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Strobe lamp to set the ignition offset angle

Joker2 7092 19
This content has been translated » The original version can be found here
  • Hello all!

    I would like to present a project aimed at practical implementation of the strobe lamp arrangement. Such a lamp is necessary for setting the ignition offset angle in internal combustion engines. I made the device a few years ago and so far it has served me flawlessly.

    Strobe lamp to set the ignition offset angle Strobe lamp to set the ignition offset angle

    Principle of operation:

    The occurrence of the stroboscopic effect can be observed when a given object moves (spins) with the same frequency (or its multiple) as the flashing light that illuminates it. Thanks to the inertia of the human eye, you can see the "stillness" of the rotating element.
    This phenomenon is used in many areas, such as automotive, where it is used to precisely adjust the ignition of an internal combustion engine.

    Description of the individual blocks of the device:

    The light source of the device is a LED type Power LED with a power of one watt, emitting light with an intensity of 38lm. It is placed on a small heat sink because it operates at high currents (up to 300mA) and emits heat. The diode can be triggered by an impulse coming from a spark plug, or by an integrated generator. The block diagram below shows the connection of all device modules. The LED flashing frequency is continuously counted with a frequency counter. To count the frequency at a voltage higher than the target 5V, a simple voltage stabilizer system was used, which reduces the pulse amplitude to 4.7V. The diode is keyed by the BD139 transistor operating in the OE circuit. In order not to exceed its rated current, the system is equipped with a stabilizer with a voltage of about 3.3V, at which the diode consumes a current of about 250mA. As a result of the LED temperature increase during operation, its internal resistance decreases, which increases the current consumed, but the heat sink surface and the LED supply voltage are selected so that the maximum current of 300mA is not exceeded during continuous operation.

    Block diagram:

    Strobe lamp to set the ignition offset angle

    Generator:

    The device uses a generator based on the TL494 chip. The structure includes an oscillator, the operating frequency of which depends on the value of RC elements on pins 5 and 6, and a comparator with emitter followers at the output. It is expanded with many other elements that give additional possibilities, but the designed device does not use any other than the previously mentioned. The principle of operation is typical. At the oscillator output, a sawtooth waveform is directed to the comparator input. The second input of the comparator is influenced by the control voltage (pin no.3). Depending on the value of the control voltage, there is a different actuation threshold of the comparator, the final effect of which is a square-wave output signal with an adjustable duty cycle (PWM). The drive voltage thus determines the pulse length in each period of the square wave output. With the help of resistors it is divided in such a way that the potentiometer changes the filling in the range from 5% to 95%. The frequency of the system can be changed smoothly in the range of 4-100Hz. The structure of the circuit includes a transistor at the comparator output, working as an emitter follower, which controls the BD139 executive transistor. A 1k resistor based on it causes the base current limitation, and 10k polarized one to ground, the other to the power supply plus, discharge parasitic capacitances, so that the waveforms based on the key and output are not distorted. The executive transistor works in a common emitter system. The 1N4007 diode at its output, connected in reverse, and in parallel to the operating LED, has negative pulses generated during the time when the transistor is not conducting.

    Schematic diagram of the generator:

    Strobe lamp to set the ignition offset angle

    Frequency meter:

