Oscilloscope recommendation for automotive usage?

I have been using a USB scope but realise just how little I know about scopes and feel the need to back track and get some basic general info before committing to a costly purchase of a bench type scope. I hope someone can find a few minutes to guide me here, please?

I have been using a Dataman USB scope

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for basic automotive diagnostic work, looking at injector and coil waveforms, reading the outputs of cam and crank sensors, both Hall effect and magnetic, watching thermistor voltage outputs, and looking at throttle position sensor outputs, etcetera. It is not an automotive specific device like, for example, some of the Picoscopes, but this has perhaps worked to my advantage, as rather than pushing on screen menu buttons to set up scaling automatically, I have had to think about what I am trying to measure and do it manually. It has helped me get a basic grasp of signal levels.

I now find carrying a laptop around and the Dataman scope, making sure the battery in the laptop doesn't go flat, being worried something's going to get knocked on the floor, blah blah, is a PITA and would also like a bench oscilloscope. Ideally I was asking about those with battery power options, but I think these will be out of my price range and I will have to continue to use a USB scope and the laptop when on the road, or inside a moving vehicle.

I now find myself realizing just how poor my grasp of scopes in general is. I need advice on whether I should be looking at analogue or digital bench scopes, what bandwidth I need to look for, and how many channels I really need. I certainly need two, but I have a Thurlby Thandar 20 MHz multiplexer

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that might allow me view multiple injector or coil patterns on a single scope input. I have never tried it as I am told you need a scope with a degree of persistence to use it, and I don't think a USB scope would have this? I would also like a colour scope, to make differentiating two or more traces easier, and I also like the USB scope for its ability to show voltage levels and things digitally on screen. I suspect, but don't know, that these criteria will mean I need to look at a digital scope?

Another thing I need advice on is depth of memory. I know Pico go on about how important this is for storing enough data to find an intermittent glitch. It's not something I have used with my Dataman USB scope, but I can see how it would be useful for finding more obtuse issues.

Size and age of machine isn't a real issue now I have decided to consider a bench based instrument. My budget is £600 UK max (about 950 US), so will probably be looking at used stuff. I quite like vintage stuff, so am not necessarily looking for anything on the basis of it "looking modern". I would not want something totally irreparable though, unless it was dirt cheap. Can anyone give me some pointers please, particularly re analogue V digital and on screen voltage level displays?

Thanks for reading.

Reply to
Chris Wilson
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[snipetty snip]

A digital scope will be lighter, smaller, run on a lower power, and have more bells and whistles than a comparably priced analog model. There are lots of dual channel, 100 MHz digitals to choose from. Past 100 MHz the price/performance curve starts to "knee," although 200/250 BW models are still reasonable.

Both Instek and Rigol have scopes that are good value for the money. Browse their respective web sites for some ideas and look at

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for a feel for prices -- I don't know of an equivalent dealer over on your side of the pond.

One thing to keep in mind is to be cautious of are the "equivalent time" sampling numbers; look at the "real time," "single sweep," or "instantaneous" sample rate to get an idea of how useful it is in capturing a single event.

A trade-off with deep memory is a lower rep rate. Some scopes let you switch between narrow (basically one screen's width) and deep buffers. A narrow buffer updates more often, which may sometimes be preferred. Probably have to dig into the manuals to find out, though.

The other nice thing about digitals is the "free" measurement functions that digital processing makes possible. Yes, one can always count divisions and multiply by the scale factors but automatic measurements sure are nice to have.

Rich Webb     Norfolk, VA
Reply to
Rich Webb










Add Owon to the list, and there is yet another one that i can't remember right now. I believe that Saelig sells on the east side of the pond. = And some of the models include battery capability. 2 Channels 50 MHz should be available under US$400. 4 channels 100 MHZ can be had for about US$800-1000. Battery capability may be extra, batteries extra on top of that. Probes may be extra. Some models may work well with true sine = wave inverters (for automotive use).



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analogue V

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