Redpitaya For Impedance analyzer - Page 1
Forum section: electronics / beginners

author: amrat.ch@gmail.com
author_rank: Newbie
timestamp: November 06, 2024, 07:52:16 am
content: Hi everyone,Anyone can give me advice if I want to buy Redpitaya to use for impedance analyzer, which model best suited and what accessories or software do I need additionally.Thanks in advance.Best rgdsAmrat

author: RoGeorge
author_rank: Super Contributor
timestamp: November 06, 2024, 07:54:15 am
content: Might be better (and cheaper) to buy a nanoVNA instead.

author: amrat.ch@gmail.com
author_rank: Newbie
timestamp: November 06, 2024, 08:43:29 am
content: Thanks RoGeorgeWhat model of nanoVNA and what software to use to Plot Impedance VS Frequency of C LI look at nanoVNA Menu structure map cant see any menu for Impedance analyzer.Please adviceThanks

author: RoGeorge
author_rank: Super Contributor
timestamp: November 06, 2024, 09:20:58 am
content: If nanoVNA is not good for you, maybe look for an Analog Discovery (AD). An AD board can make impedance charts, measure R, L, C, can be oscilloscope, spectrum analyzer, logic analyzer, signal generator, etc.Its official software is free and open source, can be installed and tested without buying the board (it can use the soundcard instead, or a simulate board to explore the software):https://digilent.com/reference/software/waveforms/waveforms-3/startIf you are into programming, it has a SDK and libraries to control the board from C, Python, Matlab, LabVIEW, etc. There are countless other tools and programs and hardware adapters for AD, either official ones, or made by the users. There are also many free tutorials and lessons for AD, with experiments about electronics.Redpitaya is a less popular choice, so I expect it to have a smaller community, less support and less software available.

author: tszaboo
author_rank: Super Contributor
timestamp: November 06, 2024, 09:31:04 am
content: Quote from: amrat.ch@gmail.com on November 06, 2024, 08:43:29 amIt would help if you could tell us what you are trying to measure. And at which frequency. And what's the expected value of the measurement. The answer would be different.

author: croma641
author_rank: Regular Contributor
timestamp: November 06, 2024, 03:45:30 pm
content: Follow this thread -https://www.eevblog.com/forum/projects/impedance-analyzer-build-and-experiments/- with VNA style correction terms (!) - and buy an used Analog Discovery Legacy (black) or 2In Youtube ->One of the most underrated project in EEVblog...

author: radiolistener
author_rank: Super Contributor
timestamp: November 06, 2024, 03:51:54 pm
content: Red Pitaya is definitely great as a radio receiver/transmitter, but it's a bad choice as a impedance analyzer due to very limited bandwidth (61 MHz) and high price. The same issue with Analog Discovery as it has even smaller bandwidth and dynamic range than Red Pitaya.NanoVNA is a vector impedance analyzer which can provide you much more for impedance measurement, because it allows to scan complex impedance across pretty wide frequency span (10 kHz - 900 MHz or up to 3-6 GHz for more expensive models). In addition it allows to see impedance in time domain as TDR (Time Domain Reflectometer).Quote from: amrat.ch@gmail.com on November 06, 2024, 08:43:29 amAny model. This is the main function of NanoVNA to measure complex reflection coefficient across selected frequency span. Since it measure it relative to constant impedance 50 Ω, its not hard to convert it and plot impedance vs frequency graph with L/C measurement and NanoVNA has this graph.Quote from: amrat.ch@gmail.com on November 06, 2024, 08:43:29 amThe NanoVNA measures impedance across a range of frequencies and presents the results in various formats. By default, it displays reflection coefficient S11 in dB or VSWR relative to a 50 Ω port impedance, though it also offers options to view measurements in Ω or as equivalent capacitance (pF) or inductance (nH).

