EEVblog Electronics Community Forum

Products => Test Equipment => Topic started by: Old Printer on September 07, 2018, 03:11:46 pm

Title: Analog Discovery as a starter scope
Post by: Old Printer on September 07, 2018, 03:11:46 pm
I always give the AD & AD2 props when a beginner is looking for a scope. It is well thought of here and I like mine very much, so much so that a year later I am still watching the Hobbyist level scope market to buy one. One of the main objections is the cost. $279 new plus at least another $15 for probes and $25 for the BNC adapter, which most of us think is a given. That's $325 plus any shipping. You can buy the Rigol 1054Z for that if you are careful and probably a few others. The argument is the wide range of other jobs the AD does well, I won't repeat them all here as the info is easy to find. My input has been that if persistent, the original AD can be found pretty cheap, comparatively. A couple months ago I got one for $50 shipped. Yesterday I stumbled on another AD1, it was $79 Buy It Now inc shipping and it looked to be in good shape, seller had excellent feedback etc. I made a quick post in a thread that someone had expressed interest in one, then deleted it and decided to make it's own thread so it would be seen by more. I got distracted, then went to bed and apparently forgot to hit "Send". :( DUH - because this morning it was nowhere to be seen. Naturally the listing is gone, it sold in a few hours. This reinforces my feeling that they are out there to be had at good prices if you are willing to create searches and stay after it. Digilent sold a lot of the original to students at the $99 price and they are sitting out there in drawers waiting to be sold. It is a great learning tool, the AD1 is 90% as good as the AD2 and should not be over looked. The main difference from AD1 to AD2 was the addition of an adjustable power supply and it only goes up to 5 volts, so that feature while handy is easily replaceable. The rest is marketing talk and a spiffy new case as they were trying to soften the blow of a $179 price increase.

PS, if someone here did mange to pickup that $79 one last night please let me know. I will feel less guilty about screwing up my post. :)
Title: Re: Analog Discovery as a starter scope
Post by: exe on September 07, 2018, 08:02:01 pm
I like my AD2 :). Concerning BNC, etc, I wouldn't be too concerned about it: 1) BNCs have common ground ruining fully differential input 2) you can do it yourself if needed.
Title: Re: Analog Discovery as a starter scope
Post by: chris_leyson on September 07, 2018, 09:09:02 pm
Nice bit of test gear if you know its limitations. I probably paid $300 for an AD1 plus the BNC breakout board, probably over priced but a very useful piece of test gear which I still use.
Title: Re: Analog Discovery as a starter scope
Post by: rstofer on September 08, 2018, 12:26:45 am
Considering all the tools, the AD2 is a bargain!  I have both the AD1 and the AD2 plus all the attachments and there is nothing like it for breadboarding a circuit.  I also have a DS1054 and a Tek 485 plus a Siglent AWG but the AD2 is perfect for working with most hobby circuit.  The other tools are nice, no doubt, but the AD2 will get the job done.

Don't forget the 27" monitor when it comes to looking at waveforms.  It really is an amazing tool that doesn't get near the respect it should.
Title: Re: Analog Discovery as a starter scope
Post by: Old Printer on September 08, 2018, 02:03:56 am
Rstofer, I do love my 27" monitor, for 65 year old eyes it is great. Also the software for the AD's is very good, probably way better than I can appreciate. These products were originally designed with engineering colleges in mind, no place for a toy. My goal with this thread is to show that they can be had pretty inexpensively and would not be a waste when it is time for a "real" scope. The other instruments included will be useful on your bench for a long time to come.
Title: Re: Analog Discovery as a starter scope
Post by: rjp on September 08, 2018, 02:16:20 am
for MCU circuits the scope +  logic analyzer +  virtual breadboard thing means you can do a  alot of testing and refinement on your laptop without heading to the workshop.
Title: Re: Analog Discovery as a starter scope
Post by: exe on September 08, 2018, 08:07:35 am
Yeah, AD2 is my main tool. Although I have a dedicated o'scope, signal generator and a logic analyzer, I use AD2 most of the time.
Title: Re: Analog Discovery as a starter scope
Post by: TheGrave on March 15, 2019, 08:43:49 pm
I bought AD2 as my first scope too (150EUR shipping included). What I need to measure initially is output waveform of presumably "pure sine" 12->220V inverters and petrol/propane generators. I assume I need to order the BNC adapter board and a pair of probes as well to do the job or is there another way?

