MANGANIN / ZERANIN enamelled wire availability - Page 1
Forum section: electronics / general

author: zhtoor
author_rank: Frequent Contributor
timestamp: June 07, 2017, 08:08:48 pm
content: Could any of the learned members of this forum guide me to the prices and suppliers ofMANGANIN / ZERANIN wire (enamelled) in different diameters for use in DIY production ofprecision resistors, and can anyone guide me on the subject as to what does this process entail?regards.

author: HighVoltage
author_rank: Super Contributor
timestamp: June 07, 2017, 11:29:21 pm
content: In Germany you can find Isabellenhütte / Heusler GmbH & Co. KG as a good supplier for the wire.http://www.isabellenhuette.de/en/precision-alloys/products/manganinr/Datatsheet enclosed.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: June 07, 2017, 11:33:16 pm
content: I haven't tried to purchase resistance wire in many years. It's gotten very hard to source in small quantities and more expensive. The offerings on eBay are absurd. Possibly Kanthal can direct you to a distributor-http://www.kanthal.com/en/products/material-datasheets/wire/resistance-heating-wire-and-resistance-wire/manganin-43/Depending on what you're doing, you might consider constantan, if you can keep the thermal emf under control. That's cheap and plentiful. Manganin has only so-so thermal properties. There are wires that are much better, but they can't be soldered. They need spot welding or brazing. Unfortunately they have the same availability and cost problems.California Fine Wire will do custom runs of most materials for a fairly reasonable price, but you'd have to buy a certain minimum amount.http://www.calfinewire.com/wire-materials.html

author: zhtoor
author_rank: Frequent Contributor
timestamp: June 08, 2017, 08:32:54 pm
content: i have asked for prices from isabellenhuette for the following:-1. MANGANIN wire, enamelled 0.022mm dia.2. MANGANIN wire, enamelled 0.032mm dia.3. MANGANIN wire, enamelled 0.05mm dia.4. MANGANIN wire, enamelled 0.07mm dia.5. MANGANIN wire, enamelled 0.1mm dia.6. ZERANIN wire, enamelled 0.04mm dia.7. ZERANIN wire, enamelled 0.06mm dia.8. ZERANIN wire, enamelled 0.08mm dia.9. ZERANIN wire, enamelled 0.12mm dia.but no reply so far.regards.

author: Cerebus
author_rank: Super Contributor
timestamp: June 08, 2017, 08:54:30 pm
content: There's a middle-sized selection here:https://www.wires.co.uk/acatalog/manganin.html

author: zhtoor
author_rank: Frequent Contributor
timestamp: June 08, 2017, 09:04:14 pm
content: Quote from: Cerebus on June 08, 2017, 08:54:30 pmdo these guys supply smaller sizes (ca. 0.02mm) ?regards.

author: Cerebus
author_rank: Super Contributor
timestamp: June 08, 2017, 09:08:11 pm
content: Quote from: zhtoor on June 08, 2017, 09:04:14 pmYou'd have to ask them. I just happened to spot the Manganin wire in passing when I was looking for some standard magnet wire.

author: Edwin G. Pettis
author_rank: Frequent Contributor
timestamp: June 09, 2017, 05:49:59 pm
content: Before you spend a bunch of money on wire, I hope you are not under the impression that you can build you own precision resistors at home, it won't work. If you're doing it with the intent to learn something about wire wound resistors in general for experimental reasons, you can do that but if you're thinking about making high accuracy, very low TCR resistors yourself, forget it. There is far more to making PWW resistors than winding some wire around a form and terminating it to leads or posts. Manganin and it variants require special processing to achieve very low TCR and long term stability, this requires knowledge and experience not available to the general public and to some degree is more difficult to work with than the newer alloys such as Evanohm. Constantan is a bit easier to work with and can be soldered as well but it is not considered good enough for PWW resistors. Alloys such as Evanohm must be welded, they cannot be soldered.Precision wire wound resistors require considerable knowledge and experience to produce high accuracy, high stability and low TCRs and the more exact precision you want, the harder it is to make, there are a great many variables present in manufacturing such resistors and is best left to those who are experienced at it.

