Is powdered carbonyl iron toroid an appropriate material for winding a small flyback transformer on? Like micrometals material #7 or 8?
I have a number of them on hand, about half an inch outside diameter. For the inductance and ratio I need the calculator shows i'll need about
30 turns on the primary and 80 on the secondary which should easily fit using say 26 gauge wire for the primary and 36, 38 for the secondary. Switching frequency between 1 and 2 MHz
I have looked at the micrometals 10 years ago. AFAIR the have extreme high permeability. So they will not be good for high frequency operation, since the BH loss loop will be dominant. Utilize the high u, and go for low frequency operation
That said, I might remember all this wrong
Cheers
Klaus
Al for e.g. material 7 carbonyl iron powder is only 4 nH/N^2, can't be that high permeability.
if I did the math right for my application it'll be operating at about
30 gauss peak from the primary current, for a U_o of say ~5 the chart looks to show about 50mW/cm^3 of core loss. The effective volume of the toroid is about 0.5 cm^3 that seems like acceptable loss for an output of under 1W
Or about 1W I should say
They have cores down to mu_r = 1, you definitely remembered something wrong. ;-)
The material in question is not quite so low mu, but low enough that its eddy current frequency is, either a few MHz or 10s, and its loss is, well, as calculated, which is fine.
Tim
-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Design Website: https://www.seventransistorlabs.com/
Micrometals has cores down to u=1, namely not magnetic at all. But their powdered-iron parts are lossy at high frequency and flux density; I've burned the paint off some. KoolMu types are better. MicroMetals may have something similar now.
At moderate power, say below 10 watts, I'd try to use a stock dual-winding inductor as an autotransformer flyback. Winding toroids is a nuisance.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
So is designing the right inductor for the job. Finding someone to wind a bunch for you probably takes less effort, but John Larkin likes to claim that he does electronic design, so he invokes the difficulty of finding a coil winding shop as his excuse.
-- Bill Sloman, Sydney
I don't have any problem with people having different political ideas, but you are just going off the deep end a just being an asshole without any provocation. Mikek
Sloman is a great fan of winding inductors, probably because he hasn't actually done it in a decade or three. I'm a great fan of buying surface-mount inductors from Coilcraft or Digikey whenever I can.
Too many old hens here, who don't design electronics, think SED is Facebook or Twitter.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
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e high permeability. So they will not be good for high frequency operation, since the BH loss loop will be dominant. Utilize the high u, and go for lo w frequency operation
d a bunch for you probably takes less effort, but John Larkin likes to clai m that he does electronic design, so he invokes the difficulty of finding a coil winding shop as his excuse.
I agree about the inductors. You can't afford to wind them in a normal prod uction facility. The last place I worked that wound coils was Cincinnati El ectronics, in the mid '70s. They needed some custom RF transformers for a c ouple NATO radio designs, and they still had coil winding machines left the re by Crosley after WW-II ended. I was amazed that the old machines ran wel l enough to produce usable components. Their in house PCB facilities were l imited to an old gang drill for single sided PCBs.
I doubt that Sloman could hand wind a usable coil, in a week.
The last custom coil that I wound was a tree feet square 60 KHz antenna for WWVB. Sveral hundred feet of hookup wire inside a square of 5/8" copper pi pe with 90 degree fittings at the corners. It was fun winding it through th e side leg of a copper tee fitting but I did it the first try and it worked well. A polystyrene capacitor and a small trimmer resulted in a very high Q antenna.
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eme high permeability. So they will not be good for high frequency operatio n, since the BH loss loop will be dominant. Utilize the high u, and go for low frequency operation
t sind a bunch for you probably takes less effort, but John Larkin likes to cl aim that he does electronic design, so he invokes the difficulty of finding a coil winding shop as his excuse.
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toduction facility. The last place I worked that wound coils was Cincinnati Electronics, in the mid '70s. They needed some custom RF transformers for a couple NATO radio designs, and they still had coil winding machines left t here by Crosley after WW-II ended. I was amazed that the old machines ran w ell enough to produce usable components. Their in house PCB facilities were limited to an old gang drill for single sided PCBs.
We wind our own motors, about 20 million per year. We did a Make Buy analys is on a small transformer, and found that we could wind a custom part cheap er than any of the suppliers we heard. We did not go down than route, since we would have to train a couple of production guys on winding transformers instead of motors and lack of let's say "branching entrepreneurship"
Sloman brings his attacks on Larkin every time he sees a chance, and it get s to be boring. Sloman would get respect if he would stick to electronics t alk and avoid all the attacks. And yes, not talk about what he did 30 years ago, today is a totally different ball game
Cheers
Klaus
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e high permeability. So they will not be good for high frequency operation, since the BH loss loop will be dominant. Utilize the high u, and go for lo w frequency operation
d a bunch for you probably takes less effort, but John Larkin likes to clai m that he does electronic design, so he invokes the difficulty of finding a coil winding shop as his excuse.
