Driver to drive?

[Martin Brown]

On 02/04/2014 23:43, Phil Hobbs wrote:

On 4/2/2014 5:24 PM, John Larkin wrote:
On Wed, 02 Apr 2014 17:11:05 -0400, Phil Hobbs
hobbs@electrooptical.net> wrote:

"Ethical blunder" is right up there with "terminological inexactitude."

Cheers

Phil Hobbs

Both sound like Bad Things to me.


Yup. In accordance with the national genius that Americans have for
euphemisms.

Cheers

Phil Hobbs

Hey. "Terminological inexactitude" was the phrase invented by Winston
Churchill in 1906 to describe lying (unparliamentary language).

More famous recently was "being economical with the truth" which was
used by a British civil servant in the "Spycatcher" book banning trial.

Climate change deniers are guilty of both and more besides.

--
Regards,
Martin Brown

 

[Jan Panteltje]

On a sunny day (Thu, 03 Apr 2014 09:58:46 +0100) it happened Martin Brown
<|||newspam|||@nezumi.demon.co.uk> wrote in <hp9%u.1$GP2.0@fx36.am4>:

On 02/04/2014 20:08, John Larkin wrote:
On Wed, 2 Apr 2014 07:42:43 -0700 (PDT), dagmargoodboat@yahoo.com
wrote:

On Wednesday, April 2, 2014 4:22:54 AM UTC-4, John Fields wrote:
On Tue, 01 Apr 2014 18:48:52 -0700, John Larkin wrote:


http://www.telegraph.co.uk/science/science-news/10738343/Forecasters-find-new-formula-for-long-range-weather.html?utm_source=dlvr.it&utm_medium=twitter

Thing is, it's easy to build a model that "simulates" past data. That can be
done with extreme accuracy... by polynomial curve fitting, for example. Heck,
Excel can do that. The more challenging thing to do is create a model that
predicts the unknown future.

---
As opposed to the known future?
---

Obviously. Lots of things are predictable, knowable, and known.

And one of them is the amount of CO2 in the atmosphere as a result of
burning fossil fuels on a business as usual basis. I suspect this will
continue until the damage done to the climate is absolutely irrefutable.

When the public finally notice that AGW is a real problem that cannot be
ignored politicians will try to blame scientists for not explaining it
to them clearly enough. This is already predictable.

It's likely that we are witnessing a historical political perversion
of the scientific community, the greatest ethical blunder in the
history of science. I feel priviliged to witness this in my lifetime.

http://www.thetimes.co.uk/tto/environment/article4051905.ece

Perhaps, but it is the deniers for hire that have sold their souls first
to big tobacco and now to the fossil fuel lobby and who have prostituted
their scientific credentials to the highest bidder.

You are such an increadible ying moron in not only this field but many others you lie about.
You are the one making a buck out of public fear for things that have nothing to to with anything
The taxes you pay is the bribe for those in power, you know propose any taxes if you can find something,
and you have friends in that realm.

Climate will always change, and has, on a regalar predictable basis:
http://www.world-mysteries.com/alignments/mpl_al3b.htm
the bad thing is that you (should) know that.
You are like green-pees, probably one of their suppliers.
You should be locked up end put to work in Siberia!

Eventually it will be impossible for anyone with a even a shred of
scientific credibility to claim that AGW is not happening.

Sun will go out, eventually, oh me oh my, idiot!
PS before that it seems you will fry a bit, not that that bothers me in the least.

 

[John Larkin]

On Thu, 03 Apr 2014 09:58:46 +0100, Martin Brown
<|||newspam|||@nezumi.demon.co.uk> wrote:

On 02/04/2014 20:08, John Larkin wrote:
On Wed, 2 Apr 2014 07:42:43 -0700 (PDT), dagmargoodboat@yahoo.com
wrote:

On Wednesday, April 2, 2014 4:22:54 AM UTC-4, John Fields wrote:
On Tue, 01 Apr 2014 18:48:52 -0700, John Larkin wrote:

http://www.telegraph.co.uk/science/science-news/10738343/Forecasters-find-new-formula-for-long-range-weather.html?utm_source=dlvr.it&utm_medium=twitter

Thing is, it's easy to build a model that "simulates" past data. That can be
done with extreme accuracy... by polynomial curve fitting, for example. Heck,
Excel can do that. The more challenging thing to do is create a model that
predicts the unknown future.

