Software based oscilloscope?
 

I want to get an oscilloscope for reading the ignition system on my car. The ones on CL are pretty cheap ($100 +/- for the sun machines) but are huge!

Does anyone know if there is a software based scope available that I can install on my laptop?

I don't know of any personally that I'd feel comfortable recommending (I'll ask my EE buddy when he gets home, we've got them lying around)

You're still going to pay for an interface. Are you concerned more about size or price? You can get a USB interface for a few hundred bucks. Look up Velleman, AEMC.

More to do with size. I already have a laptop with OBD2 software. MB specific software and if I can throw this in, I won't need to store anything else. I don't however want to spend thousands on it as it is in the end a toy (to me).

No USB dongle needed, really.

Audio ports can record at 44kHz. If you're reading +12V signals, you can build a circuit to convert them to the +/- 0.5V or so that the audio port needs.

You then use some software to view the traces:
Zelscope: Sound card oscilloscope and spectrum analyzer

You know that you will need a high voltage probe of some kind. You will also need an overlay to allow you to measure degrees of dwell. This could be done with software graphics.

I am not sure if 44KHz would give you good enough resolution for reading the ringing on the ignition trace. I have an old Sun scope that I haven't used in years. In the days of distributors, even electronic ones, it was quite useful. In today's world of COPS and crank triggers, they do not seem very necessary.

My $0.02

Good call, never really thought of that. I imagine there will still need to be something to read such sensitive waves? Mic ports (especially on laptops) are tuned to the human voice spectrum and won't be much good beyond that.

Larry

Thanks, I understand that all of this data can now be obtained through your OBDII port so they're about as useful as tits on a bull for most professional automotive technicians these days. However, I have a number of old V8's that it may be useful for.

I've seen a Snap-on scope for $175. It's not small, but it has all the leads. Maybe I should just bite the bullet and get it?

If you do a lot of work on cars with distributors a scope would definitely be useful. For electronic distributors you will need a few adapters to cover them. The problem with these old scopes is usually aged capacitors. When I got my Sun in the eighties I did a capacitor renovation to get it working. If I were to use it again now it has been so long I would probably have to do it again.

If you could see it work before buying it, it might be worth the money.

Since you are local, if you get one, I would be happy to see how much I remember about using one and give you a primer on it.

That would be gratefully appreciated. We'll keep in touch.

OK what about this?
HANTEK1008C 8CH USB Auto Scope DAQ 8CH Programmable Generator | eBay

I can't tell much about that from the link.

Don't be insulted by my question, but I have to ask about your basic knowledge of the use of an oscilloscope and electronics in general. If you are knowledgable and technical, then you will be able to decipher auto ignition patterns on a standard oscilloscope. If not, you would be better served with an automotive scope.

Do you have a link for the snap on you mentioned?

Larry, I don't really have much knowledge about them, I'm not concerned by that as I'm sure that I can learn how to use one.

The ad that I was looking at has expired but here the same model (but much more expensive).

Snap On MT1665 Digital Scope for Sale or Trade - $800 (Marana)

Yeah as long as you have basic knowledge of electronics and oscopes, you will be able to make the interpretation.

Since you brought up the subject I poked around on eBay and $800 appears to be the going rate for an automotive scope in nice shape. If you could afford the money AND get one in solid working order it would serve much better eliminating some potential serious hassles.

The problem with an automotive scope will be as I mentioned earlier, capacitor deterioration. Also, those CRT's are all old, so the tubes will possibly or probably be "gassy."

I ended up buying a Snapon MT1665 scope today from a local buyer for a couple of hundred bucks.

Now to figure out how to use it.

http://www.govliquidation.com/shared...0/45399346.jpg

Here's a manual.

http://captfiero.com/uploads/MT1665.pdf