author: Cerebus
author_rank: Super Contributor
timestamp: June 09, 2017, 05:58:31 pm
content: Quote from: Edwin G. Pettis on June 09, 2017, 05:49:59 pmTo mis-quote Mandy Rice-Davies: "Well, 'e would say that, wouldn't 'e".

author: zhtoor
author_rank: Frequent Contributor
timestamp: June 09, 2017, 06:24:16 pm
content: Thank You Mr. Pettis,could you please guide me to the process, the prices and availability of EVANOHM alloy?I understand that the EVANOHM alloy can be joined to say brass leads with a form of a spotwelder formed with a charged capacitor and a tong-like device clamping the wires together.moreover, i was thinking of using either mica, ceramic or microscope glass slides for windingthe wire on, what would be a better choice of the three in your expert opinion?your comments are highly appreciated.

author: MisterDiodes
author_rank: Frequent Contributor
timestamp: June 10, 2017, 05:09:46 am
content: zhtoor:If you think you're going to build a DIY precision resistor, I think you want to consider this: If you need a new light bulb, do you build one or just buy one ready-made? Think of all the technology that goes into a cheap incandescent bulb, or even an LED. You'll never build a light bulb on your own that's as good or as cheap as a factory made unit. You need the economy of scale to get the cost per unit down to something reasonable.It's the same with resistors: You -could- buy the wire from a custom metals mill...which will cost at least several hundred or 10's of thousands of dollars for a minimum quantity of high-grade, low TCR resistance wire. It takes quite a bit of knowledge to even know what to ask for at the mill. Once you start asking for PPM tolerances, the price goes up more than exponentially.I'm not sure what you're trying to DIY here, but you need to know that they don't give away good (or bad) quality resistance alloy. It's not cheap to make.And then comes handling the wire, and what to wind it on. Sure, you could probably make some sort of tongs to hold on to stiff,veryspringy / ornery wire and try to make a spot weld. It might work once or twice by accident but with an incredible amount of frustration. There are man-centuries worth of research time just studying how to reliably and repeatably attach resistance wire & foil to just about -anything- else without screwing up the apparent TCR. The state of the art technology in this area still far from perfect, regardless of what Vishay datasheets tell you. This is very much a "Materials Science & Black Arts" area.You want to flat-wind the wire on a glass slide? Just remember that every bend that goes into the wire can be a stress-riser to increase TCR. Every time you bend that alloy, you are destroying the carefully dispersed and annealed metal alloy structure within - and depending on what you're building you might need to anneal the wire after handling, etc.. There's a reason why round bobbins have been a very successful style for PWW resistors.Do you want your home-made resistor to work only at DC, or do you want to handle low-freq AC? What noise properties, Does it pick up mechanical vibration? Magnetic interference? Magnetic interaction with other resistors? Voltage rating? Inter-winding capacitance? Inductance?The list of those pesky details goes on and on and on and on.Good resistors are incredibly complex beasts once you get to know them - this is not a trivial project. Cerebus seemed to be teasing Edwin in his message above, but the truth is resistors are very, very hard to get right: "The devil is in the details".Before you build anything DIY: I suggest you order some resistors from Edwin if you haven't already - he's made a few million over his lifetime and knows a thing or two. Order from General Resistance, Vishay, Bourns and whomever else you can - and study and compare those first on your exploration journey - and learn -why- each type is designed the way it is. There is a resistor design style for every application, and you want to learn about that. The precision resistor thread here on this forum is also a good place to pick up some details.Another suggestion: Look up the articles Edwin wrote on the history of resistors for EDN magazine...That's packed with good information also, and will give you a hint of the troubles in store for any resistor designer.

