Question to a psychologist 

Wiring diagram for fuel tank indicator on LEDs. Capacitive fuel level sensor on ATMega8A. Checking the fuel gauge with feedback

The circuit of the digital fuel level indicator has a high degree of repeatability, even if the experience with microcontrollers is negligible, so understanding the intricacies of the assembly and tuning process does not cause problems. The Gromov Programmer is the simplest programmer that is needed to program the avr microcontroller. The Goromov programmer is well suited for both in-circuit and standard circuit programming. Below is a diagram of the control of the fuel indicator.

The photo below is a montage.

Functionality of the device:

  • is able to accurately display the current fuel level, up to a liter, supports a fuel tank from 30 to 99 liters;
  • displays information about the on-board system;
  • works taking into account the fluctuations in fuel that is observed during the movement of the car, the internal sensor in the tank makes multiple measurements and the information is displayed based on the arithmetic mean (the frequency of measurements can be set in the menu);
  • the brightness of the backlight changes depending on the current level of illumination, there are two modes in total: day and night;
  • There are two modes of indicator display of information: normal and inverse.

Microcontroller details:

R1 - 1 kOhm
R2 - 75 kOhm
R3 - 10 kOhm trimmer
R4 - 4.7 kOhm
R5, R6, R8-R11 - 10 kOhm
R23, R12-R15 - 3.3 kOhm
R24, R16-R19 - 1.8 kOhm
R20 - 2 kOhm * selected depending on the backlight
R21 - 240 Ohm
R22 - 1 KΩ * selected and set permanent
C1, C2, C15 - 0.01 microns
C3, C4, C6-C11, C13-C15 - 0.1 microns
C5 - 47 microns
C12 - 4.7 microns
L1 - 100 mH
DD1-LM7805
DD2-ATMega8
DD3-LM317T
VT1-IRFZ44
LCD1 - Nokia 1110/1200/1110i/1112.

The diagram does not indicate the PC10 connector, through which the buttons are connected and the output for installing software on the microcontroller.

You need to make two boards: one for the display; the second will be the main one. Both boards must be circular in shape and their case diameter must be 50mm. It is rather difficult to find the indicator of the mating part for the connector, so it is rational to carry out the wiring for the cable. It is also necessary to unsolder the connector from the counterpart and solder in its place only on the reverse side, solder the cable, the display itself can be attached using double-sided tape.

The main (main) board is double-sided, however, the reverse side is the base one, and stabilizers and one transistor are located on the second side, the main part of the parts is installed on the side of the tracks. The base square holes are soldered with jumpers, the rest of the holes are drilled out.

In place of the disassembled connector, the two boards are connected using contacts. A threaded sleeve is soldered under the main board, and the board is fixed to the body with one screw. There are no buttons, since from a practical point of view they are not necessary.

They are needed only when performing the initial calibration, and therefore are output to the PC10 connector, which is located on the back of the case. Signals for programming the microcontroller are also output through this artificial connector.

Instructions for setting up a digital fuel level indicator.

1 step. In-circuit programming of the microcontroller is carried out, for this you can use any programmer that is at your disposal.

2 step. Fuse setting is as follows. First you need to adjust the voltage readings. To do this, you need to connect the indicator to a voltage of 12-14V in order to configure it, we connect a voltmeter and a trimmed resistor R3 to the same power source, in which we set the values ​​\u200b\u200bthat the voltmeter displays.

3 step. Next, you need to configure the device software. First you need to set the tank capacity and calibrate it. Calibration of the fuel tank is carried out as follows, set the value of the empty tank to 0 liters and press the OK button. Then, pour 1 liter of fuel and set the value to 1 liter of fuel and press the OK button again.

This procedure must be repeated several times until the tank is full. Naturally, this process is quite long in time, but it must be completed once without fail.

During calibration, you can also record sensor readings, which will save a significant time period when performing any firmware. Other types of settings can be set according to individual preferences.

The fuel indicator will allow you to rationalize the daily consumption of gasoline and thereby save money.

The fuel level sensor responds. If it fails, the system will not determine that there is no fuel, and this threatens to fail the fuel pump. The article gives a description of the FLS, analyzes typical malfunctions, gives recommendations on diagnosing a fuel level sensor, how to repair, replace and connect.

