Tww it the dimensionless factor (how many parts you tidly-wink and lose) / (how many parts you want) which, for 0603's, runs 0.6 or so.
Tww
Started by ●October 24, 2023
Reply by ●October 24, 20232023-10-24
On 10/25/2023 0:34, john larkin wrote:> Tww it the dimensionless factor > > (how many parts you tidly-wink and lose) / (how many parts you want) > > which, for 0603's, runs 0.6 or so. >Not sure I got what tww is (looked it up, some domino thing so I guess I get it if so) but 0402 are significantly worse, a lot more than twice worse. And I have not yet done any 0201...
Reply by ●October 24, 20232023-10-24
Dimiter_Popoff <dp@tgi-sci.com> wrote:> On 10/25/2023 0:34, john larkin wrote: >> Tww it the dimensionless factor >> >> (how many parts you tidly-wink and lose) / (how many parts you want) >> >> which, for 0603's, runs 0.6 or so. >> > > Not sure I got what tww is (looked it up, some domino thing so I > guess I get it if so) but 0402 are significantly worse, a lot more > than twice worse. And I have not yet done any 0201... >I highly recommend a good set of curved jaw tweezers, with a tiny binder clip on the hinge end. That lets you micro-adjust the tension by sliding the clip, so that they open when you squeeze them edgeways, and close very gently when you release. Good Medicine. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics
Reply by ●October 24, 20232023-10-24
On Wed, 25 Oct 2023 01:12:21 +0300, Dimiter_Popoff <dp@tgi-sci.com> wrote:>On 10/25/2023 0:34, john larkin wrote: >> Tww it the dimensionless factor >> >> (how many parts you tidly-wink and lose) / (how many parts you want) >> >> which, for 0603's, runs 0.6 or so. >> > >Not sure I got what tww is (looked it up, some domino thing so I >guess I get it if so) but 0402 are significantly worse, a lot more >than twice worse. And I have not yet done any 0201...When I first saw 1206's, I thought they were tiny. Ha! I refuse to use 0402's. I default to 0805s. I'm tuning the tempco of a 50 MHz triggrered Colpitts oscillator. What a nuisance. It should have a 3.3 pF N4700 0805 cap, but the layout guy used all 0603s, so some engineer (who shall not be named) substituted an 0603 NP0. "NTC" does sound a lot like "NPO" I guess. The proper 0805 cap was custom brewed for us by Capax.
Reply by ●October 25, 20232023-10-25
On 10/25/2023 1:40, Phil Hobbs wrote:> Dimiter_Popoff <dp@tgi-sci.com> wrote: >> On 10/25/2023 0:34, john larkin wrote: >>> Tww it the dimensionless factor >>> >>> (how many parts you tidly-wink and lose) / (how many parts you want) >>> >>> which, for 0603's, runs 0.6 or so. >>> >> >> Not sure I got what tww is (looked it up, some domino thing so I >> guess I get it if so) but 0402 are significantly worse, a lot more >> than twice worse. And I have not yet done any 0201... >> > > I highly recommend a good set of curved jaw tweezers, with a tiny binder > clip on the hinge end. That lets you micro-adjust the tension by sliding > the clip, so that they open when you squeeze them edgeways, and close very > gently when you release.This sounds interesting, would you please post a photo? I manage with my normal tweezers, two of those I have are good enough to get me through placing placing a lot of 0402-s, not too hard especially if the paste has not begun to dry so they stick. But yours might be helpful on less standard operations...
Reply by ●October 25, 20232023-10-25
On 10/25/2023 1:51, john larkin wrote:> On Wed, 25 Oct 2023 01:12:21 +0300, Dimiter_Popoff <dp@tgi-sci.com> > wrote: > >> On 10/25/2023 0:34, john larkin wrote: >>> Tww it the dimensionless factor >>> >>> (how many parts you tidly-wink and lose) / (how many parts you want) >>> >>> which, for 0603's, runs 0.6 or so. >>> >> >> Not sure I got what tww is (looked it up, some domino thing so I >> guess I get it if so) but 0402 are significantly worse, a lot more >> than twice worse. And I have not yet done any 0201... > > When I first saw 1206's, I thought they were tiny. Ha! > > I refuse to use 0402's. I default to 0805s. > > I'm tuning the tempco of a 50 MHz triggrered Colpitts oscillator. What > a nuisance. It should have a 3.3 pF N4700 0805 cap, but the layout guy > used all 0603s, so some engineer (who shall not be named) substituted > an 0603 NP0. "NTC" does sound a lot like "NPO" I guess. > > The proper 0805 cap was custom brewed for us by Capax. >I often do it the other way around,the 0805 pads I make can also hold 0603. Took me a while to grasp I could do it the first time I could not find the 0805 I needed... The temp compensations I typically have to deal with are resistor tracking. Meanwhile I know which batch of which supply I have does not track too well with which other.
