LT Spice schmitt oscillator
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From: Phil Hobbs on 10 Oct 2009 08:54 John Larkin wrote: > On Fri, 09 Oct 2009 12:05:31 -0700, Joerg <invalid(a)invalid.invalid> > wrote: > >> John Larkin wrote: >>> On Thu, 08 Oct 2009 15:52:29 -0700, Rich Grise <richgrise(a)example.net> >>> wrote: >>> >>>> On Thu, 08 Oct 2009 14:46:34 -0700, John Larkin wrote: >>>> >>>>> Does anybody have a working LT Spice netlist for a simple schmitt >>>>> inverter/R-C oscillator? I tried one using the library schmitt inverter >>>>> and get obscure sim errors, and I don't understand the HELP stuff. >>>>> >>>>> What's the third pin in the corner for? Ground? >>>>> >>>> We don't do homework. ;-P >>>> >>>> Cheers! >>>> Rich >>> I want to make a low-frequency triangle wave, 1 KHz maybe, to FM >>> spread-spectrum a bunch (namely 5) of switching regulators on this >>> board I'm doing, so that they don't leak into the ADC and show up in >>> the eventual FFTs we're going to do and make birdies in the spectra. >>> >>> Neither the amplitude nor the frequency is very critical. An NC7S14M5 >>> running at 3.3 volts will give me about a 0.9 volt p-p triangle. >>> >> Why so expensive? To spread things nicely you'll probably want five >> individual oscillators all running at different and non-correlating >> frequencies. Why not just use one 74HC14 for all of them and then use >> Schmitt inverter #6 for a blinkenlight or something? > > 3.7 cents is expensive? > > I thought about splattering them separately, but don't really see any > advantage. Each switcher has one resistor to set its nominal frequency > and one more to set the FM amount. They should be all over the place. > > John > It'll be a lot easier to test with only one oscillator, too. N-dimensional testing spaces are no fun. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal ElectroOptical Innovations 55 Orchard Rd Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net
From: John Larkin on 10 Oct 2009 11:13 On Sat, 10 Oct 2009 08:54:01 -0400, Phil Hobbs <pcdhSpamMeSenseless(a)electrooptical.net> wrote: >John Larkin wrote: >> On Fri, 09 Oct 2009 12:05:31 -0700, Joerg <invalid(a)invalid.invalid> >> wrote: >> >>> John Larkin wrote: >>>> On Thu, 08 Oct 2009 15:52:29 -0700, Rich Grise <richgrise(a)example.net> >>>> wrote: >>>> >>>>> On Thu, 08 Oct 2009 14:46:34 -0700, John Larkin wrote: >>>>> >>>>>> Does anybody have a working LT Spice netlist for a simple schmitt >>>>>> inverter/R-C oscillator? I tried one using the library schmitt inverter >>>>>> and get obscure sim errors, and I don't understand the HELP stuff. >>>>>> >>>>>> What's the third pin in the corner for? Ground? >>>>>> >>>>> We don't do homework. ;-P >>>>> >>>>> Cheers! >>>>> Rich >>>> I want to make a low-frequency triangle wave, 1 KHz maybe, to FM >>>> spread-spectrum a bunch (namely 5) of switching regulators on this >>>> board I'm doing, so that they don't leak into the ADC and show up in >>>> the eventual FFTs we're going to do and make birdies in the spectra. >>>> >>>> Neither the amplitude nor the frequency is very critical. An NC7S14M5 >>>> running at 3.3 volts will give me about a 0.9 volt p-p triangle. >>>> >>> Why so expensive? To spread things nicely you'll probably want five >>> individual oscillators all running at different and non-correlating >>> frequencies. Why not just use one 74HC14 for all of them and then use >>> Schmitt inverter #6 for a blinkenlight or something? >> >> 3.7 cents is expensive? >> >> I thought about splattering them separately, but don't really see any >> advantage. Each switcher has one resistor to set its nominal frequency >> and one more to set the FM amount. They should be all over the place. >> >> John >> > >It'll be a lot easier to test with only one oscillator, too. >N-dimensional testing spaces are no fun. > >Cheers > >Phil Hobbs There's a logical fallacy, common in things like cryptography, to the effect "If I make it so confusing that I can't understand it myself, it must become random." This attitude has, literally, sunk fleets. If I set the base switcher frequencies different, and FM them from the same triangle but with different deviations, I doubt that any of them will lock. There may be beats and very brief lock-like intervals as all five of them are sweeping here and there, but the fallacy does include a bit of hidden truth: none of these interactions should make spectral lines anything like what I'd have with five CW oscillators. Aside: I was recently thinking about N-dimensional optimization in general and of of the performance of a very complex scientific instrument in particular. The particular instrument I'm working on was designed by chemists, and has very bad electronics. Adding EEs increases N by adding parameters that the chemists never imagined existed, or adds some parameters that didn't matter before because their effects were buried in noise. So we show up and, in theory, make the sweet spot even more difficuly to find than it was when life was simpler... 