Homemade automobile electronic tachometer. Homemade tachometer Do-it-yourself tachometer from a voltmeter
Tachometer consists of a 4-digit LED indicator (for accurate determination of revolutions) and a group LEDs located in a circle (for a visual, more clear, 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 ones at your discretion.
32-LED circular ruler
Dot or continuous display
4-digit display
LED gear shift indicator
Output limiter
Measurement 0-9999 or above 10000 rpm
Two display options above 9999 rpm
Options for 1 rpm, 10 rpm or 100 rpm display resolution
Automatic brightness display 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
Red line selection
Light shift speed selection
Selecting a rev limiter
Selecting the red line number of LEDs
Selecting the image update period
Choosing hysteresis for the LED line
Choice, minimum time limiter
The device can be divided into two parts:
1) control board
2) display board
The control board contains the pic16F88 controller, power supply for LEDs and control buttons. Perhaps the most interesting thing is the control buttons, which are used to adjust the tachometer. There are only three buttons:
S1 - installation
When setting up the device, the green LED34 (mode) and red LED35 (installation) LEDs display the status. 4-digit indicator with a common anode.
The device is connected to a low or high signal level. By low level we mean connection to the car’s ECU, and by high level to the ignition coil.
The MC34063 chip is a DC-DC converter that operates at a frequency of 40 kHz, switches a transistor to power LEDs with a stabilized current.
VR1 - allows you to adjust the output voltage of the MC34063 within 1.25-4V.
Inductance L1 is wound on a 28mm ferite ring with 0.5mm wire.
LM2940CT-5 5V voltage stabilizer supplies power to the control circuit. M5451 chips, LED driver.
Automatic brightness is implemented on the LDR1 element (photoresistor), which is located on the display board. The better the illumination, the lower the resistance of LDR1. The voltage on LDR1 in high light conditions 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 drivers. To adjust the automatic brightness, the VR6 element is included in the circuit, which is a 50 KOhm variable resistor.
The tachometer has an electronic rev limiter, limit out.
Settings:
To enter the settings mode, you need to hold down the up button and apply power; if the up button is not pressed, the device will go into normal operation mode. Release the button up and the display should light up, which means mode 1. The green “mode” LED will light up. You need to use the up down buttons to select mode from 1-13.
Each mode requires its own adjustment.
| Mode | Possible settings | Note |
| 1 Number of cylinders | 1-12 | selection of number of cylinders |
| 2 Red LEDs | 0-10 | Allows you to change the length of the red line display |
| 3 Red line | 0-30,000 | setting the first red LED to light up |
| 4 Turns per LED | automatically | automatically calculated from modes 2 and 3 |
| 5 Light shift | 0-30,000 | if you do not need to install beyond 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 | display refresh period is set |
| 9 Display format | 0,1,2 | set the rpm display format 0) 9999 1) 9.999-10.00 2) 9.99-10.00 |
| 10 Resolution | 0,1,10 | set the resolution to 0) 1 rpm 1) 10 rpm 10) 100 rpm |
| 11 Visualization | 0 or 1 | 0) to display a point 1) to display a continuous change |
| 12 Sensitivity | 0 or 1 | 0) for low level "0V" 1) for high level "+5V" |
| 13 Side chapel for the period | 0-510ms in 2ms steps | the minimum time is set when the cut-off output is active |
Mode 1 - Number of Cylinders: Enter 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 motorcycles, 11 or 7 for 2-cylinder asymmetrical 4-stroke engines is suitable. 9 for setting for asymmetrical 3 cylinder 4 stroke engine.
Mode 2 - red LEDs: responsible for the glow of the red strip of LEDs, select the number of LEDs that will light up, the default is 5, you can select 0-10.
Mode 3 - Red Line: This mode is used to set the maximum speed recommended for your engine. The default value is 9000. Note that 10,000 revolutions will be displayed as 10.00.
Mode 4 - revolutions per LED: this mode shows the increase in revolutions for each LED in the line, i.e. how many revolutions per LED.
Mode 5 - Light Shift: Default value is 8000 rpm, ranging from zero to above 30 thousand rpm. The setting is in x1000 format, for example 8000 is displayed as 8.00.
Mode 6 - rev limiter: this mode sets a limit on revolutions per minute. During operation, the output limiter changes when the measured revolutions go higher, then this parameter and the level of the output signal depend on the setting (see Mode 12). This setting can be changed in 100 steps from 9,900 rpm in a range from zero to above 30,000 rpm.
Mode 7 - hysteresis: to avoid the threshold value, you can set a hysteresis, for example, the following LEDs quickly turn on and off. The default setting of hysteresis is 50 rpm and can be changed by 1 from 0-255 rpm. Please note that the hysteresis value must be less than the value (see mode 4).
