On Thu, 26 Oct 2023 05:06:21 GMT, Jan Panteltje <alien@comet.invalid> wrote:>On a sunny day (Wed, 25 Oct 2023 20:45:52 -0700) it happened John Larkin ><jl@997PotHill.com> wrote in <hknjjih3rp87naoq2o2pefergou2deg7i4@4ax.com>: > >>The trick in a digital delay generator, or at least ours, is to stop >>an LC oscillator and start it when we get an external trigger, and >>then use it as our timebase. But lock it to an crystal oscillator to >>keep long delays accurate. >> >>To do that, I need a pretty stable LC oscillator, hence the tempco >>tuning. Capex made us a reel of custom N4700 ceramic caps, which can >>be used to compensate the pretty awful inductor and FR4 tempcos. >> >>HP made one delay generator that actually started and stopped a >>crystal oscillator. It didn't work very well. A quartz crystal is hard >>to kick start and is even worse to stop; it rings like a bell. > >All this makes me think about a 4046 and PLL.The 4046 has a terrible phase detector.
Tww
Started by ●October 24, 2023
Reply by ●October 27, 20232023-10-27
Reply by ●October 28, 20232023-10-28
On Saturday, October 28, 2023 at 9:53:47 AM UTC+11, john larkin wrote:> On Thu, 26 Oct 2023 05:06:21 GMT, Jan Panteltje <al...@comet.invalid> > wrote: > >On a sunny day (Wed, 25 Oct 2023 20:45:52 -0700) it happened John Larkin > ><j...@997PotHill.com> wrote in <hknjjih3rp87naoq2...@4ax.com>: > > > >>The trick in a digital delay generator, or at least ours, is to stop > >>an LC oscillator and start it when we get an external trigger, and > >>then use it as our timebase. But lock it to an crystal oscillator to > >>keep long delays accurate. > >> > >>To do that, I need a pretty stable LC oscillator, hence the tempco > >>tuning. Capex made us a reel of custom N4700 ceramic caps, which can > >>be used to compensate the pretty awful inductor and FR4 tempcos. > >> > >>HP made one delay generator that actually started and stopped a > >>crystal oscillator. It didn't work very well. A quartz crystal is hard > >>to kick start and is even worse to stop; it rings like a bell. > > > >All this makes me think about a 4046 and PLL. > The 4046 has a terrible phase detector.It has two. The exclusive-OR phase detector s fine. The J-K flip-flop based version has a flaw which can be designed around as Phil Hobbs has spelled out here. Philips designed a version of the 4046 which doesn't have the flaw, and the application notes in the data sheet spell out the problem, https://assets.nexperia.com/documents/data-sheet/74HCT9046A.pdf -- Bill Sloman, sydney
Reply by ●October 28, 20232023-10-28
On a sunny day (Fri, 27 Oct 2023 15:53:31 -0700) it happened john larkin <jl@650pot.com> wrote in <6qfojihekda4aobmgnq71rbf493sa454q0@4ax.com>:>On Thu, 26 Oct 2023 05:06:21 GMT, Jan Panteltje <alien@comet.invalid> >wrote: > >>On a sunny day (Wed, 25 Oct 2023 20:45:52 -0700) it happened John Larkin >><jl@997PotHill.com> wrote in <hknjjih3rp87naoq2o2pefergou2deg7i4@4ax.com>: >> >>>The trick in a digital delay generator, or at least ours, is to stop >>>an LC oscillator and start it when we get an external trigger, and >>>then use it as our timebase. But lock it to an crystal oscillator to >>>keep long delays accurate. >>> >>>To do that, I need a pretty stable LC oscillator, hence the tempco >>>tuning. Capex made us a reel of custom N4700 ceramic caps, which can >>>be used to compensate the pretty awful inductor and FR4 tempcos. >>> >>>HP made one delay generator that actually started and stopped a >>>crystal oscillator. It didn't work very well. A quartz crystal is hard >>>to kick start and is even worse to stop; it rings like a bell. >> >>All this makes me think about a 4046 and PLL. > >The 4046 has a terrible phase detector.HCT4046 has 3 phase detectors. 1 xor gate 2 A digital memory network. It consists of four flip–flops and some gating logic, a three state output and a phase pulse output. This comparator acts only on the positive edges of the input signals and is independent of duty cycle. 3 A digital four flip–flops and some gating logic a 3 state output and a phase pulse output See dataseet So what's your problem :-) I have used the 4046 for many things, nice chip.
