DIY budget auto test oscilliscope and current clamp

[daheee]

Looking for opinions on my choice.

I'd like a scope for diagnosing issues with my vehicles. I also need a current meter that goes up to 200 amps capable of testing the starter, etc. I am a newbie with this stuff.

Here's what I was thinking of:

OWON CP024 DC AC Current Probe for Digital Storage Oscilloscope 4A to 400A Bandwidth 200kHz 23mm Jaw Three-Gear Current Clamp

And

OWON VDS1022(I) PC Digital PC Oscilloscope.

These two items will run me roughly $350. I considered the uscope master kit from aeswave, but it lacks the higher amp current probe. I'd like something reliable - I don't want to waste my money on junk and I lack the skills to improve or fix issues.

I'm fine with using a bench scope too. And I'm fine with buying used.

Are my current picks good? Or should I consider other options?

[jal1234]

For automotive use, you'd be better off with Martin Loren's Hscope app on an Android phone or tablet, and his HS502 or HS512 scope. Depending on settings, those scopes are up to 12 bit with very low noise. Hscope is a very friendly pure Android app. You can find it on the Android playstore, and can use it in demo mode. The HS502 and HS512 come with licenses for the basic scope and automotive mode pre-installed. There is a very active group on Telegram, and Martin regularly checks in. App improvements are constant.
Martinloren.com is his website.

There are also many videos on YouTube. Just search on Hscope. Some good posters of videos are:
The Gadget playlist
Martin Loren
and Ravifix.

Do a search on Telegram for Hscope and Hscope Automotive

Jon

[daheee]

 I have bad experiences with android apps in the past, to the extent I don't use android anymore. Android only software smells, it should at least support Windows or Linux.

[daheee]

Can't I use a clamp meter, from say, Fluke, and connect it to an oscilloscope?

[Squarewave]

You can use any clamp which outputs volts.

[daheee]

You can use any clamp which outputs volts.

Pretend I am 2.

An example would be greatly appreciated, so that I don't make a mistake and buy the wrong stuff.

[tatel]

Since most cars have an OBD2 connector anyway, I guess it's pretty moot to think about needing a laptop (as in using an USB scope like the Owon) since you are going probably to have a laptop nearby.

I would care about how rugged the scope is, having recessed inputs is not a bad thing. I have seen some thread from an automotive guy having problems about  protruding BNCs losing contact with the board from mechanical damage. IIRC, newer models of the FNIRSI 1013D have recessed connectors. FNIRSI 1013 are infamous for bench work but for automotive work they are good enough. The Owon you speak about is better and probably even cheaper than the FNIRSI 1013, but does not have recessed connectors and needs to be used with a laptop. Pick your poison.

It seems pretty much *any* oscilloscope is good enough to do automotive work (mechanical ruggedness aside) , even those that fall into the "toy" category. So choosing that Owon isn't a bad decision. You could go even cheaper I think. But you want at least two channels.

Here's a video showing how to use a FNIRSI 1013 and a clamp:

https://youtu.be/lWM8zxaC4XI

A couple threads about this matter:

https://www.eevblog.com/forum/beginners/oscilloscope-recommendation-426883/

https://www.eevblog.com/forum/beginners/mains-powered-oscilloscope-for-automotive-testing/msg5578373/#msg5578373

Hope this helps

[daheee]

Thanks. I have read thru some threads.

At this time, I am trying to determine what clamp to get. The owen I am sure will work, but I'd rather get a Fluke if one can be had for a similar price.

So the Fluke, for example Fluke 323 Clamp Meter , will have bananna leads. I think I can get an adapter for that. I am just not certain if this will work or work well.

[daheee]

This is what i was thinking of:



I thought maybe it's possible to do that with the Fluke 323, and an adapter convert to bnc to go into the OWEN scope.

[daheee]

Nevermind. Those are inputs only.

So I'd need a Fluke i410 if I wanted to use a Fluke.