https://store.digilentinc.com/bnc-adapter-for-analog-discovery/

Are the Digilent probes any good? Kinda pricey in Europe (31EUR), I assume you can buy better for these kind of money.
Title: Re: Analog Discovery as a starter scope
Post by: tggzzz on March 15, 2019, 09:03:42 pm
I bought AD2 as my first scope too (150EUR shipping included). What I need to measure initially is output waveform of presumably "pure sine" 12->220V inverters and petrol/propane generators. I assume I need to order the BNC adapter board and a pair of probes as well to do the job or is there another way?

Doing that stands a very good chance of destroying the scope and anything connected to it - and that might well include you!

Unless you really know what you are doing, you don't make any mistakes, and the circuit is operating exactly as you believe it to be operating, you would be well advised to use an HV differential probe.

To understand some of the theory and practical safety concerns w.r.t. scopes and probing, you can look at some of the refs here: https://entertaininghacks.wordpress.com/library-2/scope-probe-reference-material/

Alternatively this topic regularly features on this forum. Use the search facility.
Title: Re: Analog Discovery as a starter scope
Post by: Old Printer on March 15, 2019, 11:28:32 pm
I bought AD2 as my first scope too (150EUR shipping included). What I need to measure initially is output waveform of presumably "pure sine" 12->220V inverters and petrol/propane generators. I assume I need to order the BNC adapter board and a pair of probes as well to do the job or is there another way?

https://store.digilentinc.com/bnc-adapter-for-analog-discovery/

Are the Digilent probes any good? Kinda pricey in Europe (31EUR), I assume you can buy better for these kind of money.

Take tggzzz's advice to heart. Input limit on the AD2 is 25 volts, do not depend on a 10x probe to protect it, your computer,  or you.
Title: Re: Analog Discovery as a starter scope
Post by: bitseeker on March 15, 2019, 11:57:06 pm
One thing to watch out for when shopping for a used AD/AD2 is that the micro-USB jack is OK. It seems to be one of the first things to develop problems. If solder joints just crack, you can reflow them. However, if pads get ripped off the board, it's going to be a more involved operation.

I have both AD and AD2. Has anyone tried the Analog Devices ADALM2000 (https://www.analog.com/en/design-center/evaluation-hardware-and-software/evaluation-boards-kits/ADALM2000.html)? It was a long time coming and seems very similar, but at a much lower cost. Even the breakout header is the same (it can use Digilent's BNC board).
Title: Re: Analog Discovery as a starter scope
Post by: Kosmic on March 16, 2019, 01:16:57 am
There's a comparison here https://www.eevblog.com/forum/testgear/adalm2000-vs-analog-discovery-2-vs-picoscope-2205-(2010my)/ (https://www.eevblog.com/forum/testgear/adalm2000-vs-analog-discovery-2-vs-picoscope-2205-(2010my)/)
Title: Re: Analog Discovery as a starter scope
Post by: bitseeker on March 16, 2019, 01:21:08 am
Thanks, Kosmic. I didn't see that thread.
Title: Re: Analog Discovery as a starter scope
Post by: Kosmic on March 16, 2019, 01:40:50 am
I think the adalm2000 pattern generator is more powerful. You can easily generate spi, i2c, UART protocol from the software.

On the analog side of things (oscilloscope), seem like the AD2 is better.
Title: Re: Analog Discovery as a starter scope
Post by: Old Printer on March 16, 2019, 01:45:44 am
Thanks as well Kosmic, I will check that out.
Title: Re: Analog Discovery as a starter scope
Post by: bitseeker on March 16, 2019, 02:07:36 am
Yeah, I'm glad I got the AD rather than waiting for the ADALM2000. Better software (with active development), more resolution, higher bandwidth, etc. It's worth the price difference.
Title: Re: Analog Discovery as a starter scope
Post by: TheGrave on April 04, 2019, 01:38:15 am
Doing that stands a very good chance of destroying the scope and anything connected to it - and that might well include you!

Unless you really know what you are doing, you don't make any mistakes, and the circuit is operating exactly as you believe it to be operating, you would be well advised to use an HV differential probe.