Reply by ●October 28, 20232023-10-28
On Saturday, October 28, 2023 at 3:26:59 PM UTC+11, Jan Panteltje wrote:> On a sunny day (Fri, 27 Oct 2023 15:53:31 -0700) it happened john larkin > <j...@650pot.com> wrote in <6qfojihekda4aobmg...@4ax.com>: > >On Thu, 26 Oct 2023 05:06:21 GMT, Jan Panteltje <al...@comet.invalid> wrote: > >>On a sunny day (Wed, 25 Oct 2023 20:45:52 -0700) it happened John Larkin <j...@997PotHill.com> wrote in <hknjjih3rp87naoq2...@4ax.com>:<snip>> >The 4046 has a terrible phase detector. > HCT4046 has 3 phase detectors. > 1 xor gate > 2 A digital memory network. It consists of four flip–flops and some gating logic, > a three state output and a phase pulse output. > This comparator acts only on the positive edges of the input signals and is independent of duty cycle. > 3 A digital four flip–flops and some gating logic a 3 state output and a phase pulse output > > See datasheet > > So what's your problem :-)Ignorance and over-confidence, and an unwillingness to be specific about detail.> I have used the 4046 for many things, nice chip.It has it's defects, but you can design around a lot of them, if you understand design. It's a fairly obvious derivative of Jim Thompson's 4024 and 4044 TTL VCO and phase detector chips https://datasheetspdf.com/datasheet/MC4024.html https://datasheetspdf.com/pdf-file/500730/Motorola/MC4044/1 I used both in one project, and they worked, but it wasn't fun. -- Bill Sloman, Sydney
Reply by ●October 28, 20232023-10-28
On Sat, 28 Oct 2023 04:26:51 GMT, Jan Panteltje <alien@comet.invalid> wrote:>On a sunny day (Fri, 27 Oct 2023 15:53:31 -0700) it happened john larkin ><jl@650pot.com> wrote in <6qfojihekda4aobmgnq71rbf493sa454q0@4ax.com>: > >>On Thu, 26 Oct 2023 05:06:21 GMT, Jan Panteltje <alien@comet.invalid> >>wrote: >> >>>On a sunny day (Wed, 25 Oct 2023 20:45:52 -0700) it happened John Larkin >>><jl@997PotHill.com> wrote in <hknjjih3rp87naoq2o2pefergou2deg7i4@4ax.com>: >>> >>>>The trick in a digital delay generator, or at least ours, is to stop >>>>an LC oscillator and start it when we get an external trigger, and >>>>then use it as our timebase. But lock it to an crystal oscillator to >>>>keep long delays accurate. >>>> >>>>To do that, I need a pretty stable LC oscillator, hence the tempco >>>>tuning. Capex made us a reel of custom N4700 ceramic caps, which can >>>>be used to compensate the pretty awful inductor and FR4 tempcos. >>>> >>>>HP made one delay generator that actually started and stopped a >>>>crystal oscillator. It didn't work very well. A quartz crystal is hard >>>>to kick start and is even worse to stop; it rings like a bell. >>> >>>All this makes me think about a 4046 and PLL. >> >>The 4046 has a terrible phase detector. > >HCT4046 has 3 phase detectors. >1 xor gate >2 A digital memory network. It consists of four flip–flops and some gating logic, > a three state output and a phase pulse output. > This comparator acts only on the positive edges of the input signals and is independent of duty cycle. >3 A digital four flip–flops and some gating logic a 3 state output and a phase pulse output > >See dataseet > >So what's your problem :-) > >I have used the 4046 for many things, nice chip.OK, my mistake, the 4046 has three terrible phase detectors. And one terrible VCO.
Reply by ●October 28, 20232023-10-28
On Wednesday, October 25, 2023 at 11:46:17 PM UTC-4, John Larkin wrote:> On Wed, 25 Oct 2023 13:50:35 -0700 (PDT), Fred Bloggs > <bloggs.fred...@gmail.com> wrote: > >On Wednesday, October 25, 2023 at 2:22:37?PM UTC-4, john larkin wrote: > >> On Wed, 25 Oct 2023 09:23:20 -0700 (PDT), Fred Bloggs > >> <bloggs.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 found this after an exhausting 15-second search. There are tons of others: > > > >https://www.sciencedirect.com/science/article/abs/pii/S0026269216306036 > The trick in a digital delay generator, or at least ours, is to stop > an LC oscillator and start it when we get an external trigger, and > then use it as our timebase. But lock it to an crystal oscillator to > keep long delays accurate. > > To do that, I need a pretty stable LC oscillator, hence the tempco > tuning. Capex made us a reel of custom N4700 ceramic caps, which can > be used to compensate the pretty awful inductor and FR4 tempcos. > > HP made one delay generator that actually started and stopped a > crystal oscillator. It didn't work very well. A quartz crystal is hard > to kick start and is even worse to stop; it rings like a bell.There was a line of monolithic delay line oscillators expressly made for fast start stop, don't recall any of them were tunable either. but may not have the long term stability, you're after. Aside form that it sounds generally like a DLL.
