Author Topic: EEVblog #1104 - Omicron Labs Bode 100 Teardown  (Read 16371 times)

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Offline Wolfgang

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Re: EEVblog #1104 - Omicron Labs Bode 100 Teardown
« Reply #200 on: October 24, 2018, 09:58:22 am »
Hi,

I am not a home at the moment, but I think it was a 27134PDLA Hammond / Eddystone series box.
If you wait until monday I can look it up to be 100% sure.

Regards
  Wolfgang
 

Offline Relaxe

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Re: EEVblog #1104 - Omicron Labs Bode 100 Teardown
« Reply #201 on: October 25, 2018, 12:58:06 am »
Thanks,

As the 27134PDLA is not available at Digikey/Mouser, I will fit it in the dimensionaly similar 1590T.

About the Fuse: I have selected LittleFuse 0251001.NRT1L . Does the series resistance  (0.128 Ohms) affects the circuit?

About the injection resistor, I have seen documentation claiming the resistor must match the transformer impedance. Picotest’s J2101A recommend a 5 Ohm resistor. What do you recommend?

 

Offline T3sl4co1l

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Re: EEVblog #1104 - Omicron Labs Bode 100 Teardown
« Reply #202 on: October 25, 2018, 01:10:38 am »
As seen in the rest of this thread -- lower load resistance extends LF response, at greater expense to the HF response.  HF response is most when source and load are matched; but you may not need this range, so that may be an acceptable tradeoff.

The load resistance is usually made low so that it does not interfere with the circuit it's introduced to.

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Offline Wolfgang

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Re: EEVblog #1104 - Omicron Labs Bode 100 Teardown
« Reply #203 on: October 25, 2018, 06:27:34 am »
Thanks,

As the 27134PDLA is not available at Digikey/Mouser, I will fit it in the dimensionaly similar 1590T.

About the Fuse: I have selected LittleFuse 0251001.NRT1L . Does the series resistance  (0.128 Ohms) affects the circuit?

About the injection resistor, I have seen documentation claiming the resistor must match the transformer impedance. Picotest’s J2101A recommend a 5 Ohm resistor. What do you recommend?

Hi,

I bought mine at Conrad electronics (I found an old email). I dont know if you have something similar in Canada. The box does not really matter. Now for the fuse: The allowable DC current for the high-mu cores is very small, in the range of 10mA. The fuse is just there to prevent destructions by dead  shorts. The wire resistance of the windings is a few 100Ohms so I see no issue with the fuse resistance. In total we are way below 1Ohm.

best regards
  Wolfgang
 

Offline Relaxe

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Re: EEVblog #1104 - Omicron Labs Bode 100 Teardown
« Reply #204 on: October 27, 2018, 07:13:39 am »
I just did mine,
Here's the BOM, using Mouser parts:

2x 983-T60006-L2030W514
2x 576-0251001.NRT1L
1x 546-1590T
1x 530-108-0903-1
1x 530-108-0902-1
1x 571-5-1634523-1
1x 71-AVE030020E16R0KE
optionnal: 1x 372-U1163A
I used less than 3m of twisted pair wire from a CAT7 patch chord I had laying around.

Total cost: 95 Canadian $.

Did not test yet, but posting to share the love.
Thanks again Wolfgang!
 

Offline Wolfgang

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Re: EEVblog #1104 - Omicron Labs Bode 100 Teardown
« Reply #205 on: October 27, 2018, 07:41:47 am »
Cool ! The little green things are fuses, am I right ?
Curious for the measurements now, of course !!

Regards
  Wolfgang
 
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Re: EEVblog #1104 - Omicron Labs Bode 100 Teardown
« Reply #206 on: October 27, 2018, 11:17:50 pm »
I also made a couple of these in a while ago posted about them here (including measurements):

http://www.eevblog.com/forum/testgear/looking-for-a-low-cost-way-of-measuring-dc-dc-converter-control-loop-response/msg1738013/#msg1738013

 

Offline Wolfgang

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Re: EEVblog #1104 - Omicron Labs Bode 100 Teardown
« Reply #207 on: October 28, 2018, 01:09:54 am »
Thanks, I've already seen tham. Good site !
 

Offline MilkmanCDN

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Re: EEVblog #1104 - Omicron Labs Bode 100 Teardown
« Reply #208 on: November 07, 2018, 12:31:35 pm »
Curious, what's the rating on the fuses that you used?    I'd assume it's fairly large  (>1A) as we're only trying to prevent wires from over-heating during transformer saturation.   
 

Offline Relaxe

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Re: EEVblog #1104 - Omicron Labs Bode 100 Teardown
« Reply #209 on: November 29, 2018, 12:16:32 pm »
Hey guys

I finally got around using the thing.
I installed the demo of Frequency Response Analysis option for the DSOX3000T scope. It uses the onboard signal generator and scope probes to do the magic.
To qualify my NVT-1, I plugged a BNC from the WaveGen to the VNT-1 Input, and both scope probes to the VNT-1 output.

Looks like a pretty flat response!

I attached the image of the plot, setup, and the .CSV of the results.

@MilkmanCDN: I Used 1 Amp fuses. See Mouser part#.
« Last Edit: November 29, 2018, 12:19:26 pm by Relaxe »
 

Offline Wolfgang

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Re: EEVblog #1104 - Omicron Labs Bode 100 Teardown
« Reply #210 on: November 29, 2018, 12:59:03 pm »
Curious, what's the rating on the fuses that you used?    I'd assume it's fairly large  (>1A) as we're only trying to prevent wires from over-heating during transformer saturation.   

