On Mon, 5 Oct 2020 21:37:08 -0400, bitrex <user@example.net> wrote:>On 10/5/2020 1:53 PM, John Larkin wrote: >> On Sat, 3 Oct 2020 11:29:28 -0400, bitrex <user@example.net> wrote: >> >>> On 10/3/2020 10:49 AM, jlarkin@highlandsniptechnology.com wrote: >>>> On Fri, 2 Oct 2020 22:10:30 -0700, Joerg <news@analogconsultants.com> >>>> wrote: >>>> >>>>> On 10/2/20 4:42 PM, John Larkin wrote: >>>>>> On Fri, 2 Oct 2020 13:14:58 -0700, Joerg <news@analogconsultants.com> >>>>>> wrote: >>>>>> >>>>>>> On 10/1/20 9:30 AM, jlarkin@highlandsniptechnology.com wrote: >>>>> >>>>> [...] >>>>> >>>>>>>> https://www.dropbox.com/s/uf15erm1nj3tjjk/Colpitts_125.JPG?raw=1 >>>>>>>> >>>>>>>> There are varicaps and things too. Everything affects the tempco. I >>>>>>>> can tune C4 to zap the 1st order term. >>>>>>>> >>>>>>>> Worst case, every batch of PCBs could have a different value of C4. >>>>>>>> Production would *not* like that. >>>>>>>> >>>>>>> >>>>>>> Whenever I had something like that I'd always use a varicap and some >>>>>>> sort of algorithm. The production guys didn't even have to know it was >>>>>>> there. >>>>>> >>>>>> My oscillator has a varicap, part of the PLL. Of course, a varicap has >>>>>> a tempco the varies with the applied voltage! >>>>>> >>>>> >>>>> Yeah, another error term and probably non-linear. >>>>> >>>>>>> >>>>>>> Of course, there is the other option of running the whole board in >>>>>>> transformer oil :-) >>>>>> >>>>>> Smile when you say that. >>>>>> >>>>>> It's impressive how isothermal a 10-layer board can be. Lots of >>>>>> copper! >>>>>> >>>>>> We need to rev the board, so I could add heater resistors and a >>>>>> dedicated temp sensor under the oscillator. With luck, we'd never have >>>>>> to use them. Depends on whether my tempco tuning is reproducible in >>>>>> production. >>>>>> >>>>>> Another reason to spin the layout: I was having time-delay jitter >>>>>> going through one FPGA, synchronous to a switcher in the opposite >>>>>> corner of the board. I couldn't understand that, so I disabled the >>>>>> switcher with some difficulty and hacked in a linear reg. That fixed >>>>>> it. >>>>>> >>>>> >>>>> We've had similar effects in pulsed Doppler ultrasound systems. Those >>>>> are like a princess on the pea when it comes to jitter on any of the >>>>> clocks. What I sometimes did is run a coax or (after relayout) a trace >>>>> over to the oscillator or stage that was affected and coupled in >>>>> opposite phase via a sub-pF ceramic cap. The guys usually thought that >>>>> was voodoo but it worked reliably and most of all repeatably so >>>>> production didnt have to worry about it. >>>>> >>>>> >>>>>> A real pain to do. I had to drill out some vias to disable the >>>>>> switcher. >>>>>> >>>>>> https://www.dropbox.com/s/ghu5rid4ks0bbfl/1v8_Hack.jpg?raw=1 >>>>>> >>>>>> https://www.dropbox.com/s/g4llhvgq38cqedh/1v8_hack_Jitter.jpg?raw=1 >>>>>> >>>>>> Much of that jitter is probably from the scope. >>>>>> >>>>> >>>>> Do you have a before-after comparison? >>>> >>>> I don't have a good "before" pic handy. P-P jitter was about 2x what >>>> it is now. >>>> >>>> I noticed that the jitter would squirm as a function of trigger rate. >>>> The heterodyne frequency corresponded exactly to the switching >>>> frequency of one of the LTM8078 switchers (which are themselves >>>> remarkably frequency stable.) It was the 1.8 volt Vcc_aux power supply >>>> to two FPGAs, one directly in the delay path. >>>> >>>> I doubt that Vcc_aux affects prop delay much; it doesn't for DC >>>> changes. It may do nasty capacitive things inside the chip. >>>> >>>> This Xilinx chip is very sensitive to core voltage, like -5 or -10 ps >>>> per millivolt. >>>> >>>> The whole front end of this box could have been ECL, but that takes a >>>> lot of room and power and dollars. >>>> >>>> My goal is to make a delay generator with 1 ps RMS jitter. I can >>>> probably get below 5. >>>> >>>> We'll