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Description of FLS

DUT is designed to measure and control the fuel level in the fuel tank of a vehicle. Its function is to determine the fuel level, convert it to volume and transmit data for display on an analog or digital device. The regulator pointer is on, allowing the driver to monitor the amount of fuel in the gas tank.

Device and principle of operation

According to the purpose, it is possible to conclude where the FLS is located. It is installed in the fuel tank. Depending on the type, it can be a separate element or combined with a fuel intake if a carbureted engine. On a car with an injector, it is part of the fuel supply unit.

The most common contact FLS. Their main element is a potentiometer. The principle of operation is based on a change in resistance. There are two types of such devices: lever and tubular. They differ in design.

The design of the lever type device includes a float and a potentiometer connected by a lever. The potentiometer has two sectors, a slider that contacts the sectors. One end is connected to the lever, and the other to the float. The float is constantly on the surface. With fuel consumption, it lowers, and the slider moves with it, since they are connected by a lever.

This changes the resistance of the fuel level sensor, the value of which provides information about the volume of the substance. The advantage of these devices is the simplicity of design, the disadvantage is the error of readings, especially for analog pointers.

There is no potentiometer in the tubular type device, but the principle by which it works is used.

The design includes a protective tube with a guide post along which the float moves. The float is connected to a resistance wire, which is connected to the indicator wires. Principle of operation: fuel enters the tube through the hole, the float is on the surface and moves depending on the volume of fuel in the tank. From the position of the float, the resistance changes, which is transmitted to the pointers. The lever device gives more accurate readings, but is used less frequently due to design features: it may not be suitable due to the geometry of the gas tank.

Photo gallery

You can make FLS with your own hands. To do this, you need to be able to handle a soldering iron and have knowledge of electrical engineering. When manufacturing, it should be taken into account that the signal depends on the value of the fuel level. The design of the device is quite complex. When the fuel is lowered to a certain level, the float also drops, but the data arrives at the dashboard indicator with some delay.

You can install either an analog or digital fuel gauge with your own hands. The latter gives more accurate readings, as it can correct and align the data obtained.

A self-made fuel meter consists of two modules connected by three wires. One is a capacitive sensor module, the second is a display module. The sensor model is powered by two wires. The reflector module receives a signal through the third wire, converts it into an indicator of the fuel level (the author of the video is Vova Grishechko).

Possible malfunctions and ways to eliminate them

Despite the simplicity of the design, sometimes there are problems with the FLS. If the device malfunctions, the gasoline sensor incorrectly shows the fuel level, the arrow of the analog device either does not rise or shows a full tank, etc. If the FLS is lying, then electrical and mechanical problems are possible.

The causes of electrical problems are:

  • oxidized contacts;
  • blown fuse;
  • wiring damage.

Repair of the fuel level sensor in this case consists in cleaning the contacts, replacing the fuse, ringing the power supply and replacing the damaged areas. The cause of mechanical breakdowns is most often wear and tear and violation of the rules of operation.

There are several reasons:

  • violation of the tightness of the float;
  • wear of components;
  • lever bend.

FLS gives incorrect readings when the sectors are worn out. They quickly become unusable due to the constant movement of the runner over them. If the wear is small, then to restore performance, you can bend the slider, it will again come into contact with the surface of the sector. If the wear is significant, the fuel level sensor will need to be replaced (video by Pavel Cherepnin).

Bending of the lever is possible when the fuel sensor was inaccurately removed from the tank or incorrectly installed. This will result in incorrect readings. If the float is punctured, fuel will get in and the float will not float to the surface. Naturally, incorrect information will be reflected on the devices. Mechanical malfunctions are eliminated by replacing parts or the entire device that determines the level of fuel in the tank.

Incorrect readings may be due to improper placement of the float limiter or an unadjusted fuel level sensor in the tank. Is there a way to trick the fuel level sensor. To do this, you need to adjust the angle on the rod that holds the float. By changing the angle, you can achieve that the regulator shows more accurate data.

Inaccurate pointer readings can be fooled by adjusting the angle on the rod holding the float. By bending it in different directions, you can eventually achieve more accurate readings.

Self-diagnosis of the controller

Before proceeding with the repair, you should find out if the fuel gauge or the regulator itself, located in the tank, does not work. There are special technological holes in the tank to access the wiring and indicator connectors. The location of the hatch differs on different car models, so you need to know the location of the FLS before checking the regulator.

