Beldsol costs the earth. I get very similar stuff from Temco for a fraction of the price (also eBay).
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
The ebay #28 was $17 for a quarter-pound spool, which will last me a long time.
Magnet wire is expensive. I got one quote for litz equivalent of #28 that was $150 per pound.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
that solders this stuff great.
I hate custom magnetics. Expensive, boring hassle. The technical
Yeah, I usually buy a career's worth of stuff like that too. I'll never need to buy Kester 44 again, since I got 10 spools NOS. ;)
Well, there's a lot of processing that goes into that. CPU dice are pretty expensive per pound. ;)
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
+1 on the Beldsol. I use it rather than wire wrap wire for prototype mods. Easier than stripping the 30ga wire.
Me too.
Cheers
Phil Hobbs-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics
160 North State Road #203 Briarcliff Manor NY 10510hobbs at electrooptical dot net
I didn't mean it was hard to do, rather, that it's hard on the rectifier, and lossy downstream.
Continuous mode helps that loss by reducing the a.c. flux in the core, which is another disadvantage to that super-fast discharge time--there aren't many PWM ICs fast enough when the required maximum discharge time is ~100nS to keep the inductor current in continuous mode!
But that asymmetric duty cycle is the problem with high-ratio dc-to-dc flybacks in the first place, as we all know.
That's why it's sometimes helpful to slow things down, e.g. coupled inductor, larger-valued inductor, or both. Continuous, if one can manage it, cuts peak currents in half too, reducing i^2*r loss.
Amen! Winding magnetics in production is a pain.
Cheers, James Arthur
I've posted a picture many times of a tool I got about 34 yrs ago when I worked at an electric motor repair shop. The hand tool is very convenient for scraping the varnish from almost any size wire. >
Just 3 or 4 pinch and pull maneuvers and the copper is clean. As pictured you can see I broke one blade about 15 years ago, but it has not affected its use. If anyone is interested in purchase, I should have a link on my other computer. I think it is a very handy tool, but no one has ever shown the any interest, even though I know people are using an exacto knife and trying to scrape insulation of off tiny wire. Mikek
I found the link. See center of page 10, labeled 'Wire Skinner and Straightener'.
Mikek
Correct about the load-side inductor, but no it does not need input current limiting
I have used forwards for less than 1W applications, if you need high efficiency then the forward can be scaled like any converter to almost any size although a >500W flyback borders to a crazy design
The flyback is a saturation limited converter, in that it used 1st quadrant fully of the BH curve, so the optimization of losses are normally not done for a flyback.
For the forward you can design the flux swing like you want, so you can arrange the flux losses to equal conduction losses, which is the optimal design
Cheers
Klaus
Oops, Page 9. Mikek
I've used #30 Beldsol on breadboards, but it was a tad hard to solder. My new hi-temp ersatz Metcal tip should fix that.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
It's called self-fluxing wire. My usual source has it.
and I'm fairly sure that most wire-manufacturers do it.
The other cute trick is self-bonding enamel. Wind the coil, then put enough current through it to get it to the bonding temperature, and when it cools down you have a self-supporting coil.
Great for saddle coils and other fancy stuff. Wind them circular, bend into the saddle shape, then bond.
Winding your own coils isn't just for transformers and inductors.
-- Bill Sloman, Sydney
fmr_Proto.JPG
the trick is to start from exposed copper on a fresh cut end, it get a good thermal connection and the solder seems to wick under the isolation and bu rn it off
-Lasse
Scraping it a bit with an x-acto helps start the process better. But the real trick is to use a very hot iron.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
The trick with Beldsol is to use a very hot iron with enough thermal mass to raise the connection above 750 F more or less instantly. Then its a puff of smoke and done, and nothing has time to melt.
Joe Gwinn
I bought a selection of about a dozen Thermaltronics tips (for a Metcal
500) about three years ago when they were first released. About 75% of them have failed.By comparison I've about 30 original tips (many bought 2nd hand) all over 4 years old and I can't recall any failures.
I don't know if Thermaltronics have improved in quality but I don't think I'll be bothering to find out any time soon.
Incidentally, I prefer the JBC system to the Metcal, but their soldering stations are not very reliable in my experience. Out of warranty repair cost from the manufacturer seems to be about the same cost as the purchase of a new unit.
A DIY chap realeased an open hardware design (Unisolder) which can work with JBC, Metcal and various other handpieces. I'm going to give it a try the next time I have a JBC station failure.
I only use the Thermaltronics tips on thermal-strip wire, which is a very low duty cycle. They are too hot for normal soldering.
Right, the Metcal tips are amazingly reliable and long-lasting, at least for engineering-bench use.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
"Self fluxing" is a bit of a misnomer. Rosin helps, probably acting as a solvent to get the enamel moving. A "very hot iron" may work against you, as the stuff (both enamel and rosin) turns to char and ashes before washing away.
This is all very easily confirmed visually, so do whatever looks best. If it's charring, turn it down. If it's not getting hot, and flux isn't helping, turn it up.
Tim
-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Contract Design Website: http://seventransistorlabs.com
Sadly, the habit of not designing transformers leaves you stuck with messy, expensive, sub-optimal solutions.
The design process is complicated, with lots of choices, but no more boring than any other design process. I suspect that what you are saying is that you've never bothered to get your head around all the issues involved, and find y ourself embarrassed when you have to discuss a transformer design in front of your subordinates.
There are lots of variables in a transformer design - starting with core si ze and core material, gapped or ungapped, and proceeding through turns rati o and wire size, and choosing between plain wire and Litz, and on to windin g configuration - bifilar or separate coils - plain windings or winding in banks (for lower parallel capacitance).
This means that buying an off-the-transformer is unlikely to give you anyth ing all that close to optimal. The process of getting small runs of custom transformers made by sub-contractors isn't all that demanding - no worse th an printed circuit boards. It's nice if you can avoid it, but little more s ensible than it would be to insist of building everything on off-the-shelf printed circuit boards.
-- Bill Sloman, Sydney
I think I've now found and - probably - fixed the problem. Some of the links were to my old Dutch web-site, long since dismantled.
It will be some hours before my IP up-loads the corrected file, and I won't know if it has worked until then.
-- Bill Sloman, sydney
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