To understand some of the theory and practical safety concerns w.r.t. scopes and probing, you can look at some of the refs here: https://entertaininghacks.wordpress.com/library-2/scope-probe-reference-material/ (https://entertaininghacks.wordpress.com/library-2/scope-probe-reference-material/)

Alternatively this topic regularly features on this forum. Use the search facility.

Thanks for the link, I also found some other excellent material regarding probes:

https://www.youtube.com/watch?v=xaELqAo4kkQ (https://www.youtube.com/watch?v=xaELqAo4kkQ)
http://www.dfad.com.au/links/THE%20SECRET%20WORLD%20OF%20PROBES%20OCt09.pdf (http://www.dfad.com.au/links/THE%20SECRET%20WORLD%20OF%20PROBES%20OCt09.pdf)
http://www.mit.edu/~6.331/an47fa.pdf (http://www.mit.edu/~6.331/an47fa.pdf) (Page 69 onwards)

Take tggzzz's advice to heart. Input limit on the AD2 is 25 volts, do not depend on a 10x probe to protect it, your computer,  or you.

I just realized I shot myself in the leg with a USB scope, completely forgot you can't operate it without being connected to a PC and this requires a questionably working USB isolator. So my AD2 goes for sale and I'm thinking of a sacrificial lamb like DSO-150 so that at least I don't have to worry about a 1000GBP laptop :) It's a much inferior scope but for my purposes it will do the trick.

HV differential probe is definitely outside my budget. Seeing some positive reviews on Hantek T3100, are they that bad? Even if I blow a ~30GBP scope with it I won't be crying so much :) Bear in mind that I never go anywhere 240V without a pair of certified 20KV safety gloves and boots. Better look stupid than dead ;D

This guy has a similar setup to what I'm planning to do which looks reasonably safe (there are possibly more elegant ways to connect the probe):

https://youtu.be/9iJp__9EUPw?t=82 (https://youtu.be/9iJp__9EUPw?t=82)
Title: Re: Analog Discovery as a starter scope
Post by: tggzzz on April 04, 2019, 07:19:42 am
Doing that stands a very good chance of destroying the scope and anything connected to it - and that might well include you!

Unless you really know what you are doing, you don't make any mistakes, and the circuit is operating exactly as you believe it to be operating, you would be well advised to use an HV differential probe.

To understand some of the theory and practical safety concerns w.r.t. scopes and probing, you can look at some of the refs here: https://entertaininghacks.wordpress.com/library-2/scope-probe-reference-material/ (https://entertaininghacks.wordpress.com/library-2/scope-probe-reference-material/)

Alternatively this topic regularly features on this forum. Use the search facility.

Thanks for the link, I also found some other excellent material regarding probes:

https://www.youtube.com/watch?v=xaELqAo4kkQ (https://www.youtube.com/watch?v=xaELqAo4kkQ)
http://www.dfad.com.au/links/THE%20SECRET%20WORLD%20OF%20PROBES%20OCt09.pdf (http://www.dfad.com.au/links/THE%20SECRET%20WORLD%20OF%20PROBES%20OCt09.pdf)
http://www.mit.edu/~6.331/an47fa.pdf (http://www.mit.edu/~6.331/an47fa.pdf) (Page 69 onwards)

You're welcome, and it does no harm to highlight references to the source material from that web page :)

Quote
Take tggzzz's advice to heart. Input limit on the AD2 is 25 volts, do not depend on a 10x probe to protect it, your computer,  or you.

I just realized I shot myself in the leg with a USB scope, completely forgot you can't operate it without being connected to a PC and this requires a questionably working USB isolator. So my AD2 goes for sale and I'm thinking of a sacrificial lamb like DSO-150 so that at least I don't have to worry about a 1000GBP laptop :) It's a much inferior scope but for my purposes it will do the trick.

The AD2 is, within its limitations, a very good set of test instruments. Despite having too many other scopes, I keep my AD1 and occasionally use it.

Quote
HV differential probe is definitely outside my budget. Seeing some positive reviews on Hantek T3100, are they that bad? Even if I blow a ~30GBP scope with it I won't be crying so much :) Bear in mind that I never go anywhere 240V without a pair of certified 20KV safety gloves and boots. Better look stupid than dead ;D

I don't know about that specific probe, but that class still has pitfalls:
Title: Re: Analog Discovery as a starter scope
Post by: luma on April 04, 2019, 12:11:43 pm
I just realized I shot myself in the leg with a USB scope, completely forgot you can't operate it without being connected to a PC and this requires a questionably working USB isolator. So my AD2 goes for sale and I'm thinking of a sacrificial lamb like DSO-150 so that at least I don't have to worry about a 1000GBP laptop :) It's a much inferior scope but for my purposes it will do the trick.