The indicator is checked with a multimeter. If the tank is full, then the resistance should be about 7 ohms, when half full, the resistance should be in the range from 108 to 128 ohms. If the gas tank is empty, the multimeter will read 315 to 345 ohms.

To check the regulator, you need to disconnect the wires from it and connect a resistance of 330 ohms. Next, add a 10 ohm resistor to the circuit. After starting the engine, the resistance across the resistor is measured by moving the slider. The pointer moves from the empty tank value to the full tank value.

To check the pointer, you can use a control light, a tester, using a working fuel level meter. With a working indicator, the voltage on the wires should be equal in value to the voltage in the on-board network.

Instructions for replacing and connecting the regulator with your own hands

To replace, you need to prepare a set of keys, a new FLS, know how to remove the fuel level sensor. In order to find out how to connect the FLS, you need to understand the connection diagram.

Fuel level sensor wiring diagram

The replacement procedure consists of the following steps:

  1. We drain the fuel from the tank.
  2. Next, you should determine how best to get to the regulator: through the back seat or through the luggage compartment.
  3. We remove the protective plastic cover from the fuel tank, under which the FLS is located.
  4. Disconnect the plug with wires from the regulator.
  5. We unscrew and remove all the tubes by loosening the clamps with a Phillips screwdriver.
  6. We take out the old FLS and install a new one.
  7. We make the connection according to the diagram.
  8. Assembly is carried out in reverse order.

After replacement, you need to fill the tank with fuel and check the operation of the FLS. The pointer should have a value corresponding to the volume of filled fuel.

If the fuel level sensor is buggy, then knowing how to fix it, you can save time and money on visiting the service station.


It will soon be a year since I posted mine on Datagor and for more than two years now I have been using this indicator myself. And he never let me down, going to the gas station when there are 2-3 liters left in the tank has become the norm, and this is not extreme and not window dressing, when you know that these 2 or 3 liters are definitely there and they are enough to get to the next few gas stations. to this calmly, no comparison with the flashing light of a regular device.
This concludes the philosophizing - to the point!

It is probably not clear why the actual version of V.3, when there was no version 2, actually was, here it is


But it turned out to be unsuccessful, switching regulators on the MC33063 were used for power supply, which give ripples in both directions and I could not get rid of them. And since the idea of ​​creating a KIT appeared, it was decided to make a new version, with a reliable power supply, with protection of all input circuits and on the details corresponding to the operating conditions, first of all, this is a temperature range of -40..+125°C.
So a new 3rd version appeared, made almost according to all the rules, with updated firmware.

KIT, unfortunately, turned out to be not in demand, but a lot of time was spent on it, and now it is gathering dust on a shelf, or rather in its folder.
And so that the work does not go to waste, I post all the documentation for the project, I will be glad if it is useful to someone.

From Igor (Datagor):
When analyzing personal correspondence, comments on the first article, and after conducting selective surveys, it was found that people want not just a very high-quality gas gauge, but also an alarm clock, etc. and so on (and there was a little Chinese inside and ran for beer), which turns this wonderful and completely independent development into another on-board computer (BC). At the same time, for this BC, the people wanted to pay no more than 500 rubles in assembled form. And it won't go through any gates at all ...
We didn’t make a bookmaker, and we didn’t open a subscription to a whale against such a sad background either.
Dear Sergey (HSL), in any case - our honor and thanks!
The quality of his designs is top notch.

So in order...

Scheme

Scheme of the processor unit, there are 2 modifications A5 and A2
Scheme A5

Scheme A2


The difference is in the connection of the AREF signal (reference voltage), in option A5 it is taken from the + 5V power bus, in option A2 it is taken from an internal source.
The main modification is A5, A2 is made to expand the functionality, in case the main modification fails to calibrate the tank.
On the board, this is done by different installation of the elements R11, C4, C6, this will be described in more detail below in the instructions.
The display board connector is also used for in-circuit programming

Display unit diagram


This block turned out to be universal, it has a display, controls, a stabilizer to power the display, so it can be used with other devices.

Boards

Processor board


The connector for connecting the display board is also used for in-circuit programming of the MK.

Display board


The display is connected via a standard connector and attached to the board with double-sided tape.

Specifications

Supply voltage 8-30 V
Voltage operation of the night mode backlight 10-20 V
Fuel sensor resistance (recommended) 250-500 ohm
Voltage display resolution 0.1 V
Voltage display range 8-30V
The discreteness of displaying the amount of fuel is 1 l.
Supported tank capacity range 30-99L.
Inertia range 1-10 sec.
The range of gradations of brightness 0-255 units.
Contrast gradation range 1-15 units.

