Bode-100 is a clever vector network analyzer from the folks at Omicron Labs in Austria.
www.omicron-lab.com |
Frequency range is 1Hz to 40 (or 50) MHz with adjustable bandwidth from 1Hz to 5kHz. Very useful in performing power supply tests (bode plot, PSRR,Z, reverse PSRR etc.), analysis of filters, antenna analysis etc.
Omicron regularly updates the software, and the most recent version makes impedance testing a breeze.
www.omicron-lab.com |
Frequency range is 1Hz to 40 (or 50) MHz with adjustable bandwidth from 1Hz to 5kHz. Very useful in performing power supply tests (bode plot, PSRR,Z, reverse PSRR etc.), analysis of filters, antenna analysis etc.
Omicron regularly updates the software, and the most recent version makes impedance testing a breeze.
The question arose -- how to calibrate the Bode-100 in single-port impedance mode. (Omicron sells an adapter for the purpose.)
You will also need a Pomona 1296 BNC-male to banana jack adapter, this adapter keeps the connection to the analyzer's output as short as possible.
You will have to fashion a 50 ohm load. Best to use a surface mount metal film (Vishay) to which you've attached a pair of "legs" about 1/2 inch in length. (You can also use a Caddock 15W chassis mount resistor and bend the legs to fit).
a piece of tinned #16 wire approx 1 1/2 inches in length is used for the SHORT test.
With this setup you can run the "OPEN-SHORT-LOAD" single port impedance cal routine. You can also use other resistor values to hone in one a precise impedance range.
For high impedance loads, you'll have to build a specific adapter for which Omicron has an application note.
You will also need a Pomona 1296 BNC-male to banana jack adapter, this adapter keeps the connection to the analyzer's output as short as possible.
You will have to fashion a 50 ohm load. Best to use a surface mount metal film (Vishay) to which you've attached a pair of "legs" about 1/2 inch in length. (You can also use a Caddock 15W chassis mount resistor and bend the legs to fit).
a piece of tinned #16 wire approx 1 1/2 inches in length is used for the SHORT test.
With this setup you can run the "OPEN-SHORT-LOAD" single port impedance cal routine. You can also use other resistor values to hone in one a precise impedance range.
For high impedance loads, you'll have to build a specific adapter for which Omicron has an application note.
Power supplies are amplifiers too
Hello All,
I purchased a Bode-100 to dig deeper into the mysteries of power supplies and amplifiers. These diyAudio pages are full of conversations about oscillation, stability, Power Supply Rejection Ratios and other things.
There is a book over at Omicron-Lab (and Amazon), “Power Integrity” that goes a long way towards introducing and explaining things, how to test things and how to interpret the results. This is a, what can a Bode-100 do for you, kind of book.
I found jackinnj quietly testing and reporting on these topics as they relate to sound quality and amplifier performance.
This will be a good place to share tips and tricks.
Thanks
DT
Hello All,
I purchased a Bode-100 to dig deeper into the mysteries of power supplies and amplifiers. These diyAudio pages are full of conversations about oscillation, stability, Power Supply Rejection Ratios and other things.
There is a book over at Omicron-Lab (and Amazon), “Power Integrity” that goes a long way towards introducing and explaining things, how to test things and how to interpret the results. This is a, what can a Bode-100 do for you, kind of book.
I found jackinnj quietly testing and reporting on these topics as they relate to sound quality and amplifier performance.
This will be a good place to share tips and tricks.
Thanks
DT
I don't want to disrupt any discussion on what appears to be a really appealing piece of test gear.
But, I will, just a bit, since some of the information may overlap.
Although not over the same frequency range, you can also do a lot of what the Bode 100 does with an Analog Discovery 2.
For measuring loop gain and the rest for a closed loop audio amplifier, this works pretty well:
Activity: Measuring Loop Gain [Analog Devices Wiki]
A Jensen VB-1RR works really well for T1 in the article above. For some reason, you can find these on eBay for very low prices. I think they may have been used for some sort of boat/marine video application that isn't as popular now as it once was.
