Voltage-variable capacitor doesn't work in LTSpice

[Joerg]

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/

 

[Tom Swift]

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

 

[Joerg]

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/

 

[John Larkin]

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

 

[Tom Swift]

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?

 

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.

 

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.

 

[Joerg]

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/

 

[Joerg]

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/

 

[Joerg]

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/

 

[John Larkin]

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

 

On Sat, 21 Mar 2015 07:52:02 -0700, Joerg <news@analogconsultants.com>
wrote:

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.

More serious than a triple bypass? ;-) He does angioplasty and stents
through the wrist. Don't know about ultrasound. If at all possible
he doesn't use the femoral artery. That has a lot of complications
that the wrist doesn't have. It's a straight run from the right wrist
(or elbow) to the heart.

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.

Pretty much a genes thing. My brother had a couple of stents a week
before I had the catheterization/ He, too, should have had a triple
bypass but they blew it so he'll have to wait a year for the surgery.
Another brother died of sudden death syndrome. He was the one who was
anal about all the exercise and diet stuff. He swam two miles three
times a week and did a couple of hours at the gym 7 days. Didn't help.

I got the whole zipper deal. In addition to the three cabbages, I got
a maze. ;-) All in all, it beats cancer, which other than a little
skin cancer (my mother, in her 90s), no one in my family on either
side has had.

 

[Tom Swift]

Joerg <news@analogconsultants.com> wrote:

On 2015-03-20 3:05 PM, Tom Swift wrote:

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.

Thanks for taking the time to post, Joerg. That is a very alarming
picture, and I'm glad you got out in time.

 

[Joerg]

On 2015-03-21 8:48 AM, krw@zzz.com wrote:

On Sat, 21 Mar 2015 07:52:02 -0700, Joerg <news@analogconsultants.com
wrote:

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.

More serious than a triple bypass? ;-) He does angioplasty and stents
through the wrist. Don't know about ultrasound. If at all possible
he doesn't use the femoral artery. That has a lot of complications
that the wrist doesn't have. It's a straight run from the right wrist
(or elbow) to the heart.

Bigger stuff usually only fits through the femoralis. It's pretty
routine. One of the cardiologists said that he feels like a glorified
plumber.

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.

Pretty much a genes thing. My brother had a couple of stents a week
before I had the catheterization/ He, too, should have had a triple
bypass but they blew it so he'll have to wait a year for the surgery.
Another brother died of sudden death syndrome. He was the one who was
anal about all the exercise and diet stuff. He swam two miles three
times a week and did a couple of hours at the gym 7 days. Didn't help.

But it still does other things. I bet he feels really good after
exercise. When I came home from a 36mi hard mountain bike ride yesterday
night I felt like a Viking warrior on a horse.

I got the whole zipper deal. In addition to the three cabbages, I got
a maze. ;-) All in all, it beats cancer, which other than a little
skin cancer (my mother, in her 90s), no one in my family on either
side has had.

Alzheimer's can be much worse. Many of these people know full well that
they are losing their brains but it can be agonzingly slow. Some know
exactly want they want to communicate but can't get it out. For years.

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Joerg]

On 2015-03-21 9:37 AM, Tom Swift wrote:

Joerg <news@analogconsultants.com> wrote:

On 2015-03-20 3:05 PM, Tom Swift wrote:

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.

Thanks for taking the time to post, Joerg. That is a very alarming
picture, and I'm glad you got out in time.

I hope some day we'll get real healthcare reform but that cannot come
from the current administration. Obamacare completely missed the boat.
For example, there are no provisions in that law to open the
chargemaster to patients and everyone else and also to cut ambulance
chasers out of the deal.

The chargemaster secrecy alone is huge. Case in point: Eye exam was
needed. So we inquired and at one out-of-network doctor the procedure
with prescription would have cost about $70. Called the HMO to see what
they charge. To out great surprise since we have a high-deductible plan
they said that it's no charge at all, like preventative care. So we
went. _Then_ we got a statement for $163. I called. "Oh, sorry, you were
given wrong information but it's your responsibility to check the
coverage". Which we can't because most of it isn't disclosed. This is
despicable and a serious cancer in US health care.

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Joerg]

On 2015-03-21 8:22 AM, John Larkin wrote:

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.

Oh, oh, the guys in Sacramento will come down on you now. Drought
legislation is in the making. We already started early last year to cut
the water consumption during showers to a minimum. Like not running the
water while soaping up.

--
Regards, Joerg

http://www.analogconsultants.com/

 

[John Larkin]

On Sat, 21 Mar 2015 12:38:13 -0700, Joerg <news@analogconsultants.com>
wrote:

On 2015-03-21 9:37 AM, Tom Swift wrote:
Joerg <news@analogconsultants.com> wrote:

On 2015-03-20 3:05 PM, Tom Swift wrote:

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.

Thanks for taking the time to post, Joerg. That is a very alarming
picture, and I'm glad you got out in time.


I hope some day we'll get real healthcare reform but that cannot come
from the current administration. Obamacare completely missed the boat.
For example, there are no provisions in that law to open the
chargemaster to patients and everyone else and also to cut ambulance
chasers out of the deal.

