Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:> On Wed, 18 Mar 2015 14:03:07 -0700, Joerg <news@analogconsultants.com> > wrote: > > [snip] >>> >> >> No, it's a circuit where a capacitive sensor is employed and I want to >> mimic the sensor output. The capacitor itself will be inside a somewhat >> resonant circuit so it has to behave like a real and clean capacitor. >> >> > [snip] > > I take it you haven't tried my subcircuit? > > ...Jim ThompsonJim, can I assume that your subcircuit switches capacitance between two values based on a voltage? I suspect Joerg's desire is for something that is a mite less "binary".
Voltage-variable capacitor doesn't work in LTSpice
Started by ●March 16, 2015
Reply by ●March 18, 20152015-03-18
Reply by ●March 19, 20152015-03-19
On Wed, 18 Mar 2015 17:05:28 -0700, Joerg <news@analogconsultants.com> wrote:>On 2015-03-18 4:46 PM, John Larkin wrote: >> On Wed, 18 Mar 2015 16:39:38 -0700, Joerg <news@analogconsultants.com> >> wrote: >> >>> On 2015-03-18 2:55 PM, John Larkin wrote: >>>> On Wed, 18 Mar 2015 14:03:07 -0700, Joerg <news@analogconsultants.com> >>>> wrote: >>>> >>>>> On 2015-03-18 1:46 PM, John Larkin wrote: >>>>>> On Wed, 18 Mar 2015 13:36:27 -0700, Joerg <news@analogconsultants.com> >>>>>> wrote: >>>>>> >>>>>>> On 2015-03-18 11:54 AM, Syd Rumpo wrote: >>>>>>>> On 17/03/2015 00:26, Joerg wrote: >>>>>>>>> Gentlemen, >>>>>>>>> >>>>>>>>> Setting up voltage-controlled resistors is easy: R=(V(X)+0.01) or >>>>>>>>> whatever. Works, always did. Doing the same with a capacitor fails with >>>>>>>>> this error message: >>>>>>>>> >>>>>>>>> Error on line 6 : c1 n002 0 c=(v(x)+0.01) >>>>>>>>> Unable to find definition of model "c" >>>>>>>>> >>>>>>>>> * Unknown parameter "x" >>>>>>>>> WARNING: Less than two connections to node X. This node is used by V4. >>>>>>>>> Fatal Error: Missing capacitance value for "C1" >>>>>>>>> >>>>>>>>> Both sims attached. What gives? Ideas how to make it work? Disregard the >>>>>>>>> values that wouldn't make sense for the cap here, this is just to find >>>>>>>>> the principal reason why the control method doesn't work with capacitors. >>>>>>>>> >>>>>>>> <snip> >>>>>>>> >>>>>>>> This is what I did for a time-varying capacitance. In the component >>>>>>>> 'Value' field, I put Q=(4p/(0.25 +(time*5)))*x which swept the >>>>>>>> capacitance from 16pF downwards controlled by the internal variable 'time'. >>>>>>>> >>>>>>>> I can't remember why you need the Q and the x, but you do, and it took a >>>>>>>> good while to find out - it seems you can't just vary the capacitance >>>>>>>> directly. Replace time with a voltage and the appropriate scaling and >>>>>>>> you should be good to go. >>>>>>>> >>>>>>> >>>>>>> Tried it and that completely bungled the linearity when the cap is >>>>>>> inside a resonant circuit. At least no more error messages which is >>>>>>> good. Well, maybe I just do it in hardware then, firing up the old >>>>>>> Weller. I'd have to buy a bag of varicaps but those are cheap. >>>>>> >>>>>> Are you trying to sim a VCO? Simulating oscillators is always tedious. >>>>>> >>>>> >>>>> No, it's a circuit where a capacitive sensor is employed and I want to >>>>> mimic the sensor output. The capacitor itself will be inside a somewhat >>>>> resonant circuit so it has to behave like a real and clean capacitor. >>>> >>>> Would something like this work? >>>> >>>> https://dl.dropboxusercontent.com/u/53724080/Circuits/Caps/Modulated_Cap_1.asc >>>> >>>> The cap is modulated by voltage ZZ, which in this case makes the cap >>>> ramp from 1F to 20F. That in turn sweeps the LC ringing frequency >>>> down. >>>> >>> >>> Thanks, John, that actually seems to work. Beats me why mine didn't >>> because the only difference was that I called "ZZ" "Y" instead. >> >> Well, that's what you need an expert for! >> > >Yup :-) > > >> It may matter about whitespace in the Q equation; it doesn't seem to >> like any. >> >> Well, I may find this useful in the future. >> > >I think I know what it could have been. I had a voltage rail called "X" >left in the schematic and it must have not liked that.Try this one: https://dl.dropboxusercontent.com/u/53724080/Circuits/Caps/Modulated_Cap_2.asc the peak inductor current triples from start to end, so the stored energy in the tank goes up almost 10:1. -- John Larkin Highland Technology, Inc picosecond timing laser drivers and controllers jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Reply by ●March 19, 20152015-03-19
On Wed, 18 Mar 2015 20:56:51 -0700, John Larkin <jlarkin@highlandtechnology.com> wrote:>On Wed, 18 Mar 2015 17:05:28 -0700, Joerg <news@analogconsultants.com> >wrote: > >>On 2015-03-18 4:46 PM, John Larkin wrote: >>> On Wed, 18 Mar 2015 16:39:38 -0700, Joerg <news@analogconsultants.com> >>> wrote: >>> >>>> On 2015-03-18 2:55 PM, John Larkin wrote: >>>>> On Wed, 18 Mar 2015 14:03:07 -0700, Joerg <news@analogconsultants.com> >>>>> wrote: >>>>> >>>>>> On 2015-03-18 1:46 PM, John Larkin wrote: >>>>>>> On Wed, 18 Mar 2015 13:36:27 -0700, Joerg <news@analogconsultants.com> >>>>>>> wrote: >>>>>>> >>>>>>>> On 2015-03-18 11:54 AM, Syd Rumpo wrote: >>>>>>>>> On 17/03/2015 00:26, Joerg wrote: >>>>>>>>>> Gentlemen, >>>>>>>>>> >>>>>>>>>> Setting up voltage-controlled resistors is easy: R=(V(X)+0.01) or >>>>>>>>>> whatever. Works, always did. Doing the same with a capacitor fails with >>>>>>>>>> this error message: >>>>>>>>>> >>>>>>>>>> Error on line 6 : c1 n002 0 c=(v(x)+0.01) >>>>>>>>>> Unable to find definition of model "c" >>>>>>>>>> >>>>>>>>>> * Unknown parameter "x" >>>>>>>>>> WARNING: Less than two connections to node X. This node is used by V4. >>>>>>>>>> Fatal Error: Missing capacitance value for "C1" >>>>>>>>>> >>>>>>>>>> Both sims attached. What gives? Ideas how to make it work? Disregard the >>>>>>>>>> values that wouldn't make sense for the cap here, this is just to find >>>>>>>>>> the principal reason why the control method doesn't work with capacitors. >>>>>>>>>> >>>>>>>>> <snip> >>>>>>>>> >>>>>>>>> This is what I did for a time-varying capacitance. In the component >>>>>>>>> 'Value' field, I put Q=(4p/(0.25 +(time*5)))*x which swept the >>>>>>>>> capacitance from 16pF downwards controlled by the internal variable 'time'. >>>>>>>>> >>>>>>>>> I can't remember why you need the Q and the x, but you do, and it took a >>>>>>>>> good while to find out - it seems you can't just vary the capacitance >>>>>>>>> directly. Replace time with a voltage and the appropriate scaling and >>>>>>>>> you should be good to go. >>>>>>>>> >>>>>>>> >>>>>>>> Tried it and that completely bungled the linearity when the cap is >>>>>>>> inside a resonant circuit. At least no more error messages which is >>>>>>>> good. Well, maybe I just do it in hardware then, firing up the old >>>>>>>> Weller. I'd have to buy a bag of varicaps but those are cheap. >>>>>>> >>>>>>> Are you trying to sim a VCO? Simulating oscillators is always tedious. >>>>>>> >>>>>> >>>>>> No, it's a circuit where a capacitive sensor is employed and I want to >>>>>> mimic the sensor output. The capacitor itself will be inside a somewhat >>>>>> resonant circuit so it has to behave like a real and clean capacitor. >>>>> >>>>> Would something like this