author: amrat.ch@gmail.com
author_rank: Newbie
timestamp: November 07, 2024, 03:27:27 am
content: I mean I want to plot graph of impedance vs frequency similar to LCR meter that give only impedance of particular frequency. I wish display as Graph as per image attached

author: radiolistener
author_rank: Super Contributor
timestamp: November 07, 2024, 04:10:51 am
content: Yes, NanoVNA allows to show exactly this graph. And even more, it allows to see two traces - active R and reactive X part of complex impedance Z=R+jX. And many other impedance related parameters, such as LCR, Q-factor, crystals analysis, etc.Also it allows to see impedance in time domain, where on Y axis you will see impedance and on X axis you will see propagation time, so you will see how impedance is varying across the full RF path to the load. In that way you can see how connectors and soldering affecting impedance. But don't expect much from TDR on NanoVNA, since it's bandwidth is limited to about 1.2 GHz. More modern models have 3 or 6 GHz bandwidth and it should give you better TDR resolution.Usually S11 and VSWR are more common units for such kind of measurements, so NanoVNA by default is configured to show S11 and VSWR, but you can configure it to show traces for |Z|, R and X components of Z=R+jX with no issue.So, NanoVNA will show you much more detailed and precise impedance measurement from 10 kHz to 900 MHz. Of course, you can configure frequency span as you wish, for example from 100 kHz to 50 MHz as on your screenshot, or from 100kHz to 500 MHz.For comparison, Red Pitaya cannot do it above 60 MHz.In other words, the NanoVNA can fully replace the Red Pitaya for impedance measurements, as the NanoVNA is capable of displaying all the same parameters as the Red Pitaya in impedance analyzer mode. However, the NanoVNA allows for impedance measurements over a much wider frequency range, expanding its application potential compared to the Red Pitaya.The difference is that the Red Pitaya also allows operating in receiver or transmitter mode, or as a spectrum analyzer. In contrast, the NanoVNA can only measure all parameters related to impedance.

author: amrat.ch@gmail.com
author_rank: Newbie
timestamp: November 07, 2024, 08:33:37 am
content: Dear Radiolistener,Thanks very much for very detail reply. Now I request few more info...1. Which model best suited ? regardless of price2. Will I need addtional accessories or software ?3. Any link to YouTube showing NanoVNA being used for Impedance graph ?Thanks in advance.Best rgdsAmrat

author: RoGeorge
author_rank: Super Contributor
timestamp: November 07, 2024, 08:47:26 am
content: From your other posts here, it looks to me you are going to use that (whatever you would buy) mostly for exploring and learning electronics in general.For learning and experimenting, best choice would be an Analog Discovery. It does the chart you asked for, and it has a lot of tutorials and examples to experiment with other circuits in order to learn electronics.Second best option would be ADALM2000. Same as Analog Discovery, ADALM2000 has many classes (all free), to learn electronics by practicing it and experimenting, something like these:https://wiki.analog.com/university/courses/electronics/labsSame as Analog Discovery, ADALM2000 can be used to measure components, or to display the impedance chart you want.

author: tszaboo
author_rank: Super Contributor
timestamp: November 07, 2024, 01:33:48 pm
content: Quote from: RoGeorge on November 07, 2024, 08:47:26 amSure, but something to consider:Red Pitaya ~500EURAnalog discovery ~400 EURADALM 2000 ~ 200 EURNanoVNA -H or H2 ~60EUR (make sure to buy an original one)It ultimately depends on what you want to do. If you would use the other functions of the other systems, then they could be better purchase.

author: Old Printer
author_rank: Frequent Contributor
timestamp: November 08, 2024, 02:36:49 am
content: I know nothing of the used equipment market in Thailand, but in the US the old black box version of the Analog Discovery show up on eBay at some pretty reasonable prices. I got one a few years ago for US $50 and I saw one listed a few weeks ago for $150. Not a lot has changed in the newer versions, mostly the price. You could check with Attila on the Digilent user forum, but I believe it will run the impedance analyzer as well as their latest model. You may want to pickup the add on board, but it is possible to DIY one yourself if I recall.

author: tszaboo
author_rank: Super Contributor
timestamp: November 08, 2024, 10:17:21 pm
content: Quote from: Old Printer on November 08, 2024, 02:36:49 amBasically the used equipment market outside US is just terrible.

author: coppice
author_rank: Super Contributor
timestamp: November 08, 2024, 10:19:49 pm
content: Quote from: tszaboo on November 07, 2024, 01:33:48 pmI thought dragon fruit was expensive in the UK, but that's ridiculous.