Mode 8 - Display Updates: Updates every 1ms, but this is too fast for a digital display to read if there are any RPM changes. The update will slow down the digital display to a more comfortable speed. Typically, an update period of 200 ms (or five changes per second) is appropriate. The default setting is 250ms in steps of 2 from 0-510ms.
Mode 9 - Display Format: This adjustment is mainly for servicing engines that are above 10,000 rpm. An initial setting of "0" sets the display to display from 0-9999 rpm. Above this indicator, the display shows “0” at 10,000 rpm, “1000” at 11,000, etc. Use this setting for engines that do not exceed 10 thousand rpm, or that only occasionally reach this level.
Mode 10 - resolution: if you don’t like the way the readings move when the speed increases quickly, you can lower the resolution; to lower the resolution, set “1” and the last digit will always show zero. If "2" then the last two will be zero.
Mode 11 - Visualization, Dot or Ruler: Will the LED ruler operate in dot mode (i.e. the LED is on at all times) or as a continuous change. Select "0" point mode or "1" for continuous mode.
Mode 12 - sensitivity: if set to “0” then it goes from 0 to +5V, and if “1” then from +5V to 0.
Mode 13 - period limit: the minimum time is set when the cutoff output is active
The takometer has a maximum speed limiter, the output of which can be used in a separate circuit that will limit engine speed. For example, in the ignition or fuel supply circuit.
Most modern cars are equipped with tachometers, which make it easier to select the correct gear, 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 diagram is shown in Fig. 1. Its main feature is the use of the K1003PP1 microcircuit, 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.
A signal, the frequency of which is proportional to the engine crankshaft rotation speed, is removed from the contacts of the breaker or from the shaper amplifier 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 breaker, high-voltage surges on the ignition coil winding and bring the signal to standard CMOS logic levels with normal edge slope.
Rice. 1 Tachometer diagram
The output of the Schmitt trigger triggers the standby multivibrator on IC DD2. In the main position of switch SA1 “6000″, the duration of the pulses generated by the standby 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 integrating chain R12C6 averages these pulses, and the average voltage on capacitor C6 is about 3 V. This voltage is supplied to the pin . 17 (UBX) DD2 chips. With a voltage of 3 V applied to the pin. 3 (UB) of this microcircuit and determining the scale of the display, all 12 LEDs HL1...HL12 are turned on, forming a luminous column.
At lower engine speeds, the duty cycle of the pulses at output DD1 increases, the average voltage on 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 light up. The “division price” of the LED scale is 500 rpm.
It is advisable to install LEDs of different glow colors. For example, if optimal engine operation corresponds 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 (“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 5 times and amount to 12.5 ms, and the “scale division price” will be 100 rpm.
The tachometer microcircuits DD1 and DD2 are powered through the 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 backlights are turned off, a logic signal is present at the inputs of element DD1.2. 0, output voltage - 6 V, pin. 2 DA2 - about 0.85 V, which sets a current of 25 mA through each LED. In the evening, when you turn on the backlight, the voltage on 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 tachometer printed circuit board is shown in Fig. 2. The design uses fixed MLT resistors and SPZ-19a tuning resistors. 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 stabilizer, 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 LEDs - AL307MM (yellow ones usually glow weaker than others), green LEDs with increased brightness - AL307NM6, red LEDs - AL307BM. The LED leads are bent at an angle of 90°, and their axes are directed parallel to the printed circuit board. The size of the LEDs was reduced to 5 mm using a file.
Switch SA1 is 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 the common wire or to the +6 V circuit.
Setting up the tachometer is quite simple. First, switch SA1 is set to position “6000″, 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 the breaker. The trimming resistor R9 is used to make the entire LED column glow. If necessary, select the resistance of resistor R8. Then the same operation is performed for position SA1 “1200″ at an input pulse frequency of 40 Hz.
LEDs can be arranged along a circular arc. In this case, the glow of one LED from the chain may be more effective. To ensure this mode of turning on the LEDs, their anodes should be disconnected from the outputs of the DA2 microcircuit and connected to the power pin (pin 18).
Car tachometer is a measuring device that is designed to measure the number of revolutions of the engine crankshaft per minute (rpm). Previously, mechanical tachometers were installed in cars. Modern cars have electric or electronic tachometers.
While the car engine is running, the tachometer allows you to monitor the stability of its speed at idle and while the car is moving. The stability of idle speed can be used to judge the condition of the fuel supply system, ignition system and the engine itself.