I tried to do it back in 2010 for my low distortion oscillator, and couldn' t hand wind accurately enough to produce a testable prototype, so I found a local coil-winding shop (in Venlo, about forty minutes drive away) and spent a co uple of hundred dollars worth of euros getting them to wond me a couple of prototypes.
When I shipped them over to my mate in London (he has since moved to Edinbu rgh) who had the gear to test them, they did exactly what I wanted, but the hysterisis in the heavily gapped core introduce enough distortion (harmoni cs about 95dB below the fundamental) that we moved on to an inductor free v ariant.
As we all are, when they do the job. This doesn't happen all that often,
Your tendency to post recipes for dishes you like to cook and eat suggests that you share this delusion.
Your own claim to "design" electronics isn't all that plausible. What you a ctually post suggests that you evolve your electronic circuits, rather than thinking about what you need them to do and how they might do it.
Your claim of being able to come up with a completely documented "new" desi gn in a fortnight does fit that.
-- Bill Sloman, Sydney
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eme high permeability. So they will not be good for high frequency operatio n, since the BH loss loop will be dominant. Utilize the high u, and go for low frequency operation
t sind a bunch for you probably takes less effort, but John Larkin likes to cl aim that he does electronic design, so he invokes the difficulty of finding a coil winding shop as his excuse.
s,
toduction facility. The last place I worked that wound coils was Cincinnati Electronics, in the mid '70s. They needed some custom RF transformers for a couple NATO radio designs, and they still had coil winding machines left t here by Crosley after WW-II ended. I was amazed that the old machines ran w ell enough to produce usable components. Their in house PCB facilities were limited to an old gang drill for single sided PCBs.
Depends how many turns were involved. The last time I tried I certainly cou ldn't, and had to find a coil winding shop.
Most of the places I've worked had simple coil winding machines with built- in turns counting, and I never had any trouble winding stuff on them (provi ded that I didn't go for excessively fine wire - I could manage 42 swg (0.1 mm OD) while the coil winding shop could get down to 46 swg.
for WWVB. Several hundred feet of hookup wire inside a square of 5/8" coppe r pipe with 90 degree fittings at the corners. It was fun winding it throug h the side leg of a copper tee fitting but I did it the first try and it wo rked well. A polystyrene capacitor and a small trimmer resulted in a very h igh Q antenna.
Enamelled wire gives you more copper in the same cross-sectional area, but higher inter-winding capacitance.
-- Bill Sloman, Sydney
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treme high permeability. So they will not be good for high frequency operat ion, since the BH loss loop will be dominant. Utilize the high u, and go fo r low frequency operation
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wind a bunch for you probably takes less effort, but John Larkin likes to claim that he does electronic design, so he invokes the difficulty of findi ng a coil winding shop as his excuse.
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tproduction facility. The last place I worked that wound coils was Cincinnat i Electronics, in the mid '70s. They needed some custom RF transformers for a couple NATO radio designs, and they still had coil winding machines left there by Crosley after WW-II ended. I was amazed that the old machines ran well enough to produce usable components. Their in house PCB facilities we re limited to an old gang drill for single sided PCBs.
ysis on a small transformer, and found that we could wind a custom part che aper than any of the suppliers we heard. We did not go down than route, sin ce we would have to train a couple of production guys on winding transforme rs instead of motors and lack of let's say "branching entrepreneurship"
ets to be boring. Sloman would get respect if he would stick to electronics talk and avoid all the attacks. And yes, not talk about what he did 30 yea rs ago, today is a totally different ball game
I do go after John Larkin whenever he chickens out of designing a transform er.
It's a bad approach to electronic design. I'm much more relaxed about his o ther weaknesses, but it took me quite a while to get my head around transfo rmer design, and it did pay off when I finally mastered it.
John Larkin is discouraging people from putting in the time it takes to acq uire that particular skill.
I got my last transformer wound about ten years ago, for a hobby project. I didn't need them often during my professional career - years went by when I didn't have worry about them at all. The oddest example was a transmissio n lime transformer to isolate a 125 Mbit/sec Taxichip link, which was prett y much exactly thirty years ago. I think you can now buy them off the shelf .