Keep in mind that the AD2 scope inputs are in fact differential - they are not earth referenced.  Of course, they are limited to 25V, and if you add the BNC board they are no longer differential and are connected to ground through the USB shield.  But if your use case can safely live within 25V then you should be OK.  It's the major reason I keep the AD2 on my desk here, I can just probe around low voltage circuits without much concern without sacrificing resolution like I do w/ my Micsig 50x/500x differential probes.
Title: Re: Analog Discovery as a starter scope
Post by: rstofer on April 05, 2019, 12:52:24 am
I just realized I shot myself in the leg with a USB scope, completely forgot you can't operate it without being connected to a PC and this requires a questionably working USB isolator. So my AD2 goes for sale and I'm thinking of a sacrificial lamb like DSO-150 so that at least I don't have to worry about a 1000GBP laptop :) It's a much inferior scope but for my purposes it will do the trick.

Keep in mind that the AD2 scope inputs are in fact differential - they are not earth referenced.  Of course, they are limited to 25V, and if you add the BNC board they are no longer differential and are connected to ground through the USB shield.  But if your use case can safely live within 25V then you should be OK.  It's the major reason I keep the AD2 on my desk here, I can just probe around low voltage circuits without much concern without sacrificing resolution like I do w/ my Micsig 50x/500x differential probes.

And, with the BNC adapter, you can use 10x probes.  I don't work at higher voltages so 10x is more than enough.
Title: Re: Analog Discovery as a starter scope
Post by: blue_Bandana on May 07, 2019, 05:15:02 pm
I am thinking about buying an Analog Discovery 2 (with student discount).

I think an AD2 would suit me, but i am afraid my considerations might be incomplete:
- I am pretty much a complete newbie (regarding EE)
- I don't know english translations for most technical terms --> google & search engines of limited use
- as far I understood: Intended oscilloscope bandwidth (sinus) should not exceed 1/10 of the sampling rate and frequency (square wave) should not exceed 1/10 frequency (sinus)
- my interest (so far) is heavily biased twoards programming and not towards EE. The latter is (for me & currently) a necessity to build interfaces between code and real-world.

Concerning EE I have:
- completely failed building a NE555 PWM circuit following a step by step instruction (this was the first and last time i approached electronics as a stand-alone hobby)
- decoded the infrared protocol of my air conditioner and build and programmed a custom automatic control for it (using an Arduino)
- "repaired" a PSU of a monitor ... by replacing all electrolytic-capacitors ... now the monitor kind of works again but emits a high frequency noise and needs active cooling or else it starts flickering
- "designed" my own flavour of GRBL-shield for my diy-cnc

Why i want to buy a scope? Curiosity:
- checking if the debouncing of switches on my GRBL-shield works as intended
- checking if the power-stabilization (24V) for the stepper-drivers on my GRBL-shield is effective
- checking if the gate of the mosfet (for the ir-led) on my diy-air-con-remote gets sufficient charge by my arduino-nano over the 10m cable (38kHz)
- checking if the ir-led is driven with the intended 1A
- checking why one of my raspberry-pi randomly stops after a while (brown-out / ripple / dip ???)

So ... if i understood everything correct the AD2 should be fine for square-waves up to 1MHz, which should cover all of the above. If i knew for sure i would repeatedly use an oscilloscope for the next decade, i would be willing to spend up to 1000€ on a scope but as i am not a clairvoyant ... the AD2 is rather in the price range i am willing to risk for a hobby / use-case that might not last.

Do i underestimate how addictive a scope can be, how fast i might end up wishing i had invested in a better scope?
Did i miss use-cases in my current (or near-future scope-induced) hobbies (surrounding arduino / raspberry-pi programming) that the AD2 would not cover?

thanks, blue_Bandana

P.S.:
- if you think this post is way off-topic pleas let me know, i will delete it if asked to do so
- i could get a Tektronix 465 as a gift (but analog scope + transient digital signals ...)
Title: Re: Analog Discovery as a starter scope
Post by: Fungus on May 07, 2019, 05:24:42 pm
- as far I understood: Intended oscilloscope bandwidth (sinus) should not exceed 1/10 of the sampling rate and frequency (square wave) should not exceed 1/10 frequency (sinus)

Not true.