When setting the idle speed and adjusting the engine ignition timing using a strobe light, you cannot do without a tachometer. It is necessary to simultaneously make adjustments and monitor engine speed. After each tightening of the adjustment screw, it is inconvenient to look at the readings of the tachometer installed inside the car. A mirror installed in the cabin can help out, but this is also not the best solution. It is much more convenient to have a tachometer built into a strobe light.
When making a strobe light with my own hands, I mounted a tachometer into its body. When checking and adjusting the engine's OZ, this technical solution showed ease of use.
The tachometer circuit design we bring to your attention is distinguished by its simplicity and high accuracy of readings, regardless of changes in ambient temperature and supply voltage. It has an extended scale, which allows, when using a small-sized dial indicator, to measure the engine speed with high accuracy.
Electrical circuit diagram
The presented tachometer circuit is distinguished by its simplicity and accessibility of parts for repetition due to the use of an integrated timer - the KR1006VI1 microcircuit (analogous to NE555).
The diagram consists of the following functional units. A pulse shaper made on VT1-VT2, a pulse width modulator on a DA1 chip of type KR1006VI1 and a resistor bridge on resistors R8-R13. An electrodynamic pointer microammeter is used to take readings. The disadvantages of the tachometer circuit include the need to balance the bridge for each type of milliammeter when repeating the circuit. But this is not a difficult operation.
The supply voltage to the tachometer circuit is supplied directly from the terminals of the car battery.
Principle of operation
When pulses arrive from a breaker or inductor used in a strobe, capacitor C1 is recharged through diode VD1 and resistor R1-R2, creating pulses based on transistor VT1, opening it. As a result, short positive pulses are formed on the collector of the transistor, switched on in switch mode, the duration of which is determined by the capacitance of capacitor C1. VT2 serves to invert pulses before applying them to input DA1. The shape of the pulses is shown in the electrical diagram of the tachometer on the right side, upper oscillogram. The photo below shows the block diagram of KR1006VI1.
The integrated timer KR1006VI1 is connected according to a standard pulse shaper circuit. Based on the positive edge of the pulses arriving at input 2, the microcircuit generates positive pulses at output 3 with a width that varies linearly depending on the frequency of those arriving at the input. The frequency is higher, the pulses are wider. The initial pulse width depends on the time constant of R6, R7 and C3.
The pulses coming from pin 3 of the DA1 microcircuit are sent to the left arm of the tachometer bridge, which is formed by resistors R8-R9 and R11. The right arm of the tachometer bridge, which is formed by resistors R10, R12, R13, receives a constant reference voltage of +9V from the integrated voltage stabilizer K142EN8A. Capacitor C4 prevents the tachometer needle from jerking when measuring low engine speeds. The stabilizer also provides power to all active elements of the tachometer. A microammeter is included in the diagonal of the bridge.
Thanks to this circuit solution, it was possible to eliminate nonlinear elements, obtain a linear reading of the milliammeter when the frequency changes, and ensure high accuracy of engine speed measurements due to the extended scale. Since the tachometer, for reasons of overall dimensions, uses a small-sized milliammeter from the recording level indicator of a tape recorder, whose scale length is short, it was only thanks to the extended scale that it was possible to obtain high accuracy of readings.
The K142EN series stabilizer chips provide a stable output voltage over a wide temperature range, which is why the K142EN8A chip is used in the tachometer. Capacitors C2, C5 and C6 are installed to smooth out supply voltage ripples.
Construction and details
Since the circuit is simple, I did not develop a printed circuit board. All parts, except the milliammeter, were installed on a universal breadboard measuring 30 mm×50 mm. The photo shows how the elements of the circuit are placed.
A three-pin connector is used to supply the supply voltage and input signal. The milliammeter scale is printed on a printer and glued on top of its standard scale.
The board with the parts is secured in the cover of the strobe housing with screws. The milliammeter is installed in a rectangular window cut out in the housing cover and secured with silicone.
This design for placing the tachometer provides easy access to the strobe board; just remove the cover and disconnect the connector.
Tachometer settings
If no errors were made during the installation of parts and the circuit elements are in good working order, the tachometer will immediately begin to work. It will only be necessary to adjust the values of the bridge resistors. To do this, you need to apply rectangular pulses with a frequency taken from the table below from a pulse generator to the tachometer input and calibrate the scale.
| Table for converting engine speed to frequency | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Engine speed, rpm | 700 | 800 | 900 | 1000 | 1100 | 1200 | 1500 | 2000 | 2500 | 3000 | 3500 | 4000 | 4500 | 5000 | 6000 |
| Generator frequency, Hz | 12 | 13 | 15 | 17 | 18 | 20 | 25 | 33 | 42 | 50 | 58 | 67 | 75 | 83 | 100 |
| Generator frequency, 2×Hz | 24 | 26 | 30 | 34 | 36 | 40 | 50 | 66 | 84 | 100 | 116 | 134 | 150 | 166 | 200 |
Since in cars the sensor usually produces two pulses per revolution of the engine shaft, when calibrating the tachometer you need to set the frequency on the generator to twice as high. For example, when calibrating a scale point of 800, it will be necessary to apply pulses with a frequency of not 13 Hz, but 26 Hz, to the tachometer input. A number of frequencies for this case are given in the bottom line of the table.
