Most modern cars are equipped with tachometers to help right choice transmission, which extends the life of the engine. If your car does not have such a device, then it can be made according to the proposed description.
The tachometer circuit is shown in fig. 1. Its main feature is the use of the K1003PP1 chip, designed to control a linear scale of 12 LEDs. In the standard 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 speed of the engine crankshaft, is taken from the contacts of the chopper or from the amplifier-shaper of the Hall sensor and through the voltage divider R1R2 is fed to the input of the Schmitt trigger DD1.1. The purpose of the trigger and capacitor C3 is to suppress bounce pulses at the breaker output, high-voltage surges on the ignition coil winding and bring the signal to standard CMOS logic levels with normal rise time.
Rice. 1 Tachometer circuit
The output signal of the Schmitt trigger starts the 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 capacitor C6 is about 3 V. This voltage is supplied to the pin . 17 (UBX) DD2 chips. At a voltage of 3 V applied to the pin. 3 (UB) of this microcircuit and determining the indication 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 output of DD1 increases, the average voltage across the capacitor C6 decreases in proportion to the speed, and the height of the column becomes smaller. When the engine is stopped, none of the LEDs are lit. The “division price” of the LED scale is 500 rpm.
It is advisable to install LEDs of a different glow color. For example, if optimal performance engines correspond to 2000.. .4000 rpm, LEDs HL1…HL3 can be used yellow or orange (“switch to a lower gear”), HL4…HL8 - green (“normal”), HL9…HL12 - red (“switch to 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 "division" of the scale will be 100 rpm.
Microcircuits DD1 and DD2 of the tachometer are fed through an integrated voltage regulator DA1. Capacitors C1 and C2 ensure the stability of the stabilizer.
The current through the LEDs connected to the DA2 chip is determined by the voltage at its pin. 2. In the daytime, when the instrument panel lights are off, there is a log at the inputs of the DD1.2 element. 0, at the output - voltage 6 V, on 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 at the pin. 2 is reduced to 0.4 V, which reduces the current through the LEDs to 8 mA and, accordingly, their brightness.
A drawing of the printed circuit board of the tachometer is shown in fig. 2. The design used constant resistors MLT, tuning SPZ-19a. Capacitor C5 type K73-17 for a voltage of 250 V, C6 - K50-16, the rest - KM-5 and KM-6. DA1 chip - any 6 V voltage regulator, for example, KR1157EN6 with any letter index, KR142EN5B (G), KR1180EN6, 78L06, 7806. The K561TL1 chip can be replaced with KR1561TL1, CD4093, CD4093B, and K1003PP1 with UAA180 or A277.
Orange glow LEDs - AL307MM (yellow ones usually glow weaker than others), green ones with increased brightness - AL307NM6, red ones - AL307BM. The LED leads are bent at an angle of 90°, and their axes are directed in parallel printed circuit board. The size of the LEDs is reduced to 5 mm with a file.
Switch SA1 - any small-sized 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 a common wire or to a +6 V circuit.
Setting up the tachometer is quite simple. First, the SA1 switch is set to the “6000″ position, positive polarity pulses 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 connection to a breaker. The entire LED column is lit with a trimming resistor R9. If necessary, select the resistance of the resistor R8. Then the same operation is performed for the 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 turn out to be more effective. To ensure this mode of turning on the LEDs, their anodes should be disconnected from the outputs of the DA2 chip and connected to the power output (pin 18).
Some owners of "iron horses" consider the speedometer to be the main measuring device installed on a motorcycle. Of course, the speed at which you move is important information (especially for traffic police officers). However, only a tachometer will help to “tell” whether the gear is correctly selected for a given speed, informing the motorcyclist about the number of engine revolutions. Not all bikes are equipped with this useful device. Installing a tachometer on a motorcycle with your own hands is currently quite simple.
Purpose and principle of operation of the tachometer
A tachometer is a device that measures the number of revolutions of a motorcycle engine in one minute and displays this information on the dashboard (in an easy-to-read form). The readings of this device are necessary for a motorcyclist (especially a beginner) for:
- timely gear shifting on the gearbox: as soon as the engine speed increases to certain value, it is necessary to shift to a higher gear and vice versa;
- preventing the operation of the power unit of the motorcycle at the limit modes (this is indicated by the red sector of the tachometer);
- fuel savings when the engine is running at the optimum RPM (best suited to the gear engaged, the load on the motorcycle and the road conditions).