Again, none of these are likely to be as accurate as the Omicron unit but the price may be more appealing for DIYers.
But, I will, just a bit, since some of the information may overlap.
Although not over the same frequency range, you can also do a lot of what the Bode 100 does with an Analog Discovery 2.
For measuring loop gain and the rest for a closed loop audio amplifier, this works pretty well:
Activity: Measuring Loop Gain [Analog Devices Wiki]
A Jensen VB-1RR works really well for T1 in the article above. For some reason, you can find these on eBay for very low prices. I think they may have been used for some sort of boat/marine video application that isn't as popular now as it once was.
Again, none of these are likely to be as accurate as the Omicron unit but the price may be more appealing for DIYers.
I have the predecessor -- use it for measuring the "signals on the bus" on PIC and Arduino stuff.
Red Pitaya is also a candidate although I haven't yet played with one,
Omicron works with Picotest, the latter makes current injectors, transformers etc. Very nice gear, but tres cher. Nothing for high voltages used in tube equipment, power supplies for tube gear. Would be interested in hearing ideas.
With regard to gain/phase plots - impedance, Zout, can yield the same measurement of amplifier/ power supply error correction/ stability -- somewhat less "precision" but a lot easier -- and you don't need a transformer.
True. But I think it's challenging to make good measurements of low impedances.
My feeling is that the Analog Devices suggestion - also suggested by others - is kind of analogous to the Tian simulation method for loop gain and phase. An example of that is even included with LTSpice. So, I naturally gravitated toward an approach I was already using in simulation.
Since I don't even want to do this kind of thing on a daily basis, I also am personally fixated on making the test set-up as compact as possible. My goal is to be able to store all the test gear on no more than two shelves in a closet. So, the Analog Discovery 2 certainly helps with that theme. Suitable transformers are small enough and cheap enough on eBay.
If I was going to do any of this for any sort of commercial application, my thinking would be different.
For those of us who are verbally impaired, would you be kind enough to post a pic of it showing how it's constructed, please?
CG, where did you find your kits? Seems everything is 13 to 27 weeks out. Mouser,Digikey,Element14.
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Look at page 6 of this link.
https://www.omicron-lab.com/fileadm...Measurement/App_Note_ESR_Measurement_V2_0.pdf
https://www.omicron-lab.com/fileadm...Measurement/App_Note_ESR_Measurement_V2_0.pdf
I looked at these a while back, they are expensive in Australia (note, that's not Austria!) Did you find one second hand or just pay full price and bear it?
The AD method is not equivalent to Tian, that link (and the Bode 100 method when I last checked) both assume an ideal relation between the forward and backward impedances. Tian makes multiple measurements to determine and adjust for the forward and backward impedance relation.
Best wishes
David
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Yes, but it's close. At least close enough for an audio amplifier. OK - close enough for my intended purpose; YMMV, as they say. Frank Wiedmann seems to think this approach is accurate enough.
Loop Gain Simulation - Frank Wiedmann
On an absolute basis, your comment is certainly accurate.
I think I'm missing a key element of your question - sorry.
I just looked and Digilent (the supplier) has 2330 Analog Discovery 2 units in stock, Mouser has 69, and Digikey has 510.
Perhaps your question was really directed at somebody else?
CG from your Analog Devices link, Post#4 it shows the devices from AD as "ADALM2000" a kit. It goes with the "ADALM1000".
Both of these look pretty good and I could use them for study and for tutoring etc.
But none seem available at Digikey or Mouser at their prices, There are hold outs at amazon for $100+. But I'd rather buy from distribution and not amazon.
Cheers,
Both of these look pretty good and I could use them for study and for tutoring etc.
But none seem available at Digikey or Mouser at their prices, There are hold outs at amazon for $100+. But I'd rather buy from distribution and not amazon.
