Re: [volt-nuts] PCBs with ceramic substrates
We used them in the supercomputer space long long ago. Mount 8 die to ceramic substrate, mount those to Rogers boards. Thermal wasn't really an issue as everything was bathed in Flourinert™. Was an interesting project. The Unix kernel scheduler had to make scheduling decisions based on all the usual criteria plus how far away the free CPU and/or memory was. Bob On Fri, Apr 7, 2017 at 2:12 PM, cheater00 cheater00 wrote: > Hi Attilla, > My #1 worry would be fragility. > > On Thu, 6 Apr 2017 06:39 Attila Kinali, wrote: > > > Moin, > > > > I recently wondered, why people around voltage metrology hardly > > talk about ceramic substrates (Al2O3, AlN, ...) for PCBs. > > They have surface resistivity that is as high as PTFE, have > > higher thermal conductivity, lower thermal expansion (AlN is > > even pretty close to Si). So, why then does it hardly ever get > > mentioned? Is it the cost of those? Or is there something I am > > missing? > > > > Attila Kinali > > > > -- > > You know, the very powerful and the very stupid have one thing in common. > > They don't alters their views to fit the facts, they alter the facts to > > fit the views, which can be uncomfortable if you happen to be one of the > > facts that needs altering. -- The Doctor > > ___ > > volt-nuts mailing list -- volt-nuts@febo.com > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > > and follow the instructions there. > > > ___ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/volt-nuts > and follow the instructions there. > ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Availability of 3458A in Europe after the end of 2016.
I suspect there are many many exemptions through categorical types. I have quite a few discrete components at home and subassembly type components of server class systems at work (power supplies in particular) that are 'compliant by exemption' according to the documentation. Yet on the component itself it says 'RoHS'. > On Nov 13, 2016, at 10:34, Dr. David Kirkby (Kirkby Microwave Ltd) > wrote: > >> On 13 November 2016 at 14:17, Chuck Harris wrote: >> >> RoHS does not apply to test equipment. > > Where do you get that from? When I was looking briefly the other day, there > did not seem to be a lot of exemptions. > > I'm sure Keysight must be a bit more on the ball than to put that notice, > if RoHS did not apply to test equipment. > > There's a similar notice about a power supply I have - 6674A (70 V @ 30 A > PSU). > > Dave > ___ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] LTZ1000 project build
As Dr K said, traceable and usefully calibrated are not necessarily connected. I can calibrate to any arbitrary standard I like. That standard need not be traceable if all that is important to me is consistency across all the instruments in my lab. If I, on the other hand, want to be consistent with someone else's lab, then we need to be traceable to a common source. Thus NIST. I presume most countries have a NIST like organization. How often to they cross check each other? Accreditation, on the other hand can be, as the good Dr. points out, pretty useless unless the accreditation body is, itself, held to some (professional) standard. And I'd also love to build one of these if there is enough interest. While I'm sure we can't get enough orders to get the 100pcs discount on the LTZ1000, it would be a great group project and I'd be willing to participate in bringing it to fruition. I'm also sure I can find a calibrated, traceable, reliable 3458 in the area code. The irony is that while I'm less than 15Km from the New York State Bureau of Weights & Measures Metrology group, which has all the traceable standards for the state, they cannot do high accuracy for time or voltage. My personal house standards are better than theirs for those two. By a lot. Adding one of these would add a few more orders of magnitude...:) > On May 25, 2016, at 17:06, Dr. David Kirkby (Kirkby Microwave Ltd) > wrote: > >> On 25 May 2016 at 19:24, Russ Ramirez wrote: >> >> A lot of great information Eric, thanks for sharing the link. >> >> Due to my ignorance in general on the subject of Metrology, I have the >> following question for the list. >> >> If one built a project with the LTZ1000, like the one described on xDevs >> and could set it to a value of 7.1500v at the NIST lab, and observed >> stability to 7 1/2 digits, would using that device to calibrate your own 7 >> 1/2 digit DMM be considered NIST traceable? Let's say your device is well >> insulated and battery powered, and your calibration was done at the same >> altitude and room temperature as at NIST, plus anything I left out that >> would make the conditions ideal. >> >> The above was not meant to be a trick question, and I may have asked it >> incorrectly, but I view the answers as instructive - or I hope they are. >> >> Russ > > As far as I can determine, as long as you can work out the uncertainties, > no matter how large they might b, the measurement is traceable. If you use > a 3.5 digit multimeter that is NIST traceable to calibrate a 7.5 digit > multimeter, the calibration is still NIST traceable. The calibration will > be pretty useless, and you may not be accredited, but it is still NIST > traceable. > > Or if you want to be accredited, get your mate down the local pub (bar) to > accredit you! > > On a more serious note, if people felt that design was good, and wanted to > produce the PCBs. and/or make parts available, I'd be interested. I only > have a 6.5 digit meter, but feel sure I could find someone with a 3458A in > the UK who could measure the voltage for me. > > Dave > ___ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] current-nut question .. total waste of ones time type question
There was a Circuit Cellar article on this many moons ago. Basically, it was: Take a torroid ferrite core, wrap ~20 turns of #20 through it, pass the wire you want to sense current in through the core, and hook the output of the coil to an op amp. Look at output of op amp with a/d converter. Do some math. :) I have a few on individual circuits in my electrical panel (sump pump, furnace, etc). I dipped the coil assembly in plasti-dip to insulate them. Have not looked at it in a long while though. The control processor croaked and I've never bothered to fix it. Bob > On Apr 29, 2014, at 13:25, Pete Lancashire wrote: > > Next spring I'm going be rewiring my house. And for 'fun' I want to drop a > couple current sensors on the input side of the main panel. > > Being a beginner 'nut', I'm looking for more accuracy then needed. > > Voltage, Frequency, waveform will be taken care of later, but accurate > current has be a bit flustered. > > I've been reading up on CT's Iron core and Ferrite, and on Rogowski coils. > And the many new IC's on the market that take care of a lot of things. > > Has someone done this before ? And if so any experiences to share ? > > -pete > ___ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
