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Secondary ignition waveform

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7 years 7 months ago #1431 by Rukerin
I have this Hantek Secondary ignition probe , the thing is I can not read the waveform , I don't even know if it's working correctly. Can anyone help me understand the waveform or tell me if it is possible to get more info than if I have spark or no , that i can check with a normal spark tester . I would like to be able to use it to have a little more info with it . Thanks !!



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7 years 7 months ago - 7 years 7 months ago #1434 by Andy.MacFadyen
First of all the trace is inverted from what you would normally see in illustrated examples, the inverted trace is from a reversed polarity (ie negative) spark which is typical of a one half of a wasted spark system. Wasted spark systems spark each spark plug once per revolution of the crankshaft. For every two sparks one of the sparks is wasted as it occurs at the end of the exhaust stroke. when the pressure in the cylinder is lower.

On a wasted spark system cylinders are paired as "companion cylinders" one cylinder getting a negative spark the other a conventional positive spark. If you put the probe on the companion cylinder to the one you hooked up to you will see a a wave form which is the right way up.

Also from the low spark voltage in your waveform it would appear it is actually a wasted spark which is of little use for diagnostics. Capturing a proper "useful" working spark is really a matter of setting the trigger level to capture only the higher voltage sparks. On the negatively fired plug lead on a wasted spark system all this is of couse turned upside down and the trigger level required is a high negative voltage.

If your scope has an option to invert the trace it will make this type of primary wave form much easier to understand.

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Last edit: 7 years 7 months ago by Andy.MacFadyen.

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7 years 7 months ago - 7 years 7 months ago #1439 by Andy.MacFadyen
Here is a capture from a negative fired spark lead spark lead on a wasted spark system but it is inverted to look like a normal positive spark waveform and make it easier to understand.

lh3.googleusercontent.com/bf3kQfW3GnmF9Z...ESf9Q=w1920-h1080-no


Same waveform with explanation of some features

lh3.googleusercontent.com/azIgT4XBvah7Sb...yEbjA=w1920-h1080-no

" We're trying to plug a hole in the universe, what are you doing ?. "
(Walter Bishop Fringe TV show)



Last edit: 7 years 7 months ago by Andy.MacFadyen. Reason: links added
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7 years 7 months ago #1441 by Rukerin
Replied by Rukerin on topic Secondary ignition waveform
Thanks Andy! Great pictures you got! So whats wrong with mine?? Do I need a better scope or another probe? to get a better quality image , I know the ones you got are way more useful than what I got.

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7 years 7 months ago - 7 years 7 months ago #1455 by Andy.MacFadyen
The first thing I would try is moving your trigger point down below 0v volts I would try a -20v trigger set to "Fall", then try going even lower.
Ignition primary (and secondary) voltage waveforms should really be taken at the beginning of a throttle snap as this when the ignition is stressed most.

I don't see any controls on your scope to invert te waveform which is a pain but I have a couple inverted wave forms from different scopes.

This is the inverted trace of the from the shared COP on another MG-Rover K16 EU3 engine taken on a Hantek 1008
Yellow trace is plug voltage
Blue trace is primary current.
Spark Burn Time on all these captures is around 0.9ms which is right for this model of engine, normally the range is 0.8 to sometimes over 2ms. Most engines have a similar pattern unless they have multi-spark ignition such as some Fords.


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Last edit: 7 years 7 months ago by Andy.MacFadyen.

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7 years 7 months ago #1456 by Andy.MacFadyen
This is the same setup but at a longer screen showing wasted and "working" ignition sparks.

The working ignition sparks have the most negative voltage.


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7 years 7 months ago - 7 years 7 months ago #1457 by Andy.MacFadyen
Same family of engine this one was taken on a DSO201 Nano V3 running Ben-F firmware.


[img]http://locostbuilders.co.uk/upload/2016 - 1.jpg[/img]

Both the Hantek and DSO210 give surprisingly good results for very cheap hardware

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Last edit: 7 years 7 months ago by Andy.MacFadyen.
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7 years 7 months ago #1516 by Noah
Replied by Noah on topic Secondary ignition waveform
Thanks for taking the time to post all the great waveforms Andy.