The dashboard of many modern bikes is originally equipped with this useful "informant". However, in the vast expanses of our Motherland, there is still a huge number of Soviet and Soviet motorcycles in use. Russian production(for example, "Ural", "IZH", "Voskhod"), not equipped with tachometers. By the way, many models of the legendary "Harley Davidson" and "Triumph" also do not have standard engine speed indicators. A tachometer on a motorcycle that was not installed during construction can be purchased and installed independently.
Models, manufacturers and prices
The range of tachometers designed for installation on motorcycles, mopeds and scooters is very diverse both in price, design, performance (with an arrow or digital display), and in the number of manufacturers manufacturing products for this purpose.
Universal electronic tachometer (from Chinese manufacturers "Vodool" or "Kkmoon") with LED backlight in a stainless steel case (Ø = 56 mm, case height - 60 mm) costs only 540÷650 rubles.
For the same 500÷700 rubles, you can purchase products with a digital indication of the number of revolutions per minute from Ironwalls or FCD.
Owners of expensive and prestigious brands of motorcycles (however, not equipped with a standard tachometer) can purchase and install products from the world famous and well-established Baron, Koso, J&P Cycles or Sunpro. However, the cost of these products will already be in the range from 3,000 to 12,000 rubles.
Installation and connection
Installation of tachometers, additionally installed on a motorcycle, is quite simple. The bracket, fixed on the body of the product, makes it easy to install the device on one of the bolts that fasten the steering wheel to the fork.
To install products on the steering wheel in the most convenient place for viewing, the use of a special mounting sleeve for installing additional equipment will allow. It can be easily purchased for 200÷300 rubles at any motorcycle accessories store. Some models of tachometers have such fasteners already in the package.
Some manufacturers, as part of the measuring device itself, supply a complete set of a wide variety of fasteners and wires for connection.
The connection scheme is quite simple and will not cause difficulties even for bikers who are not very “advanced” in electrics (for your information: the wire colors are indicated for tachometers from Chinese manufacturers):
- one short wire (usually black) is connected to the switched “+” of the ignition switch;
- the second short (green) - to the motorcycle frame (in a convenient place);
- the third short (black-yellow) - to the low-voltage contact of the coil going to the breaker;
- two long thin wires (black and red) - parallel to the speedometer backlight bulb.
Important! The wires for connecting tachometers from American and European manufacturers have a different color. But unlike Chinese suppliers, the kit always contains a device connection diagram.
Self-made tachometer
The most common option for making a tachometer for a motorcycle with your own hands is to use the standard TX-193-38130 instrument from a VAZ-2106 car (or VAZ-2103, or Niva-2121) as the basis for a home-made measuring device.
Manufacturing method:
- We carefully disassemble the car tachometer TX-193.
- The capacitor (with a capacity of 0.22 μF) installed in the ammeter circuit is soldered and a new one (with a capacity of 0.47 μF) is installed. Otherwise, the readings of the device will be underestimated by 2 times.
- We assemble the device in the reverse order.
- We make a case from a metal can (for example, from coffee) of a suitable diameter.
- We fix the manufactured device in the most convenient place (for example, next to the speedometer).
- Connect the device to electrical circuit motorcycle (the scheme is similar to that described above).
- We start the motorcycle and check the homemade tachometer in operation.
For information! It is economically justified to create such a “masterpiece” if it is possible to purchase a used TX-193 at a car disassembly, since a new one now costs 900÷1100 rubles.
A few years ago, I urgently needed to measure the engine speed, but there is no tachometer! How to be here? Since I needed to measure the speed desperately, the option to order a tachometer and wait for it for a month did not suit me. I had to think! And I came up with the idea to use a computer for this purpose, or rather - sound editor installed on the computer.
Sound editor "Adobe Audition" I have installed for a long time to work with sound. Therefore, it remains to come up with a way to connect the engine to the computer. This issue was resolved literally within 1 minute - IR LED receiver! I reached into the box and took out the LED, as well as the mini-jack plug. I found a piece of microphone cable and after 10 minutes the LED sensor was ready! I glued the diode itself into a pen cap.
Assembled cable.
I used a flashlight to illuminate the IR LED sensor. Also LED.
