) to display point 1) to display continuous change
12 Sensitivity	0 or 1	0) for low level "0V" 1) for high level"+ 5V"
13 Chapel for the period	0-510ms in 2ms steps	set the minimum time when the cutoff output is active

Mode 1 - number of cylinders: enter in the exact number of cylinders for a 4-stroke engine (1-12 cylinders). For example, select “2” for 1-cylinder 2-stroke, 4 for 2-cylinder 2-stroke, etc. For motorcycle, 11 or 7 are suitable for 2-cylinder asymmetric 4-stroke engines. 9 for tuning for an asymmetric 3 cylinder 4-stroke engine.

Mode 2 - red LEDs: responsible for the glow of the red LED strip, select the number of LEDs that will light up, by default 5, you can select 0-10.

Mode 3 - Red Line: This mode is used to set the maximum recommended RPM for your engine. The default is 9000. Note that 10,000 revolutions will be displayed as 10.00.

Mode 4 - RPM per LED: This mode shows the RPM gain for each LED in the bar, i.e. how many revolutions are there per LED.

Mode 5 - Light Shift: The default value is 8000 rpm, ranging from zero and above 30 thousand rpm. The setting is in x1000 format, for example 8000 is displayed as 8.00.

Mode 6 - RPM Limiter: This mode sets the RPM limitation. During operation, the output limiter changes, when the measured speed goes higher, then this parameter and the output signal level depends on the setting (see Mode 12). This setting can be changed in 100 steps from 9900 rpm in the range from zero to above 30,000 rpm.

Mode 7 - hysteresis: to avoid the threshold value, you can set hysteresis, for example, the subsequent LEDs quickly turn on and off. The default setting hysteresis is 50 rpm and can be changed in 1 from 0-255 rpm. Note that the hysteresis value must be less than the value (see mode 4).

Mode 8 - Display Updates: Refreshes every 1ms, but this is too fast for the digital display to read if there is any change in RPM. As a result of the update, the digital display will slow down to a more comfortable speed. Typically an update period of 200 ms (or five changes per second) is appropriate. The default setting is 250ms with a step of 2 from 0-510ms.

Mode 9 - Display Format: This adjustment is mainly for servicing engines that are above 10,000 rpm. An initial value of "0" sets the display to display from 0-9999 RPM. Above this figure, the display shows "0" 10000 rpm, "1000" at 11000, etc. Use this setting for engines that do not exceed 10,000 rpm, or that only occasionally reach this level.

Mode 10 - resolution: if you do not like how the readings run at a fast set of revolutions, you can lower the resolution, to lower the resolution, put "1" and the last number will always show zero. If "2" then the last two will be zero.

Mode 11 - visualization, point or ruler: whether the LED bar will operate in point mode (i.e. the LED is on at any time) or as a continuous change. Select "0" point mode or "1" for continuous mode.

Mode 12 - sensitivity: if "0" is set, then it goes from 0 to + 5V, and if "1" then from + 5V to 0.

Mode 13 - side-limit for the period: the minimum time is set when the cutoff output is active

The tacometer has a maximum speed limiter, the output of which can be used in a separate circuit that will limit the engine speed. For example, in the ignition or fuel supply circuit.