Device Main Mode Capabilities

Digital fuel level and voltage indicator allows you to control:
  • The on-board network voltage with a display accuracy of up to 0.1 volts, the permissible operating voltage range is 8-30 volts.
  • The remaining fuel in the tank with a display accuracy of 1 liter, the allowable measurement range is 30-99 liters. The recommended sensor resistance in the tank is 250-500 ohms.
  • The device is connected to the following points: ground, power, sensor in the tank, dashboard lighting or dimensions.

Device customization options

  • Possibility of setting the tank capacity from 30 to 99 liters.
  • Possibility of liter calibration of the selected container.
  • Possibility to smooth out the effects of the sensor swing in the tank by measuring the fuel level ten times and displaying the average value, with the choice of measurement time from 1 to 10 seconds.
  • The ability to set the brightness of the display backlight separately for day and night operation. The operating mode is determined by the fact that the dimensions and the backlight of the dashboard are turned on.
  • The ability to set the normal or inverse display mode.
  • Ability to set the display contrast level.

Description of operation and controls of the device

Governing bodies


Controlled by buttons Menu, Ok, Up, Down
Menu– in the main mode, enter the settings mode. In setup mode, return to the previous menu without saving current changes and exit setup mode.
Ok- Only effective in setting mode. Entering the selected item, saving the current parameters in non-volatile memory.
Up– Only effective in setting mode. Move up through the menu items, increase the current value.
Down– Only effective in setting mode. Move down through the menu items, decrease the current value.

Operating modes
Basic mode


The device enters the main mode 2 seconds after the supply voltage is applied to it. The voltage value readings appear immediately, the remaining fuel value readings appear with a delay due to the inertia setting, 1-10 seconds.

Setting mode


The settings mode is designed to configure the device for specific operating conditions. Entering the settings mode is carried out with the button Menu

Menu items
tank capacity


allows you to set the volume of the used tank. Menu buttons Up/Down varies from 30 to 99 liters. To save the selected volume, press the button Ok. To exit the menu without saving the changes made, press the button. Menu.

Calibration


allows you to calibrate the tank capacity by one liter. Calibration is carried out after selecting the required tank volume in the menu tank capacity.
Liters- in this paragraph, using the buttons Up/Down the required value of the cell of liters is set to record the calibration value. Recording the calibration value is done with the button Ok.
Sensor– shows the current value of the residual sensor
fuel. When you press a button Ok this value is stored in the current memory cell selected in the menu item Liters.
In mind– shows the value stored in the memory corresponding to the currently selected one in the item Liters, memory cell.

inertia


allows you to set the period for measuring the remaining fuel. Menu buttons Up/Down changes within 1 - 10 seconds. During the selected period of time, at regular intervals, 10 measurements of the remaining fuel are made, after which the average value is calculated.

Backlight


allows you to set the brightness of the backlight during the day and at night. The fact of day and night is determined by turning on the dimensions and lighting of the dashboard. Buttons Up/Down the desired item for Day/Night adjustment is selected. To enter the mode of changing the selected value, press the button Ok, after which the buttons Up/Down set the required backlight brightness value from 0 to 255. To save the set value, press the button Ok, to exit the current item without saving changes, press the button Menu.

Inversion


allows you to select the normal/inverse display mode. The desired item is selected using the buttons. Up/Down. Saving the selected value is done with the button Ok. To exit the current item without saving changes, press the button Menu.

Contrast


allows you to set the desired display contrast. Menu buttons Up/Down varies from 1 to 15. The selected value is saved by pressing the button Ok. Exiting the current item without saving is done with the button Menu.

Connection and initial setup


Connect the device according to the marking.
[-] Earth, it is advisable to choose a reliable contact for connecting the earth.
[+] Plus, the power supply of the on-board network, 12 volts, is connected to any point on the on-board network after the ignition switch.
[G] Dimensions, connects to the power circuit of dimensions or instrument panel lighting
[F] The fuel sensor, in order to exclude the influence of the native sensor, it is advisable to turn it off and connect the device directly to the sensor line in the tank.
Turn on the ignition, connect a voltmeter in parallel with the power supply and
check the indicator voltage readings, if necessary, adjust the indicator readings with a tuning resistor R2

Greetings dear readers! For several years in a row, I wrote about our vehicle monitoring service, about the equipment that we produce, revealing the internal aspects of production and work in general. In this article, I want to talk about the full production cycle of such a very important element of the operation of GPS monitoring and control systems as a fuel level sensor (search engines know it as FLS). There will be a theory, all drawings and diagrams for assembling this product. For those who are interested, read on.