Reply by ●October 25, 20232023-10-25
On Wed, 25 Oct 2023 07:18:58 +0300, Dimiter_Popoff <dp@tgi-sci.com> wrote:>On 10/25/2023 1:51, john larkin wrote: >> On Wed, 25 Oct 2023 01:12:21 +0300, Dimiter_Popoff <dp@tgi-sci.com> >> wrote: >> >>> On 10/25/2023 0:34, john larkin wrote: >>>> Tww it the dimensionless factor >>>> >>>> (how many parts you tidly-wink and lose) / (how many parts you want) >>>> >>>> which, for 0603's, runs 0.6 or so. >>>> >>> >>> Not sure I got what tww is (looked it up, some domino thing so I >>> guess I get it if so) but 0402 are significantly worse, a lot more >>> than twice worse. And I have not yet done any 0201... >> >> When I first saw 1206's, I thought they were tiny. Ha! >> >> I refuse to use 0402's. I default to 0805s. >> >> I'm tuning the tempco of a 50 MHz triggrered Colpitts oscillator. What >> a nuisance. It should have a 3.3 pF N4700 0805 cap, but the layout guy >> used all 0603s, so some engineer (who shall not be named) substituted >> an 0603 NP0. "NTC" does sound a lot like "NPO" I guess. >> >> The proper 0805 cap was custom brewed for us by Capax. >> > >I often do it the other way around,the 0805 pads I make can also hold >0603. Took me a while to grasp I could do it the first time I could >not find the 0805 I needed... > >The temp compensations I typically have to deal with are resistor >tracking. Meanwhile I know which batch of which supply I have >does not track too well with which other.What I'm fighting right now is the positive TC of the Coilcraft Midi-spring inductor (typically +100 PPM/c or so) and the positive TC of the PCB FR4, typically +900. The combo makes the oscillator have a serious negative TC, which the N4700 cap compensates. I have a series padder cap, in series with the NTC cap, to trim the oscillator tempco to near zero, down to the 2nd order parabola. It's tedious. Tuning takes about an hour per iteration. We have a gigantic environmental oven in the basement, but using that would take more like a day per iteration. I made my own benchtop chamber, a cardboard box with a USB fan inside, used with a heat gun and freeze spray. My $5000 Rigol scope is the frequncy counter and USB fan supply.
Reply by ●October 25, 20232023-10-25
On Wednesday, October 25, 2023 at 6:40:17 AM UTC-4, John Larkin wrote:> On Wed, 25 Oct 2023 07:18:58 +0300, Dimiter_Popoff <d...@tgi-sci.com> > wrote: > > >On 10/25/2023 1:51, john larkin wrote: > >> On Wed, 25 Oct 2023 01:12:21 +0300, Dimiter_Popoff <d...@tgi-sci.com> > >> wrote: > >> > >>> On 10/25/2023 0:34, john larkin wrote: > >>>> Tww it the dimensionless factor > >>>> > >>>> (how many parts you tidly-wink and lose) / (how many parts you want) > >>>> > >>>> which, for 0603's, runs 0.6 or so. > >>>> > >>> > >>> Not sure I got what tww is (looked it up, some domino thing so I > >>> guess I get it if so) but 0402 are significantly worse, a lot more > >>> than twice worse. And I have not yet done any 0201... > >> > >> When I first saw 1206's, I thought they were tiny. Ha! > >> > >> I refuse to use 0402's. I default to 0805s. > >> > >> I'm tuning the tempco of a 50 MHz triggrered Colpitts oscillator. What > >> a nuisance. It should have a 3.3 pF N4700 0805 cap, but the layout guy > >> used all 0603s, so some engineer (who shall not be named) substituted > >> an 0603 NP0. "NTC" does sound a lot like "NPO" I guess. > >> > >> The proper 0805 cap was custom brewed for us by Capax. > >> > > > >I often do it the other way around,the 0805 pads I make can also hold > >0603. Took me a while to grasp I could do it the first time I could > >not find the 0805 I needed... > > > >The temp compensations I typically have to deal with are resistor > >tracking. Meanwhile I know which batch of which supply I have > >does not track too well with which other. > What I'm fighting right now is the positive TC of the Coilcraft > Midi-spring inductor (typically +100 PPM/c or so) and the positive TC > of the PCB FR4, typically +900. The combo makes the oscillator have a > serious negative TC, which the N4700 cap compensates. I have a series > padder cap, in series with the NTC cap, to trim the oscillator tempco > to near zero, down to the 2nd order parabola. > > It's tedious. Tuning takes about an hour per iteration. We have a > gigantic environmental oven in the basement, but using that would take > more like a day per iteration. I made my own benchtop chamber, a > cardboard box with a USB fan inside, used with a heat gun and freeze > spray. > > My $5000 Rigol scope is the frequncy counter and USB fan supply.You're using an LC tuned Colpitts?