"Ground cannot be checked with a 10mm socket"

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7 years 6 months ago #1570 by Rukerin
Replied by Rukerin on topic Secondary ignition waveform
Sorry for taking long to reply :c I have been trying to get a waveform but did not have the chance , till today I tried . But had no good results , is there by any chance a problem using an 20:1 attenuator? Could that give me a hard time on not seeing the waveform correctly ?

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7 years 6 months ago #1571 by Andy.MacFadyen
The Hantek DIS probe has a built in protection for the scope so there should be no need for an attenuator. However the quality of these probes s pretty variable I suaspect some sold are not made by Hantek but are clones, so it is more than possiblIe you have a duff probe.
I have a busy day ahead but if I get time I will measure the resisstance of mine.

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7 years 6 months ago #2180 by VizoEdward
Hello.

Would like to know if utilizing COP probes like pico pp357 or hantek ht25 need an attenuator conected to the scope?. (This probes are the ones that have a handle with an a paddle in the end to rest on the coil)

I tried utilize them for a very brief and scary moment on my Vantage Pro. I notice the color( yellow) of the trace at the high inductive spike part of the trace change to a white. Not good!. I double check that there was no high tension leakage anywhere at the set up. Although at that moment the Vantage survive I certainly would like to evaluate this procedure before I continue.

I have use a 20:1 attenuator while getting ignition/injection coil control waveforms in the same unit. No problems.
Additionally, have scoped secondary with the capacitive ignition cable set up ( high tension extension lead+ground clip) on the same unit. also, no mayor problems.

Although I can say that the trace I saw briefly using the probes(pico357/hantek25) DO indeed look a lot better compare with the ones captured with the capacitive cable set up.

But, my concern should be with the warning my scope is sending. I have assumed, before using the probes, that they must posses internals to cope with the high tension because I neither seen any warnings concerning the use of an attenuator or any other protection device.

I have try to contact the suppliers with not answers as yet. Definitely, something in the way I am utilizing the tool is guffy, like Mr. Danner mention sometimes on his videos.

If any one can give some light on the subject.............thanks for the hand.

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7 years 6 months ago #2186 by Andy.MacFadyen
The voltages scope can take varies between different models if you are getting decent traces using a 20:1 then continue with it.
Not all scopes have a 20:1 scale as it is mainly for our type of work , but all the scopes I have used have a 10:1 I use a 10:1 attenuator quite often for injectors and solenoids.
ISTR some scopes (early Pico?) required a 30:1 attenuator when connected to ignition primaries.

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7 years 6 months ago #2188 by VizoEdward
Thanks for the reply. Indeed the captures I have done (injection/primary control) with the 20:1 attenuator are safe and I do adjust the voltage according to the conversion. But the concern with the "over the limit" voltage warnings of the scope (vantage Pro, by Snap On) by showing the change of color from yellow to white on the secondary trace firing line and part of the intermediate using the probes I mentioned on the early post, suggest something is not done right.

Yesterday received an answer from Pico Support Team, where they do mention that the probe pp357 does not need any other device to use with their own software or hardware. That is, aside from setting the scope on what probe(COP probe) the user is utilizing so it can adjust the trace- scale accordingly.

I am incline to say that my solution is a 500 or 1000 to 1 ratio attenuator with this probes in order to be safe. Since the conversion of the up to 40KV secondary circuit potential, brings the voltage to a 80V or 40 range that can be handled safely by the Vantage. But still at this moment a little unclear of this necessity on this probes. They should have the internal attenuation matched for their intend of usage.

Anyway, if any additional clarification or addition regarding this issue it will gladly appreciated. thanks

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7 years 6 months ago #2190 by matt.white
I'm very much a rookie when it comes to secondary ignition, but when you mention the 1000:1 attenuators Vizo, you're not really sending the high voltages into the scope itself surely? Isn't that the point of the earth connection on the secondary probe? So that if there is a leakage on the secondary side it simply grounds through the lead instead of destroying the scope?

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7 years 6 months ago #2196 by VizoEdward
Hello Matt. Thanks for the reply. Indeed, I understand the purpose/importance of the ground wire on a set up like this but if we assume correctly that there is no high tension leakage anywhere, the trace should be shown all yellow all through out the complete screen.