So ... if i understood everything correct the AD2 should be fine for square-waves up to 1MHz

The AD2 has 100Mhz sampling rate and 30MHz analog bandwidth. It will go much higher than 1MHz.
Title: Re: Analog Discovery as a starter scope
Post by: Old Printer on May 07, 2019, 05:43:04 pm
I only have a minute right now, but checking the current of your led would require current probes, a fairly expensive add on. Better left to a multi meter.
Title: Re: Analog Discovery as a starter scope
Post by: blue_Bandana on May 07, 2019, 06:10:51 pm
I only have a minute right now, but checking the current of your led would require current probes, a fairly expensive add on. Better left to a multi meter.

Sorry i assumed the context was obvious. The ir-led (adafruit) is sending a 38 kHz modulated signal, driving it with 1A is only within spec for this kind of use and there is already a resistor (+ above mentioned mosfet + 10m cable) in series, so i intend to measure the voltage drop across this resistor.

The AD2 has 100Mhz sampling rate and 30MHz analog bandwidth. It will go much higher than 1MHz.
The 1MHz square-wave was just intended as very conservative estimate. I should rather say: With my limited knowledge i expect all the signals i might encounter to be well below 1MHz and the capability of the AD2 should be well above 1MHz.
Title: Re: Analog Discovery as a starter scope
Post by: bitseeker on May 08, 2019, 05:04:00 am
blue_Bandana,

Welcome to the forum! Since you're a beginner and exploring different things, the AD2 (especially with student discount price) will probably be a good fit for you. It provides the functions of many different instruments, not just an oscilloscope. Use it, learn from it, and see where your interests and needs lead you. Then, you can determine if you need more specialized tools and you'll know what specific requirements you have to satisfy. You may find, like I did, that the AD2 is still useful even if you later buy other equipment.
Title: Re: Analog Discovery as a starter scope
Post by: tggzzz on May 08, 2019, 08:17:51 am
I am thinking about buying an Analog Discovery 2 (with student discount).
...
P.S.:
- if you think this post is way off-topic pleas let me know, i will delete it if asked to do so
- i could get a Tektronix 465 as a gift (but analog scope + transient digital signals ...)

It is completely OT, but you may find other useful information in other threads in the forum.

A working Tek 465 is a delight to use, but as you note capturing one-off transients is the killer use-case for digitising scopes.

Be sure you understand the right type of probe to use for an application - they and your scope (and PC) become part of the equipment being tested. In appropriate types can damage the equipment you are testing, the scope, and you.

For your applications, be aware that the scope shield is tied to mains earth (via the PC in your case), so if you attach it to something that isn't at mains earth potential then either high currents may flow or the case could be at a dangerous voltage.
Title: Re: Analog Discovery as a starter scope
Post by: exe on May 08, 2019, 11:26:26 am
Yep, AD has a differential input, which is a huge advantage over other scopes. Basically, this makes it "foolproof": you can just put your probes anywhere* in the circuit and it will work.

*of course there are cases that is not true. Like, when using a bnc-adapter, or when voltage is outside of its range, or when probe loading is too high.
Title: Re: Analog Discovery as a starter scope
Post by: tggzzz on May 08, 2019, 12:10:51 pm
Yep, AD has a differential input, which is a huge advantage over other scopes. Basically, this makes it "foolproof": you can just put your probes anywhere* in the circuit and it will work.

*of course there are cases that is not true. Like, when using a bnc-adapter, or when voltage is outside of its range, or when probe loading is too high.

A beginner has resurrected this thread, so it must be noted that is dangerously misleading to the point of being incorrect.

The AD has two earth-referenced inputs - the BNC's shields are connected together and to the protective mains earth via the PC.

You can subtract one input signal from the other, but in (the context of a scope) that is entirely different to having a differential input.
Title: Re: Analog Discovery as a starter scope
Post by: grbk on May 08, 2019, 02:42:39 pm
Yep, AD has a differential input, which is a huge advantage over other scopes. Basically, this makes it "foolproof": you can just put your probes anywhere* in the circuit and it will work.

