Making pusle generator

shortbus

Joined Sep 30, 2009
7,440
As for frequency idk, I just know it needs to work on an inductive rpm sensor.
Do you know what and how an inductive sensor works or is? Or do you mean you want to simulate the output of such a sensor?

An inductive sensor like used in a car, works by a ferrous "tooth" passing by the sensor to create a voltage output. A pulse from a pulse generator won't trigger one.
https://www.linkedin.com/pulse/inductive-hall-effect-rpm-sensors-explained-kiril-mucevski
 

Thread Starter

Jaimeperezjy

Joined Jan 8, 2020
12
Do you know what and how an inductive sensor works or is? Or do you mean you want to simulate the output of such a sensor?

An inductive sensor like used in a car, works by a ferrous "tooth" passing by the sensor to create a voltage output. A pulse from a pulse generator won't trigger one.
https://www.linkedin.com/pulse/inductive-hall-effect-rpm-sensors-explained-kiril-mucevski
That's why I'm having such a hard time figuring it out. Somehow this one is able to produce pulses that the machine picks up as rpms. Some of the other guys have posted up some amazing info I've been looking into to see how I can utilize it to make mine work.
 

MisterBill2

Joined Jan 23, 2018
5,157
So why is it that you need to create a magnetic pulse for a hall effect ignition pickup? A peak-holdd meter will allow evaluating the function, and the magnet on the distributor is the one that it has to work with. Do you have a system failure that you are trying to fix? Or something else.
 

Thread Starter

Jaimeperezjy

Joined Jan 8, 2020
12
I'm trying to develop a software to pick up these devices to stop illegal smog checks. I need to make one like this to be able to see what I need to look for when using this device and find key features to block them from use. I'm trying to reverse engineer this to stop it's use
 

MisterBill2

Joined Jan 23, 2018
5,157
"Illegal Smog Checks"? That makes no sense to me. What is being done that is illegal, and how does checking he ignition system functioning have anything to do with it?
 

Thread Starter

Jaimeperezjy

Joined Jan 8, 2020
12
"Illegal Smog Checks"? That makes no sense to me. What is being done that is illegal, and how does checking he ignition system functioning have anything to do with it?
In older cars you can trick the computer by simulating a certain rpm to run the car at a higher rpm to "clean pipe"
 

shortbus

Joined Sep 30, 2009
7,440
Do you mean that you want to detect people doing it, so their car will pass? Or are the testing places doing this? Is there already a device that is capable of doing what you want? Can you give a link to the device? Your description is sorely lacking in what is wanted. This is starting to sound like a school project.

The simplest way to detect RPM would be to use a inductive pick up on a spark plug wire, like they do with a timing light, and count the pulses.
 

MisterBill2

Joined Jan 23, 2018
5,157
What part of the world still does vehicle emissions testing? And it is not at all clear how such a pulse generator would be used to fake the test condition. The last test that I had done, the test operator was the one doing the connection of the ignition lead pickup.
If the device is intended to serve as a fake RPM source so that test results can be passing, so that a test facility can give a pass to a car that fails, there is a simpler way that does not involve electronics. Just use an air tube up the tail pipe to add air and dilute the exhaust gas and it will pass very well.
Note that I do not like any police-state anywhere, and will not give them any useful advice.
 

ci139

Joined Jul 11, 2016
1,170
And has what seems to be tv antenna cable for the loop
at the 2MHz (on a "good weather") - that the 555 can reach - the coax loop (at that length) unlikely alters anything
Basically it forms a high frequency transformer with the beginnings and the ends of the primary and secondary "winding" tied together , now
. . . as the coax shield has "worse" resistance than the core the current path on core is preferred - thus it defines the reaction current at the shield . . . e.g. as by incoming impulse the current through the core fast climbs the shield induces some opposing current ← this result as behaviour of a small inductor . . . while when pulse trail (likely longer = with flatter slope) reaches the "coax inductor" the current at the core fast fades so the shield attempts to compensate that by inducing the forward current
. . . there might be some extreamely high frequency events going on in the coax during that , but they are likely insignificant by their magnitude
https://www.google.com/search?q="shorted+from+both+ends"+"transmission+line"+inductance
 
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MisterBill2

Joined Jan 23, 2018
5,157
The coaxial cable type does not matter, it is only used to simulate the diameter of a spark plug wire. Now I am thinking that the device being presented is used to fake a different engine speed so that a car can pass an emissions tailpipe test. And it seems that the TS is seeking to find a way to detect that such a device is being used to allow a car to pass that would not pass otherwise. That sounds like something that would happen in the state of California, or some police state in another part of the world.

