I had not heard of them, either. But I'm willing to bet copper is much cheaper than platinum, so the copper RTD gets used. Bill On Mon, Sep 11, 2017 at 2:11 PM, Sean Breheny wrote: > I've never heard of a Copper RTD. While Copper has quite a high tempco of > resistance, I think it is much more difficult to get a very accurate valu= e > for it than it is for Platinum so most metal-based RTDs use Platinum. > > On Mon, Sep 11, 2017 at 1:54 PM, William Couture > wrote: > > > I ran into this sensor when I bought a cheap Chinese controller -- it > came > > with one. > > > > I write software for industrial process controllers professionally, and > > occasionally buy > > one of the cheap controllers I see around (aliexpress, ebay) just to se= e > > how they are > > built and how capable they are. > > > > I'd never heard of a CU-50 RTD, and couldn't find anything except the o= ne > > image I > > linked to. > > > > I though one of you might provide more insight. > > > > Bill > > > > On Sat, Sep 9, 2017 at 6:41 PM, wrote: > > > > > Quoting William Couture : > > > > > > > Both those charts have different thermal coefficients, and have > > different > > > > "zero" scales -- the 10R is 10R at 25C, the 100R is 100R at 0C. > > > > > > > > the 10R chart multiplied by 5.5356 is closer, but it's strange that= a > > > real > > > > chart can't be found anywhere... > > > > > > > > Bill > > > > > > They're all real- it's just that there is no international standard > > > for Cu RTDs that I know of. You have not mentioned why you want this- > > > obviously if you are buying the sensor you are going to want to go to > > > the manufacturer for the data. If you are trying to make a general > > > purpose indicator or controller.. you might want to use this (assumin= g > > > the reference temperature of 25 C is appropriate..) > > > > > > http://www.pyromation.com/Downloads/Data/427_c.pdf > > > > > > Again, scale the numbers appropriately (5:1 in this case). Anything > > that's > > > within a degree or two C at the extremes is probably better than the > > sensor > > > interchangeability. > > > > > > Where exactly did you run into a 50 ohm copper RTD? > > > > > > --sp > > > > > > > > > > > On Fri, Sep 8, 2017 at 10:15 PM, wrote: > > > > > > > >> Quoting William Couture : > > > >> > > > >> > Or possibly [OT] -- maybe I'm searching with the correct terms, > but > > > I'm > > > >> > trying to find > > > >> > an resistance chart for a CU-50 RTD probe. > > > >> > > > > >> > The best I've been able to come up with is this image, which isn= 't > > > quite > > > >> > readable: > > > >> > > > > >> > https://is.alicdn.com/img/pb/747/046/531/531046747_904.jpg > > > >> > > > > >> > Pointers to something better? > > > >> > > > > >> > Thanks! > > > >> > Bill > > > >> > > > > >> > > > >> http://www.thermometricscorp.com/PDFs/10_ohm_copper_rtd-0. > > > 00427_in_C.PDF > > > >> > > > >> Multiply numbers by 5. > > > >> > > > >> OR > > > >> > > > >> http://www.thermometricscorp.com/images/Accessories/ > > > >> thermometricscorp_2129_12162627.gif > > > >> > > > >> Halve these numbers. > > > >> > > > >> depending on whether it's 50R at 0 degrees C or at 25 degrees C. > > > >> > > > >> There may be others based on 75F or something. > > > >> > > > >> Copper RTDs are all over place in terms of the quoted resistance > (and > > > >> therefore the tempco) when you get down to the last decimal place = or > > > >> two, AFAIK there is no standard. > > > >> > > > >> One of the main applications would be homemade with a bit of wire > left > > > over > > > >> from winding the motor, so annealing and exact composition would b= e > > > >> questionable. > > > >> > > > >> --sp > > > >> > > > >> > > > >> > > > >> > > > >> > > > >> > > > >> > > > >> -- > > > >> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > > > >> View/change your membership options at > > > >> http://mailman.mit.edu/mailman/listinfo/piclist > > > >> > > > > > > > > > > > > > > > > -- > > > > Psst... Hey, you... Buddy... Want a kitten? > > > straycatblues.petfinder.org > > > > -- > > > > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > > > > View/change your membership options at > > > > http://mailman.mit.edu/mailman/listinfo/piclist > > > > > > > > > > > > > > > > -- > > > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > > > View/change your membership options at > > > http://mailman.mit.edu/mailman/listinfo/piclist > > > > > > > > > > > -- > > Psst... Hey, you... Buddy... Want a kitten? > straycatblues.petfinder.org > > -- > > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > > View/change your membership options at > > http://mailman.mit.edu/mailman/listinfo/piclist > > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 Psst... Hey, you... Buddy... Want a kitten? straycatblues.petfinder.org --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .