Resistors Used in an LM399 Circuit - Page 1
Forum section: electronics / general

author: Chance92
author_rank: Regular Contributor
timestamp: August 12, 2022, 12:51:18 pm
content: I found a reference circuit in an old Valhalla 4300B micro-ohm meter. I wonder what type of resistors these are? Do they have low temp coefficients?

author: Grandchuck
author_rank: Super Contributor
timestamp: August 12, 2022, 12:53:58 pm
content: I will guess that they are wire wound.

author: Edwin G. Pettis
author_rank: Frequent Contributor
timestamp: August 14, 2022, 03:50:42 am
content: That is easy to answer, we made those for Valhalla, back in the early '80s, we went by the name GoldStar Resistors then, we made all of their resistors....note the same yellow cases as Ultrohm Plus uses (when available). They have the same specs as Ultrohm Plus, TCR of 0±3PPM/°C. Of course they are precision wire wound resistors.

author: TiN
author_rank: Super Contributor
timestamp: August 14, 2022, 04:52:39 am
content: Spider webs and strategically tilted LM399, -10 ppms to performance

author: Chance92
author_rank: Regular Contributor
timestamp: August 14, 2022, 10:41:30 am
content: Quote from: Edwin G. Pettis on August 14, 2022, 03:50:42 amWow! Thank you for the info. I didn't expect someone from the manufacturer to answer my question. EEVblog is a magical place.

author: Chance92
author_rank: Regular Contributor
timestamp: August 14, 2022, 10:47:47 am
content: Quote from: TiN on August 14, 2022, 04:52:39 amPrecisely tilted to counter the uneven uneven air flowThis is better than I expected to be honest, considering there's a cooling fan behind without any dust filter, and 20+ years of usage of course.

author: cellularmitosis
author_rank: Unknown
timestamp: August 15, 2022, 06:35:09 am
content: Quote from: Chance92 on August 14, 2022, 10:41:30 amFYI he still manufactures them, and they are very affordable, should you happen to get bitten by the volt-but bug

author: bbqws60
author_rank: Newbie
timestamp: July 17, 2023, 08:40:39 am
content: Do you have more disassembly pictures? I want to take a look inside, but I can't find the disassembly diagram online

author: Chance92
author_rank: Regular Contributor
timestamp: July 17, 2023, 09:38:07 am
content: Quote from: bbqws60 on July 17, 2023, 08:40:39 amSure, will do that in the next few days. If you need schematics, you can find them in the manual.

author: Chance92
author_rank: Regular Contributor
timestamp: July 17, 2023, 08:42:49 pm
content: Quote from: bbqws60 on July 17, 2023, 08:40:39 amPlease see below.

author: EC8010
author_rank: Frequent Contributor
timestamp: July 18, 2023, 08:00:25 am
content: Quote from: Edwin G. Pettis on August 14, 2022, 03:50:42 amPerhaps (as you are/were in the business), you can enlighten me on some similar wirewound resistors from the 80s. I have seen pale green resistors 14mm diameter and 18mm long marked LT450/C and 0.002% tolerance (!) in values up to 2M in various bits of kit (Fluke 341A voltage calibrator, a mass spectrometer, and a gas monitor). They're definitely wirewound (shows in the impedance) and the proportions suggest they are multi-layer, which seems inevitable for the larger values. I assume they are enamelled resistance wire (manganin?). Do you know anything about these? Anything at all?

author: Mickle T.
author_rank: Frequent Contributor
timestamp: July 18, 2023, 09:56:55 am
content: Quote from: EC8010 on July 18, 2023, 08:00:25 amThese were the resistors of the British Mann Components (later Vishay-Mann).

author: EC8010
author_rank: Frequent Contributor
timestamp: July 18, 2023, 12:02:10 pm
content: Thank you so much, Mickle T. That's even more than I had hoped for. A data sheet and a dissected one!

