skipwave

Re: Ni core vs. M6 core
« Reply #60 on: August 10, 2009, 02:47:28 PM »
Hmmm. Never saw mu metal rust. Hydrochloric acid ? Nickel(II) chloride solution is green... Iron(III) chloride (ferric chloride) solution is yellow....

Ummmm, how about I just mail it to you and then you can pour scary chemicals on it?  :D

Seriously, though, if it will help with your inquiry, send me a PM with your address and I'll post this little bugger to you.
Quote from: PRR
Now, maybe you don't, or shouldn't, grab the ribbon for far-harpsichord, nor the hot condenser for snare-kissing... yet often we do.


leswatts

Re: Ni core vs. M6 core
« Reply #61 on: August 10, 2009, 03:08:46 PM »
Got it!

Nickel allergy test kit!

Can get it at a drug store.

http://www.natlallergy.com/product.asp?pn=1665&bhcd2=1249930565

Cost 12 bucks or something though. Hydrochloric is cheaper. Stomach acid is 7N HCL...but i'd have to gag myself with a spoon.

I'll email. Perhaps I could do some electrical tests on it for you.

Les

PRR

Re: Ni core vs. M6 core
« Reply #62 on: August 10, 2009, 04:04:52 PM »
> turns ratio is easy but not number of turns...

If you can sneak even one turn around the winding, you can measure the ratio to your one-turn.

leswatts

Re: Ni core vs. M6 core
« Reply #63 on: August 10, 2009, 04:27:18 PM »
Quote
If you can sneak even one turn around the winding, you can measure the ratio to your one-turn.

Why yes, that's right! If there's room. Better than swimming pool chemicals, medical test kits, or puking.

Les


leswatts

Re: Ni core vs. M6 core
« Reply #64 on: August 17, 2009, 09:56:04 AM »
I recieved the shinybox standard chinese ribbon transformer from skipwave. Thanks!

First impressions:

It looks like nickel. The shiny white appearance is unmistakable.

Lams are 0.014. They are lacquer insulated (and bonded)

Single layer primary and secondary. Primary looks to be bifilar wound. I do not see any Faraday shields.

There is enough room to sneak a few turns around it for analysis. I'll run some tests later this week. I know my Agilent impedance analyzer  would have been handy for this, but I had to return it, as it was $1200/mo rental, and the project I needed it for is finished.  :( I'm working on a shop made version though. I can do auto-nulling impedance bridges!

Anyway, it looks to be basically of good construction. Probably only cost a couple bucks or something.

Since this is unrelated to edcors conclusions about nickel in power transformers (I agree) I might start a new thread, if anybody cares. I'm just interested in doing a detailed analysis of low level mic transformers.

Oh one question skipwave....was this originally in a shielding can? (it isn't now)

Les
L M Watts Technology


skipwave

Re: Ni core vs. M6 core
« Reply #65 on: August 17, 2009, 06:03:26 PM »
Ah, yes. It was in a shielding can, which I recycled for a DIY tube microphone build.
Quote from: PRR
Now, maybe you don't, or shouldn't, grab the ribbon for far-harpsichord, nor the hot condenser for snare-kissing... yet often we do.

PRR

Re: Ni core vs. M6 core
« Reply #66 on: August 21, 2009, 10:44:10 PM »
> Primary looks to be bifilar wound.

Probably parallel? You want low-low-LOW resistance. Either use #14 house-wire (which won't make the bends), foil (money), or parallel strands of stock wire.

Bifilar for leakage inductance reduction does not make sense, unless primary and secondary are wound together. And with typical 1:30 ratio, that's very awkward. And at 200 ohm impedance and voltage-transfer not power-transfer, leakage inductance is probably not significant. Certainly not for a couple-buck target.

> I do not see any Faraday shields.

At few-hundred ohms max, you really don't need any. You Faraday when you are kicking-up to 50K at a tube grid, where picoFarads of stray coupling would leak major garbage.

> I can do auto-nulling impedance bridges!

Sure, but I could pull a manually-tuned impedance curve while you are mulling auto-null possibilities. Probably put my 200AB at 1V out, 10K series, measure the mV across the "200 ohm" winding. From DC to 200Hz, there won't be any surprise. Around 400Hz it will droop from a strict inductance, but keep rising. A 200 ohm winding may keep rising past 5KHz: the hundred-pFd winding capacitance just isn't a factor on 200 ohm audio.

ioaudio

Re: Ni core vs. M6 core
« Reply #67 on: August 22, 2009, 12:19:48 PM »
i dissected a ribbon transformer some time ago, the primary was parallel as prr suggested.
some pics can be found here: http://www.twin-x.com/groupdiy/thumbnails.php?album=178

leswatts

Re: Ni core vs. M6 core
« Reply #68 on: August 23, 2009, 08:00:28 AM »
Quote
Probably parallel? You want low-low-LOW resistance. Either use #14 house-wire (which won't make the bends), foil (money), or parallel strands of stock wire.


Right. It's parallel. Like ioaudio's pictures. It's about 22 gage wire.

Quote
Sure, but I could pull a manually-tuned impedance curve while you are mulling auto-null possibilities.

Of course. But you see, I do literally thousands of impedance measurements with my transducer design business. It's not just for an occasional diy microphone. Real time impedance magnitude/phase/frequency displays are handy.

I'm just wanting to save some money in hard times. The Agilent is a $45,000 box I had to rent for $1200/mo. I think I can do some of it's function with a shop built setup... just not to 100 MHz. I don't think i'll even have to write any code.

Les
L M Watts Technology


jdbakker

Re: Ni core vs. M6 core
« Reply #69 on: August 23, 2009, 10:32:27 AM »
I'm just wanting to save some money in hard times. The Agilent is a $45,000 box I had to rent for $1200/mo. I think I can do some of it's function with a shop built setup... just not to 100 MHz. I don't think i'll even have to write any code.

In RF terms 100MHz is pretty low; perhaps one of the DIY Vector Network Analyzers (such as this one) could be made to fit your requirements?

JDB.
[must admit I haven't looked too hard at that Agilent unit; it might be that most VNAs are too 50Ω-centric for your purposes]

EDIT: typo fix
« Last Edit: August 23, 2009, 12:26:55 PM by jdbakker »


leswatts

Re: Ni core vs. M6 core
« Reply #70 on: August 23, 2009, 12:04:42 PM »
Quote
In RF terms 100MHz is pretty low; perhaps one of the DIY Vector Network Analyzers (such as this one) could be made to fit your requirements?

Of the methods I/V, autonull, and vector network the latter is best for higher rf according to Agilent.

For my work, (audio and low frequency ultrasonic) I need this:

-real time display of real and imaginary impedance from 1 mohm to perhaps 1 megohm

-frequency to about 250 kHz

Something in that range is invaluable to measure ESR, dielectric loss, transformer parameters,transducers, etc.

The autonulling circuit is just an inverting amplifier with the device under test as the input reactance. It's limiting factor is how perfect the virtual ground is at the - input summing point. Real op amps are integrators, limiting HF performance. Agilent does some fancy stuff to even get up to 100MHz, but they achieve very high dynamic range...200 db claimed.

I'm reading up on it. Might be able to get to 250kHz with just a good low offset op amp and 4 wire kelvin connections.

Les
L M Watts Technology


 

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