author: zhtoor
author_rank: Frequent Contributor
timestamp: June 10, 2017, 05:40:55 am
content: Quote from: MisterDiodes on June 10, 2017, 05:09:46 amthanks misterdiodes for your extremely valuable insights into the subject.i live in pakistan, a third-world under-developed country where almost nothing of precision is made. you have the luxury to live in asociety where precision components are available sometimes off-the-shelf and sometimes for a small lead time. and moreover, whenwe translate the prices in USD to PKR, even a couple of bucks is quite a bit. (for example, Edwin charges USD6 per resistor, which isactually the lowest price I have ever seen of this type of resistors, is equal in price to 40Kg's of wheat in pakistan), so, the combinedeffect would be naturally to think about "doing it yourself".now regarding the question you raise:-as for considering a glass microscope slide, the material is readily available, mica is available easily too and one of the nearby townsspecializes in ceramics production so i though i could get ceramic plate type formers done at a very low costs, all these materialsshare a couple of characteristics, relatively low thermal expansion and high insulation resistance. moreover i have seen a numberof very fancy pww's wound on mica (genrad decade boxes for example).your point about introducing mechanical stress in the form of a sharp bend, i concede, i think round bobbins would be a lot better inthis department (you might get away with no-annealing after winding).initially i want the resistors to work on DC only, i dont want to do any fancy non-inductive winding styles or start winding from the center-foldof the wire to cancel inductance effect, neither do i really care about any kind of magnetics / microphonics pickup, interwinding capacitanceis not an issue for me at the moment.i certainly agree with you that the devil is in the details, that is, if you get into the details. and yes i do expect a train of devils, anyone shouldwho does any kind of development.and yes, i did read Mr. Edwin's articles a couple of months ago.sorry for my naivete, but i just want to find out myself, what does handling a .02mm precision alloy wire really mean.regards and thanks again.

author: Edwin G. Pettis
author_rank: Frequent Contributor
timestamp: June 10, 2017, 03:37:18 pm
content: Hello zhtoor,I can certainly understand your position on cost in Pakistan, I would suggest that probably the 'easiest' way to experiment with making resistors would be to acquire some Manganin or Constantan, both of which can be soldered. Welding entails somewhat more difficulty and more expensive equipment than soldering does. Constantan is less sensitive to the process of making a resistor than Manganin which requires heat treating after it is wound. You won't likely get high precision resistors out of it but they should be good enough to experiment with and not cost you too much. Do not wind the wire tightly around your flat bobbin as too tight of a turn will have bad effects on the TCR of the wire. Ceramic may be the best material for you to use if it is available not expensive, glass and mica can tend to be brittle when wrapping wire around them.The spool of wire should have the ohms per foot marked on it along with the TCR, this will tell you how long the wire needs to be for a given resistance and the TCR will tell you approximately what your resistor should measure, be aware that you likely will affect the TCR of the wire some from winding and even termination. eBay may or may not be the lowest cost source for Constantan, check the internet for wire sources but few if any wire manufacturers will sell direct to hobbyists and those 'distributors' that do sell in small quantities have a high markup, Goodfellow in Great Britain is one example. I would suggest starting out with wire between 0.2mm to 0.3mm diameter, not too small or large to work with.This wire, like all resistance wire, is springy and does not like to be wound, it will try to unwind itself which makes handling it tricky, you may need to gently clamp one end on the winding form while winding the wire onto it, you'll find that two hands are never quite enough when winding resistors.

author: zhtoor
author_rank: Frequent Contributor
timestamp: June 10, 2017, 04:08:20 pm
content: Quote from: Edwin G. Pettis on June 10, 2017, 03:37:18 pmdear sir,i am *most* grateful for your kind and informative comments. i salute you for pointing me in the right direction and i hope and praythat your business gets even better. (although your kind is diminishing, just like bob pease said.)one reason for choosing a flat former for winding resistors over a round former was that the resistance wire on the semi-finishedresistor could be manually ground using some soft abrasive and coated with some kind of varnish for final adjustment of theresistance value (up).is the suggested method of resistance modification even feasible / recommended?regards and thanks again for taking the time to answer my naive questions.may God bless you and your family.