Cheers,
This is the transformer that is in that kit. Coilcraft HPH1-1400LD Datasheet | Samples | Pricing | Buy online it is the size of my thumb nail and is priced about 5 dollars. I would need to see this thing function to believe it.
DT
DT
The ADALM2000 is in pre-release, from what I can tell. It's apparently a lower resolution (fewer bits) version of the Analog Discovery 2.
The ADALM1000 was the '2000's predecessor.
The app note applies to both units as well as the Digilent variants.
The limitation of the small transformer they suggest in the note is that it runs out of gas at low frequencies - you can only do so much with a small ferrite core. But, even with its limitations it may do the job you want - only you can answer that. If you're looking to examine closed loop properties of an audio amplifier, it's probably fine. The Jensen transformer is larger, more expensive, and covers a wider range. But, it may be overkill for you. I found that they were plentiful on eBay for not too much money, so I bought two.
I *REALLY* don't want to stomp on the discussion of the Bode-100. So far, that's all I've accomplished. For that I apologize and withdraw from the conversation...
The ADALM1000 was the '2000's predecessor.
The app note applies to both units as well as the Digilent variants.
The limitation of the small transformer they suggest in the note is that it runs out of gas at low frequencies - you can only do so much with a small ferrite core. But, even with its limitations it may do the job you want - only you can answer that. If you're looking to examine closed loop properties of an audio amplifier, it's probably fine. The Jensen transformer is larger, more expensive, and covers a wider range. But, it may be overkill for you. I found that they were plentiful on eBay for not too much money, so I bought two.
I *REALLY* don't want to stomp on the discussion of the Bode-100. So far, that's all I've accomplished. For that I apologize and withdraw from the conversation...
Hello,
With this Bode-100 setup on the bench I have tested everything within a short walk.
Here is an impedance vs frequency plot including a phase trace. I also included a FFT of the same capacitor. This capacitor is a Mallory CSR132295, Mil Spec M39003. $40plus at Digikey, cheap on ebay.
I am liking the looks of this 47uf Tant capacitor (wet slug) for bypass and even coupling. The impedance and phase curves are clean and smooth. The FFT is as good as any other (or better) I have plotted.
@CG
The link re: loop gain shows the BW starting at 10KHz, perhaps a bit high for audio, I think.
The Jensen transformer VB-1RR you noted may be an excellent tip for the Bode-100. For $30plus to $18 on ebay it is very cheap. I purchased one on ebay with BNC connectors for $38.
A note of caution the Jensen VB-1RR transformer is limited to 34V to ground where the Omicron Lab B-Wit transformer is 600V Cat II rated.
DT
With this Bode-100 setup on the bench I have tested everything within a short walk.
Here is an impedance vs frequency plot including a phase trace. I also included a FFT of the same capacitor. This capacitor is a Mallory CSR132295, Mil Spec M39003. $40plus at Digikey, cheap on ebay.
I am liking the looks of this 47uf Tant capacitor (wet slug) for bypass and even coupling. The impedance and phase curves are clean and smooth. The FFT is as good as any other (or better) I have plotted.
@CG
The link re: loop gain shows the BW starting at 10KHz, perhaps a bit high for audio, I think.
The Jensen transformer VB-1RR you noted may be an excellent tip for the Bode-100. For $30plus to $18 on ebay it is very cheap. I purchased one on ebay with BNC connectors for $38.
A note of caution the Jensen VB-1RR transformer is limited to 34V to ground where the Omicron Lab B-Wit transformer is 600V Cat II rated.
DT
Attachments
So the VB-1RR is up to 34V and is $18 - $38USD. The OmicronLab B-Wit xfrmr is good up to 600V and priced at? Couldn't we make a 10:1 voltage divider good to 340V? Does a 20:1 get us up to 680V or is my thinking incorrect? Thinking price performance ratio here.
Cheers,
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