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: July 18, 2023, 05:09:37 pm
content: IMO, the words "wire-wound" and "10M" should never be used in the same sentence.

author: TimFox
author_rank: Super Contributor
timestamp: July 18, 2023, 05:49:21 pm
content: Quote from: Conrad Hoffman on July 18, 2023, 05:09:37 pm"Never"? series HR5032N from Precision Resistor Co go up to 10 megohm as special order.2" long, 2.5 W, 1200 V ratinghttps://www.precisionresistor.com/skin/reboot/pdf/HRSeriesUltraPrecisionWireWoundResistorPDF.pdf"Well, hardly ever" --HMS Pinafore(If I remember correctly, in the late 1960s Argonne Lab built a custom 100 kV voltage divider from 10 megohm wirewounds from Julie Research Labs, but I couldn't track down a reference to them. The divider was about the same size as my downstairs half-bathroom.)

author: iMo
author_rank: Super Contributor
timestamp: July 18, 2023, 07:09:47 pm
content: My 10Meg WW resistor..

author: Edwin G. Pettis
author_rank: Frequent Contributor
timestamp: July 18, 2023, 07:17:55 pm
content: On the contrary, we used to make resistors up to 30Meg but as time and material cost rose it became too expensive for many applications except those that needed the power and stability of precision wire wound resistors. To date, the largest resistors I have made relatively recently were 3 1/3Meg to repair an ESI 1050 10Meg decade box. 1 Meg are still reasonably cost competitive. Unless you need a precision repair of resistor decade boxes, transfer standards or equipment, usually lessor resistor types will suffice.

author: Nanitamuscen
author_rank: Contributor
timestamp: July 19, 2023, 03:01:25 am
content: Previously, resistors were made from a micro-wire in glass insulation with a resistance much higher. These have a resistance of 100 MOhm and 1GOhm.

author: EC8010
author_rank: Frequent Contributor
timestamp: July 19, 2023, 08:28:49 am
content: I'm amazed to see 100M and 1G in wirewound. I first encountered a Mann 2M wirewound resistor as part of the potential divider for sampling the output of a 250VDC supply. When I came to design a replacement instrument, I quickly discovered the reason for the wirewound choice; excess noise. The supply needed to be really low noise, preferably < 10uVpk-pkover a 10s sampling aperture. High frequency noise could be filtered away, but not 1/f noise and that's where the original design's wirewound resistor came in because they produce less excess noise (which is invariably 1/f) than composition or metal film. Not being able to find high value wirewounds, I used a string of ten 1M metal film resistors as my sampling resistor and that worked.I would be most interested to hear further details from those involved in manufacture of high value wirewounds. What diameter wire? Is surface finish of the wire important? (I'm guessing it is.) If multi-layer, is insulation added between layers to solve the voltage gradient problem at one end?

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: July 19, 2023, 01:04:51 pm
content: I guess if you need it you need it, but I'm sure glad it isn't me doing the winding. Or buying the very fine wire. No doubt that isn't cheap either.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: July 21, 2023, 03:14:25 am
content: I acquired some old wire wound resistorshttps://www.eevblog.com/forum/beginners/old-wire-wound-resistors/msg4788734/#msg4788734402.2K 1/10%They are NOS and if anyone wants one or two, let me know.They have quite high inductance and that is probably a reason for using them. They probably reduced a lot of low freq noise.

author: EC8010
author_rank: Frequent Contributor
timestamp: July 21, 2023, 04:11:38 pm
content: Quote from: Wallace Gasiewicz on July 21, 2023, 03:14:25 amWith luck, you have a message.

author: Edwin G. Pettis
author_rank: Frequent Contributor
timestamp: July 21, 2023, 07:25:15 pm
content: The smallest wire I am aware of, at least in the USA is 0,000,4 diameter in Evanohm. Most modern resistor wire is coated in polyimide, my spec calls for a minimum 220°C rating, dielectric strength is a minimum of 200V even on the thinnest coating. There is no inter-layer insulation used, the voltage rating of the resistor depends on how many pi is used in the bobbin and the voltage rating usually has a significant derating in use. Wire sizes smaller than 0,001" diameter have become rather expensive, I have not requested a recent quote but my estimate is approximately $50.841 per 0,4536 Kg, so a typical spool would be somewhere in the $3.500,00-$5.000,00 range. Needles to say this size of wire is quite difficult to manufacture.I don't know what gauge of wire the Russians used but it would take about 200,000 feet of 0,000,4" wire to make a 1 G resistor. A 10 M resistor would be about 2,000 feet. Yes winding 0,000,4 wire is definitely a strain on the eyeballs and requires a very delicate touch.I try to stay at or above 0,001" wire to keep away from those heavy charges for smaller wire sizes.

