On Mon, 21 Jun 2021 08:55:46 +0200, Piotr Wyderski <bombald@protonmail.com> wrote:>John Larkin wrote: > >> In the RTD case, horrible transient values when a value is changed. >> like spiking to 500 deg C for some milliseconds, going from 48 to 49. >> Engine control computers don't like that. > >No Gray-or-compatible encoding? That's too bad. > > Best regards, PiotrIt's hard to do that with relays switching resistors, especially relays that bounce a lot. I guess it could be done, but it would take too many relays and resistors. We do resistor simulation electronically. That can be kept monotonic. -- John Larkin Highland Technology, Inc trk The cork popped merrily, and Lord Peter rose to his feet. "Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"
Wetting current
Started by ●June 17, 2021
Reply by ●June 21, 20212021-06-21
Reply by ●June 21, 20212021-06-21
You might look into the BSTJ archives. I recall chatting 20 years ago with someone from the Labs who had studied it intensively. A shortcut to them is <http://etler.com/docs/BSTJ/archive.html> -- A host is a host from coast to coast.................wb8foz@nrk.com & no one will talk to a host that's close.......................... Unless the host (that isn't close).........................pob 1433 is busy, hung or dead....................................20915-1433
Reply by ●June 22, 20212021-06-22
Bill Sloman <bill.sloman@ieee.org> wrote:> On Sunday, June 20, 2021 at 11:26:16 AM UTC+10, John Larkin wrote: >> On Sat, 19 Jun 2021 21:21:56 +0000 (UTC), Cydrome Leader >> <pres...@MUNGEpanix.com> wrote: >> >> >John Larkin <jlarkin@highland_atwork_technology.com> wrote: >> >> On Fri, 18 Jun 2021 19:08:37 +0000 (UTC), Cydrome Leader >> >> <pres...@MUNGEpanix.com> wrote: >> >> >> >>>John Larkin <jlarkin@highland_atwork_technology.com> wrote: >> >>>> On Fri, 18 Jun 2021 09:18:19 -0700 (PDT), John Walliker >> >>>> <jrwal...@gmail.com> wrote: > > <>snip> > >> >maybe you need some lovely mercury wetted relays. > > They are nice but you do have to mount them so they stray vertical. Orientation-insensitive mercury wetted reeds did get touted from time to time, but never lasted. > >> We use lots of Fujitsu FTR-B3G relays... almost 100K so far. >> >> DPDT, surface mount, small and reliable. We use the latching version at thermocouple levels. They are good up to 3 GHz too. >> >> Reeds are expensive junk. > > Of course Bell Labs develped them because they needed something more reliable than traditional relays for the telephone network. > > They were invented in Russia in 1922, but Bell Labs developed them into something useful in the 1930s - there's a 1941 US patent. > > If John Larkin doesn't like them, it probably means that he didn't use them as carefully as he should have. > > https://en.wikipedia.org/wiki/Reed_switchWell it's not 1930 anymore and the applications for reed switches are few and far in between. The wiki article even mentioned reed switches being used as sensors in old brushless motors. Awful.
