I've just spent over two weeks getting ready to do my next video. It was a combination of one of those vast underestimations one occasionally makes, combined with falling into a bit of an obsession. I am, at this point, not only wondering if it was worth it, but questioning my sanity in carrying on even when the going went beyond tough to just plain crazy. At any rate, a good video needs a visual aid, and I decided that my video needed to demonstrate stability with a pendulum. Moreover, it needed a pendulum that could be worked electronically. So, I've * Disassembled a hard drive for it's head positioner. This took a day or two. * Decided that wasn't good enough and wound my own custom coil (220 feet of #40 wire, woo hoo!). This took a false start (18 feet of #34 wire) and several days. * Mounted the coil into a custom pendulum, running on Real Ball Bearings. Several more days, and if you touch it wrong the Q goes down from about 80 to about 10, then you have to fiddle with it for several minutes so the moving parts don't rub. * Built an oscillator that uses the pendulum as its resonator (this is where stability comes in -- is an oscillator stable? How is it stable? What if it's showing chaotic behavior?). This was astonishingly frustrating, and didn't finally work until I carefully modeled the pendulum as a resonator AND took the coil inductance into account in the circuit. This part too about a week. And for all that, I now have the time base for an exceptionally inaccurate electro-mechanical clock! Check out the picture. That's one cycle of the pendulum, running off of a "tick-toc" circuit that (A) minimizes the load on the pendulum (to give a high loaded Q, essential for wringing as much accuracy as possible out of a pendulum, never mind that it's made of wood, masking tape, and car parts that I picked up off the floor), and (B) has to be started by hand (I wanted to demonstrate a hard limit cycle). http://wescottdesign.com/movies/stability_teaser.gif More on all of this when I post the video. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com I'm looking for work -- see my website!
Stability and Insanity
Started by ●May 17, 2016
Reply by ●May 17, 20162016-05-17
On Monday, May 16, 2016 at 11:41:55 PM UTC-7, Tim Wescott wrote:> I've just spent over two weeks getting ready to do my next video.(snip)> I am, at this point, not only wondering if it was worth it, but > questioning my sanity in carrying on even when the going went beyond > tough to just plain crazy.(snip)> * Built an oscillator that uses the pendulum as its resonator (this is > where stability comes in -- is an oscillator stable? How is it stable? > What if it's showing chaotic behavior?). This was astonishingly > frustrating, and didn't finally work until I carefully modeled the > pendulum as a resonator AND took the coil inductance into account in the > circuit. This part too about a week.There is an old saying about the best way to learn something is to (try to) teach it. I suspect you now know it better than ever. Sounds like fun. Reminds me about Huygens, who learned about coupled oscillators working with many clocks on the same wall. Also, it is supposed to be that women living in the same house will phase lock their periods.
Reply by ●May 17, 20162016-05-17
On Tuesday, May 17, 2016 at 2:41:55 AM UTC-4, Tim Wescott wrote:> I've just spent over two weeks getting ready to do my next video. It was > a combination of one of those vast underestimations one occasionally > makes, combined with falling into a bit of an obsession. > > I am, at this point, not only wondering if it was worth it, but > questioning my sanity in carrying on even when the going went beyond > tough to just plain crazy. > > At any rate, a good video needs a visual aid, and I decided that my video > needed to demonstrate stability with a pendulum. Moreover, it needed a > pendulum that could be worked electronically. So, I've > > * Disassembled a hard drive for it's head positioner. This took a day or > two. > > * Decided that wasn't good enough and wound my own custom coil (220 feet > of #40 wire, woo hoo!). This took a false start (18 feet of #34 wire) > and several days. > > * Mounted the coil into a custom pendulum, running on Real Ball > Bearings. Several more days, and if you touch it wrong the Q goes down > from about 80 to about 10, then you have to fiddle with it for several > minutes so the moving parts don't rub. > > * Built an oscillator that uses the pendulum as its resonator (this is > where stability comes in -- is an oscillator stable? How is it stable? > What if it's showing chaotic behavior?). This was astonishingly > frustrating, and didn't finally work until I carefully modeled the > pendulum as a resonator AND took the coil inductance into account in the > circuit. This part too about a week. > > And for all that, I now have the time base for an exceptionally > inaccurate electro-mechanical clock! Check out the picture. That's one > cycle of the pendulum, running off of a "tick-toc" circuit that (A) > minimizes the load on the pendulum (to give a high loaded Q, essential > for wringing as much accuracy as possible out of a pendulum, never mind > that it's made of wood, masking tape, and car parts that I picked up off > the floor), and (B) has to be started by hand (I wanted to demonstrate a > hard limit cycle). > > http://wescottdesign.com/movies/stability_teaser.gif > > More on all of this when I post the video. > > -- > > Tim Wescott > Wescott Design Services > http://www.wescottdesign.com > > I'm looking for work -- see my website!If it's any consolation, I thought you should know some of us lurkers around here really enjoyed your recent video (as well as your posts). Keep up the good work!