author: MisterDiodes
author_rank: Frequent Contributor
timestamp: June 10, 2017, 04:09:52 pm
content: zhtoor,Edwin beat me to it, but I was going to suggest Goodfellow as an example: 5 meters of .025mm dia manganin will run you about $140, and that's with 10ppm TCR. Not particularly good.http://www.goodfellow.comIf you just want to see what the wire feels like, if you can grab a WW resistor out of some junk equipment and cut it open.... Try winding some of that wire around a 3mm rod and watch what happens. Now imagine you are trying to spot-weld the stuff. Without the proper equipment on hand, it's just about impossible to even hang onto it correctly.I have, on occasion, seen resistance wire of various types and quality on eBay, so you might try to keep you're eyes open for that.Agreed, given your location: it will be a great challenge to keep your supply shelf stocked.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: June 10, 2017, 04:13:28 pm
content: How good a resistor are we talking about? IMO, you should be able to trim a resistor to better than 50 ppm, maybe way better if you have a good comparison standard and have thought the process through. The TCR will depend on what wire you can get, and how you treat it. IMO, stability is the tough one. How far will the resistor drift over the years and what sort of hysteresis will it have. Hard to figure out if you don't have something to compare it to. I say give it a try. If I never attempted anything until I fully understood it, I'd never do anything. I've wound quite a few decent resistors over the years, not as many or as good as Edwin, but you have to start somewhere. Because constantan is thermocouple wire, it's common and less expensive. You might also find something similar (look at the material analysis) like Jelliff Alloy 45.If you have no size constraints, use a loose winding like Guildline does (see the teardown thread). Julie Research also used a loose winding on their bobbins. Any coating or almost anything you do to stabilize the winding will contribute to TCR and drift. The common L&N resistance standards are something good to study- to see how not to do it! They're OK for many purposes, but are not ppm level resistors. There may be some useful papers at NIST. Formerly the National Bureau of Standards, they published a lot of research on resistors and other things, some of which is online. There was NBS Special Publication 300, in several volumes. Possible you can find volume 3. Here are a couple good links-http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=ADA284623http://nvlpubs.nist.gov/nistpubs/sp958-lide/063-065.pdf]http://nvlpubs.nist.gov/nistpubs/sp958-lide/063-065.pdfAlways read the bibliography and try to get useful papers listed there.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: June 10, 2017, 04:17:58 pm
content: BTW, yes, many flat card resistors have been trimmed by abrading the surface with an electric draftman's eraser and a more abrasive ink type eraser. A Cratex wheel and Moto-tool would probably work. Lots of high current shunts and heavy gage wire resistors have probably been trimmed with a fine file!

author: zhtoor
author_rank: Frequent Contributor
timestamp: June 10, 2017, 05:01:06 pm
content: Quote from: Conrad Hoffman on June 10, 2017, 04:13:28 pmthanks a lot sir!,i have my eyes on these, could you look at them and comment?P3009 bridge.http://www.ebay.com/itm/263027054105?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AITGenrad 1433B.http://www.ebay.com/itm/222366395688?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AITESI 230B.http://www.ebay.com/itm/121917352700?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AITL&N Standards.http://www.ebay.com/itm/282479645177?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AITP310 Standards.http://www.ebay.com/itm/230775595642?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AITregards.

author: HighVoltage
author_rank: Super Contributor
timestamp: June 10, 2017, 05:06:29 pm
content: If you look for resistors, take a look at this ebay seller in the Ukraine:http://www.ebay.de/itm/6pc-0-001-0-01-1-10-100-1000-Ohm-Resistance-Standard-Resistor-Rare-Manganin-/272579461969?hash=item3f77008351:g:KJEAAOSwTM5YvWer6pc 0.001 0.01 1 10 100 1000 Ohm ? Resistance Standard Resistor Rare ManganinI have bought from him and he accepts reasonable price offers.He ships very fast and I was very happy with each one of the resistors I got.