---
As opposed to the known future?
---

Obviously. Lots of things are predictable, knowable, and known.

And one of them is the amount of CO2 in the atmosphere as a result of
burning fossil fuels on a business as usual basis. I suspect this will
continue until the damage done to the climate is absolutely irrefutable.

So, it's not absolutely irrefutable? Then why do people want to supress (or
kill) sceptics?

When the public finally notice that AGW is a real problem that cannot be
ignored politicians will try to blame scientists for not explaining it
to them clearly enough. This is already predictable.

It's likely that we are witnessing a historical political perversion
of the scientific community, the greatest ethical blunder in the
history of science. I feel priviliged to witness this in my lifetime.

http://www.thetimes.co.uk/tto/environment/article4051905.ece

Perhaps, but it is the deniers for hire that have sold their souls first
to big tobacco and now to the fossil fuel lobby and who have prostituted
their scientific credentials to the highest bidder.

There's money sloshing around on both sides of the issue. Algore had made, what,
$200 million or so so far. The solar panel and windmill industries are heavily
subsidized. Scientists and institutions gain fame and fortune. IPPC members fly
jets to meet in exotic resorts.

Eventually it will be impossible for anyone with a even a shred of
scientific credibility to claim that AGW is not happening.

Or that it is.

Unfortunately, by then we will have set in train serious sea level rises
that will swamp some major coastal cities in the longer term.

Even that probably won't be enough to convince rabid right whingers like
you from insisting that it isn't happening.

Oh, it's happening. Luckily, not very fast these days.

https://en.wikipedia.org/wiki/Fileost-Glacial_Sea_Level.png



--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation

 

[Neon John]

On Wed, 2 Apr 2014 17:18:43 -0700 (PDT), makolber@yahoo.com wrote:

>It would be an interesting exercise to build a small but complex system and issue a challenge to climate modelers to model and predict the behavior of the system... Then check the predictions with measurements. We need to think of a sufficiently complex system that can be built and measured. Remember the biosphere?

That's easy. Gamma ray or neutron transport modeling codes. Two that
I use are ISOSHLD and MCNP. MCNP (Monte Carlo neutron program, now
expanded to all the radiation and particle types) is the best.

The behavior of gamma rays and neutrons in matter are extremely well
characterized and that knowledge is embodied in MCNP. And models are
easy to verify in the real world with real radiation sources,
detectors and shields.

MCNP does very well within the range of proven parameters but it can
fall on its face badly when used to extrapolate very far outsize the
"proven zone".

If a program modeling something as well characterized as radiation
transport, I can't even imagine how bad the climate models are since
none of them can be validated by real world experiments. Heck, if
they can't get a 3 day forecast correct much of the time, only the
True Believers could believe that computer codes purported to model
phenomena years in the future is anything other than GIGO

John

John DeArmond
http://www.neon-john.com
http://www.fluxeon.com
Tellico Plains, Occupied TN
See website for email address

 

[John Fields]

On Wed, 02 Apr 2014 14:06:50 -0700, John Larkin
<jlarkin@highlandtechnology.com> wrote:

Maybe we have too many scientists, as we arguably have too many
engineers.

---
I would argue: "One too many."

 

[Jim Thompson]

On Thu, 03 Apr 2014 11:05:16 -0500, John Fields
<jfields@austininstruments.com> wrote:

On Wed, 02 Apr 2014 14:06:50 -0700, John Larkin
jlarkin@highlandtechnology.com> wrote:


Maybe we have too many scientists, as we arguably have too many
engineers.

---
I would argue: "One too many."

Definitely >:-}

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[John Fields]

On Thu, 3 Apr 2014 04:21:38 -0700 (PDT), Bill Sloman
<bill.sloman@gmail.com> wrote:


>We could engineer a human population crash in a century or so if we were a sufficiently complacent bunch of morons.

---
Or, more likely, if we were wolves intent on thinning the complacent
flock.