author: bsw_m
author_rank: Frequent Contributor
timestamp: July 21, 2023, 09:11:23 pm
content: Quote from: Edwin G. Pettis on July 21, 2023, 07:25:15 pmI don't have exact information what wire diameter was used in the 1G resistor. But there are assumptions that it is the same as in MRX resistors rated 100MegaOhm and higher - the diameter of the conductive core is 2µm, the diameter of the wire on glass insulation is 13µmPhoto through a metallographic microscope is attached. As well as the look of resistive elements.Resistors on the last photo100M 0.05% (in spec, after 33 years of storage)100M 0.1% (in spec, after 33 years of storage)300M0.1%0.05% (in spec, after 33 years of storage)all have spec. TC <15ppm/°C, typical about 4-8ppm/°C

author: Edwin G. Pettis
author_rank: Frequent Contributor
timestamp: July 22, 2023, 12:13:25 am
content: Okay, 13um is about 0,000,5" diameter wire which is about 3.200 ohms/ft, so the 1 G resistor needed even more wire to reach 1G.0,000,4" diameter wire is 10um diameter wire. Either way, winding a 100M or 1G wire wound resistor is an accomplishment in itself, I wouldn't try it now, maybe 30 or 40 years ago, laughing. I'm not too surprised that they have held their tolerance, being glass and on the shelf for 33 years, pretty easy duty.

author: bsw_m
author_rank: Frequent Contributor
timestamp: July 22, 2023, 12:47:02 am
content: I apologize, I may not have been very clear in my previous post. The wire together with the insulation has a diameter of 13µm, but the wire itself has a diameter of2µm. In any case, winding such a resistor is not an easy task.

author: Edwin G. Pettis
author_rank: Frequent Contributor
timestamp: July 22, 2023, 03:55:24 am
content: I've never heard of nor seen a wire that fine from any wire source I know of, that is impressive indeed. That would have been exceedingly difficult to draw out a wire that tiny even in Evanohm alloy. 0.000078" vs 0.0004", essentially five times thinner. That would be roughly 20K ohms per foot for Evanohm alloy. That still would have been about 50,000 feet of wire.

author: EC8010
author_rank: Frequent Contributor
timestamp: July 22, 2023, 07:19:58 am
content: Quote from: bsw_m on July 22, 2023, 12:47:02 amThat's very fine wire. Some of the final generation of valves used tungsten wire 6um diameter for their control grids, and I imagine tungsten is very difficult to draw into a wire.

author: iMo
author_rank: Super Contributor
timestamp: July 22, 2023, 06:09:55 pm
content: Several weeks back I repaired by myself a 1MegOhm wirewound resistor, thus nothing special.The wire was not visible with my naked eye, I did it because I was feeling it when under strain upon taction. I made a shot under uscope, it was around 10um or less. Unfortunately it broke and about 30cm of it was 8kOhm thus my 1Meg is now by 8k lower.Here is the shothttps://www.eevblog.com/forum/projects/how-do-they-wind-coils-with-ridiculous-gages-like-56awg/msg4910013/#msg4910013

author: EC8010
author_rank: Frequent Contributor
timestamp: July 22, 2023, 06:16:20 pm
content: I've measured tungsten wires of about those dimension using a good micrometer, but I would expect resistance wire to be proper fragile, necessitating microscope. I don't imagine the postman delivers replacement parts very often where you are?

author: bsw_m
author_rank: Frequent Contributor
timestamp: July 23, 2023, 03:03:41 am
content: Quote from: Edwin G. Pettis on July 22, 2023, 03:55:24 amThe wire that was used to wind the resistors shown above has a resistance of about 860kOhm/meter or about 260kOhm/foot (this is with a wire diameter of 2µm).Which gives a more realistic 1160meters or 3.846 feet to get a resistance of 1GOhm.

author: Kleinstein
author_rank: Super Contributor
timestamp: July 23, 2023, 08:45:06 am
content: Making thin turngsten wire is not easy, but there was a large demand for such wire for producing light bulbs and tubes.Making wires from the resistor alloys may be a bit easier as they are likely less brittle.The glass encapsulated micro-wires are different from normal wires as the are drawn together with the hot glass, more like making a special kind of glass fiber.