announce this soon. >>>> >>>> https://www.dropbox.com/s/j3fycoyhpus0vpc/a4.jpg?raw=1 >>>> >>> >>> Thank u for keeping in mind that 10-12% of the adult male population is >>> color-blind and that labels on heavily-used buttons wear off >> >> The LCD is black on white. Each button is single color backlit with >> obvious text. >> >> You're straining to disapprove of a beautiful box. Why? > >????? > >> You'd better not buy one. >> >> > >No I was actually thanking youOh, I thought you were being sardonic. Or halfway sardonic. It's hard to tell. The text on the buttons is ink-jet printed on silicone. That might wear off. -- John Larkin Highland Technology, Inc Science teaches us to doubt. Claude Bernard
dangerous profession
Started by ●October 1, 2020
Reply by ●October 5, 20202020-10-05
Reply by ●October 5, 20202020-10-05
On Mon, 5 Oct 2020 21:13:18 -0400, bitrex <user@example.net> wrote:>On 10/5/2020 2:04 PM, John Larkin wrote: >> On Sat, 3 Oct 2020 23:27:35 +0000 (UTC), David Lesher >> <wb8foz@panix.com> wrote: >> >>> jlarkin@highlandsniptechnology.com writes: >>> >>> >>>> In the last week, I've been burned 6 times, shocked once, punctured >>>> (with blood) twice, and had to eat a single burger for three lunches >>>> in a row. And we are out of ice cream sandwiches. >>> >>> Speaking of "out of..". >>> <https://youtu.be/Du5YK5FnyF4> >> >> >> Shooting and killing and explosions and hatred is mostly what >> Hollywood does nowadays, while preaching gun control and peace and >> love. > >Almost like they've learned that overestimating American's intelligence >is rarely profitable.Most of the cartoon superhero movies are sold overseas.> >That is to say they know their market. > >Or China's for that matter, which will soon make up the bulk of >Hollywood's market, if it hasn't already. Much English-language nuance >doesn't translate well to Mandarin. Kind of like telling jokes to engineersViolence is the universal language. I'd expect that romantic comedies don't sell well in very different cultures. -- John Larkin Highland Technology, Inc Science teaches us to doubt. Claude Bernard
Reply by ●October 5, 20202020-10-05
> My Rigol scope for example uses one button called START/STOP to start > and stop and uses a green/red LED to indicate which mode it's in > > 10-12% of the adult male population is color blind with red/green the > most common!And the number is higher when the group self-selects, e.g. musicians. When bi-color LEDs came out, we thought it would be the coolest thing to add them to our audio fx processors. Green means you have a good signal, red means clipping. By chance, none of our beta testers were colorblind, but > 15% of our customers were, and they really raked us across the coals for that one.
Reply by ●October 5, 20202020-10-05
On 10/5/2020 9:54 PM, jlarkin@highlandsniptechnology.com wrote:> On Mon, 5 Oct 2020 21:37:08 -0400, bitrex <user@example.net> wrote: > >> On 10/5/2020 1:53 PM, John Larkin wrote: >>> On Sat, 3 Oct 2020 11:29:28 -0400, bitrex <user@example.net> wrote: >>> >>>> On 10/3/2020 10:49 AM, jlarkin@highlandsniptechnology.com wrote: >>>>> On Fri, 2 Oct 2020 22:10:30 -0700, Joerg <news@analogconsultants.com> >>>>> wrote: >>>>> >>>>>> On 10/2/20 4:42 PM, John Larkin wrote: >>>>>>> On Fri, 2 Oct 2020 13:14:58 -0700, Joerg <news@analogconsultants.com> >>>>>>> wrote: >>>>>>> >>>>>>>> On 10/1/20 9:30 AM, jlarkin@highlandsniptechnology.com wrote: >>>>>> >>>>>> [...] >>>>>> >>>>>>>>> https://www.dropbox.com/s/uf15erm1nj3tjjk/Colpitts_125.JPG?raw=1 >>>>>>>>> >>>>>>>>> There are varicaps and things too. Everything affects the tempco. I >>>>>>>>> can tune C4 to zap the 1st order term. >>>>>>>>> >>>>>>>>> Worst case, every batch of PCBs could have a different value of C4. >>>>>>>>> Production would *not* like that. >>>>>>>>> >>>>>>>> >>>>>>>> Whenever I had something like that I'd always use a varicap and some >>>>>>>> sort