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morphy_richards
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Which Oscilloscope?

Wed Jul 18, 2012 7:32 pm

There is a bewildering array of these devices available... and probably a number of white elephants mixed in too... Number of channels, digital or not, sample rate, triggers etc. What would be a comfortable bare minimum for a beginner hobbyist? One that would be useful for signal analysis and that would be useful when working with different kinds of data transmission. Are there any particular models which you would recommend and for a modest budget?

jcg
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Re: Which Oscilloscope?

Wed Jul 18, 2012 8:02 pm

While I don't have an answer, I would also like to hear opinions. On a side note, apparently you can use a sound card as an oscilloscope:

http://blog.makezine.com/2007/11/24/tur ... nto-an-os/.

Also, given that the R-Pi has no sound card, it may be difficult to turn it into an oscilloscope in this manner. Perhaps it would be possible to use some other interface to other hardware available?

From the wiki:
``DSP core: There is a DSP, but there isn't currently a public API (Liz thinks the BC team are keen to make one available at some point)''

Not sure if that might be relevant...

EDIT: here's a link to another thread:
http://www.raspberrypi.org/phpBB3/viewt ... cilloscope

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Gert van Loo
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Re: Which Oscilloscope?

Wed Jul 18, 2012 10:15 pm

Try to get a digital on. I have not use my analogue scope for years as most events I have to debug are much easier to read when you do a single capture.
In fact I was thinking of giving it a good home. It has been very loyal to me and it hurts me deeply to see it go, but it has taken only space for the last twelve years. (Gould Advance 250B)

ksangeelee
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Re: Which Oscilloscope?

Wed Jul 18, 2012 11:08 pm

I opted for a DSO-2090 oscilloscope and a Saleae Logic analyser, and have been impressed with both (in other words, I haven't outgrown them!).

Price was a major factor - I didn't want to spend extra to get features that would be wasted on my level of skill and experience (I think I paid around £250 or so for both, they may be even cheaper now).

I considered getting something that would combine scope and analyser functions, but decided to keep it simple, and get a separate device for these separate requirements.

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liz
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Re: Which Oscilloscope?

Wed Jul 18, 2012 11:13 pm

Eben and I have an ancient HP oscilloscope (analogue; sorry Gert) in the study. Does the job. Needs dusting, now I look at it closely.
Director of Communications, Raspberry Pi

kghunt
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Re: Which Oscilloscope?

Wed Jul 18, 2012 11:19 pm

In the study
Oh how the other half liveover in Cambridge. :D

jcg
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Re: Which Oscilloscope?

Wed Jul 18, 2012 11:25 pm

ksangeelee wrote:I opted for a DSO-2090 oscilloscope and a Saleae Logic analyser, and have been impressed with both (in other words, I haven't outgrown them!).
Do you use them with Linux? If so, what software works?

ksangeelee
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Re: Which Oscilloscope?

Thu Jul 19, 2012 12:16 am

jcg wrote: Do you use them with Linux? If so, what software works?
I only use the software under Windows, but I believe that Hantek have Linux software, and there's also http://www.openhantek.org/. Saleae have Linux software listed on their download site http://www.saleae.com/downloads/ - I think a demo mode is available in the official software for both devices, for trying out the user interface without hardware.

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mahjongg
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Re: Which Oscilloscope?

Thu Jul 19, 2012 12:21 am

As is often the case it's horses for courses, and also often a very personal taste.
A scope that one person thinks is brilliant, another person cannot work with.

I only have one tip, anything with a HP label at least doesn't suck!

Otherwise, it all depends on what you want to do with it!

pygmy_giant
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Re: Which Oscilloscope?

Thu Jul 19, 2012 12:39 am

It's not an oscilloscope, but I downloaded the free idealCircuit simulation software for Windows today and and am finding it easy to use. After drawing your circuit you can insert virtual probes to give osciloscope type output. I have been taking the basic parameters from device datasheets and feeding them into the generic device templates. I have copied and modelled some circuits with success - I have no idea how well it really corresponds to the really real real world though. Maybe something like that could help with modelling circuits as an intermediate measure untill you but your scope.
Ostendo ignarus addo scientia.

jcg
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Re: Which Oscilloscope?