4 more dimensions at least. This one isn't too bad. I can bench test the system to verify that we've sort of spread the switcher lines and fiddle resistors by instinct. Then we can do some real samples with the ss on and off, just for fun. That doesn't interact with anything else. Is *anyone* capable of optimizing, or even mildly improving, something as complex as a social system? John
From: Jim Thompson on 10 Oct 2009 11:49 On Sat, 10 Oct 2009 08:13:36 -0700, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: [snip] > >Is *anyone* capable of optimizing, or even mildly improving, something >as complex as a social system? > >John Sure. Just shoot all "liberals" ;-) ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
From: Joerg on 10 Oct 2009 12:12 John Larkin wrote: > On Sat, 10 Oct 2009 08:54:01 -0400, Phil Hobbs > <pcdhSpamMeSenseless(a)electrooptical.net> wrote: > >> John Larkin wrote: >>> On Fri, 09 Oct 2009 12:05:31 -0700, Joerg <invalid(a)invalid.invalid> >>> wrote: >>> >>>> John Larkin wrote: >>>>> On Thu, 08 Oct 2009 15:52:29 -0700, Rich Grise <richgrise(a)example.net> >>>>> wrote: >>>>> >>>>>> On Thu, 08 Oct 2009 14:46:34 -0700, John Larkin wrote: >>>>>> >>>>>>> Does anybody have a working LT Spice netlist for a simple schmitt >>>>>>> inverter/R-C oscillator? I tried one using the library schmitt inverter >>>>>>> and get obscure sim errors, and I don't understand the HELP stuff. >>>>>>> >>>>>>> What's the third pin in the corner for? Ground? >>>>>>> >>>>>> We don't do homework. ;-P >>>>>> >>>>>> Cheers! >>>>>> Rich >>>>> I want to make a low-frequency triangle wave, 1 KHz maybe, to FM >>>>> spread-spectrum a bunch (namely 5) of switching regulators on this >>>>> board I'm doing, so that they don't leak into the ADC and show up in >>>>> the eventual FFTs we're going to do and make birdies in the spectra. >>>>> >>>>> Neither the amplitude nor the frequency is very critical. An NC7S14M5 >>>>> running at 3.3 volts will give me about a 0.9 volt p-p triangle. >>>>> >>>> Why so expensive? To spread things nicely you'll probably want five >>>> individual oscillators all running at different and non-correlating >>>> frequencies. Why not just use one 74HC14 for all of them and then use >>>> Schmitt inverter #6 for a blinkenlight or something? >>> 3.7 cents is expensive? >>> >>> I thought about splattering them separately, but don't really see any >>> advantage. Each switcher has one resistor to set its nominal frequency >>> and one more to set the FM amount. They should be all over the place. >>> >>> John >>> >> It'll be a lot easier to test with only one oscillator, too. >> N-dimensional testing spaces are no fun. >> >> Cheers >> >> Phil Hobbs > > There's a logical fallacy, common in things like cryptography, to the > effect "If I make it so confusing that I can't understand it myself, > it must become random." This attitude has, literally, sunk fleets. > Well, the spread spectrum guys don't think so :-) > If I set the base switcher frequencies different, and FM them from the > same triangle but with different deviations, I doubt that any of them > will lock. There may be beats and very brief lock-like intervals as > all five of them are sweeping here and there, but the fallacy does > include a bit of hidden truth: none of these interactions should make > spectral lines anything like what I'd have with five CW oscillators. > The last sentence kind of sums it up. Your switcher base frequencies are all different but if you use only one modulator then they will all scoot up and down in unison. IOW it's like a clump of you-know-what sloshing around with the waves near a beach. Takes forever to disintegrate. > Aside: I was recently thinking about N-dimensional optimization in > general and of of the performance of a very complex scientific > instrument in particular. The particular instrument I'm working on was > designed by chemists, and has very bad electronics. Adding EEs > increases N by adding parameters that the chemists never imagined > existed, or adds some parameters that didn't matter before because > their effects were buried in noise. So we show up and, in theory, make > the sweet spot even more difficuly to find than it was when life was > simpler... 