Yes, I used a few 100mA IIRC. The purpose is to prevent buring the wires. The core will saturate way before that will happen.
 

Offline Wolfgang

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Re: EEVblog #1104 - Omicron Labs Bode 100 Teardown
« Reply #211 on: November 29, 2018, 01:00:49 pm »
Hey guys

I finally got around using the thing.
I installed the demo of Frequency Response Analysis option for the DSOX3000T scope. It uses the onboard signal generator and scope probes to do the magic.
To qualify my NVT-1, I plugged a BNC from the WaveGen to the VNT-1 Input, and both scope probes to the VNT-1 output.

Looks like a pretty flat response!

I attached the image of the plot, setup, and the .CSV of the results.

@MilkmanCDN: I Used 1 Amp fuses. See Mouser part#.

Looks fairly flat and OK to me ! And now much fun with the virgins !  :)
 

Offline DualTriode

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Re: EEVblog #1104 - Omicron Labs Bode 100 Teardown
« Reply #212 on: November 29, 2018, 05:28:12 pm »
Nice scope.
 

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Re: EEVblog #1104 - Omicron Labs Bode 100 Teardown
« Reply #213 on: December 02, 2018, 12:52:16 pm »
I finally got mine wound up and made a signal splitter for my HP 3577A. Still, I need to add some AC coupling on the inputs.
I think I am now set up for a new SMPS design I am building.

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Offline sixtimesseven

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Re: EEVblog #1104 - Omicron Labs Bode 100 Teardown
« Reply #214 on: December 10, 2018, 01:11:15 am »
rx8pilot:
For building up some confidence in the cal and measurements procedures, I'd recommend to rebuild the HP35676A test set:
http://hparchive.com/Manuals/HP-35676-SCHEMATIC.pdf

No need for all the fancy metalwork, and don't worry about the unknown capacitor, it still works built on a piece of SMT protoboard using some MiniMelf resistors (some of the series connected to get near the original value).

Once calibrated using the full cal procedure (again, no need for a fancy cal standards set, a wire and a 50 Ohm resistor works, you'll get some ripple at the 200MHz end), then switching the 3577A to impedance display (choose "F4" as the input to display , it's written somewhere in the manual), you can get impedance sweeps of known components (start with resistors in the 10 Ohm to k Ohm range) and get familiar with the way it works. Measure some inductors and capacitors, read the imaginary part at some frequencies and do the math to verify your reading. Inductors are quite fancy regarding their impedance over frequency, many of them are inductors at rather low frequencies only.

There's also somewhere a manual on the net (for this or the HP35677 test set) that has a better description of how to measure impedance using the 3577A than the 3577A manual.

Edit: Found it, here it is: https://cb.wunderkis.de/wk-pub/Keysight%2035676A%20Data%20Sheet.pdf

Edit 2: Don't know what you mean by "skewed", the manual has some tips regarding the RBW setting: Reverse the sweep direction and watch if the graph shifts. If it does, your sweep speed is to fast for the chosen RBW.

Edit 3: "F4" is impedance for a 50 Ohm system and calibration, "F5" is for 75 Ohm

Hi

I had planed to rebuilt the HP 35676 but I have some questions regarding it's operation as described in the manual.
First of all, if I look at this schematic, it seems to me that the 80R6 is the current sensing shunt resistor. The rest is pretty much a ~13dB T-attenuator for the reference input and a ~9dBm T-Attenuator on the voltage sensing A input.  At least that is what I first thought.

But when I read the manual, I see that for one port measurment the A/R and for 2-port the B/R functions are applied. So this would mean measurements of "V" "only"(?) In this case I assume the 80R6 resistor is used to match the two T-Attenuators which don't seem to have a 50ohms input impeadance on their own.

But, what if one would like to do V/I measurments? Could I use the 80R6 resistor as a shunt like I first thought and measure voltage over the DUT on the A port, and current trough the DUT via R-B measurment and terminate the DUT either in 50ohms / B input for a 50Ohm system or lets say at ground for a capacitor / inductor with =/ 50ohms?
If you see a "edit" on my post, assume it is a silly grammar / spelling error...
 

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Re: EEVblog #1104 - Omicron Labs Bode 100 Teardown
« Reply #215 on: December 10, 2018, 05:11:57 am »

I had planed to rebuilt the HP 35676 but I have some questions regarding it's operation as described in the manual.
First of all, if I look at this schematic, it seems to me that the 80R6 is the current sensing shunt resistor. The rest is pretty much a ~13dB T-attenuator for the reference input and a ~9dBm T-Attenuator on the voltage sensing A input.  At least that is what I first thought.

But when I read the manual, I see that for one port measurment the A/R and for 2-port the B/R functions are applied. So this would mean measurements of "V" "only"(?) In this case I assume the 80R6 resistor is used to match the two T-Attenuators which don't seem to have a 50ohms input impeadance on their own.

But, what if one would like to do V/I measurments? Could I use the 80R6 resistor as a shunt like I first thought and measure voltage over the DUT on the A port, and current trough the DUT via R-B measurment and terminate the DUT either in 50ohms / B input for a 50Ohm system or lets say at ground for a capacitor / inductor with =/ 50ohms?

Don't know if I can answer your question to your satisfaction. Afaik, the 35676 is just a voltage divider (the said 80R6 vs. the input impedance of the DUT). So the 3577 can measure the ratio of A to R and calculate the DUT's impedance within a limited range. There's no way to directly measure the current through the DUT. 
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