Digilent's Analog Discovery vs Electronics Explorer - Page 1
Forum section: electronics / beginners

author: nbritton
author_rank: Frequent Contributor
timestamp: September 23, 2015, 12:24:36 am
content: I just learned that I qualify for student pricing and would like to get Digilent's Analog Discovery or Electronics Explorer, but I'm torn between which one to get.http://www.digilentinc.com/Products/Detail.cfm?NavPath=2,842,1018&Prod=ANALOG-DISCOVERYhttp://www.digilentinc.com/Products/Detail.cfm?NavPath=2,842,843&Prod=EEBOARDThe Electronics Explorer ("EE") appears to be the more professional board, it has:4 analog channel DSO. 10-bit ADC. 40 MSa/s @ 70 MHz analog input stage.32 shared digital logic analyzer / pattern generator / gpio pins.+/-9V programmable voltage/current @ 1.5A max (2 rails I think) / also has fixed +5V/3.3V rail @ 2A. (unit powered by AC switch mode PSU)AWG 40 MSa/s / 4 MHz bandwidth. 10V peak to peak amplitude with +/- 10V offset.4 voltmeters.4 external trigger sources.Integrated breadboard all-in-one design.Cost $329The Analog Discovery ("AD") has:2 analog channel DSO. 14-bit ADC. 100 MSa/s @ 10 MHz analog input stage. (rated at 5 MHz on the datasheet)16 shared digital logic analyzer / pattern generator / gpio pins.+5V fixed PSU @ 50mA / -5v volt fixed PSU @ 50mA / 100 mA peak to peak. (unit powered by PC's USB bus)AWG 100 MSa/s / 5 MHz bandwidth. 5V peak to peak amplitude with +/- 5V offset.2 voltmeters.2 external trigger sources.Cost $159The EE is 40 MSa/s @ 70 MHz input stage bandwidth, whereas the AD has 100 MSa/s @ 10 MHz input stage bandwidth. I'm thinking these would be about equal in terms of real world system bandwidth. ADC 10-bit vs 14-bit, but the EE may have a proper input stage front end, whereas the input on the AD is going directly into the ADC. The AD appears to have a better AWG. At first glance it's not apparent that the EE supports the network analyzer feature, but in the software user guide it shows the EE being able to use the network analyzer features like bode plots. The real draw back for the AD, at least for me, is the limited PSU fixed voltage/current of 5V@50mA.

author: JoeN
author_rank: Frequent Contributor
timestamp: September 23, 2015, 01:46:58 am
content: Quote from: nbritton on September 23, 2015, 12:24:36 amCan you explain this for idiots like me? How can you get more bandwidth by throwing electronics between the input jack (BNC or whatever) and the ADC rather than having a direct connection? Now, I know in the real world you almost always need signal conditioning on a piece of test gear - amplification, voltage dividing stages (attenuation), protection, etc. before the outside signal hits the ADC's input to make sure the first 6V input to it doesn't fry it to holy hell. But I can't see how any of those extra stages actually increase bandwidth.

author: Kappes Buur
author_rank: Regular Contributor
timestamp: September 23, 2015, 02:49:18 am
content: Let me throw into the mix another choicehttp://redpitaya.com

author: nbritton
author_rank: Frequent Contributor
timestamp: September 23, 2015, 03:06:20 am
content: So I learned that the analog discovery actually has 30+ MHz bandwidth when measured to -3dB. It turns out that their 5 MHz datasheet bandwidth rating was based on -0.5dB, they used this because they thought the voltage drop at -3dB would confuse students. So at 100 MSa/s it should easily handle 25 MHz when presumably using the BNC adapter board and 10X probe. In the attached screenshot you will see that the spectral curve cuts off at 20 MHz, however, if you extrapolate where curve would cross the -3dB mark (assuming gaussian curve) it appears to be at least 50 MHz. Looking through the technical reference manual the analog devices chips that are used in the scope circuit are rated from 145 MHz to 680 MHz bandwidth.

author: mtdoc
author_rank: Super Contributor
timestamp: September 23, 2015, 03:41:24 am
content: Definitely go for the AD with BNC adapter.Higher sample rate and bandwidth.Better function generator/AWG- (and you can use the function generator DC function as another power supply if needed)Network analyzer.More portable.Less than half the price. Buy 2 if you really need 4 channels (or better - just buy a Rigol 1054Z)Get a proper power supply - and multimeter if you don't already have those.

author: nbritton
author_rank: Frequent Contributor
timestamp: September 23, 2015, 04:48:17 am
content: Quote from: Kappes Buur on September 23, 2015, 02:49:18 amThat's really neat, I love the fact that it runs Linux and you can program the instrument from the command line and even write your own applications for it!!! However, the price tag is $490 for the full kit. One thing that baffles me is their use of SMA connectors, they should have used BNC. Another nitpick about the device is you interact with it through a web browser, the web app looked really limited in terms of functionality. Digilent's WaveForms software looks really advanced in comparison.With the academic pricing for the analog discovery you can bundled an analog parts kit and a copy of multisim student edition for $10; normally these together cost $105. Dave said in his review that the bode plotting feature on this device alone is worth the cost of admission, I have to agree with him. For $220 (device + accessories) I can get a complete electronics lab to get me started. If that weren't enough, they also have developed a free analog electronics course to go along with the device. It's a really good value that I can't pass up. I still intend to buy real test equipment, but at least I can put that decision off for a few more months, that will give me the time to figure out exactly what I want.

author: Neganur
author_rank: Unknown
timestamp: September 23, 2015, 09:46:17 am
content: 235 EUR at the moment, it seems they have a hard time selling it. (some 25 EUR shipping to the USA)http://www.reichelt.de/USB-Messlabor-A-D-Messkarten/RED-PITAYA/3/index.html?&ACTION=3&LA=0&ARTICLE=146150&GROUPID=5906&artnr=RED+PITAYA

author: nbritton
author_rank: Frequent Contributor
timestamp: September 23, 2015, 09:20:32 pm
content: Quote from: Neganur on September 23, 2015, 09:46:17 amThe Red Pitaya bare board is going for $251.53 USD (197.44 + 27.55 S&H Euros) reichelt.com (Germany). It is going for $274.00 ($268.00 + $6 S&H) on Elektor (Netherlands?). You could also get the diagnostic kit which includes two SMA to BNC adapters, two 60 MHz BNC probes, and a micro-USB 2A power supply, however, this appears to be way over priced... you could get SMA to BNC adapters and BNC probes for $20 on amazon.com, and most people already have a 2A USB power supply if they own an iPad or other tablets. It's tempting at $250, however, I already placed an order for the analog discovery... maybe I'll get both.

author: miguelvp
author_rank: Super Contributor
timestamp: September 23, 2015, 09:25:42 pm
content: Analog Discovery software is pretty solid, not sure about the red pitaya but the little I recall reading in threads here is that the code always looked a bit incomplete. But at least it has source I think.Analog Discovery has an sdk library if you also want to write your own.