Reply by ●October 28, 20232023-10-28
On Sunday, October 29, 2023 at 1:49:49 AM UTC+11, John Larkin wrote:> On Sat, 28 Oct 2023 04:26:51 GMT, Jan Panteltje <al...@comet.invalid> > wrote: > > >On a sunny day (Fri, 27 Oct 2023 15:53:31 -0700) it happened john larkin > ><j...@650pot.com> wrote in <6qfojihekda4aobmg...@4ax.com>: > > > >>On Thu, 26 Oct 2023 05:06:21 GMT, Jan Panteltje <al...@comet.invalid> > >>wrote: > >> > >>>On a sunny day (Wed, 25 Oct 2023 20:45:52 -0700) it happened John Larkin > >>><j...@997PotHill.com> wrote in <hknjjih3rp87naoq2...@4ax.com>: > >>> > >>>>The trick in a digital delay generator, or at least ours, is to stop > >>>>an LC oscillator and start it when we get an external trigger, and > >>>>then use it as our timebase. But lock it to an crystal oscillator to > >>>>keep long delays accurate. > >>>> > >>>>To do that, I need a pretty stable LC oscillator, hence the tempco > >>>>tuning. Capex made us a reel of custom N4700 ceramic caps, which can > >>>>be used to compensate the pretty awful inductor and FR4 tempcos. > >>>> > >>>>HP made one delay generator that actually started and stopped a > >>>>crystal oscillator. It didn't work very well. A quartz crystal is hard > >>>>to kick start and is even worse to stop; it rings like a bell. > >>> > >>>All this makes me think about a 4046 and PLL. > >> > >>The 4046 has a terrible phase detector. > > > >HCT4046 has 3 phase detectors. > >1 xor gate > >2 A digital memory network. It consists of four flip–flops and some gating logic, > > a three state output and a phase pulse output. > > This comparator acts only on the positive edges of the input signals and is independent of duty cycle. > >3 A digital four flip–flops and some gating logic a 3 state output and a phase pulse output > > > >See dataseet > > > >So what's your problem :-) > > > >I have used the 4046 for many things, nice chip. > > OK, my mistake, the 4046 has three terrible phase detectors. And one terrible VCO.That's just compounding your original mistake. There's nothing "terrible" about either of the two phase detectors - you just have to be aware of their limitations and design around them. The VCO is fine for most applications - it has its limitations but this is a cheap integrated circuit, not something that you'd sell to a National Standards Laboratory. -- Bill Sloman, Sydney
Reply by ●October 28, 20232023-10-28
On Sat, 28 Oct 2023 08:24:59 -0700 (PDT), Fred Bloggs <bloggs.fredbloggs.fred@gmail.com> wrote:>On Wednesday, October 25, 2023 at 11:46:17?PM UTC-4, John Larkin wrote: >> On Wed, 25 Oct 2023 13:50:35 -0700 (PDT), Fred Bloggs >> <bloggs.fred...@gmail.com> wrote: >> >On Wednesday, October 25, 2023 at 2:22:37?PM UTC-4, john larkin wrote: >> >> On Wed, 25 Oct 2023 09:23:20 -0700 (PDT), Fred Bloggs >> >> <bloggs.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 found this after an exhausting 15-second search. There are tons of others: >> > >> >https://www.sciencedirect.com/science/article/abs/pii/S0026269216306036 >> The trick in a digital delay generator, or at least ours, is to stop >> an LC oscillator and start it when we get an external trigger, and >> then use it as our timebase. But lock it to an crystal oscillator to >> keep long delays accurate. >> >> To do that, I need a pretty stable LC oscillator, hence the tempco >> tuning. Capex made us a reel of custom N4700 ceramic caps, which can >> be used to compensate the pretty awful inductor and FR4 tempcos. >> >> HP made one delay generator that actually started and stopped a >> crystal oscillator. It didn't work very well. A quartz crystal is hard >> to kick start and is even worse to stop; it rings like a bell. > >There was a line of monolithic delay line oscillators expressly made for fast start stop, don't recall any of them were tunable either. but may not have the long term stability, you're after. Aside form that it sounds generally like a DLL.Coaxial ceramic resonators are interesting here. They are sold as RF resonators, but are actually shorted delay lines. So one can make an instant-start and instant-stop oscillator from one of them, which I've done. They are not as temperature stable as a crystal, but way better than an LC oscillator. The minimum available frequency is around 500 MHz, and the delay-line impedance is low, like 10 ohms, and they are sole-source, mostly custom parts, so turn out the be not very practical. https://www.knowlescapacitors.com/getattachment/6543eb28-409f-4e2f-b251-b1575cc124c8/Ceramic-Resonators