-- Bill Sloman, Sydney
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.high permeability. So they will not be good for high frequency operation, since the BH loss loop will be dominant. Utilize the high u, and go for low frequency operation
a bunch for you probably takes less effort, but John Larkin likes to claim that he does electronic design, so he invokes the difficulty of finding a coil winding shop as his excuse.
John Larkin doesn't like designing special purpose multi-winding inductors, and tries to discourage other people from doing it.
My experience is that you can get much better performing multi-winding indu ctors by designing them to do the job you need them to do.
The problem is that multi-winding inductors - when compared with other pass ive components - have a lot more variables to play with, and you chance of picking up a commercially available part that will do your job well are a w hole lot poorer than they are with things like resistors and capacitors and single winding inductors.
Pushing this point may strike you as being anti-social, but my point of vi ew is that pushing a personal prejudice that discourages people from exploi ting an accessible range of design options is decidedly anti-social, to the point of being downright irresponsible.
-- Bill Sloman, Sydney
If you have to design a custom inductor, you can have it made in volume, cheap, in China or India.
I just specified a custom signal transformer, for a synchro/digital converter, and my transformer supplier will design and make them for us. He has them manufactured in China.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
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o wind a bunch for you probably takes less effort, but John Larkin likes to claim that he does electronic design, so he invokes the difficulty of find ing a coil winding shop as his excuse.
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production facility. The last place I worked that wound coils was Cincinna ti Electronics, in the mid '70s. They needed some custom RF transformers fo r a couple NATO radio designs, and they still had coil winding machines lef t there by Crosley after WW-II ended. I was amazed that the old machines ra n well enough to produce usable components. Their in house PCB facilities w ere limited to an old gang drill for single sided PCBs.
lysis on a small transformer, and found that we could wind a custom part ch eaper than any of the suppliers we heard. We did not go down than route, si nce we would have to train a couple of production guys on winding transform ers instead of motors and lack of let's say "branching entrepreneurship"
What kind of volume?
The joys of rapid international communication.
Even I get occasional e-mails from China offering that kind of service.
I've even got a file folder where I put the more plausible offers.
-- Bill Sloman, Sydney
Why?
I've designed many transformers and inductors. It was necessary. They were unique and were for 40-500HP inverters and not available off-the-shelf. Also, the special ancillary magnetics. Given a choice, I would have selected something already available and got on with the project. I mastered the designs in about a month of study. How long did it take you?
How do you know?
In your opinion, of course.
I design a circuit first which may include an inductor or transformer. I then look for an appropriate device to do the job. I can usually find something that will work. I may adjust my circuit slightly to get best performance with what I selected.
If I can't get the COTS magnetic device I need, then I design it. Having no tools to wind it myself means that I must write specifications for it then search for a facility to wind it. Then I must characterize the item when it arrives. This takes much longer than just getting a COTS item if I can find it.
Not irresponsible at all in my opinion and your statement that it is "downright irresponsible" is downright irresponsible.
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treme high permeability. So they will not be good for high frequency operat ion, since the BH loss loop will be dominant. Utilize the high u, and go fo r low frequency operation
But
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wind a bunch for you probably takes less effort, but John Larkin likes to claim that he does electronic design, so he invokes the difficulty of findi ng a coil winding shop as his excuse.
deas,
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l production facility. The last place I worked that wound coils was Cincinn ati Electronics, in the mid '70s. They needed some custom RF transformers f or a couple NATO radio designs, and they still had coil winding machines le ft there by Crosley after WW-II ended. I was amazed that the old machines r an well enough to produce usable components. Their in house PCB facilities were limited to an old gang drill for single sided PCBs.
nalysis on a small transformer, and found that we could wind a custom part cheaper than any of the suppliers we heard. We did not go down than route, since we would have to train a couple of production guys on winding transfo rmers instead of motors and lack of let's say "branching entrepreneurship"
t gets to be boring. Sloman would get respect if he would stick to electron ics talk and avoid all the attacks. And yes, not talk about what he did 30 years ago, today is a totally different ball game
former.
is other weaknesses, but it took me quite a while to get my head around tra nsformer design, and it did pay off when I finally mastered it.
Hard to say. I certainly didn't have to manage it in one hit, because I nev er did all that much of it, and most of what I did was pretty straightforwa rd.
acquire that particular skill.
He keeps on telling us that designing special purpose transformers and gett ing them wound is hard work, and never posts anything about the advantages that can accrue from putting in that effort.
That strikes me as being actively discouraging.
-- Bill Sloman, Sydney
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