Reply by ●May 17, 20162016-05-17
On 17.05.2016 12:14, herrmannsfeldt@gmail.com wrote:> On Monday, May 16, 2016 at 11:41:55 PM UTC-7, Tim Wescott wrote: >> I've just spent over two weeks getting ready to do my next video. > > (snip) >> I am, at this point, not only wondering if it was worth it, but >> questioning my sanity in carrying on even when the going went beyond >> tough to just plain crazy. > > (snip) >> * Built an oscillator that uses the pendulum as its resonator (this is >> where stability comes in -- is an oscillator stable? How is it stable? >> What if it's showing chaotic behavior?). This was astonishingly >> frustrating, and didn't finally work until I carefully modeled the >> pendulum as a resonator AND took the coil inductance into account in the >> circuit. This part too about a week. > > There is an old saying about the best way to learn something is to (try to) teach it. > > I suspect you now know it better than ever. > > Sounds like fun. > > Reminds me about Huygens, who learned about coupled oscillators working > with many clocks on the same wall. Also, it is supposed to be that women living > in the same house will phase lock their periods. >Or circadian rhythm. The fun part is that circadian clocks actually operate within each cell of an organism, and can be modeled as a negative feedback loop. Quoting "Molecular Biology of the Cell" by Alberts (6th ed.), pp. 876-878: "Having a circadian clock enables an organism to anticipate the regular daily changes in its environment and take appropriate action in advance. Of course, the internal clock cannot be perfectly accurate, and so it must be capable of being reset by external cues such as the light of day. Thus, circadian clocks keep running even when the environmental cues (changes in light and dark) are removed, but the period of this free-running rhythm is generally a little less or more than 24 hours. External signals indicating the time of day cause small adjustments in the running of the clock, so as to keep the organism in synchrony with its environment. Following more drastic shifts, circadian cycles become gradually reset (entrained) by the new cycle of light and dark, as anyone who has experienced jet lag can attest." ... "In Drosophila and many other animals, including humans, the heart of the circadian clock is a delayed negative feedback loop based on transcription regulators: accumulation of certain gene products switches off the transcription of their own genes, but with a delay, so that the cell oscillates between a state in which the products are present and transcription is switched off, and one in which the products are absent and transcription is switched on." Gene
Reply by ●May 17, 20162016-05-17
On 5/17/2016 1:41 AM, Tim Wescott wrote:> I've just spent over two weeks getting ready to do my next video. It was > a combination of one of those vast underestimations one occasionally > makes, combined with falling into a bit of an obsession. > > I am, at this point, not only wondering if it was worth it, but > questioning my sanity in carrying on even when the going went beyond > tough to just plain crazy. > > At any rate, a good video needs a visual aid, and I decided that my video > needed to demonstrate stability with a pendulum. Moreover, it needed a > pendulum that could be worked electronically. So, I've > > * Disassembled a hard drive for it's head positioner. This took a day or > two. > > * Decided that wasn't good enough and wound my own custom coil (220 feet > of #40 wire, woo hoo!). This took a false start (18 feet of #34 wire) > and several days. > > * Mounted the coil into a custom pendulum, running on Real Ball > Bearings. Several more days, and if you touch it wrong the Q goes down > from about 80 to about 10, then you have to fiddle with it for several > minutes so the moving parts don't rub. > > * Built an oscillator that uses the pendulum as its resonator (this is > where stability comes in -- is an oscillator stable? How is it stable? > What if it's showing chaotic