[tatel]

Oh man, it seems you have a big empanada between your hears. You'll need to do your homework, can't expect us to do the work for you. But, there are some hints:

That FNIRSI oscilloscope+current clamp in the video linked before, will do the work at about half the budget you mentioned in your original post. Since the Owon you mentioned is cheap, I guess most of the money was in the current clamp. I just checked and it seems that clamp could be bought on amazon for less than $30

https://www.amazon.com/HoldPeak-HP-605A-Current-Adapter-Clamp/dp/B07X8HYLHR

As said in the video and previous responses, you can use any current clamp that produces a voltage, which is what an oscilloscope measures. Ideally you would look for a current clamp provided with a BNC connector, but banana-to-BNC adapters are a thing if needed. You should look for a quality one, perhaps from digikey and from a reputable brand, because cheaper ones can have bad insulation. But you could get a cheap one to start with.

https://www.amazon.com/Binding-Coaxial-Splitter-Connector-Adapter/dp/B07TC1L8RP

While Fluke stuff is excellent, I very much doubt you need a Fluke clamp to do what you need. If your engine needs a couple hundreds amperes to crank, no problem if the clamp reads 175, 225 or 100 amperes, what you are looking for is the relation between current peaks (indicating that compression is at his peak) and injector/firing pulses, that is what gives you about how your engine is working. All four cylinders show equal current peaks at the appropriate time relative to firing pulse? Then it's OK. One of the four shows half the peak? Then that cylinder has half the compression. Firing pulse is missing at compression peak? You'll need to check why is that happening. And so on and on.

Hantek has a current clamp that produces either 1 mV/A or 10 mV/A, meaning that a 200 A current would be seen in your oscilloscope either as a 200 mV or a 2V signal. It has a BNC connector and costs $75-100:

https://www.amazon.com/dp/B09NC6F6NB

Please note, I'm not an expert at all, I just use a dirty cheap $40 toyscope to look at my car's sensors. So don't quote me on this matter. I'm just trying to give you some clues, because it seems obvious to me you are at a loss right now. Hoping this will help you. But, if you don't do your homework, nothing will help.

[daheee]

I've been trying to research this, actually. But given my lack of knowledge, it's difficult for me to know if my thinking is correct.

I believe I only need a 60amp clamp. Thought I needed 200. That should handle most of my needs. ScannerDanner uses a 60amp one to measure the flow to the starter for things like a compression test.

I appreciate your help, and I agree I don't need expensive stuff for my needs -- but I've done the whole buy cheap buy it twice enough to be wary. I think I have enough information now. Thanks again for your help.

[ADT123]

I've been trying to research this, actually. But given my lack of knowledge, it's difficult for me to know if my thinking is correct.

I believe I only need a 60amp clamp. Thought I needed 200. That should handle most of my needs. ScannerDanner uses a 60amp one to measure the flow to the starter for things like a compression test.

I appreciate your help, and I agree I don't need expensive stuff for my needs -- but I've done the whole buy cheap buy it twice enough to be wary. I think I have enough information now. Thanks again for your help.

I would be surprised if he used a 60A clamp - compression test often needs >200A  Perhaps he was using a 600A clamp?  See
https://www.picoauto.com/library/automotive-guided-tests/petrol for some example waveforms

[daheee]

 low amp probe (60 amp) compression testing by scannerdanner



I may purchase the uscope. Still thinking about it, provided the low amp probe that comes with the master kit can do what scannerdanner did in the video.

[ADT123]

low amp probe (60 amp) compression testing by scannerdanner



I may purchase the uscope. Still thinking about it, provided the low amp probe that comes with the master kit can do what scannerdanner did in the video.

The current measured was off the screen at the start then >120A.  It worked OK with that specific current clamp but best not to plan to use a clamp at 2x or more of its rated range.  High compression engines will be higher currents still.  Not trying to sell you anything but for compression you need a "high amps" clamp

[daheee]

Here's another respected vtube mechanic, appears to be using the same clamp meter tho (guessing at the size of the clamp where smaller indicates low amp)

https://youtu.be/buqkld9DhY0?t=481

So does this work only for that specific clamp? Or does the auto industry disagree with you?

[ADT123]

Here's another respected vtube mechanic, appears to be using the same clamp meter tho (guessing at the size of the clamp where smaller indicates low amp)

https://youtu.be/buqkld9DhY0?t=481

So does this work only for that specific clamp? Or does the auto industry disagree with you?

It may be that specific clamp can be used at 2 or 3 x its rated range but given typical currents are 100A to 200A (more for high compression and diesel) most people use a "high amps" clamp (eg 600A).  This one peaks at 700A and once the engine is turning is over 300A https://www.picoauto.com/library/automotive-guided-tests/diesel