author: iMo
author_rank: Super Contributor
timestamp: July 23, 2023, 09:14:01 am
content: I've been thinking to use this kind of wires (ie from old wire wound resistors) for creating a divider for 399/1000 circuits. I mean to wind it on a small bobbin/former as a coil with a tap. Not an easy exercise though.. For a total resistance of the divider say 20k you would need couple of meters of such a wire..The problem (among others) is the higher the resistivity the shorter the wire but the harder to place the tap precisely. I made my ww resistor for myADR1001 (110ohm) trying to fit 10V, I did it with a wire where the 110ohm was around 18cm (great) but I was not able to cut it such it fit, finally I used another wire where I needed around 1m (well, still ok..) of the wire and it was much easier (and I am off by 130uV).PS: FYI - the ADR1001 has got all those difficult resistor dividers on chip and ovenized, what has been used for fitting the 10V at the output is the RISET resistor (around 110ohm, it sets zener's current) which "10V output tuning sensitivity" around those 110ohm is roughly +/- 250uV per -/+ 1ohm change..

author: bsw_m
author_rank: Frequent Contributor
timestamp: July 23, 2023, 02:20:16 pm
content: Quote from: Kleinstein on July 23, 2023, 08:45:06 amAbsolutely correct!

author: alm
author_rank: Super Contributor
timestamp: July 23, 2023, 03:24:11 pm
content: Quote from: iMo on July 23, 2023, 09:14:01 amDepends on the type of wire. I believe common types for precision wirewound resistors are either Manganin or Evanohm and similar brands. Manganin has to be treated very carefully in terms of stress and heat otherwise you risk shifting the tempco, but you can solder it. The tempco is generally not very low (in the order of 10 ppm/K best case). Evanohm and similar alloys from other manufacturers is superior to Manganin in both heat tolerance and temperature coefficient, but can't be soldered with any degree of reliability and has to be welded. Read anything by Edwin Pettis since he is (one of) the industry expert on precision wirewound resistors.He wrote a really interesting two part article together with another person that won't help you make your own resistors but gives a fascinating insight into the precision wirewound industry:The last half-century: Wirewound resistors Part oneThe last half-century: Wirewound resistors Part two

author: iMo
author_rank: Super Contributor
timestamp: July 23, 2023, 04:10:54 pm
content: Interesting reading, thanks. I would prefer Manganin as it is solderable and easy to get from old ww resistors, and when wound as the "divider" on the same bobbin (a bobbin with 3 legs) the TC could cancel, imho.You may wind the R1, then make the tap (almost anywhere around the expected R1 value), and then do wind the R2, where you will finetune the length of the R2 such it fits the "ratio R1/R2" (by cutting the wire slowly down, soldering, measuring, and so on until it fits).The absolute value of R1+R2 does not matter here. I think it is doable..

author: Kleinstein
author_rank: Super Contributor
timestamp: July 23, 2023, 05:07:16 pm
content: NiCr based resistors are expected to have better long term stability (comes with better tolerance to temperature) than copper based alloys (e.g maganin) too. Manganin is lower specific resistance and may have a lower thermal EMF. Together with the easier conacts this makes it attractive for low value resistors and shunts.

author: iMo
author_rank: Super Contributor
timestamp: July 23, 2023, 05:20:36 pm
content: How to check the wire is Manganin or something else? Imagine you have a bunch of ww resistors from 1k - 1Meg.

author: Kleinstein
author_rank: Super Contributor
timestamp: July 23, 2023, 06:38:50 pm
content: Quote from: iMo on July 23, 2023, 05:20:36 pmTo do this non destructive could be a bit challanging. One point may be the 2nd oder TC. AFAIK this is not changing much with the aging details on manganin (though it may change with the exact alloy, like different manganin variants). I would expect a high 2nd order effect for manganin than NiCr.Another chances could be from the magnetic properties: NiCr should be slightly magnetic (maybe just paramagnetic). Still the connecting wires may make this test tricky if they are magnetic.Another point could be to get the resistor types and find data sheets that tell the alloy. More open designs may show the way the wire is connected: Manganin is usually soldered, while NiCr is welded in some way. NiCr is a bit more modern, but there is also also older CuNi (konstantan), which is not good with a rather high thermal EMF.For the lower resistance range there is manganin wire avaiable. I got some from Ebay that worked out quite well: TC well below 10 ppm/K and very low thermal EMF (I can hardly tell it appart from pure copper or give the sign). Just the resistance is a bit higher than nominal (may be some 5% on the diameter).