Thu Jul 19, 2012 1:10 am

@mahjongg: I've used some pretty nice Tectronix digital storage scopes too, but they are $$$. However, usually you get what you pay for.

@OP: It might be a good plan to look for an older used name-brand digital storage oscilloscope like HP or Tectronix. As long as you get it from a reputable place and make sure it works before you buy, you can't really go wrong with those. If you have some idea of your requirements that can narrow down your search quite a bit. How many probes do you need? What resolution do you need? You will spend quite a bit more up front for the name-brand equipment, but buying one thing that works >> buying n things that don't. If you have to replace an `inexpensive' USB scope once you have gained nothing over a decent used one.

@pygmy_giant: Also check out ng-spice and gnucap.

tufty
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Re: Which Oscilloscope?

Thu Jul 19, 2012 6:19 am

Gert van Loo wrote:Try to get a digital on. I have not use my analogue scope for years as most events I have to debug are much easier to read when you do a single capture.
In fact I was thinking of giving it a good home. It has been very loyal to me and it hurts me deeply to see it go, but it has taken only space for the last twelve years. (Gould Advance 250B)
I'd take it off your hands, but I suspect shipping would kill the deal. Unless you fancy making a visit to the alps...

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morphy_richards
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Re: Which Oscilloscope?

Thu Jul 19, 2012 8:18 am

I think I want one of these.

greypower
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Re: Which Oscilloscope?

Thu Jul 19, 2012 9:13 am

Yes, the DPScope works well. Aimed at the hobbist market , but then thats what I am. Probably more info on the Pixaxe foum.
The software is for Windows (sorry about that folks!)

pygmy_giant
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Re: Which Oscilloscope?

Thu Jul 19, 2012 1:27 pm

Something like one of those does look good - if only there was something avaiable and fully developed that could turn the Pi into an affordable oascilloscope, like on the panalyser thread.
Ostendo ignarus addo scientia.

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morphy_richards
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Re: Which Oscilloscope?

Thu Jul 19, 2012 6:25 pm

That would be weird, testing gpio outputs from the pi's gpio by using probes attached to the pi's gpio. It kind of reminds me of recursion :?

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morphy_richards
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Re: Which Oscilloscope?

Thu Jul 19, 2012 6:33 pm

greypower wrote: The software is for Windows (sorry about that folks!)
That's a shame. I scoured windows vista off my hp laptop a few months ago. I'm not sure if it would be fast enough to virtualised xp or how well WINE would work. The only Windows machine in the house belongs to Mrs Morphy_Richards.

Bakul Shah
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Re: Which Oscilloscope?

Fri Jul 20, 2012 3:27 am

Gert van Loo wrote:Try to get a digital on. I have not use my analogue scope for years as most events I have to debug are much easier to read when you do a single capture.
In fact I was thinking of giving it a good home. It has been very loyal to me and it hurts me deeply to see it go, but it has taken only space for the last twelve years. (Gould Advance 250B)
I have fond memories of looking at the metastability problem of a badly designed synchronizer on an analog Tektronix 'scope -- with all the external lights turned off to see the very faint delayed transition of the output signal (the ckt worked ok *most* of the time)! So I am partial to analog 'scopes but yes, a digital 'scope is far more useful these days.

I've heard good things about the Rigol digital 'scopes but they are about $350 and up. Rigol 1052E has 50Mhz BW (and sample rate of 1GSa/s). Rigol 1102E has dual analog channels as well (for another $300 or or so).

For occasional use only, a local "hackerspace", if one exists, may be better where one can share such tools with other hobbyists.

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reiuyi
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Re: Which Oscilloscope?

Fri Jul 20, 2012 6:20 pm

Just don't get a "USB" oscilloscope, they're a real waste of money and each time you do a measurement you're essentially risking of destroying your computer. In my point of view those USB-styled oscilloscopes without screens are merely sound cards as they often have a 5-volt maximum

Analogue oscilloscopes are cool because you can often get them for free from universities or schools who are disposing of old stuff. You often find them on eBay or other local trading sites for less than $100 (second hand of course). They take up a lot of space nonetheless.

The guy from EEVblog did several reviews on entry-level oscilloscopes that can be as cheap as 200$ brand new. Just have a look around here:
http://www.youtube.com/user/EEVblog/vid ... cilloscope

pygmy_giant
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Re: Which Oscilloscope?

