Joerg <news@analogconsultants.com> wrote:> On 2015-03-19 5:38 PM, Tom Swift wrote:>> Cool! That signal appears to be much more complex. Good thing you're >> doing it and not me!> Let's hope you and I never need the equipment that this is for but > it'll be good it's there, just in case.You must be at the point now where you walk into a Doctor's office or operating room, look around and say to yourself. "I designed that, and that, and that...." Pretty good insurance in case you ever get sick. They're fixing you with your own stuff! You should post a list of all the instruments you have designed so we can be sure they use nothing else when they want to cut us open:)
Voltage-variable capacitor doesn't work in LTSpice
Started by ●March 16, 2015
Reply by ●March 20, 20152015-03-20
Reply by ●March 20, 20152015-03-20
On 2015-03-20 9:35 AM, Tom Swift wrote:> Joerg <news@analogconsultants.com> wrote: > >> On 2015-03-19 5:38 PM, Tom Swift wrote: > >>> Cool! That signal appears to be much more complex. Good thing you're >>> doing it and not me! > >> Let's hope you and I never need the equipment that this is for but >> it'll be good it's there, just in case. > > You must be at the point now where you walk into a Doctor's office or > operating room, look around and say to yourself. "I designed that, and > that, and that...." >Not anymore, I moved largely away from med tech. This is the only major med project I am involved in right now and for the foreseeable future. Much of that market got jinxed by Obamacare and I saw it coming, so branched out into industrial electronics and stuff.> Pretty good insurance in case you ever get sick. They're fixing you with > your own stuff! > > You should post a list of all the instruments you have designed so we can > be sure they use nothing else when they want to cut us open:) >When it comes to intravascular ultrasound, yes, then I'd like to be diagnosed with one of our machines if that is ever necessary. Because it is the only fully electronic system on the planet and I sure would not like them to snake a catheter with a spinning shaft up into my coronary blood vessels. Not that it's inherently too unsafe but it kind of scares me. Plus IMHO our image quality is better and more consistent. -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●March 20, 20152015-03-20
On Thu, 19 Mar 2015 16:57:15 -0700, Joerg <news@analogconsultants.com> wrote:>On 2015-03-19 2:55 PM, John Larkin wrote: >> On Thu, 19 Mar 2015 13:30:47 -0700, Joerg <news@analogconsultants.com> >> wrote: >> >>> On 2015-03-19 8:37 AM, John Larkin wrote: > >[...] > >>> >>>> I you make an instantaneous change in C, LT Spice conserves charge, so >>>> doesn't conserve energy. Spice doesn't need to conserve energy. >>>> >>> >>> SPICE has weirdnesses. When I tried to massage the stimulus pulse for >>> the cap values using LC the capacitor action flatlined. The stimulus >>> itself looks ok, it's just that the formula in the cap seems to choke. >>> So I had to restrict it to RC. Beats me why but for now it's good enough. >>> >>> Thanks again for all the hints. I got it to run and produce a useful WAV >>> output for the software engineer. 60 cardiac cycles. Ba-bump .. ba-bump >>> .. ba-bump .. ba-bump .. ba-bump ............... *BEEEEEEEEEP* .... just >>> kidding ... >> >> >> This is fun: >> >> https://dl.dropboxusercontent.com/u/53724080/Circuits/Current_Sources/Isink_NAN.asc >> >> LTS doesn't mind zero value resistors or caps, but it doesn't like L=0 >> in this circuit. >> > >But it works if you give the inductor 1 femtohenry. Nothing in the world >could ever have such a low inductance.Weird, but that little current sink, with L=0, runs at home but gets NAN crashes when I run it at work. Must be some different Spice setting. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Reply by ●March 20, 20152015-03-20
Joerg <news@analogconsultants.com> wrote:> On 2015-03-20 9:35 AM, Tom Swift wrote:>> You must be at the point now where you walk into a Doctor's office or >> operating room, look around and say to yourself. "I designed that, >> and that, and that...."> Not anymore, I moved largely away from med tech. This is the only > major med project I am involved in right now and for the foreseeable > future. Much of that market got jinxed by Obamacare and I saw it > coming, so branched out into industrial electronics and stuff.Just out of curiosity, why would Obamacare affect the med tech business? There would still be a need for equipment, and as far as I can tell, the equipment cost would not change. What happened to ruin the business?