of algorithm. The production guys didn't even have to know it was >>>>>>>> there. >>>>>>> >>>>>>> My oscillator has a varicap, part of the PLL. Of course, a varicap has >>>>>>> a tempco the varies with the applied voltage! >>>>>>> >>>>>> >>>>>> Yeah, another error term and probably non-linear. >>>>>> >>>>>>>> >>>>>>>> Of course, there is the other option of running the whole board in >>>>>>>> transformer oil :-) >>>>>>> >>>>>>> Smile when you say that. >>>>>>> >>>>>>> It's impressive how isothermal a 10-layer board can be. Lots of >>>>>>> copper! >>>>>>> >>>>>>> We need to rev the board, so I could add heater resistors and a >>>>>>> dedicated temp sensor under the oscillator. With luck, we'd never have >>>>>>> to use them. Depends on whether my tempco tuning is reproducible in >>>>>>> production. >>>>>>> >>>>>>> Another reason to spin the layout: I was having time-delay jitter >>>>>>> going through one FPGA, synchronous to a switcher in the opposite >>>>>>> corner of the board. I couldn't understand that, so I disabled the >>>>>>> switcher with some difficulty and hacked in a linear reg. That fixed >>>>>>> it. >>>>>>> >>>>>> >>>>>> We've had similar effects in pulsed Doppler ultrasound systems. Those >>>>>> are like a princess on the pea when it comes to jitter on any of the >>>>>> clocks. What I sometimes did is run a coax or (after relayout) a trace >>>>>> over to the oscillator or stage that was affected and coupled in >>>>>> opposite phase via a sub-pF ceramic cap. The guys usually thought that >>>>>> was voodoo but it worked reliably and most of all repeatably so >>>>>> production didnt have to worry about it. >>>>>> >>>>>> >>>>>>> A real pain to do. I had to drill out some vias to disable the >>>>>>> switcher. >>>>>>> >>>>>>> https://www.dropbox.com/s/ghu5rid4ks0bbfl/1v8_Hack.jpg?raw=1 >>>>>>> >>>>>>> https://www.dropbox.com/s/g4llhvgq38cqedh/1v8_hack_Jitter.jpg?raw=1 >>>>>>> >>>>>>> Much of that jitter is probably from the scope. >>>>>>> >>>>>> >>>>>> Do you have a before-after comparison? >>>>> >>>>> I don't have a good "before" pic handy. P-P jitter was about 2x what >>>>> it is now. >>>>> >>>>> I noticed that the jitter would squirm as a function of trigger rate. >>>>> The heterodyne frequency corresponded exactly to the switching >>>>> frequency of one of the LTM8078 switchers (which are themselves >>>>> remarkably frequency stable.) It was the 1.8 volt Vcc_aux power supply >>>>> to two FPGAs, one directly in the delay path. >>>>> >>>>> I doubt that Vcc_aux affects prop delay much; it doesn't for DC >>>>> changes. It may do nasty capacitive things inside the chip. >>>>> >>>>> This Xilinx chip is very sensitive to core voltage, like -5 or -10 ps >>>>> per millivolt. >>>>> >>>>> The whole front end of this box could have been ECL, but that takes a >>>>> lot of room and power and dollars. >>>>> >>>>> My goal is to make a delay generator with 1 ps RMS jitter. I can >>>>> probably get below 5. >>>>> >>>>> We'll announce this soon. >>>>> >>>>> https://www.dropbox.com/s/j3fycoyhpus0vpc/a4.jpg?raw=1 >>>>> >>>> >>>> Thank u for keeping in mind that 10-12% of the adult male population is >>>> color-blind and that labels on heavily-used buttons wear off >>> >>> The LCD is black on white. Each button is single color backlit with >>> obvious text. >>> >>> You're straining to disapprove of a beautiful box. Why? >> >> ????? >> >>> You'd better not buy one. >>> >>> >> >> No I was actually thanking you > > Oh, I thought you were being sardonic. Or halfway sardonic. It's hard > to tell. > > The text on the buttons is ink-jet printed on silicone. That might > wear off. > >RUN and STOP will probably wear off before anything else so making it say RATE/STOP should help defer any key-swaps for many years. The printing on my car's start button is already wearing off it's been less than 4 years, couldn't they emboss it or something? Chevrolet cheap bastards