    The frequency meter circuit is based on the AVT-2269 kit with minor modifications. However, half of the system is used, because in the designed device measuring the frequency up to 1kHz it is fully sufficient (3 seven-segment displays). The task of the meter is to count the pulses in a given time unit and display them on the display. The meter is clocked with a quartz-stabilized generator with a frequency of 32.768kHz. This frequency is divided by 214, which gives 2 Hz at its output, and then on the two D-type monostable flip-flops by 4, which gives a waveform with a frequency of 0.5 Hz, in which the low and high states last one second. During the high state, the logic gate is open and the second input is influenced by the measured signal. It is then counted by the counter, snapped with a LATCH latch and displayed on the seven-segment displays that are multiplex-controlled. The entire cycle is repeated every second. The arrangement in practice did not cause any major problems, but it is extremely capricious. It needs a very stable power supply (a small variable component caused incorrect operation), and a supply voltage of 5V, although the integrated circuits used can work up to 15-18V. At a voltage higher than 5V, even by half a volt, the system freezes, stopping the previously indicated value and stays in the latch. The measured signal must also have a strictly defined voltage amplitude (4.2V-5V), therefore, in order to extend the possibilities of measuring signals to 15V, the measured voltage stabilization (peak cut) was applied to the value of 4.7V on the Zener diode. The maximum relative error of the frequency measurement of the system is 0.1% + 1 significant digit. In order to calculate the error, the system was compared with the TCX0-5 reference made according to L-18 / WT-6860-074.

    Schematic diagram of the frequency meter:

    Strobe lamp to set the ignition offset angle

    Power system:

    The power supply provides 9V for the generator, 5V for the frequency meter circuit, and 3.3V for the LED operating diode. The output voltages are very stable. The TL413 chip was used to obtain the reference voltage. Its value is set to 9V and then divided to 5V and 3.3V by voltage dividers. Voltage from 10.5V to 15V can be applied to the input of the power supply for the unchanging parameters of the entire system. The range covers the voltages that may occur in the automotive installation. The reference voltage, after filtering on the capacitors, goes to the positive inputs of the LM324 operational amplifiers. These amplifiers control the output transistors directly, and their negative inputs have output voltages. The operational amplifier always tends to the "virtual zero" between the positive and negative inputs, so all changes in the output voltages are compensated by them, so that the output is always, regardless of the load and temperature, the set voltage with a high accuracy. The additional capacitances filter out the voltage and allow time for the feedback (which is itself very fast) to respond to current pulses. Such pulses are taken by an executive LED diode, so its voltage must be rigid so that there is no fading effect during operation.

    Schematic diagram of the power supply:

    Strobe lamp to set the ignition offset angle

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    About Author
    Joker2
    Level 23  
    Offline 
    Joker2 wrote 681 posts with rating 255, helped 56 times. Live in city Częstochowa. Been with us since 2006 year.
  • #2
    Krzysztof Kamienski
    Level 43  
    Sorry, there is something I don't understand. If a colleague wanted to build a non-contact tachometer, it was not easier to shine a laser on a glued reflection on a rotating element and count the reflected flashes through the phototransistor and the counter? So how do these types of tachometers work? I can't see the trigger system on the diagram, too, when working as a "car" strobe, the use of which is now pointless, in modern internal combustion engines with ECU? And the last thing - this type of LED used by Kolege as an illuminator has a lot light inertia Building a "fast" strobe on it is problematic to say the least.
  • #3
    Euzebiusz23091998
    Level 15  
    I used to use a simple strobe to set the ignition made of NE555 and a few white LEDs, it was used to set the ignition of mopeds where it was fine and it could be done quite well. The only drawback was the need to turn off the light due to the small amount of light from this toy.
  • #4
    Mikroprocesorowiec
    Level 12  
    TL494 is probably an exaggeration. You can easily do it on the mentioned NE555 or one of Schmitt's goals. You don't actually see how the TL494 is synchronized.
    The frequency meter can be done on one microcontroller. The measurement will last as long as the signal period, and you don't need to wait a second or 10 when you want to be accurate to 0.1Hz.
    Why a power supply on operational amplifiers? No protection against short circuit, overload, overheating. Short circuit protection is one resistor and a diode! But why build stabilizers, the LM78xx could not be used?

    I could use an "unhelpful post" button, I would have something to click.
  • #5
    tomus2k
    Level 25  
    TL 494 is not synchronized, the measurement is made by using the strobe effect of standing still. You set the LED blinking frequency with the potentiometer until the marker on the flywheel illuminated by this LED stops moving and on the frequency meter you read the frequency of the generator, which is equal to revolutions per minute. The accuracy of the human eye, but in the automotive industry it is enough. You don't need lasers.