Reply by ●March 20, 20152015-03-20
On Fri, 20 Mar 2015 10:34:18 -0700, Joerg <news@analogconsultants.com> wrote:>On 2015-03-20 9:35 AM, Tom Swift wrote: >> Joerg <news@analogconsultants.com> wrote: >> >>> On 2015-03-19 5:38 PM, Tom Swift wrote: >> >>>> Cool! That signal appears to be much more complex. Good thing you're >>>> doing it and not me! >> >>> Let's hope you and I never need the equipment that this is for but >>> it'll be good it's there, just in case. >> >> You must be at the point now where you walk into a Doctor's office or >> operating room, look around and say to yourself. "I designed that, and >> that, and that...." >> > >Not anymore, I moved largely away from med tech. This is the only major >med project I am involved in right now and for the foreseeable future. >Much of that market got jinxed by Obamacare and I saw it coming, so >branched out into industrial electronics and stuff. > > >> Pretty good insurance in case you ever get sick. They're fixing you with >> your own stuff! >> >> You should post a list of all the instruments you have designed so we can >> be sure they use nothing else when they want to cut us open:) >> > >When it comes to intravascular ultrasound, yes, then I'd like to be >diagnosed with one of our machines if that is ever necessary. Because it >is the only fully electronic system on the planet and I sure would not >like them to snake a catheter with a spinning shaft up into my coronary >blood vessels. Not that it's inherently too unsafe but it kind of scares >me. Plus IMHO our image quality is better and more consistent.Just the idea of a catheter snaking around inside scares me. Not much choice, though. Fortunately, my doc uses the wrist as the entry point (when possible). Don't know anything about spinning stuff, though.
Reply by ●March 20, 20152015-03-20
On Fri, 20 Mar 2015 22:05:05 GMT, Tom Swift <spam@me.com> wrote:>Joerg <news@analogconsultants.com> wrote: > >> On 2015-03-20 9:35 AM, Tom Swift wrote: > >>> You must be at the point now where you walk into a Doctor's office or >>> operating room, look around and say to yourself. "I designed that, >>> and that, and that...." > >> Not anymore, I moved largely away from med tech. This is the only >> major med project I am involved in right now and for the foreseeable >> future. Much of that market got jinxed by Obamacare and I saw it >> coming, so branched out into industrial electronics and stuff. > >Just out of curiosity, why would Obamacare affect the med tech business? >There would still be a need for equipment, and as far as I can tell, the >equipment cost would not change. What happened to ruin the business?Med device tax, for one.