Reply by ●October 29, 20232023-10-29
On a sunny day (Sat, 28 Oct 2023 07:49:21 -0700) it happened John Larkin <jl@997PotHill.com> wrote in <no7qji5c7ak2m46cmmuq7misqaqlrt4nkr@4ax.com>:>On Sat, 28 Oct 2023 04:26:51 GMT, Jan Panteltje <alien@comet.invalid> >wrote: > >>On a sunny day (Fri, 27 Oct 2023 15:53:31 -0700) it happened john larkin >><jl@650pot.com> wrote in <6qfojihekda4aobmgnq71rbf493sa454q0@4ax.com>: >> >>>On Thu, 26 Oct 2023 05:06:21 GMT, Jan Panteltje <alien@comet.invalid> >>>wrote: >>> >>>>On a sunny day (Wed, 25 Oct 2023 20:45:52 -0700) it happened John Larkin >>>><jl@997PotHill.com> wrote in <hknjjih3rp87naoq2o2pefergou2deg7i4@4ax.com>: >>>> >>>>>The trick in a digital delay generator, or at least ours, is to stop >>>>>an LC oscillator and start it when we get an external trigger, and >>>>>then use it as our timebase. But lock it to an crystal oscillator to >>>>>keep long delays accurate. >>>>> >>>>>To do that, I need a pretty stable LC oscillator, hence the tempco >>>>>tuning. Capex made us a reel of custom N4700 ceramic caps, which can >>>>>be used to compensate the pretty awful inductor and FR4 tempcos. >>>>> >>>>>HP made one delay generator that actually started and stopped a >>>>>crystal oscillator. It didn't work very well. A quartz crystal is hard >>>>>to kick start and is even worse to stop; it rings like a bell. >>>> >>>>All this makes me think about a 4046 and PLL. >>> >>>The 4046 has a terrible phase detector. >> >>HCT4046 has 3 phase detectors. >>1 xor gate >>2 A digital memory network. It consists of four flip–flops and some gating logic, >> a three state output and a phase pulse output. >> This comparator acts only on the positive edges of the input signals and is independent of duty cycle. >>3 A digital four flip–flops and some gating logic a 3 state output and a phase pulse output >> >>See dataseet >> >>So what's your problem :-) >> >>I have used the 4046 for many things, nice chip. > >OK, my mistake, the 4046 has three terrible phase detectors. And one >terrible VCO.Well, opinions are still allowed (I hope see https://arstechnica.com/tech-policy/2023/10/the-uks-problematic-online-safety-act-is-now-law/ ) But it depends on what you call 'terrible' I have sued 4046 (going back to the old CMOS since the seventies?) for things like FM audio modulation, demodulation, data clock recovery, what not. So do I understand it right if you wanted to sync an LC oscillator with an external pulse, have it restart (so phase shifted) in an instant? If all you need is phase shift and no frequency shift then a variable delay would work? Bit like summer winter time here, got up one hour early it seems.... LC oscillators are (due the the Q (even higher Q for xtal based oscillators) ) not so easy to adjust in a 'flash'. Discharging the timing cap in an RC like one should not be that hard. I once build a video FM modulator with 2 74121 one shots in series as oscillator.. sixties). And how about that gun diode oscillator.... and the unijunction oscillator, that last one is easily controlled, triggered, used it for synced timebase in a camera I designed in the sixties. Still have some from ebay :-)
Reply by ●October 29, 20232023-10-29
On 2023-10-25 00:09, Dimiter_Popoff wrote:> 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... > >Something like these: <https://www.amazon.com/Officemate-Micro-Binder-Clips-31030/dp/B003U4U3YQ>. You take off the silver handles and just use the black spring part. That and a little jar of acetone for cleaning flux off the tweezers makes an excellent combination that reduces the tiddly-wink problem by a lot. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