author: BravoV
author_rank: Super Contributor
timestamp: June 10, 2017, 05:29:42 pm
content: Even you managed to build the resistor, the real question is, do you have good / adequate instruments (or access to it) to verify it's accuracy, drift, tcr etc ?

author: zhtoor
author_rank: Frequent Contributor
timestamp: June 10, 2017, 05:34:09 pm
content: Quote from: BravoV on June 10, 2017, 05:29:42 pmsaving up for some of those(see reply #17)regards.

author: BravoV
author_rank: Super Contributor
timestamp: June 10, 2017, 05:54:06 pm
content: Quote from: zhtoor on June 10, 2017, 05:34:09 pmI'm not raining your parade, but still no, at least not enough.Why ? Those are "USED" equipments, and they're not that cheap either, and what if those expensive standards when arrived at your home, you enthusiastically opened it up , but ended like ..... this->IET resistance capacitance box too good to be true... or even worst ...Start saving on high precision test equipment that "can be trusted" first, or at least get a pass that allow you to access those precision measurement instruments which are properly calibrated.Once you settled above major step, then start the high precision resistor manufacturing adventure.Not the reverse path that imo, you're currently pursuing.Other wise all of these are useless, cause whats the point you can build a manganin / zeranin resistor and etc, but you can't be sure as you can not verify them if they're better than those 5 cents resistors ?We are talking metrological's grade resistors right ? And yes, metrology is not cheap.My 2 1/4 watt resistors worth of advice.

author: zhtoor
author_rank: Frequent Contributor
timestamp: June 10, 2017, 06:23:01 pm
content: Quote from: BravoV on June 10, 2017, 05:54:06 pmi would be very lucky to do metrology grade resistors in a couple of decades (if i am lucky *and* alive!),but one does what one *can*.regards.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: June 10, 2017, 06:44:56 pm
content: This is a quick off-the-cuff comment on the list of things above, not carefully researched truth!3009- only 0.1 to 1%, not the precision we're probably talking about.1433- These are usually quite good, though also misunderstood. They were used to make up custom bridge circuits back in the day, and make various other measurements, but are not the reference calibration standards people believe them to be today. Some have been overloaded, so you have to buy carefully. That said, 0.01% is pretty good and every bench should have a couple. I've never paid more than $50 at hamfests and fleamarkets, though usually for the older grey ones.230B- I'm not sure if this is two terminal or 4 terminal. I've got a very nice full ESI bridge setup that's 2 terminal, making it maybe one step better than a good DVM.L&N resistors- Decent if calibrated often, but usually with a large TCR. They often are filled with ancient oil that's become acidic and changed the value. Nice to have a few, but not worth what people tend to think. Most labs got rid of them decades ago.P resistors- No experience, but my guess is they're as good or better than the L&N resistors. That said, they're new, so expect them to settle down for a couple years. You need somebody to re-measure them periodically.Remember, none of this voltnut stuff is perfectly stable. You have to find somebody to measure your basic standards periodically. If you have several standards to intercompare, you can go quite a while without calibration and with high confidence, but sooner or later it has to be done.

author: branadic
author_rank: Super Contributor
timestamp: June 11, 2017, 02:40:58 pm
content: QuoteDon't know the age of Edwin G. Pettis, but at a certain point it would be great he transfers all his knowledge of making precision wirewound resistors to someone, before he retires or ... . Otherwise we end up with the same situation when Jim Williams or Bob Pease passed away, a loss of knowledge.I guess I'm not alone with this opinion, that's why most of the guys here on this forum try to find out as much as possible from Edwin on one or the other way.-branadic-

author: zhtoor
author_rank: Frequent Contributor
timestamp: June 11, 2017, 03:37:11 pm
content: Quote from: branadic on June 11, 2017, 02:40:58 pmhello -branadic-,if you don't mind, let me say that it is the newer generation (that is us) who are mostly at fault. we do not value our elders the way we ought to.we do not revere them, we do not cherish them, we do not appreciate them, and that is mostly the reason we are creating our own loss,because, because of our callous attitude towards our elders, they are not sympathetic to us (and rightly so!).it is we, who have to mend our ways.really best wishes, i do not intend to malign anybody, and especially not you.regards.