 

[Bill Sloman]

On Friday, 4 April 2014 02:52:44 UTC+11, Neon John wrote:
> On Wed, 2 Apr 2014 17:18:43 -0700 (PDT), makolber@yahoo.com wrote:

<snip>

If a program modeling something as well characterized as radiation
transport, I can't even imagine how bad the climate models are since
none of them can be validated by real world experiments.

The climate models being advertised by the UK Meteorology service were being validated on historical data. If you train your model on the same data, it's well known that you have to split your data and reserve a separate batch purely for testing.

Heck, if they can't get a 3 day forecast correct much of the time, only the
True Believers could believe that computer codes purported to model
phenomena years in the future is anything other than GIGO.

The distinction between modelling weather and climate is well known. The thermodynamics that determine how much rain can fall on a province in a month provides a much tighter constraint on climate models, than the same thermodynamics do on the weather question of how much rain is going to fall on a suburb in an afternoon.

The "butterfly effect" makes long term weather forecasting impossibly difficult (at least with current technology). Climate forecasting is at least potentially feasible.

--
Bill Sloman, Sydney

 

[Bill Sloman]

On Friday, 4 April 2014 02:43:44 UTC+11, John Larkin wrote:

On Thu, 03 Apr 2014 09:58:46 +0100, Martin Brown
|||newspam|||@nezumi.demon.co.uk> wrote:
On 02/04/2014 20:08, John Larkin wrote:
On Wed, 2 Apr 2014 07:42:43 -0700 (PDT), dagmargoodboat@yahoo.com
wrote:
On Wednesday, April 2, 2014 4:22:54 AM UTC-4, John Fields wrote:
On Tue, 01 Apr 2014 18:48:52 -0700, John Larkin wrote:

<snip>

And one of them is the amount of CO2 in the atmosphere as a result of
burning fossil fuels on a business as usual basis. I suspect this will
continue until the damage done to the climate is absolutely irrefutable.

So, it's not absolutely irrefutable? Then why do people want to supress (or
kill) sceptics?

Bad choice of words there. I think that what was meant was "until the damage done to the climate is so serious that even the most ignorant head-in-the-sand Pollyanna has to recognise it".

And people don't want to kill sceptics. They want to kill climate change deniers, who aren't sceptical seekers after truth, but rather cynical spreaders of doubt, who are being paid to keep public opinion more sympathetic to the continuing (well-paid) excavation of fossil carbon and its sale as fuel than it would be if the public were better informed about the consequences..

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

Quite a few of them were previously engaged in telling us that smoking wasn't really as dangerous to our health as the medical researchers were claiming. Killing a bunch of them back then would have saved a few people from dying of lung cancer.

When the public finally notice that AGW is a real problem that cannot be
ignored politicians will try to blame scientists for not explaining it
to them clearly enough. This is already predictable.

It's likely that we are witnessing a historical political perversion
of the scientific community, the greatest ethical blunder in the
history of science. I feel priviliged to witness this in my lifetime.

http://www.thetimes.co.uk/tto/environment/article4051905.ece

Perhaps, but it is the deniers for hire that have sold their souls first
to big tobacco and now to the fossil fuel lobby and who have prostituted
their scientific credentials to the highest bidder.

There's money sloshing around on both sides of the issue. Algore had made, what, $200 million or so so far. The solar panel and windmill industries are heavily subsidized. Scientists and institutions gain fame and fortune. IPPC members fly jets to meet in exotic resorts.

Tokyo may be exotic - to you - but it is scarcely a resort.

Eventually it will be impossible for anyone with a even a shred of
scientific credibility to claim that AGW is not happening.

Or that it is.

Wrong. It is happening, and the evidence is already irrefutable. You don't take it seriously, but that's because you chose not to do any serious thinking or reading about the subject, allowing your opinions to be pre-fabricated by the Murdoch Press (who are presumably being paid - at some level - by the fossil carbon extraction industry to spread deceitful propaganda).

Unfortunately, by then we will have set in train serious sea level rises
that will swamp some major coastal cities in the longer term.

Even that probably won't be enough to convince rabid right whingers like
you from insisting that it isn't happening.

Oh, it's happening. Luckily, not very fast these days.

https://en.wikipedia.org/wiki/Fileost-Glacial_Sea_Level.png

It won't be fast until the Greenland ice sheet starts sliding off into the ocean, which it is, but not all that fast (at the moment).