behavior?). This was astonishingly > frustrating, and didn't finally work until I carefully modeled the > pendulum as a resonator AND took the coil inductance into account in the > circuit. This part too about a week. > > And for all that, I now have the time base for an exceptionally > inaccurate electro-mechanical clock! Check out the picture. That's one > cycle of the pendulum, running off of a "tick-toc" circuit that (A) > minimizes the load on the pendulum (to give a high loaded Q, essential > for wringing as much accuracy as possible out of a pendulum, never mind > that it's made of wood, masking tape, and car parts that I picked up off > the floor), and (B) has to be started by hand (I wanted to demonstrate a > hard limit cycle). > > http://wescottdesign.com/movies/stability_teaser.gif > > More on all of this when I post the video. >For your next demo, use an electromagnet to lift a metal ball and hold it suspended. Sense the height with a light sensor. Use PID to achieve stability. I saw an article that did this 30 or so years ago. They used a hollow steel ball with a map of the earth painted on. Can't remember the diameter of the ball, but maybe 1".
Reply by ●May 17, 20162016-05-17
On 05/17/2016 09:15 AM, John S wrote:> On 5/17/2016 1:41 AM, Tim Wescott wrote: >> I've just spent over two weeks getting ready to do my next video. It was >> a combination of one of those vast underestimations one occasionally >> makes, combined with falling into a bit of an obsession. >> >> I am, at this point, not only wondering if it was worth it, but >> questioning my sanity in carrying on even when the going went beyond >> tough to just plain crazy. >> >> At any rate, a good video needs a visual aid, and I decided that my video >> needed to demonstrate stability with a pendulum. Moreover, it needed a >> pendulum that could be worked electronically. So, I've >> >> * Disassembled a hard drive for it's head positioner. This took a day or >> two. >> >> * Decided that wasn't good enough and wound my own custom coil (220 feet >> of #40 wire, woo hoo!). This took a false start (18 feet of #34 wire) >> and several days. >> >> * Mounted the coil into a custom pendulum, running on Real Ball >> Bearings. Several more days, and if you touch it wrong the Q goes down >> from about 80 to about 10, then you have to fiddle with it for several >> minutes so the moving parts don't rub. >> >> * Built an oscillator that uses the pendulum as its resonator (this is >> where stability comes in -- is an oscillator stable? How is it stable? >> What if it's showing chaotic behavior?). This was astonishingly >> frustrating, and didn't finally work until I carefully modeled the >> pendulum as a resonator AND took the coil inductance into account in the >> circuit. This part too about a week. >> >> And for all that, I now have the time base for an exceptionally >> inaccurate electro-mechanical clock! Check out the picture. That's one >> cycle of the pendulum, running off of a "tick-toc" circuit that (A) >> minimizes the load on the pendulum (to give a high loaded Q, essential >> for wringing as much accuracy as possible out of a pendulum, never mind >> that it's made of wood, masking tape, and car parts that I picked up off >> the floor), and (B) has to be started by hand (I wanted to demonstrate a >> hard limit cycle). >> >> http://wescottdesign.com/movies/stability_teaser.gif >> >> More on all of this when I post the video. >> > > For your next demo, use an electromagnet to lift a metal ball and hold > it suspended. Sense the height with a light sensor. Use PID to achieve > stability. > > I saw an article that did this 30 or so years ago. They used a hollow > steel ball with a map of the earth painted on. Can't remember the > diameter of the ball, but maybe 1".It was longer ago than that--iirc it was called "Li'l Atlas", and it could spin the ball as well as suspend it. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
Reply by ●May 17, 20162016-05-17