In order not to experience difficulties when calibrating tachometer scales, you need to know the principle of operation of the bridge circuit. Here is a schematic diagram of a DC bridge. If the ratios of the values of resistors R1/R2 and R3/R4 are equal, the voltages at the diagonal points of the bridge A and B are equal, and the current does not flow through mA, the arrow is at zero.
If, for example, we decrease the value of resistor R1, then the voltage at point A will increase, but at point B it will remain the same. Current will flow through the milliammeter located diagonally on the bridge and the needle will deflect. That is, with a constant voltage at point B and a change in voltage at point A, the needle of the device will move relative to the scale.
In the tachometer circuit, the function of resistor R1 is performed by resistor R9, and so on. As the engine speed increases, the frequency and width of the pulses from the output of the microcircuit increases and thus the voltage at the left connection point of the milliammeter increases, the flowing current increases and the arrow deviates. The resistors in the bridge arms are selected in such a ratio that the bridge is initially unbalanced, and voltage equality at the milliammeter connection points occurs at 700 engine revolutions.
The resistor values in the diagram are indicated with a milliammeter frame resistance of 1.2 kOhm. If you use a device that has a different frame resistance, you will have to select the value of resistors R8, R9 and R12, R13, temporarily replacing them with variables. After calibrating the device, the resistance of the variable resistors is measured and they are replaced with constant ones.
Switch S1 can be omitted and the device can be configured to measure in the required range on one scale. In this case, the measurement accuracy will be reduced by half. With a stretched instrument scale, such accuracy will also be sufficient.
A tachometer made according to the proposed scheme is a complete device and can be used to measure the rotation speed of any shafts, for example, a motor boat engine, electric motors. Hall sensors, photo and electromagnetic sensors can be used as sensors. It is enough to modify the circuit of the input pulse shaper.
A simple universal tachometer on the ATtiny2313 microcontroller
This simple tachometer on the ATtiny2313 can count the number of revolutions of any engine, be it multi-phase, multi-stroke, etc. It can be useful in automobiles and motorcycles to display engine speed. In this case, it does not matter at all how many strokes or cylinders the engine has. It can also be used in conjunction with electronic motor controllers, either single or three phase.
The tachometer circuit is very simple - one ATtiny2313 microcontroller and a four-character LED indicator. For simplicity purposes, there are no transistor switches. The indicator can be used with both a common cathode and a common anode - this is selected in the source code. The tachometer can count revolutions per second as well as per minute, making it completely versatile.
Additionally, the device has the ability to programmatically control the brightness: normal and reduced. If the jumper is open, then the normal brightness is set. When the contacts are closed, the brightness decreases.
Click to enlarge
Let's move directly to the diagram. If the device is connected directly to a motor controller with TTL levels, then pulses can simply be applied to pin 6 of the microcontroller. Otherwise, you should make a simple transistor level converter.
To obtain and stabilize the supply voltage of +5 volts, a linear stabilizer 1117 with a low voltage drop is used for greater efficiency.
An indicator from a microwave oven with a common anode is used as an LED indicator. Since it already contains 220 Ohm resistors, they are not provided on the printed circuit board.
There are as many as 10 jumpers on the top side of the PCB, but they are very easy to install.
SMD components are installed on the reverse side: these are two 22 pF capacitors for the quartz resonator, a stabilizer chip and filter capacitors.
The quartz resonator for the ATtiny2313 microcontroller can be set to 8 or 4 MHz, this is set in the source code and controls the prescaler.
The mode for displaying revolutions - per second or per minute - is set similarly in the source code. To display the number of revolutions per minute, the calculated number of revolutions per second is simply multiplied by software by 60. It is possible to programmatically round the calculated values. These nuances are commented in the source code.
When flashing the microcontroller firmware, you need to install fuses:
CKSEL1=0
BODLEVEL0=0
BODLEVER1=0
SPMEN=0
The source code is written in C in Codevision AVR. It was borrowed from another project - a tachometer for a three-bladed helicopter.