author: alm
author_rank: Super Contributor
timestamp: July 24, 2023, 12:15:11 am
content: Quote from: iMo on July 23, 2023, 04:10:54 pmAs a first order approximation this is correct, but note that this only applies if the heating on both sides is the same. If you have a 10:1 voltage divider, then one leg will dissipate 9x more heat than the other, so it will reach a higher temperature.

author: Edwin G. Pettis
author_rank: Frequent Contributor
timestamp: July 24, 2023, 04:19:42 am
content: Hi, after doing some research, there are no alloys that are anywhere near the resistance per meter (or foot) that you have 'calculated'.Tungsten is over 150 times lower in resistance per unit length than Evanohm, Tungsten, the smallest diameter wire I could find was 0,000,3" diameter, if it could be drawn to 2um diameter would be 17984 ohm per meter while Evanohm, at the same diameter, would be 65.616,8 ohm per meter. That is using the most common form of Evanohm 800 alloy, there are also a 825 and 875 alloy variants of Evanohm which would increase the resistance a little bit further. The TCR of Tungsten is +45 PPM/°C.There are absolutely no pure metal or alloy that gets anywhere near 860K/m in a wire form, even at 2um diameter, even 1um wouldn't get you there even if a wire could be drawn that tiny (Gold is the only candidate here and its resistance is far too low).While I am not directly disputing your measurement of the wire's diameter (how accurate?), the resistance per meter and calculated length are not possible.

author: bsw_m
author_rank: Frequent Contributor
timestamp: July 24, 2023, 06:30:23 am
content: I disassembled a simpler resistor of 1Mohm nominal. It is wound with a wire with a diameter (without glass insulation) of~50μmmy mistake, wire diameter 5um. Photo of the wire under a microscope (optical magnification 200x), resistance of the resistive element and its dimensions (in metric system) below in the photo. If necessary, I can try to take a meter of wire and measure its resistance.P.S. Please note, this wire is not drawn out. It is casted in glass insulated.

author: iMo
author_rank: Super Contributor
timestamp: July 24, 2023, 06:35:31 am
content: Quote from: Edwin G. Pettis on July 24, 2023, 04:19:42 amThe resistors are old Soviet era resistors. Soviets were known for creating special exotic alloys unknown for outside world, and because the number of western spies in USSR R&D institutes was (and still is) by several orders of magnitude lower than vice versa, it could be you just face such a mystery alloy..

author: iMo
author_rank: Super Contributor
timestamp: July 24, 2023, 06:40:20 am
content: Quote from: alm on July 24, 2023, 12:15:11 amI talk here aprox 1:2 ratio (like in a typical LM399 circuit with 7V->10V opamp amplifier).

author: Kleinstein
author_rank: Super Contributor
timestamp: July 24, 2023, 07:14:28 am
content: Looking at the wire inside the glass can overestimate the wire diameter, as the glass acts as a kind of magnifier.

author: bsw_m
author_rank: Frequent Contributor
timestamp: July 24, 2023, 07:55:45 am
content: No problem, the wire diameter was measured after removing the glass. Wire diameter50um, my mistake, wire diameter 5um.The resistance of the 10cm long wire was also measured and it was 6.92kOhm. It wasn't really very easy, but I got through it.Sorry, I got a messed up wire diameter calculation (I'll double-check and recalculate everything after I get some rest)Double-checked myself. The real diameter of this wire is5µm.

author: MegaVolt
author_rank: Frequent Contributor
timestamp: July 24, 2023, 09:24:54 am
content: The Russian wiki has a table with resistance per meter.https://ru.wikipedia.org/wiki/%D0%9C%D0%B8%D0%BA%D1%80%D0%BE%D0%BF%D1%80%D0%BE%D0%B2%D0%BE%D0%B41 GΩ hermetic resistor design:

author: bsw_m
author_rank: Frequent Contributor
timestamp: July 24, 2023, 09:31:30 am
content: Quote from: MegaVolt on July 24, 2023, 09:24:54 amThe link has very incomplete data.Already in the 60's, casted microwires with a core diameter of 0.1µm were produced.And another example, a 5µm diameter microwire made of 53kxgs alloy will have resistance >102kOhm/meter.