4 more dimensions at least. > > This one isn't too bad. I can bench test the system to verify that > we've sort of spread the switcher lines and fiddle resistors by > instinct. Then we can do some real samples with the ss on and off, > just for fun. That doesn't interact with anything else. > > Is *anyone* capable of optimizing, or even mildly improving, something > as complex as a social system? > Yes, but that would go OT here. OT as in Old testament :-) -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Fred Bartoli on 10 Oct 2009 18:18
John Larkin a �crit : > On Sat, 10 Oct 2009 08:54:01 -0400, Phil Hobbs > <pcdhSpamMeSenseless(a)electrooptical.net> wrote: > >> John Larkin wrote: >>> On Fri, 09 Oct 2009 12:05:31 -0700, Joerg <invalid(a)invalid.invalid> >>> wrote: >>> >>>> John Larkin wrote: >>>>> On Thu, 08 Oct 2009 15:52:29 -0700, Rich Grise <richgrise(a)example.net> >>>>> wrote: >>>>> >>>>>> On Thu, 08 Oct 2009 14:46:34 -0700, John Larkin wrote: >>>>>> >>>>>>> Does anybody have a working LT Spice netlist for a simple schmitt >>>>>>> inverter/R-C oscillator? I tried one using the library schmitt inverter >>>>>>> and get obscure sim errors, and I don't understand the HELP stuff. >>>>>>> >>>>>>> What's the third pin in the corner for? Ground? >>>>>>> >>>>>> We don't do homework. ;-P >>>>>> >>>>>> Cheers! >>>>>> Rich >>>>> I want to make a low-frequency triangle wave, 1 KHz maybe, to FM >>>>> spread-spectrum a bunch (namely 5) of switching regulators on this >>>>> board I'm doing, so that they don't leak into the ADC and show up in >>>>> the eventual FFTs we're going to do and make birdies in the spectra. >>>>> >>>>> Neither the amplitude nor the frequency is very critical. An NC7S14M5 >>>>> running at 3.3 volts will give me about a 0.9 volt p-p triangle. >>>>> >>>> Why so expensive? To spread things nicely you'll probably want five >>>> individual oscillators all running at different and non-correlating >>>> frequencies. Why not just use one 74HC14 for all of them and then use >>>> Schmitt inverter #6 for a blinkenlight or something? >>> 3.7 cents is expensive? >>> >>> I thought about splattering them separately, but don't really see any >>> advantage. Each switcher has one resistor to set its nominal frequency >>> and one more to set the FM amount. They should be all over the place. >>> >>> John >>> >> It'll be a lot easier to test with only one oscillator, too. >> N-dimensional testing spaces are no fun. >> >> Cheers >> >> Phil Hobbs > > There's a logical fallacy, common in things like cryptography, to the > effect "If I make it so confusing that I can't understand it myself, > it must become random." This attitude has, literally, sunk fleets. > > If I set the base switcher frequencies different, and FM them from the > same triangle but with different deviations, I doubt that any of them > will lock. There may be beats and very brief lock-like intervals as > all five of them are sweeping here and there, but the fallacy does > include a bit of hidden truth: none of these interactions should make > spectral lines anything like what I'd have with five CW oscillators. > > Aside: I was recently thinking about N-dimensional optimization in > general and of of the performance of a very complex scientific > instrument in particular. The particular instrument I'm working on was > designed by chemists, and has very bad electronics. Adding EEs > increases N by adding parameters that the chemists never imagined > existed, or adds some parameters that didn't matter before because > their effects were buried in noise. So we show up and, in theory, make > the sweet spot even more difficuly to find than it was when life was > simpler... 4 more dimensions at least. > > This one isn't too bad. I can bench test the system to verify that > we've sort of spread the switcher lines and fiddle resistors by > instinct. Then we can do some real samples with the ss on and off, > just for fun. That doesn't interact with anything else. > > Is *anyone* capable of optimizing, or even mildly improving, something > as complex as a social system? > Hmmm, you mean like bringing democracy to a foreign country? -- Thanks, Fred. |