work? >>>>> >>>>> https://dl.dropboxusercontent.com/u/53724080/Circuits/Caps/Modulated_Cap_1.asc >>>>> >>>>> The cap is modulated by voltage ZZ, which in this case makes the cap >>>>> ramp from 1F to 20F. That in turn sweeps the LC ringing frequency >>>>> down. >>>>> >>>> >>>> Thanks, John, that actually seems to work. Beats me why mine didn't >>>> because the only difference was that I called "ZZ" "Y" instead. >>> >>> Well, that's what you need an expert for! >>> >> >>Yup :-) >> >> >>> It may matter about whitespace in the Q equation; it doesn't seem to >>> like any. >>> >>> Well, I may find this useful in the future. >>> >> >>I think I know what it could have been. I had a voltage rail called "X" >>left in the schematic and it must have not liked that. > > >Try this one: > >https://dl.dropboxusercontent.com/u/53724080/Circuits/Caps/Modulated_Cap_2.asc > >the peak inductor current triples from start to end, so the stored >energy in the tank goes up almost 10:1.I you make an instantaneous change in C, LT Spice conserves charge, so doesn't conserve energy. Spice doesn't need to conserve energy. -- John Larkin Highland Technology, Inc picosecond timing laser drivers and controllers jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Reply by ●March 19, 20152015-03-19
On 2015-03-19 8:37 AM, John Larkin wrote:> On Wed, 18 Mar 2015 20:56:51 -0700, John Larkin > <jlarkin@highlandtechnology.com> wrote: > >> On Wed, 18 Mar 2015 17:05:28 -0700, Joerg <news@analogconsultants.com> >> wrote: >> >>> On 2015-03-18 4:46 PM, John Larkin wrote: >>>> On Wed, 18 Mar 2015 16:39:38 -0700, Joerg <news@analogconsultants.com> >>>> wrote: >>>> >>>>> On 2015-03-18 2:55 PM, John Larkin wrote: >>>>>> On Wed, 18 Mar 2015 14:03:07 -0700, Joerg <news@analogconsultants.com> >>>>>> wrote: >>>>>> >>>>>>> On 2015-03-18 1:46 PM, John Larkin wrote: >>>>>>>> On Wed, 18 Mar 2015 13:36:27 -0700, Joerg <news@analogconsultants.com> >>>>>>>> wrote: >>>>>>>> >>>>>>>>> On 2015-03-18 11:54 AM, Syd Rumpo wrote: >>>>>>>>>> On 17/03/2015 00:26, Joerg wrote: >>>>>>>>>>> Gentlemen, >>>>>>>>>>> >>>>>>>>>>> Setting up voltage-controlled resistors is easy: R=(V(X)+0.01) or >>>>>>>>>>> whatever. Works, always did. Doing the same with a capacitor fails with >>>>>>>>>>> this error message: >>>>>>>>>>> >>>>>>>>>>> Error on line 6 : c1 n002 0 c=(v(x)+0.01) >>>>>>>>>>> Unable to find definition of model "c" >>>>>>>>>>> >>>>>>>>>>> * Unknown parameter "x" >>>>>>>>>>> WARNING: Less than two connections to node X. This node is used by V4. >>>>>>>>>>> Fatal Error: Missing capacitance value for "C1" >>>>>>>>>>> >>>>>>>>>>> Both sims attached. What gives? Ideas how to make it work? Disregard the >>>>>>>>>>> values that wouldn't make sense for the cap here, this is just to find >>>>>>>>>>> the principal reason why the control method doesn't work with capacitors. >>>>>>>>>>> >>>>>>>>>> <snip> >>>>>>>>>> >>>>>>>>>> This is what I did for a time-varying capacitance. In the component >>>>>>>>>> 'Value' field, I put Q=(4p/(0.25 +(time*5)))*x which swept the >>>>>>>>>> capacitance from 16pF downwards controlled by the internal variable 'time'. >>>>>>>>>> >>>>>>>>>> I can't remember why you need the Q and the x, but you do, and it took a >>>>>>>>>> good while to find out - it seems you can't just vary the capacitance >>>>>>>>>> directly. Replace time with a voltage and the appropriate scaling and >>>>>>>>>> you should be good to go. >>>>>>>>>> >>>>>>>>> >>>>>>>>> Tried it and that completely bungled the linearity when the cap is >>>>>>>>> inside a resonant circuit. At least no more error messages which is >>>>>>>>> good. Well, maybe