On 05/17/2016 09:31 AM, Phil Hobbs wrote:> On 05/17/2016 09:15 AM, John S wrote: >> On 5/17/2016 1:41 AM, Tim Wescott wrote: >>> I've just spent over two weeks getting ready to do my next video. It was >>> a combination of one of those vast underestimations one occasionally >>> makes, combined with falling into a bit of an obsession. >>> >>> I am, at this point, not only wondering if it was worth it, but >>> questioning my sanity in carrying on even when the going went beyond >>> tough to just plain crazy. >>> >>> At any rate, a good video needs a visual aid, and I decided that my video >>> needed to demonstrate stability with a pendulum. Moreover, it needed a >>> pendulum that could be worked electronically. So, I've >>> >>> * Disassembled a hard drive for it's head positioner. This took a day or >>> two. >>> >>> * Decided that wasn't good enough and wound my own custom coil (220 feet >>> of #40 wire, woo hoo!). This took a false start (18 feet of #34 wire) >>> and several days. >>> >>> * Mounted the coil into a custom pendulum, running on Real Ball >>> Bearings. Several more days, and if you touch it wrong the Q goes down >>> from about 80 to about 10, then you have to fiddle with it for several >>> minutes so the moving parts don't rub. >>> >>> * Built an oscillator that uses the pendulum as its resonator (this is >>> where stability comes in -- is an oscillator stable? How is it stable? >>> What if it's showing chaotic behavior?). This was astonishingly >>> frustrating, and didn't finally work until I carefully modeled the >>> pendulum as a resonator AND took the coil inductance into account in the >>> circuit. This part too about a week. >>> >>> And for all that, I now have the time base for an exceptionally >>> inaccurate electro-mechanical clock! Check out the picture. That's one >>> cycle of the pendulum, running off of a "tick-toc" circuit that (A) >>> minimizes the load on the pendulum (to give a high loaded Q, essential >>> for wringing as much accuracy as possible out of a pendulum, never mind >>> that it's made of wood, masking tape, and car parts that I picked up off >>> the floor), and (B) has to be started by hand (I wanted to demonstrate a >>> hard limit cycle). >>> >>> http://wescottdesign.com/movies/stability_teaser.gif >>> >>> More on all of this when I post the video. >>> >> >> For your next demo, use an electromagnet to lift a metal ball and hold >> it suspended. Sense the height with a light sensor. Use PID to achieve >> stability. >> >> I saw an article that did this 30 or so years ago. They used a hollow >> steel ball with a map of the earth painted on. Can't remember the >> diameter of the ball, but maybe 1". > > It was longer ago than that--iirc it was called "Li'l Atlas", and it > could spin the ball as well as suspend it. > > Cheers > > Phil Hobbs > >Found it. It was _fifty_ years ago: http://www.coilgun.info/lev_popelex1966/home.htm Cheers Phil "Old magazines rule" Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
Reply by ●May 17, 20162016-05-17
On 5/17/2016 8:34 AM, Phil Hobbs wrote:> On 05/17/2016 09:31 AM, Phil Hobbs wrote: >> On 05/17/2016 09:15 AM, John S wrote: >>> On 5/17/2016 1:41 AM, Tim Wescott wrote: >>>> I've just spent over two weeks getting ready to do my next video. It was >>>> a combination of one of those vast underestimations one occasionally >>>> makes, combined with falling into a bit of an obsession. >>>> >>>> I am, at this point, not only wondering if it was worth it, but >>>> questioning my sanity in carrying on even when the going went beyond >>>> tough to just plain crazy. >>>> >>>> At any rate, a good video needs a visual aid, and I decided that my video >>>> needed to demonstrate stability with a pendulum. Moreover, it needed a >>>> pendulum that could be worked electronically. So, I've >>>> >>>> * Disassembled a hard drive for it's head positioner. This took a day or >>>> two. >>>> >>>> * Decided that wasn't good enough and wound my own custom coil (220 feet >>>> of #40 wire, woo hoo!). This took a false start (18 feet of #34 wire) >>>> and several days. >>>> >>>> * Mounted