If the Greenland and Antarctic ice sheets had to melt in place, it would be a very slow process. What happened with the Laurentian ice sheet at the end of the last ice age was that it slid off Canada in big chunks, got into the Atlantic (where it produced an immediate sea level rise) and melted there (leaving lots of "accidental" boulders on the ocean floor).

This - or something related - dumped enough fresh water into the Atlantic to stop the Gulf Steam for 1300 years, producing the Younger Dryas and very cold weather around the North Atlantic. Even you would probably notice that..

--
Bill Sloman, Sydney

 

[Bill Sloman]

On Friday, 4 April 2014 03:20:12 UTC+11, John Fields wrote:

On Thu, 3 Apr 2014 04:21:38 -0700 (PDT), Bill Sloman

bill.sloman@gmail.com> wrote:

snip

We could engineer a human population crash in a century or so if we were a sufficiently complacent bunch of morons.

Or, more likely, if we were wolves intent on thinning the complacent
flock.

Could be. The people who are paying for the denialist propaganda don't have much use for their US work force. They've out-sourced the work to China for now, and presumably expect to replace the Chinese with robots when they start to get expensive. A population crash would minimise the amount they'd have to spend on subsidising the lower-paid.

This might be short-sighted. The declining population would probably resent being decimated, and might go to the trouble of finding those responsible for the debacle and lynching every last one of them.

--
Bill Sloman, Sydney

 

On Thursday, April 3, 2014 7:09:31 PM UTC+13, Jim Thompson wrote:

On Wed, 2 Apr 2014 22:51:51 -0700 (PDT), gyansorova@gmail.com wrote:



On Wednesday, April 2, 2014 5:40:31 PM UTC+13, Sylvia Else wrote:

I have the circuit whose LTSPICE text is given below. The voltage



sources and voltage controlled switches are only there to set the



initial voltages on the capacitors. Thus the circuit of interest



consists of two capacitors and two resistors.







I've been trying to determine an equation that describes the voltage on



C2 as it varies with time, but with my limited mathematical skill,



haven't been able to. I end up with differential equations that contain



the voltage on C1 as well, in a way that I can't substitute for.







Any thoughts?







Sylvia.





First of all can we see a circuit diagram instead of a Spice listing!!!

Secondly what voltage is the input ie dc a sine wave etc



Sylvia posted an LTspice .ASC file, which _is_ a schematic.



...Jim Thompson

--

| James E.Thompson | mens |

| Analog Innovations | et |

| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |

| San Tan Valley, AZ 85142 Skype: Contacts Only | |

| Voice480)460-2350 Fax: Available upon request | Brass Rat |

| E-mail Icon at http://www.analog-innovations.com | 1962 |



I love to cook with wine. Sometimes I even put it in the food.

Well all I see is a list of numbers! I need a real circuit diagram.

 

[Clifford Heath]

On 04/04/14 15:04, Jim Thompson wrote:

On Fri, 04 Apr 2014 14:03:58 +1100, Clifford Heath
no.spam@please.net> wrote:
From my archives (and recently provided to Robert Macy for his noise
experiments)...
Some IC models (NPN) from that era...

Thanks, that second one is the same one I copied into the ASC file
below. is the CA3046_ORG the model originally from Intersil, and the
other is yours?

My device is actually LM3046, but I don't expect any differences that
would affect things at 30MHz, though perhaps at 150.

Layouts are referenced in my other response.

Clifford Heath.