Reply by ●June 22, 20212021-06-22
On 23/6/21 8:32 am, Cydrome Leader wrote:> Bill Sloman <bill.sloman@ieee.org> wrote: >> On Sunday, June 20, 2021 at 11:26:16 AM UTC+10, John Larkin wrote: >>> On Sat, 19 Jun 2021 21:21:56 +0000 (UTC), Cydrome Leader >>> <pres...@MUNGEpanix.com> wrote: >>> >>>> John Larkin <jlarkin@highland_atwork_technology.com> wrote: >>>>> On Fri, 18 Jun 2021 19:08:37 +0000 (UTC), Cydrome Leader >>>>> <pres...@MUNGEpanix.com> wrote: >>>>> >>>>>> John Larkin <jlarkin@highland_atwork_technology.com> wrote: >>>>>>> On Fri, 18 Jun 2021 09:18:19 -0700 (PDT), John Walliker >>>>>>> <jrwal...@gmail.com> wrote: >> >> <>snip> >> >>>> maybe you need some lovely mercury wetted relays. >> >> They are nice but you do have to mount them so they stray vertical. Orientation-insensitive mercury wetted reeds did get touted from time to time, but never lasted. >> >>> We use lots of Fujitsu FTR-B3G relays... almost 100K so far. >>> >>> DPDT, surface mount, small and reliable. We use the latching version at thermocouple levels. They are good up to 3 GHz too. >>> >>> Reeds are expensive junk. >> >> Of course Bell Labs develped them because they needed something more reliable than traditional relays for the telephone network. >> >> They were invented in Russia in 1922, but Bell Labs developed them into something useful in the 1930s - there's a 1941 US patent. >> >> If John Larkin doesn't like them, it probably means that he didn't use them as carefully as he should have. >> >> https://en.wikipedia.org/wiki/Reed_switch > > Well it's not 1930 anymore and the applications for reed switches are few > and far in between. The wiki article even mentioned reed switches being > used as sensors in old brushless motors. Awful.Bosch are still using reed switches to make their dishwashers unreliable So much for "German engineering" CH
Reply by ●June 24, 20212021-06-24
Clifford Heath <no.spam@please.net> wrote:> On 23/6/21 8:32 am, Cydrome Leader wrote: >> Bill Sloman <bill.sloman@ieee.org> wrote: >>> On Sunday, June 20, 2021 at 11:26:16 AM UTC+10, John Larkin wrote: >>>> On Sat, 19 Jun 2021 21:21:56 +0000 (UTC), Cydrome Leader >>>> <pres...@MUNGEpanix.com> wrote: >>>> >>>>> John Larkin <jlarkin@highland_atwork_technology.com> wrote: >>>>>> On Fri, 18 Jun 2021 19:08:37 +0000 (UTC), Cydrome Leader >>>>>> <pres...@MUNGEpanix.com> wrote: >>>>>> >>>>>>> John Larkin <jlarkin@highland_atwork_technology.com> wrote: >>>>>>>> On Fri, 18 Jun 2021 09:18:19 -0700 (PDT), John Walliker >>>>>>>> <jrwal...@gmail.com> wrote: >>> >>> <>snip> >>> >>>>> maybe you need some lovely mercury wetted relays. >>> >>> They are nice but you do have to mount them so they stray vertical. Orientation-insensitive mercury wetted reeds did get touted from time to time, but never lasted. >>> >>>> We use lots of Fujitsu FTR-B3G relays... almost 100K so far. >>>> >>>> DPDT, surface mount, small and reliable. We use the latching version at thermocouple levels. They are good up to 3 GHz too. >>>> >>>> Reeds are expensive junk. >>> >>> Of course Bell Labs develped them because they needed something more reliable than traditional relays for the telephone network. >>> >>> They were invented in Russia in 1922, but Bell Labs developed them into something useful in the 1930s - there's a 1941 US patent. >>> >>> If John Larkin doesn't like them, it probably means that he didn't use them as carefully as he should have. >>> >>> https://en.wikipedia.org/wiki/Reed_switch >> >> Well it's not 1930 anymore and the applications for reed switches are few >> and far in between. The wiki article even mentioned reed switches being >> used as sensors in old brushless motors. Awful. > > Bosch are still using reed switches to make their dishwashers unreliable > > So much for "German engineering"I've never buy anything from bosch but a few power tools. european appliances are just pure trash when it comes to design and repairability. Oh, the cars too.
Reply by ●June 30, 20212021-06-30
On Friday, June 18, 2021 at 2:11:47 PM UTC-7, John Larkin wrote:> On Fri, 18 Jun 2021 19:08:37 +0000 (UTC), Cydrome Leader > <pres...@MUNGEpanix.com> wrote:> >What's some weirdness you see with reed relay logic?>... I discovered reed twang some years ago. The reed wiggles like a struck > bell when it's energized, very complex waveforms lasting many > milliseconds. In the coil mag field, that makes biggish voltages.That's why one 'powers' a relay coil, instead of signalling it. The motion of the contacts means the device is an electric motor, with all the back-EMF you expect, generated by moving magnetic parts in the field of the coil.