the coil into a custom pendulum, running on Real Ball >>>> Bearings. Several more days, and if you touch it wrong the Q goes down >>>> from about 80 to about 10, then you have to fiddle with it for several >>>> minutes so the moving parts don't rub. >>>> >>>> * Built an oscillator that uses the pendulum as its resonator (this is >>>> where stability comes in -- is an oscillator stable? How is it stable? >>>> What if it's showing chaotic behavior?). This was astonishingly >>>> frustrating, and didn't finally work until I carefully modeled the >>>> pendulum as a resonator AND took the coil inductance into account in the >>>> circuit. This part too about a week. >>>> >>>> And for all that, I now have the time base for an exceptionally >>>> inaccurate electro-mechanical clock! Check out the picture. That's one >>>> cycle of the pendulum, running off of a "tick-toc" circuit that (A) >>>> minimizes the load on the pendulum (to give a high loaded Q, essential >>>> for wringing as much accuracy as possible out of a pendulum, never mind >>>> that it's made of wood, masking tape, and car parts that I picked up off >>>> the floor), and (B) has to be started by hand (I wanted to demonstrate a >>>> hard limit cycle). >>>> >>>> http://wescottdesign.com/movies/stability_teaser.gif >>>> >>>> More on all of this when I post the video. >>>> >>> >>> For your next demo, use an electromagnet to lift a metal ball and hold >>> it suspended. Sense the height with a light sensor. Use PID to achieve >>> stability. >>> >>> I saw an article that did this 30 or so years ago. They used a hollow >>> steel ball with a map of the earth painted on. Can't remember the >>> diameter of the ball, but maybe 1". >> >> It was longer ago than that--iirc it was called "Li'l Atlas", and it >> could spin the ball as well as suspend it. >> >> Cheers >> >> Phil Hobbs >> >> > Found it. It was _fifty_ years ago: > > http://www.coilgun.info/lev_popelex1966/home.htm > > Cheers > > Phil "Old magazines rule" HobbsOh, thanks, Phil. That makes me 20 years older than I thought I was :P
Reply by ●May 17, 20162016-05-17
On Tue, 17 May 2016 08:15:42 -0500, John S wrote:> On 5/17/2016 1:41 AM, Tim Wescott wrote: >> I've just spent over two weeks getting ready to do my next video. It >> was a combination of one of those vast underestimations one >> occasionally makes, combined with falling into a bit of an obsession. >> >> I am, at this point, not only wondering if it was worth it, but >> questioning my sanity in carrying on even when the going went beyond >> tough to just plain crazy. >> >> At any rate, a good video needs a visual aid, and I decided that my >> video needed to demonstrate stability with a pendulum. Moreover, it >> needed a pendulum that could be worked electronically. So, I've >> >> * Disassembled a hard drive for it's head positioner. This took a day >> or two. >> >> * Decided that wasn't good enough and wound my own custom coil (220 >> feet of #40 wire, woo hoo!). This took a false start (18 feet of #34 >> wire) and several days. >> >> * Mounted the coil into a custom pendulum, running on Real Ball >> Bearings. Several more days, and if you touch it wrong the Q goes down >> from about 80 to about 10, then you have to fiddle with it for several >> minutes so the moving parts don't rub. >> >> * Built an oscillator that uses the pendulum as its resonator (this is >> where stability comes in -- is an oscillator stable? How is it stable? >> What if it's showing chaotic behavior?). This was astonishingly >> frustrating, and didn't finally work until I carefully modeled the >> pendulum as a resonator AND took the coil inductance into account in >> the circuit. This part too about a week. >> >> And for all that, I now have the time base for an exceptionally >> inaccurate electro-mechanical clock! Check out the picture. That's >> one cycle of the pendulum, running off of a "tick-toc" circuit that (A) >> minimizes the load on the pendulum (to give a high loaded Q, essential >> for wringing as much accuracy as possible