******************************************************************
.MODEL CA3046_ORG NPN IS=3.860200F BF=120 NF=1.04845 VAF=61.1026 IKF=
+ 50.000000M ISE=3.100000P NE=2.16533 BR=100.101000M NR=1.04845 ISC=0
+ NC=1 RB=214.644 RBM=214.644 RE=721.362980M RC=9.2065 CJE=1.249000P
+ VJE=899.999940M MJE=499.999970M TF=210.000000P XTF=1.85 VTF=1.585
+ ITF=50.000000M PTF=0 CJC=1.000000P VJC=749.999940M MJC=333.000000M
+ XCJC=499.999970M TR=10.000000N CJS=6.300000P VJS=749.999940M MJS=
+ 499.999970M XTB=1.5 EG=1.11 XTI=3 KF=0 AF=1 FC=499.999970M
*
*COPYRIGHT Š 1997 INTERSIL CORPORATION
*ALL RIGHTS RESERVED
*
*CA3046 PSpice MODEL
*REV: 2-24-97
** ----- BJT MODEL -----
*
.model CA3046 NPN
+ (IS = 10.0E-15 XTI= 3.000E+00 EG = 1.110E+00 VAF= 1.00E+02
+ VAR = 1.000E+02 BF = 145.7E+00 ISE = 114.286E-15 NE = 1.480E+00
+ IKF = 46.700E-03 XTB = 0.000E+00 BR = .1000E+00 ISC = 10.005E-15
+ NC = 2.000E+00 IKR = 10.00E-03 RC = 10.000E+00 CJC = 991.71E-15
+ MJC = 0.333E-00 VJC = 0.7500E-00 FC = 5.000E-01 CJE = 1.02E-12
+ MJE = .336E-00 VJE = 0.750E-00 TR = 10.000E-09 TF = 277.01E-12
+ ITF = 1.750E-00 XTF = 309.38E+00 VTF= 16.37E+00 PTF = 0.000E+00
+ RE = 0.0E+00 RB = 0.00E+00
*
*COPYRIGHT Š 1997 INTERSIL CORPORATION
*ALL RIGHTS RESERVED
*
*CA3086 PSpice MODEL
*REV: 2-24-97
** ----- BJT MODEL -----
*
.model CA3086 NPN
+ (IS = 10.0E-15 XTI= 3.000E+00 EG = 1.110E+00 VAF= 1.00E+02
+ VAR = 1.000E+02 BF = 156.6E+00 ISE = 114.886E-15 NE = 1.470E+00
+ IKF = 36.700E-03 XTB = 0.000E+00 BR = .1000E+00 ISC = 10.005E-15
+ NC = 2.000E+00 IKR = 10.00E-03 RC = 10.000E+00 CJC = 991.79E-15
+ MJC = 0.333E-00 VJC = 0.7500E-00 FC = 5.000E-01 CJE = 1.02E-12
+ MJE = .336E- 00 VJE = 0.750E-00 TR = 10.000E-09 TF = 278.55E-12
+ ITF = .770E-00 XTF = 91.38E+00 VTF= 18.37E+00 PTF = 0.000E+00
+ RE = 0.0E+00 RB = 0.00E+00
*
*COPYRIGHT Š 1997 INTERSIL CORPORATION
*ALL RIGHTS RESERVED
*
*CA3127 PSpice MODEL
*REV: 2-13-97
** ----- BJT MODEL -----
*
.model CA3127 NPN
+ (IS = 3.20p XTI= 3.000 EG = 1.110 VAF= 100
+ VAR = 100 BF = 95.2E ISE = 20.586p NE = 1.990
+ IKF = 61.500m XTB = 0 BR =100m ISC = 10.805n
+ NC = 2.000n IKR = 10m RC = 10m CJC = 281.1f
+ MJC = 0.138 VJC = 0.75 FC = 0.5 CJE = 651.9f
+ MJE = .336 VJE = 0.750 TR = 10n TF = 122.61p
+ ITF = 1.600p XTF = 2.050K VTF= 307 PTF = 0
+ RE = 0 RB = 0
* Application Note MM9701
******************************************************************
.SUBCKT CA3046PAK 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Q1 1 2 3 [SUB] CA3046
Q2 5 4 3 [SUB] CA3046
Q3 8 6 7 [SUB] CA3046
Q4 11 9 10 [SUB] CA3046
Q5 14 12 13 [SUB] CA3046
RSUB SUB 13 1
.ENDS CA3046PAK
******************************************************************

Folk,

Thanks to some good help here in the past, I have a nice clean
oscillator (for my new fox transmitters), but I'm having trouble with
the LTSpice simulation at higher frequencies. I'm assuming that the
Intersil Spice model for the CA3046 is bad, and I know JT has a better one.

Anyhow, I have two questions about the attached LTSpice schematic.