0. Introduction

Looking ahead, I’ll say that there will be three articles, in this one I will talk about the simplest option for determining the level of diesel fuel (only diesel, use on gasoline vehicles is absolutely prohibited, as it is explosive). In the following articles, if the reader is interested, of course, we will consider a digital fuel level sensor, and at the very end I plan to lay out the circuit and firmware of the monitoring device that I described in this article.

1. A bit of theory

The most popular fuel level sensor is an electric capacitor, consisting of two tubes placed inside each other, a fuel tank is installed, the level of which is measured. Diesel freely penetrates into the space between the tubes, the signal of a change in the fuel level in the tank is a change in the electrical capacitance of the sensor.

When the fuel level in the tank changes, the relative dielectric constant of the space between the capacitor plates changes, since the dielectric constant of fuel and air is generally different. And since the capacitance is directly proportional to the dielectric constant of the insulator, the electrical capacitance of the sensor also changes as a result. Most of the sensors are made of aluminum or copper, because they are the least affected by aggressive environments. Of the many methods for measuring the capacitance value of a capacitor and then converting its capacitance into a proportional change in the constant voltage at the output, the pulse-width method was chosen as quite simple and reliable, but at the same time providing the necessary level of measurement accuracy. A reservation is immediately required, this is the easiest method in terms of finances and quite simple in terms of assembling the FLS method for determining the level of diesel fuel.

2. Description of the operation of the electrical circuit of the fuel level sensor



Fig 2. Schematic diagram of the fuel level sensor (FLS) ()

To increase the stability and accuracy of the reading, all elements of the circuit are used with a minimum temperature coefficient. Resistors are used with a 1% tolerance, microcircuits are selected with improved parameters in contrast to household counterparts, for example: SE555N instead of NE555N, and LM358D instead of LM258D.
A master oscillator is assembled on the U1 SE555N chip and the elements R1, R2 and C1. Since the stability of the indication strongly depends on it, a precision polystyrene capacitor K71-7 1% is used as capacitor C1, they were usually installed in Soviet color TVs in line-scan master oscillators. You can replace it with something modern, but the availability and price of these capacitors makes them very attractive, and they were born back in the distant year, when the USSR monitored the quality of the elements produced quite well.
From the output of the 3rd microcircuit U1, rectangular pulses start a single vibrator assembled on the U2 SE555N microcircuit. As a single vibrator capacitor, a sensor placed in the fuel is used, so its capacitance will depend on the fuel level, and therefore, the pulse width at output 3 of the U2 microcircuit will also change with the fuel level.
To ensure a linear dependence of the pulse width on the filling level of the sensor with fuel, a charging current is supplied to the fuel sensor from a current stabilizer made on the U3.2 chip and the Q1 BC856BT transistor. Also, by changing the charging current, the circuit is tuned to different sizes of sensors. The circuit is configured by selecting resistors R6 and R7 to obtain 1.8-1.9 volts at the output of the circuit, with a “dry” sensor.
From output 3 of the U2 microcircuit, the pulses go to the integrator assembled on the elements R8 and C6.
Further, the integrated voltage, having formed on the capacitor C6, enters the low-pass filter, made on R10 and C10.
Then a constant voltage is supplied to a DC amplifier made on a U3.1 chip.
From the output of the 1st microcircuit U3.2, the signal, through a filter made on the elements R17, C12, C14 and C15, goes to the output.
Resistor R16 is used to prevent self-excitation of the amplifier when operating on a capacitive load.
The divider is made on resistors R9 and R11 provides the necessary constant bias for the DC amplifier to operate in linear mode.
The voltage regulator for powering the electronic circuit is placed according to the classical scheme on the U4 LM317MDT chip.
As a result, at the output, we get an analog signal empty tank 1.8V full 6.0V (there is a dependence on the height of the FLS), which is linear and directly proportional to the fuel level in the tank\tank\storage. Then, applying the Kalman filter, you can remove fuel surges, display the calculation of the average consumption, etc.

In reality, it will look something like this:

Graph fuel level + speed.

