Secondary ignition waveform

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.

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.

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

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?

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

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.

Good capture (normal idle)
Red Trace Channel 1 Hantek Capcitive Plug Lead Probe --- inverted by scope.
Yellow Trace Channel 2 Autoditex COP Probe

Red Trace Channel 1 Hantek Capacitive Probe 200mv/div
Yellow Trace Channel 2 --- No Probe No Physical Connection ! 200mv/div :dry: ?????

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.

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

I did a bit of experimentation measuring the actual resisstances of the Hantek HT25 probe with an my trusted Uni-T UT203 meter --- interesting result.

At Scope BNC: + to Ground 33k ohms,
At Pickup: + to Ground 33K ohms
Scope end to Pickup End 0 Ohms on both + and Ground conductors.

So any over voltage protection and attenuation going on inside the black box on the lead isn't being done by reisstors

Hello AM. The stated attenuation spec of the HT25 is 10K, according to enclose information sheet they provide with the tool. I believe that is accurate, as seen on your last two waveforms with 200 ms/dv or 2V per screen for a max of 20KV. Anyway, still that HT25 tool is not the one I refer in my case. Check on Hantek website for item HT25COP.

Let me ask you: I do not know the brand of scope you use, looking at the photos you send with the capture waveform it seem to be a Hantek. Now, does it change color on the trace on you when selected voltage scale is under the value of the actual captured signal. For example, in my case I selected a scale of 15KV per screen to view the secondary @ idle, but I can see the trace passing that point way up out of the screen. Is it possible that is the reason I am having this issue of change of color on my trace? Is this normal on any brand of scope or is it unique to Snap on products?. O worst yet indeed more voltage is coming in to the scope that it can handle?

By the way good trick on the capture o f the rover trace with your hand over the coil ! . Is it a 75 Land Rover?. It does recall some fun memories.

I really don't know about Snap-On scopes other than watching the vieos of Paul using them I have never had the pleasure of owning one.
My main scope is an Owon SDA7120v with the optional battery I like it because I like having real knobs and buttons It isn't perfect for automotive work but I find it quick and easy to use and I got it at a very good price. I have a Hanktek 1008 I keep is reserve in case I need more than two channels.
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I was sitting waiting for the grand kids coming out of school and did some web browsing on protecting scope inputs and capacitive probes, interesting.
From what I can gather the output voltage of a capacitive probe is controlled by simply linking the ground and signal wires by a ressistor and capictor in parrallel.

The over voltage protection in the scope is also pretty simple just 4 diodes that act the same way as the zenner diode in a motorcycle voltage regulator and simply dump any excess voltage back to ground.

That captures were taken not from a Land-Rover but this car a now high mileage Rover 75 the last car model Rover made before they went bust 11 years later we still have a couple of them in the family fleet --- we used have a lot of various Rovers and MGs but the family are going Nissan and Renault

Not to be sad and worry AM. at the very least you are expanding your frontiers with all those car manufactures in your hands. Add an American or German make to the list more international. Renault sure did not fair well with the American public. If my memory serve me well they have several F-1 championship under their belt. Nice.

My Snap On Vantage Pro bundle is 11.4 ( circa 2010) not even close to what Mr. Danner operate. Got it used, but still a treasure worth keeping it safe from misusage...........hope.

On any case, looks like my main concern with the usage of the HP25COP/Pico pp357) on this scope still inconclusive. Should I give it a green light to try the same capture on a different voltage scale?. Apparently that what Snap On thinks. I am tempted to do it but...............certainly will be nice to have the right answer?

Did you check the Hantek item HT25COP? Aside for what is happening to me it seem it is a better tool than the HT25.

I am having this exact same issue with my Snapon Verus Edge and the Hantek HT25. My secondary ignition waveform looks like a really really tiny current ramp. I even bought a second HT25 thinking my first one was faulty with the same issue. I wish someone would find a solution for this.

Eureka! I solved the issue of the changing color of the waveform on my Vantage with the HT25COP. It is indeed a relief. Both work pretty well together.

Now, Rob: First, a question: Are you using the Hantek HT25 (capacitive) wire with a clamp on one end, BNC connector at the other. Or are you using the Hantek HT25 COP ignition probe with the handle on one end, paddle( that you rest on the coil) at the other?. With both I am getting a trace I can certainly work. But the selection of the scope mode, scaling, trigger,etc must be change according to which of the two is used.

Example: A Secondary ignition waveform, COP system, at idle*.

With the HT25: Lab scope: Volts DC 400mv/div (2Vper screen); 10ms time; Channel 1 normal trigger@ rising slope with a 2ms delay, level 1.0V. Use the HT extension lead, Keep it away from other coils .

With the HT25COP: Ignition scope,single cylinder Ignition: Volts KV at 15KV; 20ms; channel 1, normal trigger @rising slope, 10ms delay, level 4KV. Important: Install a 20:1 attenuator! , rest the probe paddle square on top of the selected coil.

*To test at higher RPM adjust accordingly.

Andy.MacFadyen wrote: 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.

That's absolutely wild! I'm admittedly novice when it comes to secondary waveforms, but I have never seen or heard of anyone capturing a waveform with that method.

I suspect it won't work on some plug top coils, these captures were taken from a plug top coil with a wasted spark for the companion cylinder.
Interestingly the alternator ripple is alao being picked up--- that is really crazy.
I have seen a short video on YouTube of another method that I will try out next time I get a suitable vehicle in.


link to video

I'm having fun with my Hantek 1008C and tried it out on my ignition system today using the HT25 inductive clamp probe. My 98 Mazda 626 GF 2L uses a coil pack waste spark system with each coil firing two plugs simultaneously. I'm pretty new to scopes. Like really new.

I took a short one minute video and captured a few individual wave forms. Going over that video in slow motion I saw quite a variety of waveform shapes, however the fire lines were all about 2 milliseconds which is supposedly pretty good and close to the maximum possible. I don't think the scope was displaying every single spark event because I had the trigger set fairly high, however these two basic waveforms were the most common:



This seems pretty normal, but I was wondering why that second spike was so high? Just allot of energy to wring out?



This is the other common one, and I'm assuming this is the waste spark?



My odd numbered cylinders where upside down like this. I wanted to do the 10k X scaling for this probe, but couldn't get it to work, so I just left it in mV.

I mentioned that I saw a variety of waveforms on slow-mo in the linked video; how much do I care about the exact shape especially of regarding the shape of the burn line?

A waste spark system is exactly that on any single cylinder every 2nd spark is wasted there isn't any point looking at wasted sparks. On a the the wasted sparks peak voltage is lower peak voltage and the spark line voltage is lower. As a result at the end of the spark energy is left over this causes the rising voltage forming the toe at the end of the spark.
When looking at ignition secondary traces on wasted spark systems the trigger level should be set high enough to trigger only ignition firing sparks not wasted sparks.
If you find a significant "toe" voltage at the end of an actually firing spark then it could point to a plug lead or plug shorted to ground or a spark plug gap set too narrow.
With a wasted spark system the companion cylinder can also affect the spark line on the cylinder you are looking at.