I glued the sensor with a piece of adhesive tape on the nose of the model, and simply held the flashlight with my hand. The distance between the sensor and the flashlight is 5...7 cm. The luminous flux from the flashlight illuminates the receiving LED, and the propeller interrupts (modulates) the luminous flux. As a result, the LED generates pulses. The sensor is connected to the microphone input of the sound card. The voltage required for the operation of the LED is provided by the design of the microphone jack of the sound card. Any sound card is designed to work with electret microphone, since it needs a supply voltage of + 5 Volts. Therefore, this voltage is present at the center pin.
microphone jack and goes to the LED, which ensures its operation. As a result, the pulses that occur during the rotation of the propeller are fed through the microphone input to the sound card, and the "Adobe Audition" editor records all this as a normal sound file.
To measure the engine speed, it is enough to record within a few seconds. It's enough. This is what we will see on the screen in the sound editor window.
First of all, I want to note that at the very bottom of the Editor there is a time scale, it is on it that the engine speed is determined. In this case, the recording time was 9 seconds. The arrow shows the timeline at the bottom of the Editor window. Now we need to scale up the sound file. In order not to count the impulses in one second (it takes a long time to count them), we will count them in a time interval of 0.1 seconds, and then multiply by 10. First, on the timeline, select a recording section of just over 0.5 seconds and stretch it to full screen.
The selected area ~ 0.5 sec stretched to full screen. The timeline has also expanded.
Now on the timeline we select a segment of time smooth 0.1 sec - 3.1 to 3.2 sec.
and also stretch it to full screen. Now you can see clear impulses, which are not difficult to calculate.
We count the impulses in the time interval of 0.1 sec. - there are 42 of them.
Now for some simple arithmetic. Once per 0.1 sec. we have 42 pulses, which means in 1 sec. 420 of them were received from the sensor. And in 1 minute 420 x 60 sec. = 25200 pulses. But since the screw has 2 blades and interrupts the light flux twice, the result must be divided by 2 and we get 12600 revolutions per minute. Which is what needed to be determined. In the case of a 3-bladed propeller, we divide the result by 3. In the case of a 4-bladed propeller, we divide by 4. Such an unusual tachometer - the synthesis of an IR diode, a computer and a sound editor completely satisfied me! And the question of purchasing an "iron" tachometer in a store,
I dropped by myself. And refused to buy.
On flights in the field, I don’t need a tachometer, and at home a computer and a cable with an LED are always at hand.
I think that not all colleagues at home already have a tachometer, but I want to measure the engine speed! In this case, my experience, I hope my comrades will come in handy. "Adobe Audition" can be downloaded for free from here http://www.fayloobmennik.net/2293677 . You can use another sound editor, whatever you like. My sound file of this engine test, recorded by the Editor, is here. In this article, I wanted to show that if necessary, if you really want, in most cases that arise with us, modelers, you can come up with a worthy replacement for the necessary, but missing, device. I hope the Chinese comrades are not offended by me.
The main task of a tachometer in a car is to help select the correct gear, which has a positive effect on engine life. Most cars already have an analog tachometer and when its needle approaches the red mark, it is necessary to upshift.
In addition, car owners use for adjustment work, both at idle, and to control the engine speed while driving.
The physical principle of the tachometer is based on counting the number of pulses that are recorded by the sensors, the order in which they arrive, as well as the pauses between these pulses.
In this case, the counting of the number of pulses can be performed various methods: forward, reverse and both directions. The results obtained are usually transformed into the values we need. Such a value can be considered hours, minutes, seconds, meters and the like.
The design of all tachometers allows you to reset the obtained values. The accuracy of these measurement results is rather arbitrary, about 500 rpm, the most accurate electronic tachometers are measured with an error of up to 100 rpm.
Automobile tachometers are of two types digital and analog. The digital automobile tachometer consists of the following blocks:
CPU
ADC 8 bits or more
Fluid temperature sensor;
Electronic display
Idle valve diagnostic optocoupler
Processor reset block.
On the display of a digital automobile tachometer, the results of measurements of the shaft and engine revolutions are displayed. A digital tachometer is very useful for adjusting operations with electronic ignition units of a car engine, for accurately setting economizer thresholds, etc.
Analog car tachometers are more common and understandable to a greater number of motorists. It shows the measurement results with a moving arrow.
Usually analog tachometer consists of:
chip
magnetic coil
wires for reading information from the crankshaft
graduated scale
arrow
Such a tachometer works as follows. The signal from the crankshaft goes through the wires to the microcircuit, which determines the position of the arrow on the graduated dial.