1) When I set it to 30MHz, LTSpice says the oscillator will start nicely
(even up to 150MHz in fact). Now I know that the (calculated) Colpitts
capacitance ratio is bad, as is the base capacitor, but with the
physical circuit built in a tight layout in SMD and a range of more
sensible capacitances substituted, I can't get it to oscillate above
about 12MHz. Why does it not want to run in real life, when Spice says
it should? Can someone provide me a better CA3046 model please, or say
what else might be going on?

2) I'd like some insight into the correct formulae to calculate the
Colpitts capacitive divider ratio, and the minimum safe base coupling
capacitor. The CA3046 data sheet says that Cbe and Ccb are both in the
range of 0.6pF, and the Ft is around 300MHz. So at 150MHz I only have
3dB of gain to play with, so that Cbe means I need at least a couple of
pF to drive the base, and the divider ratio has to give reasonable
drive. If anyone could suggest better "rule of thumb" for calculating
these things from Ft and Cin, I'd appreciate it.

Clifford Heath
-- Cut Here for OscProblem.asc --
Version 4
SHEET 1 2160 1200
WIRE 304 -336 192 -336
WIRE 752 -336 304 -336
WIRE 192 -288 192 -336
WIRE 192 -176 192 -208
WIRE 192 -176 -64 -176
WIRE 432 -176 192 -176
WIRE 528 -176 432 -176
WIRE 192 -128 192 -176
WIRE 752 -96 752 -336
WIRE 304 -48 304 -336
WIRE 432 -48 432 -176
WIRE -48 0 -64 0
WIRE 32 0 -48 0
WIRE 96 0 32 0
WIRE 192 0 192 -48
WIRE 192 0 160 0
WIRE 240 0 192 0
WIRE 32 64 32 0
WIRE 528 64 528 -176
WIRE -48 144 -48 0
WIRE 432 160 432 32
WIRE 32 208 32 128
WIRE 304 208 304 48
WIRE 304 208 32 208
WIRE 368 208 304 208
WIRE 192 256 192 0
WIRE 304 256 304 208
WIRE 32 272 32 208
WIRE -48 384 -48 224
WIRE 32 384 32 336
WIRE 32 384 -48 384
WIRE 192 384 192 336
WIRE 192 384 32 384
WIRE 304 384 304 336
WIRE 304 384 192 384
WIRE 432 384 432 256
WIRE 432 384 304 384
WIRE 528 384 528 128
WIRE 528 384 432 384
WIRE 752 384 752 -16
WIRE 752 384 528 384
WIRE 752 400 752 384
FLAG 752 400 0
FLAG -64 0 Vosc
IOPIN -64 0 Out
FLAG -64 -176 Vbias
IOPIN -64 -176 Out
SYMBOL voltage 752 -112 R0
WINDOW 123 24 126 Left 2
WINDOW 39 24 111 Left 2
SYMATTR InstName V1
SYMATTR Value 3.2v
SYMBOL cap 16 64 R0
SYMATTR InstName C1
SYMATTR Value {C1}
SYMBOL cap 16 272 R0
SYMATTR InstName C2
SYMATTR Value {C2}
SYMBOL ind -64 128 R0
SYMATTR InstName L3
SYMATTR Value {L1}
SYMBOL npn 240 -48 R0
SYMATTR InstName Q1
SYMATTR Value CA3046
SYMBOL res 176 -144 R0
SYMATTR InstName R4
SYMATTR Value 100k
SYMBOL npn 368 160 R0
SYMATTR InstName Q2
SYMATTR Value CA3046
SYMBOL res 176 -304 R0
SYMATTR InstName R2
SYMATTR Value 47k
SYMBOL cap 512 64 R0
SYMATTR InstName C4
SYMATTR Value {100/(F0*10k)}
SYMBOL res 288 240 R0
SYMATTR InstName R6
SYMATTR Value 2.2k
SYMBOL cap 160 -16 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C3
SYMATTR Value {C3}
SYMBOL res 176 240 R0
SYMATTR InstName R3
SYMATTR Value 100k
SYMBOL res 416 -64 R0
SYMATTR InstName R8
SYMATTR Value 10k
TEXT 864 -424 Left 2 !.tran 0 {10u + (2000/F0)} 0 {1/(F0*50)}
TEXT -96 -384 Left 2 !.param F0=30Meg
TEXT -96 440 Left 2 !; Calculate main tank components from F0, ZT and
stray capacitances:\n.param CSTRAY1=1.7p CSTRAY2=0.8pF\n.param
L1={ZT/(2*PI*F0)} DIV=17 C2={1/(2*PI*F0*(ZT/DIV)) - CSTRAY1}
CT={(1/(2*PI*F0*ZT)) - CSTRAY2} C1={1/((1/CT) - (1/C2))}\n.MEASURE L1_
PARAM L1\n.MEASURE C1_ PARAM C1\n.MEASURE C2_ PARAM C2
TEXT 872 232 Left 2 !.param ZCouple1=5k C3={max(1/(2*PI*F0*ZCouple1),
1pF)}\n.MEASURE C3_ PARAM C3
TEXT -96 -344 Left 2 !.param ZT=350
TEXT 872 144 Left 2 !.MEASURE C4_ PARAM {100/(F0*10k)}
TEXT 864 -320 Left 2 !*COPYRIGHT Š 1997 INTERSIL CORPORATION\n*ALL
RIGHTS RESERVED\n*\n*CA3046 PSpice MODEL\n*REV: 2-24-97\n** ----- BJT
MODEL -----\n*\n.model CA3046 NPN\n+ (IS = 10.0E-15 XTI=3.000E+00
EG=1.110E+00 VAF=1.00E+02\n+ VAR=1.000E+02 BF=145.7E+00 ISE=114.286E-15
NE=1.480E+00\n+ IKF=46.700E-03 XTB=0.000E+00 BR=.1000E+00
ISC=10.005E-15\n+ NC=2.000E+00 IKR=10.00E-03 RC=10.000E+00
CJC=991.71E-15\n+ MJC=0.333E-00 VJC=0.7500E-00 FC=5.000E-01
CJE=1.02E-12\n+ MJE=.336E-00 VJE=0.750E-00 TR=10.000E-09
TF=277.01E-12\n+ ITF=1.750E-00 XTF=309.38E+00 VTF=16.37E+00
PTF=0.000E+00\n+ RE=0.0E+00 RB=0.00E+00
TEXT -96 -424 Left 2 ;Change these parameters to vary the operating
frequency and tank impedance
TEXT 696 560 Left 2 ;This model was initially designed and built (works
fine) at 3.58 MHz.\nWhen run at any frequency up to 150MHz, it still
simulates fine.\nHowever, the physical circuit only reaches half
amplitude at 12MHz,\nand doesn't start at all much above that, even when
larger C3 and\nsmaller C1/C2 ratio is used (to overcome lower gain,
input capacitance;\n1pf for C3 cannot ever be enough with Cbe=0.5pF
Ft=300MHz).\nI'd really like to know why. Is my CA3046 model wrong?