author: CopperCone
author_rank: Super Contributor
timestamp: June 11, 2017, 04:10:35 pm
content: There is only so much that you can do to a metal.you can1) alloy it with something2) offer some kind of heat treatment/cryo treatment (change its crystalline form)3) put it under some amount of stressALSO, brazing is not hard. You just need to get some high silver (55%+), or gold alloy ($$$$) braze (both stick to anything) and a torch. A home depot mapp/oxy would probobly do, or something like a smith jewlers torch.. between $50-$400$ (not absurd considering the cost of the instruments and materials).loose wire will be more sensitive to shock and vibration (allows it to deform) but it will be more resistant to thermal changes (strain gauge error)tightly wound/potted wire will be less sensitive to shock and vibration but you have parasitic strain gauge effects.I think you can figure it out. Also, with metals you can purify them by heating them in a reducing environment (i.e. hydrogen) (like how you treat mu metal after its bent)perhaps you need to anneal coils in a hydrogen furnace after you bend (deform) them to increase stabilityit seems a knowledge of metallurgy is required.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: June 11, 2017, 04:25:20 pm
content: Ha! Watch out on the Smith Little Torch. The real thing is supposedly a great product, but the world is full of bogus knock-off copies. They sell for about $40-80 and are dangerous junk. They leak, the threads don't fit and there's no sapphire in the tips. The tip off is the gas knob is blue. It's supposed to be green and Smith has never ever used a blue knob, only green. I just bought one, discovered it was a fake, and returned it. My plan was to use it for silver brazing resistance wire!

author: Cerebus
author_rank: Super Contributor
timestamp: June 12, 2017, 12:19:50 am
content: Quote from: CopperCone on June 11, 2017, 04:10:35 pmYes, it seems that it is.https://en.wikipedia.org/wiki/Hydrogen_embrittlementNow I may not be a metallurgist, but it seems to me that suggesting taking steps that are going to chemically alter alloys carefully formulated to have particular characteristics is not the wisest course of action to suggest.Further, if a $6 PWW resistor is out of reach in the OP's country, then recommending a $400 torch is perhaps not the thing to be doing.

author: zhtoor
author_rank: Frequent Contributor
timestamp: June 13, 2017, 05:45:39 pm
content: i understand from Edwin's comments that ceramic is probably the best substrate to do experimental manganin wire resistors,but while i acquire ceramic substrates (bobbins or plates), how about using a glass microscope slide wrapped in kapton tape,like the one in:-https://www.amazon.com/3M-5413-Polyimide-Silicone-Adhesive/dp/B009OWZUYQ/ref=sr_1_3?ie=UTF8&qid=1497375354&sr=8-3&keywords=3m+5413and using the resultant as a "card" for winding resistors on?any comments shall be highly appreciated.regards.

author: Vtile
author_rank: Super Contributor
timestamp: June 13, 2017, 06:06:10 pm
content: If you use glass (microscope slides) you can also form it with regular propane torch, that is if it is so called soda-lime glass and not borosilicate aka pyrex^tm etc.This way you might get the sharp edges out or use some regular window glass for the first experiments.The trap is that it might explode while working with it or while cooling it after. The trick is to cool it slowly to not allow the internal tensions to form if it tends to shatter while cooling.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: June 13, 2017, 06:08:50 pm
content: Mica gives you a thinner resistor and thus less inductance. Glass should work- you can use a diamond hone to round the edges (do it wet). So many mica card resistors have been made by so many people, I don't think they're rocket science.