    For the LM78xx, as suggested by the microprocessor, the voltage difference (3V) is needed for proper operation. In this case, the supply of minimum 10V, stabilized voltage of 9V, the condition will not be met for 9V.
  • #6
    User removed account
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  • #7
    tomus2k
    Level 25  
    R-MIK you are right, but the microprocessor is wrong. I was quietly hoping he would improve on LDO. And then I will say that the TL494 has an internal V-ref 5V PIN 14 stabilizer, and it can be powered from 7 to 40V - PIN12. So why the 9V?
  • #8
    User removed account
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  • #9
    Freddy
    Level 43  
    Explain to me Joker2 as it is - there are 6 displays on the diagram, and 3 on the PCB - which is true :) ?
  • #10
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  • #11
    Freddy
    Level 43  
    R-MIK wrote:
    So buddy, before you start writing something, please read all the material, there is no GB and hundreds of pages.
    Buddy, but I am asking the author, not you, and I expect more explanations from the author.
    If you were reading this carefully and not writing provocative posts, you would know why I'm asking the question.
  • #12
    web69
    Level 29  
    Let the author explain to me how to set the ignition in an old gasoline using this strobe ... I can't see the triggering of HV anywhere.
  • #13
    User removed account
    User removed account  
  • #14
    Joker2
    Level 23  
    Krzysztof Kamienski wrote:
    Sorry, there is something I don't understand. If a colleague wanted to build a non-contact tachometer, it was not easier to shine a laser on a glued reflection on a rotating element and count the reflected flashes through the phototransistor and the counter? So how do these types of tachometers work? I can't see the trigger system on the diagram, too, when working as a "car" strobe, the use of which is now pointless, in modern internal combustion engines with ECU? And the last thing - this type of LED used by Kolege as an illuminator has a lot light inertia Building a "fast" strobe on it is problematic to say the least.


    A colleague below answered the first and third doubts with his post.

    Euzebiusz23091998 wrote:
    I used to use a simple strobe to set the ignition made of NE555 and a few white LEDs, it was used to set the ignition of mopeds where it was fine and it could be done quite well. The only drawback was the need to turn off the light due to the small amount of light from this toy.


    As for the second doubt; there is no trigger circuit in the schematic because "The diode can be triggered by an impulse from the spark plug" but it is not, because I personally did not need it.

    Mikroprocesorowiec wrote:
    TL494 is probably an exaggeration. You can easily do it on the mentioned NE555 or one of Schmitt's goals. You don't actually see how the TL494 is synchronized.
    The frequency meter can be done on one microcontroller. The measurement will last as long as the signal period, and you don't need to wait a second or 10 when you want to be accurate to 0.1Hz.
    Why a power supply on operational amplifiers? No protection against short circuit, overload, overheating. Short circuit protection is one resistor and a diode! But why build stabilizers, the LM78xx could not be used?

    I could use an "unhelpful post" button, I would have something to click.


    Sure, and if I did on the NE555, you would write why I use the antediluvian scalak. You can do anything on a microcontroller. But do you have to? Will you let me do what I want? The same applies to the stabilizers on operational amplifiers.
    I leave the last sentence without comment. You may not like it, but why the irony ...

    R-MIK wrote:
    ... I will look at why this 9V must be so presidential.
    Alw, let's think about 5 or 3V3. I'm shorting (when starting) and what?


    It doesn't have to be "that precise." After making a short circuit, the fuse will burn.

    tomus2k wrote:
    R-MIK you are right, but the microprocessor is wrong. I was quietly hoping he would improve on LDO. And then I will say that the TL494 has an internal V-ref 5V PIN 14 stabilizer, and it can be powered from 7 to 40V - PIN12. So why the 9V?