3. Drawing of the fuel level sensor, materials

FIGURE 3. Fuel gauge drawing (link to large drawing)

It has already been mentioned that aluminum is mainly used, as can be seen from the drawing, the outer tube is soldered in any convenient way into the “head” of the FLS. In the production of our sensors, we use welding, because. we have access to it, though not the most aesthetically beautiful option, but it is reliable and time-tested. Inside, an aluminum rod is used, for fixing which a thread is cut in the upper part. Bushings are used from a special fluoroplastic, which is as tolerant as possible to diesel fuel.

4. Bottom line

The vast majority of fuel level sensors presented on the GPS market of the CIS and the world are built on this solution. Each manufacturer makes its own changes to increase the accuracy of fuel level measurement, such as an accelerometer, temperature sensors, digital signal processing, and more. The scheme presented by me is the simplest, ready to work, as they say, in the fields without any difficulties. A respected reader with direct hands may well make any improvements that can be used both for their own purposes and for commercial needs.

PS. A little erotica about how such goodness is installed on equipment can be

Manufacturers install many devices in the car. The driver monitors the speed, distance traveled, temperature, fuel level ... In the case of water-engine equipment, the prerogative of the choice of measuring instruments is up to the user. The navigator himself decides what exactly to control.

A level gauge on a boat or boat is an important device. It is dangerous to be left without gasoline far from the coast. It is also necessary to control the amount of drinking or technical water - in order to replenish stocks in time.

For both water and fuel

Previously, liquid level sensors were strictly divided into water and fuel. The key difference lay in the floats, which react differently to water and oil products. Subsequently, manufacturers have improved technology and unified the device. Today, the same submersible sensors are lowered into both boat and water tanks. Differences are only in the symbols on the pointer - the water icon or the gas station icon.

The use of stainless and petrol-resistant materials saves from corrosion and other damages, and such a level gauge does not work with contaminated liquid. Impurities and mechanical inclusions will disable it. Designed for wastewater.

Differences in types, designs and standards

What to focus on starting from scratch? Usually the sensor is purchased first. It is selected according to the depth of the fuel tank (or other tank, the volume of the contents of which must be measured). Flange dimensions are usually standard: sensor manufacturers are guided by the dimensions of the tanks.

According to the principle of operation, the sensors are divided into several groups. Two of them are the most common.

Reed float sensor due to its simplicity and reliability, it is used in many measuring systems. It is a guide tube, inside which, following the liquid, a float moves vertically, in contact with the reed switches. It is impossible to shorten the tube: the operating range of the sensor is “laid” into its length.

The second common option is float switch with potentiometer. The principle of operation is based on a change in resistance. This type is convenient for the ability to adjust for tanks of different heights. Just a salvation for shipowners who, having made a tank according to individual dimensions, are faced with the inability to choose a depth gauge from the standard ones. The depth of the fuel tank is, say, 283 mm. And the sensors are 275 or 300 mm! With a large tank area, each centimeter of depth means a considerable volume of liquid. So sensors that can be adjusted are indispensable in such cases.

USA and EURO

Both sensors and level indicators have two resistance standards: with the European range (10-190 ohms) and the American (240-33 ohms).

A pair with matching range standards must be correctly set: 10 - empty tank, 190 - full (respectively, 240 and 33). If the pointer and the sensor do not match on the working signal, the indicator will not work correctly and show the opposite.

Accordingly, different standards cannot be mechanically combined: the European range does not "join" with the American one. But there is a way out. Any pointer with any sensor will help synchronize.

Less common are systems operating on other principles. For example, based on changes in current. A practical option for stationary containers of known volume. Due to the precise discretion and the digital display, it is possible to keep a punctual record of the consumption of liquids, for example, when refueling cars.

Ultrasonic sensors are even rarer, but working according to the modern NMEA-2000 protocol are gradually gaining popularity. Their convenience is based on the ability to connect level gauges with "smart" systems. Data can be transmitted over any distance, computers will not only inform about the current fuel consumption, but also warn: what distance can be traveled on its remnants.

Black on white, arrows or numbers...

Pointers are usually chosen based on taste preferences in design and the style of interior design of the vessel. Manufacturers offer different options: white, black, gold, with and without rims, digital and analog. You can choose an indicator for both conservatives (wood, fabric, leather) and high-tech connoisseurs; and cheaper, and "more abruptly".