...Jim Thompson

 

[Clifford Heath]

On 04/04/14 14:33, RobertMacy wrote:

On Thu, 03 Apr 2014 20:03:58 -0700, Clifford Heath <no.spam@please.net
wrote:

1. SAME model for CA3046 is that in a package, or as a chip?

I'm using LM3046, which is the replacement for the CA3046 - all five
transistors are meant to be the same (though one - the one I use for
AGC) has its emitter joined to the substrate. I don't know how its
parameters differ, but I'm sure its Ft and gain are not worse than the
CA3046.

Note that the circuit implemented at 3.6MHz behaves almost exactly as it
simulates. It's at higher frequencies that things go awry.

> 2. L3 is a 'perfect' inductor??

Well, no, obviously. It's a T37-6 toroid up to 12MHz, air-core on 8mm or
6mm for my experiments at 30Mhz, 50MHz and 150MHz.

any photos? of the circuitry? Don't wish to cast aspersions, but layout
above 10 MHz starts to become important. up there a short connection is
no longer a connection,

Yes, I'm aware of that. I've routed it single-sided on a copper rear
plane, using 0805 components throughout. Within that constraint, I'll be
very surprised if you can find a way to substantially improve it... but
here are the snapshots of this part of the circuit (from Eagle):
<http://cjh.polyplex.org/electronics/fox/Oscillator.brd.png>
<http://cjh.polyplex.org/electronics/fox/Oscillator.sch.png>

The other three transistors are n/c in this test board, but in the
3.6MHz version they're a phase splitter and push-pull output driver.

unless it's wider than long, it's an inductor.

resistors have inductance, caps have inductance, everything has stray
cap to gnd, and the effect of phase shift along the circuitry ??? I
know, but a few degrees is a few degrees.