    9V for the generator. The TL494 datasheet indicates the minimum recommended voltage of 7V. So it may not be 5V.

    R-MIK wrote:
    ... And nowadays, it's more like a stab. impulse. Here we have LEd, powered by 5V, so "com is with us". Switching power supply is indicated. If someone is afraid of them (without an oscilloscope, it may be a problem if the impulse does not work), you can buy a ready-made Chinal oc module for $ 1 (I prefer to see a 3x more expensive solution on other popular chips).


    As I wrote at the very beginning: "I made the device a few years ago and it has served me flawlessly so far." Back then, Ali was not as popular as it is now. The rest of the impulse stabilizers too.

    Freddy wrote:
    Explain to me Joker2 as it is - there are 6 displays on the diagram, and 3 on the PCB - which is true :) ?


    As R-MIK wrote, nothing more, nothing less:

    R-MIK wrote:
    Freddy wrote:
    Explain to me Joker2 as it is - there are 6 displays on the diagram, and 3 on the PCB - which is true :) ?

    However, I have already spoken about this project and there is something noteworthy (according to me), the author wrote that:
    Quote:
    However, half of the system is used, because in the designed device measuring the frequency up to 1kHz it is fully sufficient (3 seven-segment displays).

    So buddy, before you start writing something, please read all the material, there is no GB and hundreds of pages.


    On the other hand, if you still "expect a more detailed explanation":

    Freddy wrote:
    R-MIK wrote:
    So buddy, before you start writing something, please read all the material, there is no GB and hundreds of pages.
    Buddy, but I am asking the author, not you, and I expect more explanations from the author.
    If you were reading this carefully and not writing provocative posts, you would know why I'm asking the question.


    As I wrote in the description, I used half of the kit because I needed to measure the frequency up to 100Hz. The next segments were not needed. Does my answer satisfy you? If so, I would like to say that I expect a bit of culture from you and others. You quarrel like children.

    web69 wrote:
    Let the author explain to me how to set the ignition in an old gasoline using this strobe ... I can't see the triggering of HV anywhere.


    One of my colleagues has already explained:

    tomus2k wrote:
    ... the measurement is made by using the strobe effect of standing still. You set the LED blinking frequency with the potentiometer until the marker on the flywheel illuminated by this LED stops moving and on the frequency meter you read the frequency of the generator, which is equal to revolutions per minute. The accuracy of the human eye, but in the automotive industry it is enough. You don't need lasers.
    ....


    Triggering "HV" can be done in many different ways.


    R-MIK wrote:
    It is rather the project of the I Kameleon.


    Is the forum for everyone and everyone can upload the construction they want? Have I broken any point in the regulations? You broke with this post because it adds nothing to the topic.

    R-MIK wrote:
    He got ESP and he is very serious about everything.
    These gifts should be given e.g. 7 days after publication.


    Why do you think I have everything in deep respect? I added the topic yesterday at 23:49. Not even a day has passed! Do you think I have nothing to do but wait for every answer that comes up and need to answer it quickly? Participate in your quarrel about nothing? What is this anger and talk for?

    R-MIK wrote:
    In fact, I will show the seal of salaks and other electronic elements, I will write that miracles can be done and I will get ESP.


    Why did you summarize me so negatively? This is not a "salak seal" but a project of a simple personal-use measuring device. What do you mean? Do you know that you can take away from a beginner the enthusiasm, joy and willingness to do anything with such a cold and malicious comment? And this is also at the most famous Polish forum, which is to encourage the study of Electronics ...
  • #15
    User removed account
    User removed account  
  • #16
    Freddy
    Level 43  
    Joker2 wrote:
    As R-MIK wrote, nothing more, nothing less:
    Joker2 wrote:
    On the other hand, if you still "expect a more detailed explanation":
    I expect so, because then your diagram is wrong and it should be corrected.
    Joker2 wrote:
    If so, I would like to say that I expect a bit of culture from you and others.
    Where do you see the lack of culture here - if you point it out to me, I'll apologize.
  • #17
    tomus2k
    Level 25  
    Joker2 wrote:


    9V for the generator. The TL494 datasheet indicates the minimum recommended voltage of 7V. So it may not be 5V.


