Automotive scope - choosing a bandwidth?
Turbo Mini Forums

I'm thinking of purchasing a good scope (thinking digital storage scope via PC) that would have a good enough resolution for seeing the individual teeth on the crank pulley at 7000rpm...
For example:

The frequency capacity is easy to estimate for my needs, but the minimum bandwidth needed to get a good resolution at that frequency is what I'm struggling to determine.

If anyone has used and got a good reccomendation on a scope, I'd like to hear it.

Cheers,

would look into standalone units from uni-t. not quite agilent, but they have a good reputation, good following from enthusiasts, and cheap as chips. Cant comment on the bandwith issue sorry, tbo i dont thing iv ever bothered looking into it, automotive stuff is pretty slow in the grand scheme of things even a pc soundcard can be used to read trigger wheels at modest rpm.

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

For automotive, or general usage ?

For automotive, Picoscope is the one to have

I have a cheap USB Stingray scope. Ive used it at idle speeds and 2-3k, but not 7k. Dont see why it wouldnt work just fine though.

There are other similar scopes about if you search for them, probably better than mine. I bought it about 5-6 years ago although wouldnt use it that often

Weird that the trace in the picture shows the scope backwards, G-A rather than normal left to right.

Edited by stevieturbo on 1st Oct, 2012.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

Even at 7k the frequency of the pulses will only be around 70Hz, hardly a fast wave.

To get rid of any ailiasing double that, 140Hz. As most scopes run at MHz you won't have a problem.

The analogue bandwidth quoted on scopes is the maximum siganal frequency it will measure. for automotive use you can get away with something quite basic.

We have a couple of these in work

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

Reason I asked, is that I've tried to use a scope and it would go down into the mhz range, but there just wasn't enough clarity in the trace to get a clean wave. That is the problem I was seeing - more of a "sampling rate" issue than a pure frequecy capacity.

I'd love to have the unit shown in the attached image once again (which is mistakenly labelled incorrectly of course) but I don't even remember what it was called, to start looking for one.





I'll look at the uni-t and picotech

Edited by turbodave16v on 2nd Oct, 2012.

I've found a fluke 123 locally for $300 (about 200 quid)... Although it's only 2 channel, it looks like it's a useful tool...

Doesn't look like it can be exported to the PC though.

Might go take a look however. Anyone have experience of these?

Edited by turbodave16v on 2nd Oct, 2012.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

Stevie - that is interesting. Do you have any screen captures?
ah - just two channels, Damn. There is a world of difference from two to four channels in cost. Perhaps I should just have a rethink on what I really need.

Edited by turbodave16v on 2nd Oct, 2012.

Here's a snapshot trace of an early Subaru cam trigger. Probably around 1-2000rpm, cant quite remember.
2 wire magnetic, with 3,1,2,1 tooth pattern. I think I recorded them with a resolution of about 20us.



And this is a narrowband lambda trace working properly.
It's switching around 7 times per second. Ive zoomed so you can clearly see the trace. But you can easily zoom in so far on both that it almost looks like a horizontal line, or zoom out so it's just a scribble. So there really is plenty of resolution.



If you download the software I can email the files to look at yourself.

Edited by stevieturbo on 2nd Oct, 2012.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

What about one of these ? Most are pricey except for the base version ?


http://www.bitscope.net/store/?p=list&a=list&i=cat+0

edit to add.

It's always worth searching Youtube as well ! just search for USB Scope and you'll get plenty of hits. People make videos of everything

Edited by stevieturbo on 2nd Oct, 2012.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

found a review for the DSO 203(quad) that showed sampling limitations at 150+khz

http://www.youtube.com/watch?v=Ajl21ne6JaU...D509F278EAB8843

This the sort of thing your referring to? sadly the dso's specs are well exaggerated, so you can use it as a ballpark for a samples/sec to give you an idea what you need :(

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

A wee gem i forgot about, the Rigol DS1052E, can be soft-hacked to 100mhz. only 2 channel though.

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

You may want to look at this: http://www.ebay.com/itm/DSO3064-PC-USB-Dig...=item3371145976

I have no experience with it but it has 4 traces and is rated at 60MHz for 200MSa/s; more realistically if you use all 4 channels the maximum frequency is probably about 5MHz but it's not bad. It's only an 8-bit sample so it will be a bit rough. But it's not expensive and it has quite a few accessories.

Jean

http://www.jbperf.com/

Jean, I was seriously looking at the Hantek, but there seem to be so many quality complaints with their scopes that I just don't want to be spending money on something that might go poof...

I have just picked up a fluke123, so will have a play with that. Seems really cool, but definately not what I am really looking for.

Dave, where did you see these complaints? I have made a few quick checks on Google but didn't really see anything either on the DSO3064 or Hantek in general.

And that fluke looks nice but it is definitely not in the same class as the Hantek.

Jean

http://www.jbperf.com/

Sorry yes, divided by too many 60s. I thought it looked a bit low, but as you say, still bugger all.

On 2nd Oct, 2012 stevieturbo said:

On 2nd Oct, 2012 wil_h said:
Even at 7k the frequency of the pulses will only be around 70Hz, hardly a fast wave.

To get rid of any ailiasing double that, 140Hz. As most scopes run at MHz you won't have a problem.

The analogue bandwidth quoted on scopes is the maximum siganal frequency it will measure. for automotive use you can get away with something quite basic.

We have a couple of these in work

Surely 6000rpm ( easier maths ) is rotating 100 times per second. That's already 100Hz.

then say 36 teeth every rotation, that's 36 x 100 = 3600Hz. 3.6khz

Still not that fast really though

This is the one I have http://www.easysync-ltd.com/product/520/ds1m12.html

A standalone unit would be much easier to use though, but the big screen on a laptop and ability to record and view later are nice.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will