In a car, it is best to have both types of tachometer. So the digital one does an excellent job of adjusting the idle speed, checking the operation of the EPHX control unit (forced idle economizer) and checking the standard tachometer (because the digital tachometer has much higher accuracy). While driving, it is much more convenient to use a regular analog tachometer, because the human eye and brain analyze analog information better and faster than its digital value, and better accuracy while driving is not required at all.
In addition, tachometers are also classified according to the installation method. There is a regular and remote car tachometer. The first is mounted directly in the dashboard of the car. "He" is simpler and is used in most cars. The remote tachometer is designed to be installed on the dashboard. They are used to give the car more tuning appearance. The design of the remote tachometer has a leg for fixing it on the dashboard.
Below is a diagram of a quasi-analogue electronic tachometer. The principle of its work is the following. The engine speed is displayed on a simplified linear LED scale. Scale digital tachometer consists of nine LEDs. Each of them roughly corresponds to 600 rpm of the engine. At idle, only the first LED is lit. The tachometer is adjusted by selecting the resistance R6. Depending on it, you can set the indicators to the required number of cylinders. You can also change the division price.
The Hall sensor, which is present in the electronic system ignition, shaft position sensor and others. The main thing is that the sensor sends pulses to our circuit, which change the resistance of the resistor R1.
This circuit works like a simple frequency counter. The pulses that constantly come from the engine sensor are fed to the counting input of the K561IE8 decimal counter, and then to the LEDs. You can power the circuit from the cigarette lighter or.
Diode VD1 KD522 protects the circuit from incorrect connection of the power polarity. The crankshaft speed sensor sends pulses to the base of the transistor VT1. We select the resistance R1 depending on the sensor (in the diagram, the resistance is selected for the Hall sensor in the non-contact ignition system of a carburetor engine). From the output VT1, the pulses fall on the Schmitt trigger, made on the elements D1.1-D1.2. It converts the pulses into the required rectangular shape. Capacitor C2 filters interference, paired with resistor R4, it forms a filter that cuts high-frequency pulses. From Output D1.2, the pulses are sent to the counter.
The multivibrator assembled on the elements of the D1.3 and D1.4 microcircuit generates clock pulses with a frequency depending on R6. These pulses go to the chain C3-R7, which generates an impulse to reset the counter D2. Superbright LEDs HL1-HL9 are connected directly to the outputs of the K561IE8 counter. With R9, you can adjust the brightness of the display.
LEDs 1-4 on the printed circuit board are connected with a mounting wire.
Adjustment of the design begins with the calculation of the value of the resistor R1 in accordance with the magnitude of the incoming pulses. Then we replace R6 with 1 Ohm variable resistors in series and a 10 kOhm constant resistor. Next, we twist the variable resistor to the maximum resistance. Then we twist it so that only two LEDs light up at idle speed of the engine. We note this position of the tuning resistor. Then we reduce the resistance so that only one LED is lit. Then we adjust the resistor in the middle position. Next, we measure the resulting resistance R8 with a multimeter.
Good afternoon, dear radio amateurs! As we know, a tachometer is a measuring device that serves to measure the speed of rotation of the shafts of mechanisms. In cars, mechanical tachometers were previously installed to measure the speed of the engine crankshaft, modern cars are equipped with electric or electronic ones. Recently I found a simple tachometer straight from the 90s in my folder with diagrams. I didn’t collect it myself, but my uncle collected it, he says it works well. Unfortunately, the photo is no longer available. The principle of operation is based on the conversion of alternating voltage, taken from the windings of the car's generator, into a constant voltage proportional to the crankshaft speed and changing the length of the luminous strip in the IN-13 indicator gas discharge lamp. Here is a diagram of this device:
A 6.3 volt transformer, a 6.3 volt winding was used as the primary winding, and a 220 volt winding as the secondary. The diode bridge is designed for 400-500 volts, amperage is not important. Resistors R1-R2 of 2 watts (5 watts are also possible). Capacitors C1-C2 are necessarily non-polar.
Tachometer setting
The device is configured as follows: by selecting capacitors C1, C2 and resistor R4, ensure that at idle the luminous strip of the indicator lamp is approximately 10 mm long (with a shorter length, increase the capacitances 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. Scheme sent Vasily R.
