What Oscilloscope

[crossy67]

I'm looking for an oscilloscope to test things like ABS sensors. I have very little experience at all with them so I'm looking for some advice regarding what to look for and how much I'm likely to need to spend. I have seen storage scopes, am I right in thinking they won't provide live real time data?

[Matt Seabrook]

Pico scopes are very good. The two channel scopes are good value for money. Watch out for going too cheep on a scope because they may just not be fast enough to give you reliable results. Next thing to do would be to get your self on a course to learn how to get the best out of the tool if you aren't already experienced using a scope.


http://www.picoauto.com/2ch-starter-kit.html £575 + vat

Edited by Matt Seabrook on Sunday 13th July 11:28

[crossy67]

Wow, £700 is a bit more than I was expecting, I only need it to check the odd crank or ABS sensor. The small hand held devices not good then? There are some proper scopes on Ebay for £2-300.

Something like this maybe? http://www.ebay.co.uk/itm/Hantek-DSO5072P-Digital-...

Or something like this. http://www.ebay.co.uk/itm/Uni-T-UT-81B-Multimeter-...

[Matt Seabrook]

I don't know anybody in the trade that uses scopes like that with any success. The Pico is about as cheap as it gets for an automotive scope both Snap-on and Bosch which are the other favourites are thousands of pounds.

[Super Slo Mo]

crossy67 said:

Wow, £700 is a bit more than I was expecting, I only need it to check the odd crank or ABS sensor. The small hand held devices not good then? There are some proper scopes on Ebay for £2-300.

Something like this maybe? http://www.ebay.co.uk/itm/Hantek-DSO5072P-Digital-...

Or something like this. http://www.ebay.co.uk/itm/Uni-T-UT-81B-Multimeter-...

We have something similar to the Uni-T one in our travelling toolkits. For general electronics diagnosis, assuming you know what to do with one, they're ok. They have their limitations, but I would expect it to be able to do what you require. Having said that, I'm not in the Motor Trade, so perhaps they won't.

If you're anywhere near North Staffs, you're welcome to have a look at mine to see if it's adequate.

[crossy67]

Thanks for the advice chaps. And thanks for the offer Slo mo, unfortunately I'm a long way away or I'd have jumped at the chance.

To be honest if the only option is the £700 one I'm going to have to say I'm oot. I only thought about buying one to try to resolve an ABS fault, my scanner tells me the where the fault is, sensor is seeing a signal as the wheel speed is showing and consistent with the others but that doesn't mean the wheel bearing isn't damaged (I think). Hence why I just want something that's going to tell me if the ABS signal is correct.

[Mr2Mike]

Matt Seabrook said:

I don't know anybody in the trade that uses scopes like that with any success. The Pico is about as cheap as it gets for an automotive scope both Snap-on and Bosch which are the other favourites are thousands of pounds.

That's because

1) IME most people in the trade need the hand holding that the Pico-scope gives you.
2) Bench scopes are pretty fragile and wouldn't last long in a commercial workshop.

If you have the first clue about electrical and electronic circuits, a proper dual channel (or more) digital scope is perfectly fine for most[1] automotive uses, and will usually be of far higher specification than a Pico scope of equivalent price.



1. For measuring high voltage circuits like ignition coil primaries, check the maximum input volt specs. of the scope and probe. Ideally a differential probe should be used for this kind of measurement, but will cost double the price of a cheap digital scope.

[Matt Seabrook]

[quote=Mr2Mike]


That's because

1) IME most people in the trade need the hand holding that the Pico-scope gives you.
/quote]

The Pico scope is very good if you need you hand holding or not. It's fast enough to capture glitches and also can bus signals. The nice feature with it is you can freeze the image and zoom in on anything you need to look at. It does need attenuators for checking things like petrol injectors which will see 60ish volts back EMF and ignition coils will need a 400 volt scale for the primary side. Even diesel injectors need a scale of 120volt to capture the wave form on some. A digital scope can be great for capturing cam and crank singles with triggers set to freeze the image in the correct place to view the waveform. From this you can tell things like came timing issue. But that is getting a little more advanced and probably not what the OP is looking for. I started using a lab scope more than 15 years ago but now wouldn't be with out my digital scopes. A Pico is on my to buy list but it will be the four channel advanced kitchen funds permit.

[BigTom85]

I did lots of research on this, and like you I couldn't justify £1k for a Pico set up for occasional hobby use.

I ended up with a Uni-T 81B, and have found it a very good tool for what it does, and would wholeheartedly recommend one.

[mauld]

An auto electrician recommended this one to me a VELLEMAN HPS140

http://www.velleman.co.uk/contents/en-uk/p374_hps1...

[Zad]

To be honest, you only need something as simple as the Velleman. You aren't doing in-depth electronics development, despite what the marketing people will tell you, and those $$$ scopes are way over the top. I use a £300 Fluke meter every day, but for 99% of the time a £5 Maplin special will do the same job. Without the right attenuator, the bench scopes (as with any non-automotive scope) will also implode as soon as they go near a high tension signal, so don't waste your money.

If you are measuring PWM mark/space ratios and frequency, you might well be better spending the money on a good automotive multimeter. Even a £45 Chinese ARM based scope (Search Ebay for DSO NANO) will tell you if you have clean switching voltages, and what the frequency or ratio is.

[Mr2Mike]

Zad said:

To be honest, you only need something as simple as the Velleman. You aren't doing in-depth electronics development, despite what the marketing people will tell you, and those $$$ scopes are way over the top. I use a £300 Fluke meter every day, but for 99% of the time a £5 Maplin special will do the same job. Without the right attenuator, the bench scopes (as with any non-automotive scope) will also implode as soon as they go near a high tension signal, so don't waste your money.

The Velleman scope is only rated for 100v pk-pk input, and my Chinese digital bench scope is rated for 400v pk-pk input. What makes you think the Velleman going to survive an experience with a high tension signal better than a bench scope?

BTW, 'high tension' usually refers to the kind of voltages you get on the secondary on the ignition coil, you need specialised probes to measure this irrespective of the scope.

A scope-meter is probably the most convenient solution for automotive work, but having only a single channel is quite limiting.

[mauld]

Mr2Mike said:

The Velleman scope is only rated for 100v pk-pk

You would use a x10 probe which attenuated the voltage and therefore increases the voltage range.

[Mr2Mike]

mauld said:

You would use a x10 probe which attenuated the voltage and therefore increases the voltage range.

But you could also use a 10x (or 100x) probe on a bench scope, so that doesn't really justify the Velleman scope.

Also note that the probe itself will have a voltage limit which may be lower than you'd expect e.g. plenty of 10x probes have a 200v limit.