USB oscilloscope

  1. Wightsparks

    Wightsparks Forum Supporter

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    Thanks all for the input, esp @sako243 , @Henrik and @Red'n'Black
    I have looked at the cheaper versions of the Picoscope - the Hantek for example and I think I am inclined to pay the extra , one for the better and constantly updated software but two there is a stronger used market so if/when I find I need to upgrade I will not be out of pocket - not to mention that the cheap end the accessories cost a lot relative to the scope and they would be kept.

    I do like the idea of portable - but I want a decent size touch screen.

    The Automotive Picoscopes have built in higher over voltage safety (2500v), but with the 2204 I will just have to be careful as it's 100V and read range is 20v. The leads have switchable 10x attenuation. If I acquired another inline 10x attenuator - I assume would give it a destruction level of up to 10,000v :o
     
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  2. Henrik Member

    Almost exactly my use case :)

    The 20 pound scope does this for me without the faff of laptops etc. One caveat of it, though: the user interface is non-intuitive / insane.

    The most advanced thing I'll ever do with it is check injector latencies. My colleague is building a guitar pedal at the moment, and it's not behaving properly, and he has used the cheapo scope to debug the pedal as well.
     
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  3. Wightsparks

    Wightsparks Forum Supporter

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    :clapping:
     
  4. sako243

    sako243 Member

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    Be careful about assumptions, you don't know what they've done internally. Normally when you read high voltages like that you'd use differential probes as normally there's a path to ground internally within the scope. You can inadvertently set up nasty ground loops which cause a lot of power to flow through that path.

    E.g. Quite high but short voltage transients can be snubbed by diodes and or caps. However they'll be designed for short transients (there's a special class of diodes called ESD diodes which protect inputs against static discharge) so might only be rated for a continuous power dissipation of a few mWs, which is fine for a 20kV spike lasting a microsecond. Put 10kV on the input and suddenly you're asking it to dump 10s of Watts with predictable results.

    At silly voltages insulation ratings and the like also come into play, simply put the cable itself may not survive 10kV on it.
     
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  5. Wightsparks

    Wightsparks Forum Supporter

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    I was thinking prevention of destruction rather than measuring - strictly automotive.

    Picked up a lightly used Asus tablet/mini laptop for £60, going to work nicely as an oscilloscope.

    The normal Picoscope s/w works fine (it feeds a demo signal in if you don't have the unit yet) but the Automotive stuff is just amazing - select what you want to test and it takes you to a help and explanation page, - and loads up a known good waveform for you as well as adjusting all the settings. Like this https://www.picoauto.com/library/automotive-guided-tests/diesel/

    2019-10-11 17.59.31.jpg
     
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  6. Wightsparks

    Wightsparks Forum Supporter

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    Urrgh .. so the wallet won over the heart, found a badly described Hantek 6022be (as mentioned by @Henrik ) on amazon for £48 and just could not justify the extra £70 for the Pico (£99+VAT) without knowing I'll actually use it. Also found 2 lots of 3rd party software for it which seems to be the biggest complaint.
     
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  7. mtt.tr

    mtt.tr Member

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  8. Wightsparks

    Wightsparks Forum Supporter

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    Thanks, that is interesting, I'll have a read.
    Just spent the same again in connectors and bits - quickly realised that the probes that come with a scope are of no use on a car so I needed BNC to 4mm banana connector cables, then a probe/crocs/back test pin kit, then a 1:20 attenuator. Awful lot of fake tut to be avoided, managed to find some proper Hantek leads that look to be of a decent quality.
    First thing will be a relative compression test on the Jag, followed by working out how to use the cam and crank sensor to check the timing..
     
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  9. Wightsparks

    Wightsparks Forum Supporter

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    Well that didn't last long! Tried out the Hantek and 3 variations of software for it (Hantek's, OpenHantek and BasicScope) and quickly discovered what I didn't know I needed, which is AC coupling. It would appear that almost every Oscilloscope has this... except the Hantek I bought :doh:. Thanks to the miracles of Amazon it's going back.
    Now having found out that I don't need normal 'scope probes and with a bit of Amazon discount I've ordered a Picoscope 2204 without probes for just and extra £40.
     
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  10. Henrik Member

    Ah, that's a shame, but good that Amazon takes it back anyway :)
     
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  11. 123hotchef Member

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    Let us know how you get on with it mate.
     
  12. Wightsparks

    Wightsparks Forum Supporter

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    Shiny new 2204 Picoscope arrived yesterday, smaller than the Hantek but what a difference in the software.

    The AC coupling I mentioned is to enable you to look at the AC fluctuation on top of a DC voltage - say the ripple from an alternator or the loads on a battery when cranking, but even though the Pico has it, - it's not needed as you can just zoom in to look at that section as much as you like.

    The Automotive software is really good (though officially it does not work with this scope) giving all the parameters needed to look at sensors/actuators along with an explanation and sample good waveform.

    Not used it in anger yet but already decided I need at least a low amp clamp - more money !

    Will be all over the broken X-type Jag with it tomorrow if it stops raining. Hoping to be able to see the pressure drops in the common rail caused by the injectors firing along with the cam/crank signals and the relative compression in the cylinders
    Have been watching hours of car 'scope diagnostics - really interesting stuff.
     
  13. mtt.tr

    mtt.tr Member

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    Glad its working, how much did it cost you?
     
  14. Wightsparks

    Wightsparks Forum Supporter

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  15. Wightsparks

    Wightsparks Forum Supporter

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