Reply by ●October 25, 20232023-10-25
On Wed, 25 Oct 2023 09:23:20 -0700 (PDT), Fred Bloggs <bloggs.fredbloggs.fred@gmail.com> wrote:>On Wednesday, October 25, 2023 at 6:40:17?AM UTC-4, John Larkin wrote: >> On Wed, 25 Oct 2023 07:18:58 +0300, Dimiter_Popoff <d...@tgi-sci.com> >> wrote: >> >> >On 10/25/2023 1:51, john larkin wrote: >> >> On Wed, 25 Oct 2023 01:12:21 +0300, Dimiter_Popoff <d...@tgi-sci.com> >> >> wrote: >> >> >> >>> On 10/25/2023 0:34, john larkin wrote: >> >>>> Tww it the dimensionless factor >> >>>> >> >>>> (how many parts you tidly-wink and lose) / (how many parts you want) >> >>>> >> >>>> which, for 0603's, runs 0.6 or so. >> >>>> >> >>> >> >>> Not sure I got what tww is (looked it up, some domino thing so I >> >>> guess I get it if so) but 0402 are significantly worse, a lot more >> >>> than twice worse. And I have not yet done any 0201... >> >> >> >> When I first saw 1206's, I thought they were tiny. Ha! >> >> >> >> I refuse to use 0402's. I default to 0805s. >> >> >> >> I'm tuning the tempco of a 50 MHz triggrered Colpitts oscillator. What >> >> a nuisance. It should have a 3.3 pF N4700 0805 cap, but the layout guy >> >> used all 0603s, so some engineer (who shall not be named) substituted >> >> an 0603 NP0. "NTC" does sound a lot like "NPO" I guess. >> >> >> >> The proper 0805 cap was custom brewed for us by Capax. >> >> >> > >> >I often do it the other way around,the 0805 pads I make can also hold >> >0603. Took me a while to grasp I could do it the first time I could >> >not find the 0805 I needed... >> > >> >The temp compensations I typically have to deal with are resistor >> >tracking. Meanwhile I know which batch of which supply I have >> >does not track too well with which other. >> What I'm fighting right now is the positive TC of the Coilcraft >> Midi-spring inductor (typically +100 PPM/c or so) and the positive TC >> of the PCB FR4, typically +900. The combo makes the oscillator have a >> serious negative TC, which the N4700 cap compensates. I have a series >> padder cap, in series with the NTC cap, to trim the oscillator tempco >> to near zero, down to the 2nd order parabola. >> >> It's tedious. Tuning takes about an hour per iteration. We have a >> gigantic environmental oven in the basement, but using that would take >> more like a day per iteration. I made my own benchtop chamber, a >> cardboard box with a USB fan inside, used with a heat gun and freeze >> spray. >> >> My $5000 Rigol scope is the frequncy counter and USB fan supply. > >You're using an LC tuned Colpitts?Yes. It uses a SAV551 phemt as a source follower driving the usual two caps back into the tank. Here's my temp chamber. https://www.dropbox.com/scl/fi/ncxlgwgyvyoxexzmfqyk3/T660_Temp_Chamber.jpg?rlkey=oud1q89ygu5nafd2i5nym6jii&raw=1 I blast it with a heat gun or freeze spray to evaluate tempco. This gadget has a pretty narrow pull range PLL to lock the triggered LC oscillator to a crystal oscillator, and it will fail lock if temperature changes the LC osc frequency more than maybe 1000 PPM. We use a digital capacitor to center the frequency to close to 50 MHz at powerup, but then it's usually cold, and can't drift more than the 1000 PPM after that. Tedious. DOGBERRY: But truly, if I were as tedious as a king, I would find it in my heart to give it all to you, your Worship. LEONATO: All thy tediousness on me, ah?
