Scope: Ignition System Spike

This is what is starting to really piss me off about these newsgroups. They say a picture is worth a thousand words but in the case of complex electronics, it may be more like a million. Screw the bandwidth and allow attachments for both clarity of the O.P. and potential solutions. We are supposed to be in the business of communcating, not trying to find out how much bandwidth can be saved. This is pure bullshit...and please don't remind me about alt.binaries.schematics.electronic because for whatever reason, many people don't use it.

Putting attachments on messages will make it significantly more costly for some to access the group, and slower for many. Web-sites are widely available free, and are probably the easier way.

You can't safely use any of those things except the capacitor, but even it won't be very effective unless supplemented by a choke in series with the 12V line. These filters are commonly used for removing noise from car stereos.

I don't know how a 5V spike can affect your ignition, but is it causing the secondary spike rather than the latter causing the former? In other words, can you make the ignition module fire without the coil primary attached to it (a low voltage 60 Hz square wave should be able to simulate the Hall sensor signal)?

The trouble is that as soon as you allow binaries, the nasties come out of the woodwork. That (and its possible legal implications) is why a lot of news servers (mine included) simply won't allow them.

Paul Burke

It's very effective to load the picture onto some (free) webspace somewhere and include the URL in your posting. That way, people downloading the whole newsgroup, and all the world's newsservers, don't end up paying the disproportionate overheads for the relatively few people who are going to be diving into that level of detail on any one thread. The volume and nature of binaries on Usenet means that much of the usenet infrastruture simply chooses not to take them anyway.

Thanks for the thoughts. I would think it would be the latter causing the former, but will relook. I'm guessing the spike may be a normal noise artifact. I should have also stated that the spike V diminishes, the further I get from the coil and the closer I get to the batt, which might be expected. I was hoping that placing a properly spec'd diode, on wire 123B by the 15 (+) terminal, might be an easy fix, but acknowledge your caveat.

I'm not sure why the other posts, as included a URL for the wiring diagram. The site does sometimes go down(?), but has been up and running during a few intermittent cks both yesterday and today.

If the signal changes as you describe by moving the leads away from the coil, what is happening (sounds like) is that your leads are picking up noise from the ignition coil.

Dedicated automotive scopes are purposely engineered to filter out this noise, sometimes too well.

Maybe get back to the AES guys and see if they don't have a set of leads with better filtering than what you've got.

Otherwise, unless you're experiencing false triggering from the noise spikes, you can just ignore them (obviously). A large part of scope useage is trial and error and learning exactly what to get excited about.

My LS-2000 is so sensative that sometimes I have to switch off the flourescent shop lights.

The bad news (for me) is that I'm seriously eyeballing the Ferrett V-92 4 channel. 8^)

The spike is about 1/2 reduced at the ignition key.

A lot of that ahead of me! but is interesting stuff

I'm still working on getting their low-amp probe :-). I saw your helpful para, in another injector thread, on how it will help discern mechanical/load/solenoid driver behavior (amongst other things). I didn't download the flyer, but the V-92 looks state of the art. A tech was telling me about the (rapid?) growth of software, that has waveform samples per component, per vehicle make and model

I would like to get a handheld scope of some sort, but still with a reasonably large display screen. Or maybe just transfer the data to the 'puter