Reply by ●March 21, 20152015-03-21
On 2015-03-20 11:31 AM, John Larkin wrote:> On Thu, 19 Mar 2015 16:57:15 -0700, Joerg <news@analogconsultants.com> > wrote: > >> On 2015-03-19 2:55 PM, John Larkin wrote: >>> On Thu, 19 Mar 2015 13:30:47 -0700, Joerg <news@analogconsultants.com> >>> wrote: >>> >>>> On 2015-03-19 8:37 AM, John Larkin wrote: >> >> [...] >> >>>> >>>>> I you make an instantaneous change in C, LT Spice conserves charge, so >>>>> doesn't conserve energy. Spice doesn't need to conserve energy. >>>>> >>>> >>>> SPICE has weirdnesses. When I tried to massage the stimulus pulse for >>>> the cap values using LC the capacitor action flatlined. The stimulus >>>> itself looks ok, it's just that the formula in the cap seems to choke. >>>> So I had to restrict it to RC. Beats me why but for now it's good enough. >>>> >>>> Thanks again for all the hints. I got it to run and produce a useful WAV >>>> output for the software engineer. 60 cardiac cycles. Ba-bump .. ba-bump >>>> .. ba-bump .. ba-bump .. ba-bump ............... *BEEEEEEEEEP* .... just >>>> kidding ... >>> >>> >>> This is fun: >>> >>> https://dl.dropboxusercontent.com/u/53724080/Circuits/Current_Sources/Isink_NAN.asc >>> >>> LTS doesn't mind zero value resistors or caps, but it doesn't like L=0 >>> in this circuit. >>> >> >> But it works if you give the inductor 1 femtohenry. Nothing in the world >> could ever have such a low inductance. > > Weird, but that little current sink, with L=0, runs at home but gets > NAN crashes when I run it at work. Must be some different Spice > setting. >Lesson learned: Go home when you want to solve a really tough problem. No kidding, I solved one (a difficult safety feature that I am sure the Federales will insist on) yesterday on a 36mi mountain bike ride. Then around mile 30 a large rock got kicked up by the front wheel and hit me in the right shin at a delta-V of 15-20mph. It still hurts. -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●March 21, 20152015-03-21
On 2015-03-20 3:05 PM, Tom Swift wrote:> Joerg <news@analogconsultants.com> wrote: > >> On 2015-03-20 9:35 AM, Tom Swift wrote: > >>> You must be at the point now where you walk into a Doctor's office or >>> operating room, look around and say to yourself. "I designed that, >>> and that, and that...." > >> Not anymore, I moved largely away from med tech. This is the only >> major med project I am involved in right now and for the foreseeable >> future. Much of that market got jinxed by Obamacare and I saw it >> coming, so branched out into industrial electronics and stuff. > > Just out of curiosity, why would Obamacare affect the med tech business? > There would still be a need for equipment, and as far as I can tell, the > equipment cost would not change. What happened to ruin the business? >Several things, the most important ones being: 1. A new 2.3% medical device tax, as Keith said. This gets creamed off the top from gross revenue, not from profits. So a start-up that naturally won't be able to make profits for the first few years will have to fork over an additional tax. More established companies that run only a slim profit got that wiped out. 2. Culling of services and fees. In order to finance this gigantic welfare expansion the president and his people thought it smart to simply cut reimbursements and such. If a doctor can barely break even, how do they think he or she will do if they cut down another 21% or whatever? Anyhow, this has predictably resulted in a souring of the investment climate and it has become much tougher to find funding for a medical device start-up. While I participate in the development of an idea that did manage to get funded I also found in my other consulting work that the pocket books in med devices for R&D and thus also for consulting work are now a lot tighter. They are not in fields such as oil, gas, industrial and so on. Therefore, that's where my work mainly headed. -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●March 21, 20152015-03-21