I just do it in hardware then, firing up the old >>>>>>>>> Weller. I'd have to buy a bag of varicaps but those are cheap. >>>>>>>> >>>>>>>> Are you trying to sim a VCO? Simulating oscillators is always tedious. >>>>>>>> >>>>>>> >>>>>>> No, it's a circuit where a capacitive sensor is employed and I want to >>>>>>> mimic the sensor output. The capacitor itself will be inside a somewhat >>>>>>> resonant circuit so it has to behave like a real and clean capacitor. >>>>>> >>>>>> Would something like this work? >>>>>> >>>>>> https://dl.dropboxusercontent.com/u/53724080/Circuits/Caps/Modulated_Cap_1.asc >>>>>> >>>>>> The cap is modulated by voltage ZZ, which in this case makes the cap >>>>>> ramp from 1F to 20F. That in turn sweeps the LC ringing frequency >>>>>> down. >>>>>> >>>>> >>>>> Thanks, John, that actually seems to work. Beats me why mine didn't >>>>> because the only difference was that I called "ZZ" "Y" instead. >>>> >>>> Well, that's what you need an expert for! >>>> >>> >>> Yup :-) >>> >>> >>>> It may matter about whitespace in the Q equation; it doesn't seem to >>>> like any. >>>> >>>> Well, I may find this useful in the future. >>>> >>> >>> I think I know what it could have been. I had a voltage rail called "X" >>> left in the schematic and it must have not liked that. >> >> >> Try this one: >> >> https://dl.dropboxusercontent.com/u/53724080/Circuits/Caps/Modulated_Cap_2.asc >> >> the peak inductor current triples from start to end, so the stored >> energy in the tank goes up almost 10:1. >That probably only works in the cyber world :-)> 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 ... -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●March 19, 20152015-03-19
On Thu, 19 Mar 2015 13:30:47 -0700, Joerg <news@analogconsultants.com> wrote:>On 2015-03-19 8:37 AM, John Larkin wrote: >> On Wed, 18 Mar 2015 20:56:51 -0700, John Larkin >> <jlarkin@highlandtechnology.com> wrote: >> >>> On Wed, 18 Mar 2015 17:05:28 -0700, Joerg <news@analogconsultants.com> >>> wrote: >>> >>>> On 2015-03-18 4:46 PM, John Larkin wrote: >>>>> On Wed, 18 Mar 2015 16:39:38 -0700, Joerg <news@analogconsultants.com> >>>>> wrote: >>>>> >>>>>> On 2015-03-18 2:55 PM, John Larkin wrote: >>>>>>> On Wed, 18 Mar 2015 14:03:07 -0700, Joerg <news@analogconsultants.com> >>>>>>> wrote: >>>>>>> >>>>>>>> On 2015-03-18 1:46 PM, John Larkin wrote: >>>>>>>>> On Wed, 18 Mar 2015 13:36:27 -0700, Joerg <news@analogconsultants.com> >>>>>>>>> wrote: >>>>>>>>> >>>>>>>>>> On 2015-03-18 11:54 AM, Syd Rumpo wrote: >>>>>>>>>>> On 17/03/2015 00:26, Joerg wrote: >>>>>>>>>>>> Gentlemen, >>>>>>>>>>>> >>>>>>>>>>>> Setting up voltage-controlled resistors is easy: R=(V(X)+0.01) or >>>>>>>>>>>> whatever. Works, always did. Doing the same with a capacitor fails with >>>>>>>>>>>> this error message: >>>>>>>>>>>> >>>>>>>>>>>> Error on line 6 : c1 n002 0 c=(v(x)+0.01) >>>>>>>>>>>> Unable to find definition of model "c" >>>>>>>>>>>> >>>>>>>>>>>> * Unknown parameter "x" >>>>>>>>>>>> WARNING: Less than two connections to node X. This node is used by V4. >>>>>>>>>>>> Fatal Error: Missing capacitance value for "C1" >>>>>>>>>>>> >>>>>>>>>>>> Both sims attached. What gives? Ideas how to make it work? Disregard the >>>>>>>>>>>> values that wouldn't make sense for the cap here, this is just to find >>>>>>>>>>>> the principal reason why the control method doesn't work with capacitors. >>>>>>>>>>>> >>>>>>>>>>> <snip> >>>>>>>>>>> >>>>>>>>>>> This is what I did for a time-varying capacitance. In the component >>>>>>>>>>> 'Value' field, I put Q=(4p/(0.25 +(time*5)))*x which swept the >>>>>>>>>>> capacitance