Remember I am using a Snap On scanner (VantagePro). As I read the scope specs sheet the maximum input voltage the unit support is +-200 DCV V. Certainly the screen is changing colors on me, from yellow at the beginning, from turn on,system voltage, up to the point on the firing line and part of the intermediate (coil oscillations) that the voltage trace seem to passe above the +-200V threshold that it is capable of handling, there at those moments the trace is definitely white. This is what I am most concern.

I believe, when you choose an attenuator is because your decision on what ratio to use is based on the expected max Voltage of the circuit you are connected to. For instance, coil primary control with max voltage up to 400. That voltage will go directly to the scope circuitry through the leads. To choose a ratio 20:1 would be reasonable.

That is why I believe COP ignition probes like picopp357 and Hantek HT25COP units must have internally attenuation ratio on 1000 unit to 1. But if this assumption is true, why my scope is flagging the situation? If everything was set right, the trace would be evenly colored all through out the screen. Yellow all the time, not yellow on some parts and white in others. So is it because the probes do not have the internal attenuation or there are not functioning right or an external attenuator should be used with the set up.

As, always eager to arrive to a clear understanding what is going on?. The input you guys bring to this issue is the best. Thanks for following up the discussion. Certainly I am eager to start utilizing well the probes that from what I seen so far, the trace details are much better that anything I have been able to capture with the tools/knowledge I have.

Thanks

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7 years 6 months ago #2201 by Andy.MacFadyen
I had a half hour to spare so took a couple of caputures on my daily runner using using my Hantek capacitive probe and my Autoditex COP probe simultaneously on the same cylinders
I got a couple of good captures. One of which turned up something unexpected.

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7 years 6 months ago - 7 years 6 months ago #2202 by Andy.MacFadyen
Good capture (normal idle)
Red Trace Channel 1 Hantek Capcitive Plug Lead Probe --- inverted by scope.
Yellow Trace Channel 2 Autoditex COP Probe

" We're trying to plug a hole in the universe, what are you doing ?. "
(Walter Bishop Fringe TV show)



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7 years 6 months ago #2204 by Andy.MacFadyen
Red Trace Channel 1 Hantek Capacitive Probe 200mv/div
Yellow Trace Channel 2 --- No Probe No Physical Connection ! 200mv/div :dry: :unsure: ?????

" We're trying to plug a hole in the universe, what are you doing ?. "
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7 years 6 months ago - 7 years 6 months ago #2206 by Andy.MacFadyen
The method used to do the capture was to use a basic crocodile clip lead. Scope ground connected to a block ground, scope positive is gripped in one hand while the palm of the other hand is simply held about 2 to 6 inches above the coil.
I have since tried it with DSO201 Nano and it also works nicely with that. ;)


" We're trying to plug a hole in the universe, what are you doing ?. "
(Walter Bishop Fringe TV show)



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7 years 6 months ago #2213 by VizoEdward
As mention on the two waveform captures done by AM , the tools he utilize are Hantek 25 and the Autoditex COP probes. Both tools utilize a capacitive pick up clamp with a decay of 10K to 1 ratio, as stated on their spec sheets. The fitting of the 200mv/div fit the voltage scalling well.

In my case, I have utilize the Hantek HT25COP and Pico pp357(TA204). Neither of the two utilize a clamp around the HT wire, the probe is rested on top of the coil. These are the ones in question? Are this probes made to be used with out external attenuation devices placed in line with the sensing circuit.?. Or are they plug and go devices like the should be. In any case I have received notes from Pico and Snap On support Teams on the matter. Pico mention that their tool does not need nothing on their hardware/software units. Snap on goes about telling about the same. Most important I wanted to know why? my trace changes color, as I have previously mention on several post today. To Snap On it seem I have a problem with the screen set up.

Is the solution to this matter to try again with a different voltage scale? so it seem to Snap On. Simple. But the point is that I would like to have a little of more info before I risk the health of my dear scope. Which by the way is a Vantage Pro one that I got through a lot of effort and to damage it for ignorance will indeed be not a good thing. The biggest attenuator that I own is a 20:1, all with be easy if I had one 1,000 to 1 or even one(10K) like it is used on the capacitive clamp type. In that scenario will plug it, check result and most certainly that way answer every thing for me but I do not have it.

So again, if any light on the matter can be pointed this way. Thanks a lot

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