Im sure they regret not having potted the transformer now...
Im sure they regret not having potted the transformer now...
I doubt it....their customer base is probably very unlikely to bother making their own transformer. As much as I like to save money, spending a few days and at least a couple hundred $$ on failed attempts is a terrible way to 'save' $500.
Those looking for a bargain price were never going to be a viable customer anyway.
That's not ferrite and it's definitely not powdered iron, that's got to be nanocrystalline and nothing else. Most likely Vacuumschmeltze, probably https://www.mouser.com/ProductDetail/Vacuumschmelze/T60006-L2040-W453?qs=sGAEpiMZZMs2JV%252bnT%2fvX8PvC43ppqs%252bksq4V5kp6Ay4%3d or similar.Oh s***t, it's blue! http://allegro.pl/rdzen-magnetec-m-083-rtn-40x25x15-nanoperm-i7430998721.html I don't know, I can't find the actual one, this looks like the closest, but still could work. I couldn't find a way to source the cores, always hard here in Argentina, if someone can source them would be cool to see some tests.
Never seen any in blue, I wonder if they got them as special order, or if there's another mfg I don't know about. IIRC, it was just VAC and HMG (former Metglas) doing rapid-quench materials, but maybe there's new ones from China I don't know about?
Checking, I see very little on Ali Express, so probably not.
That's not ferrite and it's definitely not powdered iron, that's got to be nanocrystalline and nothing else. Most likely Vacuumschmeltze, probablyThat's for sure, the banner picture on the ones I posted had blue and brown cores, the ones I found for sale with the part numbers I was looking shown blue pictures but that's the only reference I got and I can't even read the web in that language!
When the transformer secondary is connected to the DUT,
it will most likely cause a short circuit.
Why is there no coupling cap in the box?
I just thinking, the output and input of the instrument are single ended and both connected to the same ground. The transformer is balanced. I have no experience with this kind a measurements but if you use it to isolate the DUT from the analyser then you need two of them for 2 port measurements. One on the input and one on the output.
I think you must connect it between two baluns to measure how it behaves for real isolation.
We have all we need to reverse engineer that transformer! Construction method, number of turns, impedance analysis, freq response... It's just matter of finding the right core material, with the impedance and number of turns permeability could be estimated... Would someone sell cores out of that material?
If you could sell a $100 unit with the same performance, you'd sell a truck load of them.
Would be interesting to try and duplicate their design and what performance it has with just some random core.
Theoretically, this is all correct. In practice, I personally have never seen any documentation or video using two isolation transformers or common mode chokes.
Do you have a working example of this somewhere on the web ?
I reverse engineered the entire design and ran a cost analysis on a 10 piece basis.
The BOM cost is 110.84 including nominal labor/machining fees.
That's PTFE coated wire - 1USD a foot and there is about 24USD worth of wire on that core. I'll build one and characterize it.
I reverse engineered the entire design and ran a cost analysis on a 10 piece basis.
The BOM cost is 110.84 including nominal labor/machining fees.
That's PTFE coated wire - 1USD a foot and there is about 24USD worth of wire on that core. I'll build one and characterize it.
The omicron claim of 1Hz to 10MHz is pure marketing; at band corners they are 15dB down and have phase errors of 70°.
Of course you could try to reproduce the omicron injection transformer 1:1.
An alternative could be to use a stock ISDN or current transformer and to add a damping/compensation network to flatten out amplitude and phase response. Most swept generators have by far enough output for this approach, and the injected stimulus voltages are normally very small in order not to overdrive the DUT. When I tried this and if you apply the same criteria (5% phase error), results are not so vastly different from what omicron offers (e.g. 100Hz to a few 100kHz). The omicron claim of 1Hz to 10MHz is pure marketing; at band corners they are 15dB down and have phase errors of 70°. If you apply 1dB amplitude and 5°C phase error criteria
the range for them is ca. 50Hz to a few 100kHz (information from the datasheet of the B-WIT100). The big difference is that you have a 40dB power attenuation for the homebrew approach, which does not hurt at all in most cases.
https://electronicprojectsforfun.wordpress.com/injection-transformers/
I see it the same way, its marketing. Of course you can calibrate this out, but you could do the same with a homebrew probe. The homebrew has further advantages (4kV isolation voltage plus less capacitance). I wonder why Dave was so impressed by this transformer.
Of course you could try to reproduce the omicron injection transformer 1:1.
An alternative could be to use a stock ISDN or current transformer and to add a damping/compensation network to flatten out amplitude and phase response. Most swept generators have by far enough output for this approach, and the injected stimulus voltages are normally very small in order not to overdrive the DUT. When I tried this and if you apply the same criteria (5% phase error), results are not so vastly different from what omicron offers (e.g. 100Hz to a few 100kHz). The omicron claim of 1Hz to 10MHz is pure marketing; at band corners they are 15dB down and have phase errors of 70°. If you apply 1dB amplitude and 5°C phase error criteriaI like my phases in ºK, as ºC aren't absolute...
I agreeQuotethe range for them is ca. 50Hz to a few 100kHz (information from the datasheet of the B-WIT100). The big difference is that you have a 40dB power attenuation for the homebrew approach, which does not hurt at all in most cases.
https://electronicprojectsforfun.wordpress.com/injection-transformers/One could also make a current amplifier and build a current transformer for the same freq range which might be easier, LF in current mode is much more forgiving than voltage mode, then terminate the transformer with the proper resistor and go from there. All that seems fine for the average lab, but this transformers exists for a reason, also, 1:1 transformer have better
This is from a transformer I've built some years ago for audio applications, source impedance was low, like 10Ω at most. The wiggle in the top end is due to the sound card I used, not coming from the transformer, I wander how it keeps going to a higher frequency, I only got the sound card at the time, so not much over 20kHz to work with at the time but I still have some of those at home, I'd only expect to get to a few tens kHz, is a big chunk of iron with a lot of turns, but I could wind a smaller one with less turns and better insulated wire to try.
For stability analysis I dont see a case where a 1:1 transformer is needed, because injected signal level is always very low in order to remain in the linear domain. I would be curious about a practical example of a 1:1 caseI see it the same way, its marketing. Of course you can calibrate this out, but you could do the same with a homebrew probe. The homebrew has further advantages (4kV isolation voltage plus less capacitance). I wonder why Dave was so impressed by this transformer.It's specs aren't 1Hz to 10MHz, at least not in Dave's measurement, 5º was happening around 1.5MHz but at 1Hz was only 3º out. Test setup can influence on the measurement but his were at least as clean as you will get in a measurement setup. You don't need more than that, you need smooth transfer function without too much attenuation, as you can pick the reference from the output of the transformer, maybe a 3rd coil could be useful for that as it will reflect what the output is putting out better than the input coil and you wouldn't need a differential probe. In any case I wouldn't trust that what the generator is sending is the same as what the device is getting.
JS