out of a pendulum, never mind >> that it's made of wood, masking tape, and car parts that I picked up >> off the floor), and (B) has to be started by hand (I wanted to >> demonstrate a hard limit cycle). >> >> http://wescottdesign.com/movies/stability_teaser.gif >> >> More on all of this when I post the video. >> >> > For your next demo, use an electromagnet to lift a metal ball and hold > it suspended. Sense the height with a light sensor. Use PID to achieve > stability. > > I saw an article that did this 30 or so years ago. They used a hollow > steel ball with a map of the earth painted on. Can't remember the > diameter of the ball, but maybe 1".I've done that. You need a honkin' big electromagnet to make it work with a plain steel load. The executive desk-toys with the floating globes use big (30mm dia x 10mm) rare-earth magnets, and float the ball a little bit below the neutral point. I believe that they use hall effect sensors to detect the magnet proximity. -- Tim Wescott Control systems, embedded software and circuit design I'm looking for work! See my website if you're interested http://www.wescottdesign.com
Reply by ●May 17, 20162016-05-17
On Tue, 17 May 2016 08:15:42 -0500, John S wrote:> On 5/17/2016 1:41 AM, Tim Wescott wrote: >> I've just spent over two weeks getting ready to do my next video. It >> was a combination of one of those vast underestimations one >> occasionally makes, combined with falling into a bit of an obsession. >> >> I am, at this point, not only wondering if it was worth it, but >> questioning my sanity in carrying on even when the going went beyond >> tough to just plain crazy. >> >> At any rate, a good video needs a visual aid, and I decided that my >> video needed to demonstrate stability with a pendulum. Moreover, it >> needed a pendulum that could be worked electronically. So, I've >> >> * Disassembled a hard drive for it's head positioner. This took a day >> or two. >> >> * Decided that wasn't good enough and wound my own custom coil (220 >> feet of #40 wire, woo hoo!). This took a false start (18 feet of #34 >> wire) and several days. >> >> * Mounted the coil into a custom pendulum, running on Real Ball >> Bearings. Several more days, and if you touch it wrong the Q goes down >> from about 80 to about 10, then you have to fiddle with it for several >> minutes so the moving parts don't rub. >> >> * Built an oscillator that uses the pendulum as its resonator (this is >> where stability comes in -- is an oscillator stable? How is it stable? >> What if it's showing chaotic behavior?). This was astonishingly >> frustrating, and didn't finally work until I carefully modeled the >> pendulum as a resonator AND took the coil inductance into account in >> the circuit. This part too about a week. >> >> And for all that, I now have the time base for an exceptionally >> inaccurate electro-mechanical clock! Check out the picture. That's >> one cycle of the pendulum, running off of a "tick-toc" circuit that (A) >> minimizes the load on the pendulum (to give a high loaded Q, essential >> for wringing as much accuracy as possible out of a pendulum, never mind >> that it's made of wood, masking tape, and car parts that I picked up >> off the floor), and (B) has to be started by hand (I wanted to >> demonstrate a hard limit cycle). >> >> http://wescottdesign.com/movies/stability_teaser.gif >> >> More on all of this when I post the video. >> >> > For your next demo, use an electromagnet to lift a metal ball and hold > it suspended. Sense the height with a light sensor. Use PID to achieve > stability. > > I saw an article that did this 30 or so years ago. They used a hollow > steel ball with a map of the earth painted on. Can't remember the > diameter of the ball, but maybe 1".https://www.electronics-related.com/showarticle/526/levitating-globe- teardown-part-1 https://www.electronics-related.com/showarticle/527/levitating-globe- teardown-part-2 -- Tim Wescott Wescott Design Services http://www.wescottdesign.com I'm looking for work -- see my website!
