Scope for beginner.

[Seekonk]

We're both old enough that we can be honest.  I see people posting here with these scopes and a problem.  My first thought is why does this guy that has no idea what he is doing have a better scope than I do!  It didn't make them any better in electronics.  I have a 50 yer career in electronics and I can do anything I need without one.  I was given a $70 USB scope by a customer and that project was canceled. I find it has amazing capability for the price.  You get direct reading voltage, time and frequency with the ability to store an image.  This assumes you have a spare laptop so you can program and scope at the same time.  I really like the larger screen and that it is portable.

Then you can use what you save to buy other equipment and some neat modules on ebay.

[Gyro]

I wholeheartedly agree (not 50 years in the business a lot of the way towards it). There's no point it spending all your premium bond money now when something lesser and cheaper will fulfill your foreseeable needs and free up money for things to actually monitor!

[rstofer]

Hello Hotspur,

If you're mainly interested in monitoring what the digital I/O pins of Arduino and Pi are doing, at least initially, then you could look at a cheap USB logic analyser. This is of course a digital-only device, but does have the advantage of being able to monitor 8 signals at once.

It clearly doesn't replace a scope in being able to monitor analogue signals, but it would still compliment it in being able to do protocol decoding and long traces. An example is:

http://www.ebay.co.uk/itm/Hobby-Components-USB-24M-8CH-24MHz-Logic-Analyser-Test-Hook-Clips-/161309241759?var=&hash=item258ec7b19f:m:mFNflGSPKkU1xYLv248m4Nw

P.S. It would provide 'instant gratification' and be easy to slip past "er indoors" too. 

What a dandy price!  The shipping is nearly as much...

Mostly I play with digital and I find a logic analyzer to be more useful than a scope or at least an old analog scope.  The 1054Z has a great deal more capability. I'm not going to throw my scopes in the trash heap but if I were limited in budget and wanted to see digital kinds of signals from a Raspberry Pi (or similar), I would opt for a device like the above.  At a minimum, it would get me started.  I could fool around with servos and watch the pulse width change, I could capture and decode SPI, I2C and RS232, I could write a ton of Python code to make things happen in the real world and watch the inputs and outputs on the LA.

For the little bit extra, I would think the test clips option would be a great way to go but given the fact that most boards have headers, they aren't nearly as useful as the female contacts.  Maybe I would save the money.

Given the cheap shipping to the US, I may just buy one so I can play with the software.


ETA:  I just ordered one to play with.

[SewingYard]

I must say, I am overwhelmed by the feedback to a queston I am sure has been asked before. Many thanks to you all.
From all the information gleaned I would really like to get the Rigol 1054z but I find it difficult to justify the cost. The cheapest I can find is £331.20. To buy that would entail telling fibs to the Old Dutch:)
The 1054z appears to have everything, 4 channels, good screen resolution and a thumbs up by Dave. I also like the looks of the Siglent and have seen one for sale for £242. I think I can justify that to "er indoors".
I think I will brood on the options for another couple of weeks, just to see in my premiums bonds are able to resolve my dilemma.
The real problem is that I have never used a scope and not all that sure that I need one, the idea of messing about with a scope does appeal. I find electronics almost akin to magic and to be able to see a representation of these invisible signals I feel sure will greatly assist in understanding.
Again many thanks for you feedback and advice.

Personally if I was your age and looking for a very basic scope to play with then I'd probably go with the DS1052E - I got my MSO1104Z-S from here, they seem like a decent outfit and I looked for days trying to find cheaper:

https://www.rigol-uk.co.uk/Rigol-DS1052E-Digital-Oscilloscope-p/ds1052e.htm

I'm very impressed with my Rigol scope, it was recommended in AoE, thats what made my mind up!

[sokoloff]

Given the cheap shipping to the US, I may just buy one so I can play with the software.

Those things are all over Aliexpress with free shipping. Item 32626161819 or search for "USB Logic 8CH".

I can't vouch for any particular seller, as I bought one but haven't had occasion to use it yet.

[rstofer]

Personally if I was your age and looking for a very basic scope to play with then I'd probably go with the DS1052E - I got my MSO1104Z-S from here, they seem like a decent outfit and I looked for days trying to find cheaper:

There's a reason I bought a 1054 and that is the fact the Raspberry PI kinds of signals, specifically SPI, need more than 2 channels.  I already had a 2 channel scope; I wanted 4 channels!