from 16pF downwards controlled by the internal variable 'time'. >>>>>>>>>>> >>>>>>>>>>> I can't remember why you need the Q and the x, but you do, and it took a >>>>>>>>>>> good while to find out - it seems you can't just vary the capacitance >>>>>>>>>>> directly. Replace time with a voltage and the appropriate scaling and >>>>>>>>>>> you should be good to go. >>>>>>>>>>> >>>>>>>>>> >>>>>>>>>> Tried it and that completely bungled the linearity when the cap is >>>>>>>>>> inside a resonant circuit. At least no more error messages which is >>>>>>>>>> good. Well, maybe I just do it in hardware then, firing up the old >>>>>>>>>> Weller. I'd have to buy a bag of varicaps but those are cheap. >>>>>>>>> >>>>>>>>> Are you trying to sim a VCO? Simulating oscillators is always tedious. >>>>>>>>> >>>>>>>> >>>>>>>> No, it's a circuit where a capacitive sensor is employed and I want to >>>>>>>> mimic the sensor output. The capacitor itself will be inside a somewhat >>>>>>>> resonant circuit so it has to behave like a real and clean capacitor. >>>>>>> >>>>>>> Would something like this work? >>>>>>> >>>>>>> https://dl.dropboxusercontent.com/u/53724080/Circuits/Caps/Modulated_Cap_1.asc >>>>>>> >>>>>>> The cap is modulated by voltage ZZ, which in this case makes the cap >>>>>>> ramp from 1F to 20F. That in turn sweeps the LC ringing frequency >>>>>>> down. >>>>>>> >>>>>> >>>>>> Thanks, John, that actually seems to work. Beats me why mine didn't >>>>>> because the only difference was that I called "ZZ" "Y" instead. >>>>> >>>>> Well, that's what you need an expert for! >>>>> >>>> >>>> Yup :-) >>>> >>>> >>>>> It may matter about whitespace in the Q equation; it doesn't seem to >>>>> like any. >>>>> >>>>> Well, I may find this useful in the future. >>>>> >>>> >>>> I think I know what it could have been. I had a voltage rail called "X" >>>> left in the schematic and it must have not liked that. >>> >>> >>> Try this one: >>> >>> https://dl.dropboxusercontent.com/u/53724080/Circuits/Caps/Modulated_Cap_2.asc >>> >>> the peak inductor current triples from start to end, so the stored >>> energy in the tank goes up almost 10:1. >> > >That probably only works in the cyber world :-) > > >> 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. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Reply by ●March 19, 20152015-03-19
Joerg <news@analogconsultants.com> wrote: [...]> 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 ...Another method might be to search google for 'heart sounds'. You will find many examples of normal and abnormal sounds to work with. Find a site that allows you to download the file in MP3 format, such as http://depts.washington.edu/physdx/heart/demo.html A normal heart sounds like http://depts.washington.edu/physdx/audio/normal.mp3 Download it and listen in VLC to see if it's what you want. Then search google for MP3 to WAV converters. Watch out for ones that want you to download a 'download management' file. Skip those ones. There's a good online site at http://audioformat.com/mp3-to-wav In this case, the normal.mp3 file is 154,227 bytes, and the WAV file is 850,220 bytes. There seems to be some mashup at the beginning, but otherwise it sounds exactly like the MP3 file. You can probably edit it and trim the part you want or extend it. You can find all kinds of abnormalities to listen to. I have a young and very pretty doctor who just gave me a complete physical. I have absolutely no idea how she can memorize all those different sounds. There are hundreds of them. But maybe you can put them in your device and have them detected automatically.