*of course there are cases that is not true. Like, when using a bnc-adapter, or when voltage is outside of its range, or when probe loading is too high.

A beginner has resurrected this thread, so it must be noted that is dangerously misleading to the point of being incorrect.

The AD has two earth-referenced inputs - the BNC's shields are connected together and to the protective mains earth via the PC.

You can subtract one input signal from the other, but in (the context of a scope) that is entirely different to having a differential input.

What you say is true when using the BNC adapter board but is incorrect when using the AD without the BNC adapter board.

Without the BNC adapter board, the AD has "true" differential inputs, no scope math required. See the Analog Discovery manual, page 4, first paragraph: https://reference.digilentinc.com/_media/analog_discovery%3Aanalog_discovery_rm.pdf

The same is true for the AD2.

With the adapter board, the negative differential inputs are both tied to the BNC shields and earth (through the PC), which exe alluded to.

With that said, however, I would not describe using the inputs differentially as "foolproof" and I agree that the limitations and dangers should be explicitly stated, especially in a discussion with a beginner.
Title: Re: Analog Discovery as a starter scope
Post by: exe on May 08, 2019, 05:24:33 pm
The AD has two earth-referenced inputs - the BNC's shields are connected together and to the protective mains earth via the PC.

I mentioned this in my answer.
Title: Re: Analog Discovery as a starter scope
Post by: blue_Bandana on May 09, 2019, 09:19:48 pm
Ordered an AD2 today, should be delivered tomorrow and the moment i completed the transaction i realized ... i need a Logic-Level-Converter ... Arduino 5V ... AD2 3.3V ... that's the kind of "i am afraid of missing something" i was talking about.

A TXS0108E based logic-level-converter should do the trick?

To set the record straight, i consider myself a newbie compared to the average scope-using eevblog user, i have been soldering the past ~10 years and repaired simple electronics for family and friends but i am not the "bins of ic's / gates etc in the cupboard" type, rather the "if a resistor or a big cap doesn't help let's put in an even bigger cap ... or plop in an arduino (even for the most basic logic things)"... i was always limited to the "multimeter-world". Only 1 short in 10 years  8).
Being able to solve differential equations in advanced physics in highschool and scoring 100% on every test didn't help me a bit, when circuits do not behave as ideal as "school theory", when every component starts to be a bit of everyting (L-C-R) and even changes behaviour with frequency ... i never had enough of a reason to get a scope but finally decided i don't need a reason to get one.
Title: Re: Analog Discovery as a starter scope
Post by: egonotto on May 09, 2019, 11:53:58 pm
Hello

gratuliere zum neuen Gerät :) (congrats to the new AD2)


If you want use the Logic Analyzer inputs you dont need necessarily Logic-Level-Converter because :

"Input logic: LVCMOS (1.8V/3.3V, 5V tolerant)"

https://reference.digilentinc.com/reference/instrumentation/analog-discovery-2/reference-manual?redirect=1#refnotes:1:note1


Best regards
egonotto

PS: There is a good reference:
https://reference.digilentinc.com/reference/instrumentation/analog-discovery-2/reference-manual





Title: Re: Analog Discovery as a starter scope
Post by: Fungus on May 10, 2019, 07:41:15 am
Ordered an AD2 today, should be delivered tomorrow and the moment i completed the transaction i realized ... i need a Logic-Level-Converter ... Arduino 5V ... AD2 3.3V ... that's the kind of "i am afraid of missing something" i was talking about.

A TXS0108E based logic-level-converter should do the trick?

From the manual:
(https://www.eevblog.com/forum/testgear/analog-discovery-as-a-starter-scope/?action=dlattach;attach=731382;image)
Title: Re: Analog Discovery as a starter scope
Post by: exe on May 10, 2019, 08:35:23 am
"Input logic: LVCMOS (1.8V/3.3V, 5V tolerant)"

Yeah, this thing was made to survive students, I'd be very surprised if it was that easy to toast it :).
Title: Re: Analog Discovery as a starter scope
Post by: bitseeker on May 10, 2019, 11:12:03 pm
The only worrisome part of the AD is the microUSB connector. It's rather common for one or more pins to break from its pads. Be mindful of the USB cable and all should be well.