You want to sync on CS' going low and then capture MISO, MOSI and CLK.  That takes 4 channels.  I'll eventually hack the 1054 to get the 100 MHz but in the meantime, I can use all of the channels.

It is almost inevitable that any expansion of the PI will involve SPI.  For the $70 difference, I just can't get behind the 1052 over the 1054.  But it's not my allowance!

[Renegade]

After doing my research, I went with the Rigol D1054Z. Just my 2 satoshis.

[hamster_nz]

After doing my research, I went with the Rigol D1054Z. Just my 2 satoshis.

If you intend to do digital, if at all possible, also get yourself one of those inexpensive USB logic analyzers. I've got one, and  compared with looking at a scope they are a godsend.... Got a once a second software glitch on a busy I2C bus? Nearly impossible to isolate on a cheap scope, piece of cake with one of these... Just capture 5 seconds worth, maybe also add a gpio pin or two as a reference signal and you will find it in a flash...

[Karlo_Moharic]

I would recommend you this http://www.batronix.com/shop/oscilloscopes/Siglent-SDS1072CML.html , for price is better than the similar Rigol one , and it has a bigger screen.Which is something you might appreciate.

[vk6zgo]

Although the OP presents as a "beginner" in Electronics,this not his "first rodeo".

If he decided to go for a second hand high spec analog 'scope,as a Marine Engineer with many years of experience,he  would probably have a much less steep learning curve than many younger folk.

Old style Marine Engineers are quite used to working things out from indirect indications,so he probably would not be worried about "counting squares" on a CRT rather than  being "spoon fed" information via the multitude of readouts presented on a DSO.

[Hotspur]

You guys are certainly a source of good ideas. I am going to try a logical analyser, nothing to lose, everything to gain, as Gyro apply put it "It would provide instant gratification". This option would leave me with much dollar to spend on Ebay acquiring gadgets to analyse. Sounds good. I have also just watched Dave's EEVBLOG 704 (all 1hr 18m and 44 sec) and at best I only understood about 25%, I can envisage getting into all kinds of trouble with the 4 channel Rigol:) A case of running too early me thinks.
I have just realised that OP does not mean old pensioner:)
I know I'm old, but no need to rub it in:)
As the "Bard" put it  "Last scene of all,
That ends this strange eventful history,
Is second childishness and mere oblivion,
Sans teeth, sans eyes, sans taste, sans everything."
A lot of truth in second childhood, I would never have thought in my younger days that I would find so much enjoyment in playing with little flashing lights. That is really all I'm doing, not like you guys building and designing useful things.
When, or if, I get more adventurous and (hopefully) knowledgeable, then I will get my oscilloscope. In the meantime I will continue to play happily and lurk the forums seeking inspiration, guidance and knowledge.
Many thanks for imparting your expertise and your patience.

[danadak]

The cheapo logic analyzers are like this on ebay -


http://www.ebay.com/itm/24MHz-8-Channel-USB-Logic-Analyzer-8-CH-Logic-Analyzer-for-Arduino-MCU-/191685084604?hash=item2ca15245bc:g:KFYAAOSwyQtV1vOO


search ebay, different versions come with / without grippers, etc..

These all use the Saelae software, free for download. https://www.saleae.com/?gclid=CKOwgNKVrMwCFcUmhgod5PMBSA

Note they claim its good for 24 Mhz, my experience that's a tad aggressive in specsmanship.

Regards, Dana.

[Gyro]

I have just realised that OP does not mean old pensioner:)
I know I'm old, but no need to rub it in:)
As the "Bard" put it  "Last scene of all,
That ends this strange eventful history,
Is second childishness and mere oblivion,
Sans teeth, sans eyes, sans taste, sans everything."
A lot of truth in second childhood, I would never have thought in my younger days that I would find so much enjoyment in playing with little flashing lights. That is really all I'm doing, not like you guys building and designing useful things.

You certainly haven't lost the ability to wax lyrical I see. 
You have a PM by the way.

[rstofer]

You guys are certainly a source of good ideas. I am going to try a logical analyser, nothing to lose, everything to gain, as Gyro apply put it "It would provide instant gratification". This option would leave me with much dollar to spend on Ebay acquiring gadgets to analyse. Sounds good. I have also just watched Dave's EEVBLOG 704 (all 1hr 18m and 44 sec) and at best I only understood about 25%, I can envisage getting into all kinds of trouble with the 4 channel Rigol:) A case of running too early me thinks.