author: EC8010
author_rank: Frequent Contributor
timestamp: July 24, 2023, 02:59:36 pm
content: Quote from: bsw_m on July 24, 2023, 09:31:30 am102 kohm per metre sounds an awful lot. So I took a hard look at the photographs. Knowing how difficult it is to take photographs through a microscope, I assumed that most of the turns in the "wire under microscope" shot were out of focus and invisible, but that the two adjacent turns on the right hand side represent the winding pitch of 20um. The active length of the resistor is about 18mm, so it has 900 turns. For 5um wire and 1M, that would need a rho of 170 compared to the 43 of manganin, which seems perfectly possible. The huge gain from winding single layer is that you don't need lacquered wire, so you can use the available space more efficiently.Using the photograph of the dissected LT450 resistor earlier in this thread (and an LT450 that I could measure), I estimated its internal bobbin size and calculated what wire diameter and length would achieve 1M in the volume available. I assumed 8um thick lacquer and needed 411m of 15um manganin wire. That was 2.4 kohm per metre. Oh, and 20,465 turns.

author: mawyatt
author_rank: Super Contributor
timestamp: July 24, 2023, 04:33:11 pm
content: Quote from: alm on July 24, 2023, 12:15:11 amIn the concept that iMo proposed, making a continuous WW resistor and tapping the appropriate point for the divider, the power is dissipated equally along the physical resistor because each incremental segment sees the same current and thus the same dissipation per length because of constant effective resistance per length of the resistor.So if our understanding is correct, then iMo's concept wouldn't experience any change in voltage division ratio due to temperature, either ambient or induced (self heating). Of course in reality there will be some variations in this due to resistor non-uniformity, especially at the tap and ends.Best,

author: alm
author_rank: Super Contributor
timestamp: July 24, 2023, 09:04:53 pm
content: Quote from: mawyatt on July 24, 2023, 04:33:11 pmI agree that that would mitigate the problem, but it is important to stay aware of it and not blindly assume that matching tempco of resistors means no net tempco on the output of the divider, especially because the TC of manganin can be quite substantial. Dissipation at the ends near the leads will be much higher than in the middle.

author: iMo
author_rank: Super Contributor
timestamp: July 25, 2023, 06:54:15 am
content: The power dissipation is not a big issue, imho, as it will be constant. We talk here the feedback divider - the biggest trouble maker with the 7->10V amplifier.With say (R1+R2) in a typical range 5k to 20k the Ptot will be 20mW to 5mW. That is not small, but constant (as the 10V output will be +/- couple of ppm worst case).With both R1 and R2 wound on the same bobbin the temperature difference between R1 and R2 should stay constant, afaik. With changing the ambient the temperature of (R1+R2) will change accordingly, but the difference stays the same.The ratio will beRatio = R1*(1+TC*(Tr1-25)) / R2*(1+TC(Tr2-25)), where (Tr1+Tamb)-(Tr2+Tamb)=const.Basically the Vishay divider with 3 legsPS: I would even try with lower valued (R1+R2), like 1k. We use usually transistor buffer at the output, thus the 10mA via the divider cannot hurt (100mW), imho, the elevated temperature of the divider may even help to repel the humidity inside the resistor off.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: July 26, 2023, 01:48:38 am
content: Totally OT, but manganin is also used to make high pressure sensors-https://strainblog.micro-measurements.com/content/manganin-pressure-gages

author: iMo
author_rank: Super Contributor
timestamp: July 26, 2023, 10:04:32 am
content: Quote from: Conrad Hoffman on July 26, 2023, 01:48:38 amThus we should not use the manganin resistors in ref sources inside a submersible made of carbon fibre

author: iMo
author_rank: Super Contributor
timestamp: July 27, 2023, 12:24:11 pm
content: Some first hand info on Manganin. The TC in Graph 1 and 2.It looks like they produce a specific compositions for specific box with minimum TC..

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: July 27, 2023, 06:02:34 pm
content: The above data sheet refers to technical info regarding aging (and soldering/brazing), so here's that. I also consider the thermal emf against copper. There are some alloys that would be excellent, except they have a high thermocouple voltage.

author: Kleinstein
author_rank: Super Contributor
timestamp: July 27, 2023, 06:17:24 pm
content: The use in pressure sensors is not because of special, extra strong reaction to pressure or strain. This are normal DMS. The relative resistance change with strain is quite similar between metal alloys. The choice is more to look for alloys with low TC and a low tendency for mechanical creepage and a suitable thermal expansion depending on the material of the elastic element.