Obamacare sold out to all the big stakeholders, to get it to pass. I
suspect that it was actually designed to fail.

The chargemaster secrecy alone is huge. Case in point: Eye exam was
needed. So we inquired and at one out-of-network doctor the procedure
with prescription would have cost about $70. Called the HMO to see what
they charge. To out great surprise since we have a high-deductible plan
they said that it's no charge at all, like preventative care. So we
went. _Then_ we got a statement for $163. I called. "Oh, sorry, you were
given wrong information but it's your responsibility to check the
coverage". Which we can't because most of it isn't disclosed. This is
despicable and a serious cancer in US health care.

Yup. Published price lists should be mandatory. There's no other
business that can charge whatever they want after the product is
delivered.


--

John Larkin Highland Technology, Inc
picosecond timing laser drivers and controllers

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

On Sat, 21 Mar 2015 12:29:37 -0700, Joerg <news@analogconsultants.com>
wrote:

On 2015-03-21 8:48 AM, krw@zzz.com wrote:
On Sat, 21 Mar 2015 07:52:02 -0700, Joerg <news@analogconsultants.com
wrote:

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.

More serious than a triple bypass? ;-) He does angioplasty and stents
through the wrist. Don't know about ultrasound. If at all possible
he doesn't use the femoral artery. That has a lot of complications
that the wrist doesn't have. It's a straight run from the right wrist
(or elbow) to the heart.


Bigger stuff usually only fits through the femoralis. It's pretty
routine. One of the cardiologists said that he feels like a glorified
plumber.

I can believe that. My cardiologist doesn't do anything past the
plumbing. If more is needed he passes it off to the surgeon. He's
good but real surgery is not his specialty.

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.

Pretty much a genes thing. My brother had a couple of stents a week
before I had the catheterization/ He, too, should have had a triple
bypass but they blew it so he'll have to wait a year for the surgery.
Another brother died of sudden death syndrome. He was the one who was
anal about all the exercise and diet stuff. He swam two miles three
times a week and did a couple of hours at the gym 7 days. Didn't help.


But it still does other things. I bet he feels really good after
exercise. When I came home from a 36mi hard mountain bike ride yesterday
night I felt like a Viking warrior on a horse.

Drugs do the same thing, in the same way. Dopamine, Serotonin, and
Endorphins.

I got the whole zipper deal. In addition to the three cabbages, I got
a maze. ;-) All in all, it beats cancer, which other than a little
skin cancer (my mother, in her 90s), no one in my family on either
side has had.


Alzheimer's can be much worse. Many of these people know full well that
they are losing their brains but it can be agonzingly slow. Some know
exactly want they want to communicate but can't get it out. For years.

Agreed.

 

[Joerg]

On 2015-03-21 3:50 PM, krw@zzz.com wrote:

On Sat, 21 Mar 2015 12:29:37 -0700, Joerg <news@analogconsultants.com
wrote:

On 2015-03-21 8:48 AM, krw@zzz.com wrote:
On Sat, 21 Mar 2015 07:52:02 -0700, Joerg <news@analogconsultants.com
wrote:

[...]

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.

Pretty much a genes thing. My brother had a couple of stents a week
before I had the catheterization/ He, too, should have had a triple
bypass but they blew it so he'll have to wait a year for the surgery.
Another brother died of sudden death syndrome. He was the one who was
anal about all the exercise and diet stuff. He swam two miles three
times a week and did a couple of hours at the gym 7 days. Didn't help.


But it still does other things. I bet he feels really good after
exercise. When I came home from a 36mi hard mountain bike ride yesterday
night I felt like a Viking warrior on a horse.

Drugs do the same thing, in the same way. Dopamine, Serotonin, and
Endorphins.

But with exercise it only happens after reaching a certain endurance
level. When I started intense biking 1-1/2 years ago I was huffing and
puffing after 15 mile of hills and my only thought was "Get me off of
this bike!". Now it's different.

[...]

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Tom Swift]

Joerg <news@analogconsultants.com> wrote:

The chargemaster secrecy alone is huge. Case in point: Eye exam was
needed. So we inquired and at one out-of-network doctor the procedure
with prescription would have cost about $70. Called the HMO to see what
they charge. To out great surprise since we have a high-deductible plan
they said that it's no charge at all, like preventative care. So we
went. _Then_ we got a statement for $163. I called. "Oh, sorry, you were
given wrong information but it's your responsibility to check the
coverage". Which we can't because most of it isn't disclosed. This is
despicable and a serious cancer in US health care.

From the discussion, I understand med tech companies aren't making much
money, and are laying off people. Doctors are barely able to scrape by.

From Wikipedia, "According to the World Health Organization (WHO), the
United States spent more on health care per capita ($8,608), and more on
health care as percentage of its GDP (17.2%), than any other nation in
2011."

http://en.wikipedia.org/wiki/Health_care_in_the_United_States

So who is making all the money in health care? Is it the hospitals with
their obscene chargemaster lists?