I tend to learn things when the need arises.  If you pick up one of the Raspberry PIs with the intent to add any external circuitry, even a blinking LED, just creating the project will increase your knowledge and, after you finish hanging on some kind of SPI gadget, you will suddenly realize that you now know enough to understand episode 704.  This knowledge will just come from doing.  And re-doing...  And re-doing...

It may seem like a giant leap but I really think there is a lot to learn by just running example programs on boards like the Arduino and Raspberry PI.  In most cases, the code is given but probing the pins will provide a lot of insight.

Personally, I think the Arduino is the better platform for beginners.  You don't have to learn Linux just to blink an LED using Python.  There is a ton of example code and the platform is well understood.  Code will be written in C or C++.  The IDE is crap but it grows on you.  Just make sure your Arduino is of the 3.3V flavor, not 5V, just to protect the logic analyzer.  I'm assuming the Hobby Components Logic Analyzer is rated for 3.3V inputs but I haven't researched it yet.  I did order one.  My Digilent Analog Discovery is rated for 3.3V but it has protection up to +-20V.  Many such devices do a similar thing.  They use series resistors and clampling diodes external to the counter logic.

One thing about logic analyzers, they don't deal well with very slow signals.  They simply run out of buffer memory before the transitions.  It is common to blink an LED once per second.  This may be hard to see on a logic analyzer.  So, increase the speed by a factor of 1000 (to pick a number) when watching the pulse train on the logic analyzer.  Where I really see the utility of the LA is when dealing with one of the serial streams: SPI, I2C or RS-232.  The signals are fairly fast, they come in packets and we are interested in the contents.

Nothing ever works right coming out of the gate and that's where the creative stuff starts.  Instrumenting experiments to see why things don't work.  It's no fun if everything works first try.

[rstofer]

Thinking about the Arduino as a first choice, I got around to the idea of outputting an 8 bit counter to pins as an exercise for all 8 channels of a logic analyzer.  Here is such a project:
https://gist.github.com/adamatan/3188066

Now here's where the fun starts...  Notice that the pins are set on or off one at a time in the showBinNumber routine.  This is a quirk of using the Arduino library functions but it will be interesting to watch the 8 bits change in sequence on a fast logic analyzer.  Ordinarily, I would set up the project to use an 8 bit port (to avoid splitting the output over two ports) and write the entire byte all at once.  Alas, that's not the Arduino way.

To get the speed up high enough for the LA, consider changing or removing the delay(256-i).  At a minimum, make the delay a constant value like delay(100) or whatever.  The variable delay time just makes things messy.  I would remove it.  The Arduino isn't very fast and digitalWrite is fairly slow.  Running full out, it won't tax the LA.

There is a lot to learn in this little example and it gives a bit of practice using the LA.  A perfect place to start.

There's not too much happening in the world of logic chips (7400 series stuff) these days.  Everything is done with a microcontroller or a CPLD/FPGA.  So, when it comes to watching sequential kinds of signals with a LA, they will most often be coming from a very high level device.  There's a lot less wire wrapping and a lot more typing.

Before selecting an Arduino, we need to know if the LA will handle 5V signals.  If not, a 3.3V Arduino must be selected.  Here is a sample of the range of Arduino boards:
https://www.sparkfun.com/search/results?term=arduino

Here is an Arduino 'stamp' board that can be used with breadboards.  It will need headers but those are cheap.  It is powered by the USB connection so no external power supply is needed.  There is a solder jumper that changes the board from 3.3V to 5V if that is desired
https://www.sparkfun.com/products/12587

Stackable headers:
https://www.sparkfun.com/search/results?term=stackable+header
Figure out what you'll need because this little board doesn't have the standard Arduino layout.

There is a process for adding all of the Sparkfun boards to the Arduino IDE and it is linked to the product page:
https://learn.sparkfun.com/tutorials/pro-micro--fio-v3-hookup-guide

[hamster_nz]

One thing about logic analyzers, they don't deal well with very slow signals.  They simply run out of buffer memory before the transitions.  It is common to blink an LED once per second.  This may be hard to see on a logic analyzer.  So, increase the speed by a factor of 1000 (to pick a number) when watching the pulse train on the logic analyzer.  Where I really see the utility of the LA is when dealing with one of the serial streams: SPI, I2C or RS-232.  The signals are fairly fast, they come in packets and we are interested in the contents.