author: Vtile
author_rank: Super Contributor
timestamp: June 13, 2017, 06:15:51 pm
content: Quote from: Conrad Hoffman on June 13, 2017, 06:08:50 pmNope, found in every toaster in kitchen

author: zhtoor
author_rank: Frequent Contributor
timestamp: June 13, 2017, 06:24:21 pm
content: and what would be the way to "anneal" the wound manganin resistor on either glass slide with honed edges or mica?what kind of temperature treatment would be required to sort-of pre-age these resistors? assuming manganin or zeranin wire is used.regards and thanks again for your valuable comments.

author: CopperCone
author_rank: Super Contributor
timestamp: June 14, 2017, 06:14:48 am
content: Quote from: Cerebus on June 12, 2017, 12:19:50 amhttp://mumetal.co.uk/?tag=hydrogen-heat-treatmentperhaps he has a friend with a torch or knows a welder. They like to use gas in poor countries because its cheap. It's everywhere. You can probably go to a scrap yard, buy a guy a sandwich and he will do it for you. It's not impossible to do with a big torch, a small one is just harder to overheat with. Also any jewelry designer will have one. Or car mechanic.I am just giving my ideas. Also, you can polish wire. I'm not sure what else you can do with it to change its characteristics.

author: Cerebus
author_rank: Super Contributor
timestamp: June 14, 2017, 01:50:21 pm
content: Quote from: CopperCone on June 14, 2017, 06:14:48 amMu metal, used in sheets for shielding is very different from tiny thin resistance wire used for, well, resistance. You might as well say that as it's OK to treat ferritic mu metal with hydrogen that it'd be fine to use it on the steel swing arms of a car's suspension. As I say, I'm no metalurgist, and I'd be happy to be proven wrong by a couple of relevant examples, but my engineering Spidey Sense tells me you're on the wrong track.

author: zhtoor
author_rank: Frequent Contributor
timestamp: June 14, 2017, 03:41:35 pm
content: proposed resistor stabilization / aging method:say the resistor which is to be stabilized is 10K.apply 100 volts for 5min then 0v for 5minapply 90 volts for 10min then 0v for 5min...so on....the time (5min) can be a variable according to the resistance ora voltage ramp-up followed by a plateau followed by a ramp-down over a period of say a couple of hours.ie; a programmable heating profile generation waveform for resistor stabilization.regards and comments required.

author: Edwin G. Pettis
author_rank: Frequent Contributor
timestamp: June 17, 2017, 10:53:11 pm
content: Well, if you really want to mess up an alloy's TCR characteristic, use a torch on it, Manganin will go absolutely crazy as it has a relatively low temperature for messing up the TCR (hence always used at low power and room temperature for precision), even excessive soldering time will cause changes (locally). Evanohm will tolerate up to about 300°C without major changes, anything over that is going to majorly change its TCR, even under 300°C for sufficiently long will cause modification to the TCR. The only reliable termination of Evanohm is proper welding and Manganin is almost always soldered but it can be welded to copper of course under the proper conditions.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: June 18, 2017, 11:42:02 am
content: The thermal conductivity of most resistance alloys is low. My guess, and it's just a guess, is that a brazed connection can be made with little trouble. Obviously one heats the terminal only. With heavier wire you'd probably want a heat block/sink of some sort. IMO, spot welding is better, but I don't know what materials can be reliably spot welded together.

author: zhtoor
author_rank: Frequent Contributor
timestamp: June 18, 2017, 02:58:28 pm
content: i think in case of fine wire joints, it would be very important to consider the amount of energy delivered to the joint in the spot welding process.an experiment is in order to see what kind of energies could be delivered to the joint for different sizes of manganin wire joints.some kind of "energy decade box" of capacitors maybe?regards and thanks again to Mr. Edwin, MisterDiodes, Conrad Hoffman and others.