(additional comments deleted)
 

Reloadron

Joined Jan 15, 2015
5,099
What part of the world still does vehicle emissions testing? And it is not at all clear how such a pulse generator would be used to fake the test condition. The last test that I had done, the test operator was the one doing the connection of the ignition lead pickup.
If the device is intended to serve as a fake RPM source so that test results can be passing, so that a test facility can give a pass to a car that fails, there is a simpler way that does not involve electronics. Just use an air tube up the tail pipe to add air and dilute the exhaust gas and it will pass very well.
Note that I do not like any police-state anywhere, and will not give them any useful advice.
The world? I can narrow that down for you to several counties in the state of Ohio located in the U.S.A. While there is a move to eliminate this testing it still exist and I just had to have my truck emission tested. No test and your plates are revolked, pretty simple really. While I see most of this as nonsense believe me it is very real and one need not travel far to find it. Depending on make, model and year it can be a simple OBD II check or tailpipe emission to actually running the vehicle on a treadmill. Testing is required every two years in affected counties. Can't speak for other states but emission testing is very much alive and well here. In some states like CA there is emission control testing to, in many cases, include motorcycles.

Ron
 

dendad

Joined Feb 20, 2016
3,313
How much fun is it to follow a car that is belching clouds of smoke?
I see nothing wrong with emission testing. Why is that a "Police State" action?
If you follow that argument, why regulate the driving on a specified side of the road? Or any of the many rules that make our society work?
 

MisterBill2

Joined Jan 23, 2018
5,157
How much fun is it to follow a car that is belching clouds of smoke?
I see nothing wrong with emission testing. Why is that a "Police State" action?
If you follow that argument, why regulate the driving on a specified side of the road? Or any of the many rules that make our society work?
The4 problem is that it does not just affect "those cars belching smoke." It affects a whole lot of folks, and depending on who is interpreting the test results you may pay hundreds of dollars for a fix that was not required. Back when Michigan had emission testing I ran into that. "Your car needs the $49.95 tuneup" was the song. Went to a different station and passed very well. Perhaps in some Utopia all testing places are accurate and honest. I have never been to utopia.
 

Reloadron

Joined Jan 15, 2015
5,099
Emission testing aside for a moment simulating an engine tachometer signal can be a very easy or difficult task depending on several variables and all vehicles or ECM modules are not created the same so the trick becomes knowing what the ECM is looking for. I have an old speed pick up laying here which I believe came out of one of my old GMC Suburban trucks. This is the type Shortbus describes and measured off a crankshaft gear. The output is a sine wave. Unfortunately this one became loose and got a little too close to the gear teeth. :) Point being the output was a sine wave and that is what the ECM looked for and actually a given number of sine waves per single rotation. Then a matter of converting to revolutions per unit of time or in most cases RPM (Revolutions Per Minuit) Some vehicles use hall effect sensors which output a square or rectangular waveform and again a given number of pulses per revolution. So for a simulation one would need to know not only the type signal the ECM is looking for but also the frequency for given speeds. All tachometer systems on all vehicles are not created equally. Rather that try an build a pulse generator I would just think about buying an off the shelf function / signal generator and be done with it and that assumes one knows the frequency verse RPM relationship the ECM wants to see.

Ron
 

Reloadron

Joined Jan 15, 2015
5,099
Perhaps in some Utopia all testing places are accurate and honest. I have never been to utopia.
Here in the Utopia of Ohio all testing stations are state run using the same identical test systems and methods which produce repeatable results. This was finally done to eliminate the problems of fraud and non repeatable results between systems in the old method. Additionally the equipment at all test stations is subject to periodic calibration. So Utopia is only down the road and right beside Michigan and really is not quite what I would call Utopia.

Testing is Free but let's get real on that note as nothing is free, the actual cost of running and maintaining the test stations cost is indirectly passed along to the motorist.

Ron
 

Reloadron

Joined Jan 15, 2015
5,099
I thought Utopia is Victoria, Australia ;)
Right now I have concerns for my friends down under. Not just the people but the animals. Years ago during my travel days I really enjoyed Australia and New Zealand. I would call Victoria a Utopia. Nice place with real nice people. :)

Ron
 
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