Reply by ●June 30, 20212021-06-30
On Saturday, June 19, 2021 at 6:26:16 PM UTC-7, John Larkin wrote:> We use lots of Fujitsu FTR-B3G relays... almost 100K so far. > > DPDT, surface mount, small and reliable. We use the latching version > at thermocouple levels. They are good up to 3 GHz too. > > Reeds are expensive junk.Do your FTR-B3G things work while wet with solvents, hot, and in a corrosive atmosphere? Can you position them to serve as coil-current or B-field detectors? How's the explosion-proofing on those make/break events, in case you need 'em in a petroleum-handling facility? Did you ever pot an assembly with relays? Reeds have their uses. I'm puzzled how there's a thermocouple problem; other than length of the capsule, there's nothing to encourage thermal gradients, and both glass-seal metal elements ARE the same alloy. Contact plating is a few microns, not a problem at all.
Reply by ●June 30, 20212021-06-30
On Wed, 30 Jun 2021 11:30:46 -0700 (PDT), whit3rd <whit3rd@gmail.com> wrote:>On Saturday, June 19, 2021 at 6:26:16 PM UTC-7, John Larkin wrote: > >> We use lots of Fujitsu FTR-B3G relays... almost 100K so far. >> >> DPDT, surface mount, small and reliable. We use the latching version >> at thermocouple levels. They are good up to 3 GHz too. >> >> Reeds are expensive junk. > >Do your FTR-B3G things work while wet with solvents, hot, and in a corrosive atmosphere?They work great in our products. DPDT, nanovolt offsets, 3 GHz bandwidth, $1.32 for the non-latching surface-mount version.>Can you position them to serve as coil-current or B-field detectors?Coil current, sure. They have coils. But I want signal switching, not mag field detectors. Reed relays are fun B_field sensors. If one is energized, it can keep an adjacent one from dropping out. The open coil field leaks all over the place.>How's the explosion-proofing on those make/break events, in case you need 'em in a >petroleum-handling facility? >Did you ever pot an assembly with relays? > >Reeds have their uses. >I'm puzzled how there's a thermocouple problem; other than length of the capsule, >there's nothing to encourage thermal gradients, and both glass-seal metal elements >ARE the same alloy. Contact plating is a few microns, not a problem at all.Nice in theory, but they have terrible thermocouple offsets in real life. The coil gets hot and the leads are not the same metal as the reeds.
Reply by ●June 30, 20212021-06-30
On Wed, 30 Jun 2021 11:00:01 -0700 (PDT), whit3rd <whit3rd@gmail.com> wrote:>On Friday, June 18, 2021 at 2:11:47 PM UTC-7, John Larkin wrote: >> On Fri, 18 Jun 2021 19:08:37 +0000 (UTC), Cydrome Leader >> <pres...@MUNGEpanix.com> wrote: > >> >What's some weirdness you see with reed relay logic? > >>... I discovered reed twang some years ago. The reed wiggles like a struck >> bell when it's energized, very complex waveforms lasting many >> milliseconds. In the coil mag field, that makes biggish voltages. > >That's why one 'powers' a relay coil, instead of signalling it. >The motion of the contacts means the device is an electric motor, >with all the back-EMF you expect, generated by moving >magnetic parts in the field of the coil.Why do some people love and defend reeds? They are expensive, unreliable, usually just SPST, twang, have big thermals, are giant compared to a modern telecom relay, and have to be kept apart from one another. You and sloman love reeds and love China. You're probably the same person.
Reply by ●June 30, 20212021-06-30
On Wednesday, June 30, 2021 at 1:40:53 PM UTC-7, John Larkin wrote:> On Wed, 30 Jun 2021 11:30:46 -0700 (PDT), whit3rd <whi...@gmail.com> > wrote: > >On Saturday, June 19, 2021 at 6:26:16 PM UTC-7, John Larkin wrote:> >Reeds have their uses. > >I'm puzzled how there's a thermocouple problem; other than length of the capsule, > >there's nothing to encourage thermal gradients, and both glass-seal metal elements > >ARE the same alloy. Contact plating is a few microns, not a problem at all.> Nice in theory, but they have terrible thermocouple offsets in real > life. The coil gets hot and the leads are not the same metal as the > reeds.The leads are part of the magnetic circuit, they ARE the same metal in all the examples I've seen. Are you talking about RELAY leads, or reed leads? Coil dissipation is less of an issue in latching relays, but you can make those with reeds if you care to. It's an easy design with a cruciform pole piece.