    Joker2: You didn't understand. The TL494 power supply is from 7V to 40V, so a stabilized 9V source is not needed because you assume the system will work in the range of 10-15V (automotive installation). You just feed it through a simple filter from the car's installation.
    In addition, the system has led out ext. stabilized source with a capacity of 10mA, it is enough as a reference voltage for frequency control, and as a reference voltage of stabilizer amplifiers, so TL413 will also be redundant and that's it.
    Correct the LED on the generator diagram. :idea:
  • #18
    web69
    Level 29  
    I still do not know how to set the ignition in Tico ... Let my colleague the author explain to me how to set the ignition to 17 ° before TDC. The blinking led will give me information about the frequency / revolutions, not about the moment of the spark ...
  • #19
    Joker2
    Level 23  
    tomus2k wrote:
    Joker2 wrote:


    9V for the generator. The TL494 datasheet indicates the minimum recommended voltage of 7V. So it may not be 5V.


    Joker2: You didn't understand. The TL494 power supply is from 7V to 40V, so a stabilized 9V source is not needed because you assume the system will work in the range of 10-15V (automotive installation). You just feed it through a simple filter from the car's installation.
    In addition, the system has led out ext. stabilized source with a capacity of 10mA, it is enough as a reference voltage for frequency control, and as a reference voltage of stabilizer amplifiers, so TL413 will also be redundant and that's it.
    Correct the LED on the generator diagram. :idea:


    You're right. This would simplify the deal. Thank you for the substantive comment and pointing to the error in the diagram (I have already corrected it).

    web69 wrote:
    I still do not know how to set the ignition in Tico ... Let my colleague the author explain to me how to set the ignition to 17 ° before TDC. The blinking led will give me information about the frequency / revolutions, not about the moment of the spark ...


    You can use a probe like this:
    http://sklep.gotronik.pl/sonda-wysokiego-napi...le-zaplonowe-produkcji-hantek-ht25-p-104.html

    However, the measurement itself is described in the link below using the example of the Polonaise :)
    https://www.elektroda.pl/rtvforum/topic2033050.html


    I recorded a short video of the operation of the device, where you can observe the strobe effect. I put a round cardboard disc with a red insulation strip glued on it. When the rotation speed is equal to the strobe frequency, the belt will not move (or move slowly).

    [movie: eb49968224] https://filmy.elektroda.pl/12_1508958703.mp4 [/ movie: eb49968224]

    At the maximum speed of the drill (3600 rpm), the instrument read 60 Hz. It even is ;)
    This simple experience gave me a lot of joy and made me realize that no matter if you are building an oscilloscope or a circuit continuity tester. It is important that what you do gives you satisfaction. Greater than getting an Arduino board, which of course increases the possibilities and it is very nice on the part of the Portal that it decided to reward the contestants so much.
    However, I regret to say that people who intrusively accuse participants of participating in the competition only for the tile (usurping the right to dispose of them and having, for example, 6 devices on their account) did not think what they wrote or have problems with performing simple operations arithmetic. Because this tile costs PLN 20 with shipping on the Allegro, and $ 3 on Aliexpress. This is less than a salary for one hour of work, and yet it takes a few hours to describe the device itself and draw diagrams ...
  • #20
    web69
    Level 29  
    I know how to set the ignition, but I don't think my colleague the author ... The project is called "strobe lamp for setting the ignition offset angle" and this device does not meet this condition. No HV trigger input, no ECU trigger input. You gave a reference to the WN oscilloscope probe, but you do not have it and you did not check if it could work ... Call it, for example: a strobe tachometer, although not too much, because the display shows the result in Hz, not in rpm.