Sat Jul 21, 2012 10:51 pm

I know nothing about oscilloscopes, but like the look of this one: http://www.velleman.eu/products/view/?id=384636
Ostendo ignarus addo scientia.

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rurwin
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Re: Which Oscilloscope?

Sat Jul 21, 2012 11:22 pm

Soundcard scopes are OK if you don't need to capture fast signals, but they are limited to a few tens of kilohertz, whereas even a cheap proper scope has a bandwidth of 1MHz. USB ones like the Picoscope may be faster, but I note that that is indeed limited to 4V input. Digital scopes may not catch fast transients, but they have many more features.

If anyone wants one and is in pick-up distance of Leicester, I have two analogue scopes that I want to get rid of. A single channel 1MHz that I bought as a second brand new for £80, and a dual channel 10MHz (IIRC) without probes that I got for £20 used from a junk shop that didn't know what it was. Both analogue. Both in perfect working order. I replaced them with a cute digital one and then failed to sell them. So anyone taking them off my hands for a reasonable consideration would make the Mrs very happy.

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reiuyi
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Re: Which Oscilloscope?

Sun Jul 22, 2012 10:28 am

Just don't buy a soundcard/USB scope. You'll regret it the minute you first use the damn thing. They're expensive as can be and their functionality is extremely limited. I'm not even sure why there are so many European electronics companies stocking up on these things, while elsewhere in the world they're more difficult to find. In the end everyone is still free to buy anything they like, though this is the advice I'd give to anyone. The stuff I work with is often 5-24V and those voltages would kill many soundcard oscilloscope.

The person above me is one of so many examples that there's thousands of analogue scopes just laying around in attics and garages waiting to be picked up for free or for a small charge. The only thing you need to often do is a local pickup. You don't want any mail service throwing with your breakable oscilloscope, after all :D, and the shipping fees can be horrendous with heavy gear.

Anyway, as for bandwidth.. especially with modern-day SMPS designs, I'd go for at least 10mhz single-channel as a starter oscilloscope. They're not that expensive and you'll be certain you won't be running into any limitations for years!

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Re: Which Oscilloscope?

Tue Jul 24, 2012 4:23 pm

pygmy_giant wrote:I know nothing about oscilloscopes, but like the look of this one: http://www.velleman.eu/products/view/?id=384636
unfortunately I cant recommend a velleman personal scope. I have one and it has been nothing but trouble. It will only work on alkaline batteries but eats them very quickly ! cant get it to work with NiCd or NiMh at all because it always crashes within minutes ! it wont boot up when powered by a +9V supply either ! not good at all

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morphy_richards
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Re: Which Oscilloscope?

Fri Jul 27, 2012 10:55 am

arm wrote:
unfortunately I cant recommend a velleman personal scope. I have one and it has been nothing but trouble. It will only work on alkaline batteries but eats them very quickly ! cant get it to work with NiCd or NiMh at all because it always crashes within minutes ! it wont boot up when powered by a +9V supply either ! not good at all
Is it not just that the alternative PSUs you've been trying are unable to deliver enough current?
Perhaps you need a more beefy power supply?

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reiuyi
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Re: Which Oscilloscope?

Sun Jul 29, 2012 9:39 am

morphy_richards wrote:
arm wrote:
unfortunately I cant recommend a velleman personal scope. I have one and it has been nothing but trouble. It will only work on alkaline batteries but eats them very quickly ! cant get it to work with NiCd or NiMh at all because it always crashes within minutes ! it wont boot up when powered by a +9V supply either ! not good at all
Is it not just that the alternative PSUs you've been trying are unable to deliver enough current?
Perhaps you need a more beefy power supply?
This is just a personal guess on my behalf: many 9v adapters that I have in my house are transformers with 4 diodes and a small capacitor inside them. They are hardly ever regulated by logic IC. I bet if you use one of those "selectable voltage" adapters (which are always regulated), it will work just fine on your pocket oscilloscope.. Most digital devices won't accept unregulated power

Though in all honesty, there's many reasons to dislike or dissuade Velleman products. To me they appear to sell a lot of low-brand low-quality goods that'll still cost you a bite out of your wallet if you're not careful. I have several velleman multimeters and they're all rubbish; even the beeper function (which is the only function I dare to use with confidence) is terrible.

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