On 2015-03-20 4:51 PM, krw@zzz.com wrote:> On Fri, 20 Mar 2015 10:34:18 -0700, Joerg <news@analogconsultants.com> > wrote: > >> On 2015-03-20 9:35 AM, Tom Swift wrote: >>> Joerg <news@analogconsultants.com> wrote: >>> >>>> On 2015-03-19 5:38 PM, Tom Swift wrote: >>> >>>>> Cool! That signal appears to be much more complex. Good thing you're >>>>> doing it and not me! >>> >>>> Let's hope you and I never need the equipment that this is for but >>>> it'll be good it's there, just in case. >>> >>> You must be at the point now where you walk into a Doctor's office or >>> operating room, look around and say to yourself. "I designed that, and >>> that, and that...." >>> >> >> Not anymore, I moved largely away from med tech. This is the only major >> med project I am involved in right now and for the foreseeable future. >> Much of that market got jinxed by Obamacare and I saw it coming, so >> branched out into industrial electronics and stuff. >> >> >>> Pretty good insurance in case you ever get sick. They're fixing you with >>> your own stuff! >>> >>> You should post a list of all the instruments you have designed so we can >>> be sure they use nothing else when they want to cut us open:) >>> >> >> When it comes to intravascular ultrasound, yes, then I'd like to be >> diagnosed with one of our machines if that is ever necessary. Because it >> is the only fully electronic system on the planet and I sure would not >> like them to snake a catheter with a spinning shaft up into my coronary >> blood vessels. Not that it's inherently too unsafe but it kind of scares >> me. Plus IMHO our image quality is better and more consistent. > > Just the idea of a catheter snaking around inside scares me. Not much > choice, though. Fortunately, my doc uses the wrist as the entry point > (when possible). Don't know anything about spinning stuff, though. >This is for the more serious stuff such as snaking up ultrasound catheters or stents riding on balloon catheter tips. They go in through a cut in the femoral artery where they place a temporary lockable port, just during the procedure. Get a ton of exercise, don't smoke, don't eat bad stuff and you might never need this done. But for some people the conditions are heredetary, not much they can do about it. A friend of ours just got a whole new heart valve delivered and installed with such a procedure. They didn't have to crack his chest for open heart surgery, a procedure he might not have survived due to other medical conditions. -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●March 21, 20152015-03-21
On Sat, 21 Mar 2015 07:35:48 -0700, Joerg <news@analogconsultants.com> wrote:>On 2015-03-20 11:31 AM, John Larkin wrote: >> On Thu, 19 Mar 2015 16:57:15 -0700, Joerg <news@analogconsultants.com> >> wrote: >> >>> On 2015-03-19 2:55 PM, John Larkin wrote: >>>> On Thu, 19 Mar 2015 13:30:47 -0700, Joerg <news@analogconsultants.com> >>>> wrote: >>>> >>>>> On 2015-03-19 8:37 AM, John Larkin wrote: >>> >>> [...] >>> >>>>> >>>>>> I you make an instantaneous change in C, LT Spice conserves charge, so >>>>>> doesn't conserve energy. Spice doesn't need to conserve energy. >>>>>> >>>>> >>>>> SPICE has weirdnesses. When I tried to massage the stimulus pulse for >>>>> the cap values using LC the capacitor action flatlined. The stimulus >>>>> itself looks ok, it's just that the formula in the cap seems to choke. >>>>> So I had to restrict it to RC. Beats me why but for now it's good enough. >>>>> >>>>> Thanks again for all the hints. I got it to run and produce a useful WAV >>>>> output for the software engineer. 60 cardiac cycles. Ba-bump .. ba-bump >>>>> .. ba-bump .. ba-bump .. ba-bump ............... *BEEEEEEEEEP* .... just >>>>> kidding ... >>>> >>>> >>>> This is fun: >>>> >>>> https://dl.dropboxusercontent.com/u/53724080/Circuits/Current_Sources/Isink_NAN.asc >>>> >>>> LTS doesn't mind zero value resistors or caps, but it doesn't like L=0 >>>> in this circuit. >>>> >>> >>> But it works if you give the inductor 1 femtohenry. Nothing in the world >>> could ever have such a low inductance. >> >> Weird, but that little current sink, with L=0, runs at home but gets >> NAN crashes when I run it at work. Must be some different Spice >> setting. >> > >Lesson learned: Go home when you want to solve a really tough problem. >No kidding, I solved one (a difficult safety feature that I am sure the >Federales will insist on) yesterday on a 36mi mountain bike ride. Then >around mile 30 a large rock got kicked up by the front wheel and hit me >in the right shin at a delta-V of 15-20mph. It still hurts.I get all my best ideas in the shower. Luckily, our water heater has an 80 gallon tank. -- John Larkin Highland Technology, Inc picosecond timing laser drivers and controllers jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