Reply by ●October 25, 20232023-10-25
On 25/10/2023 19:22, john larkin wrote:> On Wed, 25 Oct 2023 09:23:20 -0700 (PDT), Fred Bloggs > <bloggs.fredbloggs.fred@gmail.com> wrote: > >> On Wednesday, October 25, 2023 at 6:40:17?AM UTC-4, John Larkin wrote: >>> On Wed, 25 Oct 2023 07:18:58 +0300, Dimiter_Popoff <d...@tgi-sci.com> >>> wrote: >>> >>>> On 10/25/2023 1:51, john larkin wrote: >>>>> On Wed, 25 Oct 2023 01:12:21 +0300, Dimiter_Popoff <d...@tgi-sci.com> >>>>> wrote: >>>>> >>>>>> On 10/25/2023 0:34, john larkin wrote: >>>>>>> Tww it the dimensionless factor >>>>>>> >>>>>>> (how many parts you tidly-wink and lose) / (how many parts you want) >>>>>>> >>>>>>> which, for 0603's, runs 0.6 or so. >>>>>>> >>>>>> >>>>>> Not sure I got what tww is (looked it up, some domino thing so I >>>>>> guess I get it if so) but 0402 are significantly worse, a lot more >>>>>> than twice worse. And I have not yet done any 0201... >>>>> >>>>> When I first saw 1206's, I thought they were tiny. Ha! >>>>> >>>>> I refuse to use 0402's. I default to 0805s. >>>>> >>>>> I'm tuning the tempco of a 50 MHz triggrered Colpitts oscillator. What >>>>> a nuisance. It should have a 3.3 pF N4700 0805 cap, but the layout guy >>>>> used all 0603s, so some engineer (who shall not be named) substituted >>>>> an 0603 NP0. "NTC" does sound a lot like "NPO" I guess. >>>>> >>>>> The proper 0805 cap was custom brewed for us by Capax. >>>>> >>>> >>>> I often do it the other way around,the 0805 pads I make can also hold >>>> 0603. Took me a while to grasp I could do it the first time I could >>>> not find the 0805 I needed... >>>> >>>> The temp compensations I typically have to deal with are resistor >>>> tracking. Meanwhile I know which batch of which supply I have >>>> does not track too well with which other. >>> What I'm fighting right now is the positive TC of the Coilcraft >>> Midi-spring inductor (typically +100 PPM/c or so) and the positive TC >>> of the PCB FR4, typically +900. The combo makes the oscillator have a >>> serious negative TC, which the N4700 cap compensates. I have a series >>> padder cap, in series with the NTC cap, to trim the oscillator tempco >>> to near zero, down to the 2nd order parabola. >>> >>> It's tedious. Tuning takes about an hour per iteration. We have a >>> gigantic environmental oven in the basement, but using that would take >>> more like a day per iteration. I made my own benchtop chamber, a >>> cardboard box with a USB fan inside, used with a heat gun and freeze >>> spray. >>> >>> My $5000 Rigol scope is the frequncy counter and USB fan supply. >> >> You're using an LC tuned Colpitts? > > Yes. It uses a SAV551 phemt as a source follower driving the usual two > caps back into the tank. > > Here's my temp chamber. > > https://www.dropbox.com/scl/fi/ncxlgwgyvyoxexzmfqyk3/T660_Temp_Chamber.jpg?rlkey=oud1q89ygu5nafd2i5nym6jii&raw=1 > > I blast it with a heat gun or freeze spray to evaluate tempco. This > gadget has a pretty narrow pull range PLL to lock the triggered LC > oscillator to a crystal oscillator, and it will fail lock if > temperature changes the LC osc frequency more than maybe 1000 PPM. > > We use a digital capacitor to center the frequency to close to 50 MHz > at powerup, but then it's usually cold, and can't drift more than the > 1000 PPM after that. > > Tedious. > > DOGBERRY: But truly, if I were as tedious as a king, I would find it > in my heart to give it all to you, your Worship. LEONATO: All thy > tediousness on me, ah? >I assume that board has an MCU and with many now including on chip temperature measurement can you use the digital capacitor to do the temp compensation in software? piglet