Reply by ●March 19, 20152015-03-19
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. -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●March 19, 20152015-03-19
On 2015-03-19 3:41 PM, Tom Swift wrote:> Joerg <news@analogconsultants.com> wrote: > > [...] > >> 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 ... > > Another method might be to search google for 'heart sounds'. You will > find many examples of normal and abnormal sounds to work with. Find a > site that allows you to download the file in MP3 format, such as > > http://depts.washington.edu/physdx/heart/demo.html > > A normal heart sounds like > > http://depts.washington.edu/physdx/audio/normal.mp3 > > Download it and listen in VLC to see if it's what you want. Then search > google for MP3 to WAV converters. Watch out for ones that want you to > download a 'download management' file. Skip those ones. There's a good > online site at > > http://audioformat.com/mp3-to-wav > > In this case, the normal.mp3 file is 154,227 bytes, and the WAV file is > 850,220 bytes. There seems to be some mashup at the beginning, but > otherwise it sounds exactly like the MP3 file. You can probably edit it > and trim the part you want or extend it. >The problem is that I need the aortic pressure signal and not the sound. I've mimicked it with an asymmetrical RC sawtooth for now, good enough to test the software initially.> You can find all kinds of abnormalities to listen to. I have a young and > very pretty doctor who just gave me a complete physical. I have > absolutely no idea how she can memorize all those different sounds. There > are hundreds of them. But maybe you can put them in your device and have > them detected automatically. >It comes with experience of maybe she has a knack for it. As a kid I was pretty good at diagnosing car engine troubles by ear. Until a kablouie kind of accident in the army messed up my hearing. Once I told my dad a valve on his new 5-cylinder Audi may be bad, probably an exhaust valve. So he brought it to the dealer. They laughed. "Phhht ... it's brand new and besides, what does a kid know?". My dad insisted. So they did a compression test and sure enough it failed the test on one cylinder. Major engine tear down and its exhaust valve had a deep V-cut burned into it from the side, totally toast. It was a warranty repair. -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●March 19, 20152015-03-19
Joerg <news@analogconsultants.com> wrote:> The problem is that I need the aortic pressure signal and not the > sound. I've mimicked it with an asymmetrical RC sawtooth for now, good > enough to test the software initially.Cool! That signal appears to be much more complex. Good thing you're doing it and not me!
Reply by ●March 20, 20152015-03-20
On 2015-03-19 5:38 PM, Tom Swift wrote:> Joerg <news@analogconsultants.com> wrote: > >> The problem is that I need the aortic pressure signal and not the >> sound. I've mimicked it with an asymmetrical RC sawtooth for now, good >> enough to test the software initially. > > 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. Ultimately I'll feed in a WAV file with real data once I obtain data in a non-proprietary format, which won't be too long now. Meantime I can fake events by sprinkling in random error signals via PWL and running them through analog circuitry. -- Regards, Joerg http://www.analogconsultants.com/