That is true of the stand-alone Logic Analyzers, where the art was in being able to find the magic trigger that would give you the 8192 samples you wanted. You need to know what you were looking for before you could capture the unknown event you wanted to see (a bit of a chicken and egg problem!)

The modern, inexpensive PC (<$10 on ebay) LAs are nothing more than an 8-bit digital input to USB bridge, which captures the inputs and ships them to the PC for analysis. Collecting 10s of seconds or longer is no problem. 8 channels at 24M samples/s for 10 seconds is about 256 MB of data sitting in RAM that you can sift through. As long as the event happened somewhere in there then you have got it, just keep looking & searching till you find it.

[Hotspur]

It may seem like a giant leap but I really think there is a lot to learn by just running example programs on boards like the Arduino and Raspberry PI.  In most cases, the code is given but probing the pins will provide a lot of insight.

Thank you for the info, you have given me plenty to think about. I am sure you are right, the way to learn is by the hands-on approach. Reading and watching video are of course indispensable tools to assist the learning process, but are not a substitute for getting down to the nitty-gritty.
During my sea-going career it was often necessary to enact ad-hoc and innovative solutions to various problems and I was always confident (maybe misplaced) that I would rise to, and find a solution to the challenge. But with electronics it is very different, what is happening in a circuit is rarely observable or self-evident. It is not always possible from observing the symptoms to correctly diagnose the real problem.
I am finding it very challenging because I have to keep re-learning things, my short term memory is rather suspect. I can still recall engineering formula from 50 or 60 years ago but forget things about op-amps I did a couple of weeks ago, but such is life:)

[rstofer]

Just for giggles, I decided to try that counter program I linked above on an Arduino Mega.  The board was chosen because it was the first one I found.

At the same time, my new 27" monitor showed up so now I have a pair - one for the IDE, one for the logic analyzer.  Alternately, one for the IDE and one for the reference manuals.  In any event, I'm a happy camper!

The results?  Well, using my Digilent Analog Discovery over the 8 channels and setting 2 ms/div, with a trigger on bits 0..6 = 0 and falling edge of bit 7, I get a very nice graph with one full cycle of bit 7 plus a bit.  Bit 0 is pretty small (horizontally) but that is to be expected; it is 1/128th of bit 7.

Resetting the time base to 200 uS/div and taking another sample, the staircase effect of switching one bit at a time becomes apparent.  It's important to take another sample rather than just expanding the scale because expanding the scale will make the edges look more sloped than they should.

I look forward to seeing how the Hobby Components LA compares.  It will be awhile due to international shipping.  Slow boats...

27" scopes and logic analyzers are good!

[rstofer]

One thing about logic analyzers, they don't deal well with very slow signals.  They simply run out of buffer memory before the transitions.  It is common to blink an LED once per second.  This may be hard to see on a logic analyzer.  So, increase the speed by a factor of 1000 (to pick a number) when watching the pulse train on the logic analyzer.  Where I really see the utility of the LA is when dealing with one of the serial streams: SPI, I2C or RS-232.  The signals are fairly fast, they come in packets and we are interested in the contents.

That is true of the stand-alone Logic Analyzers, where the art was in being able to find the magic trigger that would give you the 8192 samples you wanted. You need to know what you were looking for before you could capture the unknown event you wanted to see (a bit of a chicken and egg problem!)

The modern, inexpensive PC (<$10 on ebay) LAs are nothing more than an 8-bit digital input to USB bridge, which captures the inputs and ships them to the PC for analysis. Collecting 10s of seconds or longer is no problem. 8 channels at 24M samples/s for 10 seconds is about 256 MB of data sitting in RAM that you can sift through. As long as the event happened somewhere in there then you have got it, just keep looking & searching till you find it.

You are correct, I goofed...  The Analog Discovery will happily sample at 500 HOURS/div down to 10 nS/div.  But the sample memory isn't very deep on the AD.  I am looking at 2000 samples at 100 kHz when set to 2 mS/div, 4000 samples when set for 10 nS/div.  So, you can divide up those samples any way you want but that is all the samples there are.  It does not sample at 50 MHz for 500 HOURS. 

Other LAs have a different setup where they stuff the data into the PC and on to the disk.  They advertise up to 1 Terabyte of sample memory.  Well, maybe, but it's going to depend on the USB bus shoveling the data.  But with this arrangement, it is possible to look through a LOT of samples.  It's my understanding that the Hobby Components LA uses this approach.  It should be fun!

Cool thing about FPGA projects is the ability to create a trigger wherever you want.