Briefly about the setup: it is necessary to determine in advance how many pulses per 1 revolution will be supplied to the tachometer input. For example, if their source is a three-phase motor controller on LB11880, then it produces three impulse for each spindle revolution. Therefore, you should specify this value in your source code.
Selecting an indicator - with a common anode or with a common cathode (unnecessary value - comment out):
//#define Anode
#define Cathode
Number of tachometer pulses per 1 shaft revolution:
#define byBladeCnt 2
Selecting the frequency of the quartz resonator - 0x00 for 4 MHz, 0x01 - for 8 MHz:
#define Prescaler 0x01
RPM display selection:
lTmp = (62500L * 60L * (long)wFlashCnt);
To display the number of revolutions per second, you need to remove the multiplication by 60:
lTmp = (62500L * (long)wFlashCnt);
In order to disable rounding of values, you need to comment out the following lines:
If (byDisplay > 4)
{
wRpm++;
R += 10;
}
Since this particular design uses a very specific indicator, the PCB layout is not included.
Some owners of “iron horses” consider the speedometer to be the main measuring instrument installed on a motorcycle. Of course, the speed at which you are moving is important information (especially for traffic police officers). However, only a tachometer, informing the motorcyclist about the number of engine revolutions, will help “tell” whether the gear is selected correctly for a given speed. Not all bikes are equipped with this useful device. Installing a tachometer on a motorcycle with your own hands is now 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) to:
- timely gearbox speed switching: as soon as the engine speed increases to a certain value, it is necessary to switch to a higher gear and vice versa;
- preventing the operation of the motorcycle power unit at extreme conditions (this is indicated by the red sector of the tachometer);
- fuel economy if the engine operates at optimal speed (the one most appropriate to the gear engaged, the load on the motorcycle and road conditions).
The dashboard of many modern bikes is initially equipped with this useful “informant”. However, in the vast expanses of our Motherland, there are still a huge number of Soviet and Russian-made motorcycles in use (for example, “Ural”, “IZH”, “Voskhod”) that are 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 for a motorcycle that was not installed during construction can be purchased and installed yourself.
Models, manufacturers and prices
The range of tachometers intended for installation on motorcycles, mopeds and scooters is very diverse both in price, design, execution (with an arrow or digital display), and in the number of manufacturers producing products for this purpose.
A universal electronic tachometer (from Chinese manufacturers “Vodool” or “Kkmoon”) with LED backlighting 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, those 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 range from 3,000 to 12,000 rubles.
Installation and connection
Installation of tachometers additionally installed on a motorcycle is quite simple. A bracket attached to the body of the product allows you to easily install the device on one of the bolts securing the steering wheel to the fork.
Installing the products on the steering wheel in the most convenient place for viewing will allow the use of a special fastening coupling for installing additional equipment. It can be easily purchased for 200–300 rubles at any motorcycle accessories store. Some tachometer models have such fastening devices already included in the delivery kit.
Some manufacturers supply a complete set of a wide variety of fasteners and wires for connection along with the measuring device itself.
The connection diagram is quite simple and will not cause difficulties even for bikers who are not very “advanced” in electrical engineering (note: the colors of the wires are indicated for tachometers from Chinese manufacturers):
- We connect one short wire (usually black) to the switched “+” of the ignition switch;
- the second short one (green) – to the motorcycle frame (in a convenient place);
- the third short (black and yellow) - to the low-voltage contact of the coil going to the breaker;
- two long thin wires (black and red) - parallel to the speedometer light bulb.
Important! The tachometer connection wires from American and European manufacturers have different colors. But unlike Chinese suppliers, the kit necessarily includes a diagram for connecting the device.
Making your own tachometer
The most common option for making a tachometer for a motorcycle with your own hands is to use the standard TX-193-38130 device from a VAZ-2106 (or VAZ-2103, or Niva-2121) car as a basis for a homemade measuring device.
Manufacturing method:
- We carefully disassemble the TX-193 car tachometer.
- We unsolder the capacitor (capacity 0.22 µF) installed in the ammeter circuit and install a new one (capacity 0.47 µF). Otherwise, the device readings will be underestimated by 2 times.
- We assemble the device in reverse order.
- We make a body from a metal can (for example, a coffee can) of a suitable diameter.
- We mount the manufactured device in the most convenient place (for example, next to the speedometer).
- We connect the device to the electrical circuit of the motorcycle (the circuit is similar to that described above).
- We start the motorcycle and check the homemade tachometer in operation.
For information! Creating such a “masterpiece” is economically justified if it is possible to purchase a used TX-193 at a car disassembly site, since a new one now costs 900–1100 rubles.