Yes. But when you run the model I posted at 150MHz, it simulates just
fine, even though the capacitance ratio and base coupling capacitor
clearly show that it should not have enough gain to start. Even at
30MHz, and even after playing with a range of different values, the real
thing still doesn't start. At 12MHz it only reaches 50mV p-p, not the
100mV that the AGC limits it to. Clearly a long way from what the sim is
saying, and I need to know why.

But first, I'd like a better guess (or I know, math...) at plausible
values for these parts to make it oscillate at 30MHz, before I try 50 or
150.

BTW, if you're the guy working at Linear on this sim, props to you. I
downloaded the Mac version recently, and though it is extraordinarily
strange for a Mac app, it's so nice not to have Windows running under Wine.

Clifford Heath.

Example of 'macroscopic high frequency modeling: modeled an EMC
Conducted Test [made models for the LISN], complete with AC chord
models, gnded sheet metal planes, etc.
SOLAR ELECTRONICS LISN 8012-50-R-24-BNC
RHODE & SCHWARZ LISN ESH2-Z5
in order to explain, design SMPS line filtering and found out that above
10MHz, everything just kind of falls apart. go from accurate to errors
worse than 2 to 3 dB, which is still better than a guess, but did not
feel solid enough, just too 'squishy' for my taste. Once problem solved
could not justify going back to find out what was not quite right. I
always thought it just parasitics that aren't represented well.

 

[George Herold]

On Thursday, April 3, 2014 11:57:57 PM UTC-4, Sylvia Else wrote:

On 4/04/2014 12:48 PM, Jim Thompson wrote:

On Thu, 03 Apr 2014 18:40:39 +1100, Sylvia Else
...Jim Thompson



Thanks.

After looking at some stuff relating to solving simultaneous 1st order
differential equations, I learnt that two first order simultaneous
equations in two variables can be written as a single second order
differential equation in one variable, which I do know how to solve.


So I went back, and saw how that could be achieved

The result is a rather involved function of the six variables (C1, C2,
R1, R2, V1 and V2).

This is not actually an electronic circuit, but a representation of the
thermal behaviour of a water heater. Consequently I don't know the
values of V1, C1 or R1. I was hoping to infer them from the equation and
the measured behaviour. I'd end up with three simultaneous equations to
solve, which, given their complexity, would probably have to be done
numerically.

Ahh I've done that. Usually you can stare at it and find one RC that dominates the behavior. You'll want to model the heater as a current source.
Temperature corresponds to voltage and Energy is like charge. So a one watt heater is like a 1 amp current source.
The heat capacity of the water should be pretty easy to get. What else is unknown? (One issue you may have in modelling is if there are convective heat currents in the water.) So what are your R's and C's?

George H.

Maybe I still will, out of interest, but it'll be a lot simpler to
interpolate from those measurements that I do have, and probably more
than adequate.



Sylvia.

 

[piglet]

Could you try inserting a few k-ohm resistor
in series with Q2 base on your real-world circuit,
just to reduce loading on the tuned circuit? Or
even simpler just try lifting the base connection
on Q2 and see if it will start oscillation at the
higher frequencies?

piglet

 

[Clifford Heath]

On 04/04/14 20:58, piglet wrote:

Could you try inserting a few k-ohm resistor
in series with Q2 base on your real-world circuit,
just to reduce loading on the tuned circuit? Or
even simpler just try lifting the base connection
on Q2 and see if it will start oscillation at the
higher frequencies?

Yes, there's a trace beside the square via I could cut.
(The osc transistor is top-right, AGC top-left)
The C3 base coupling cap is already only a very weak
link from the tank though... perhaps too weak.

The components shown on the Eagle fragments are for 3.6MHz;
10pF is worth over 4k at that frequency (and works fine).
I've dropped it to a variety of much smaller values for
higher frequency operation to let that tank run free.

 

[Chris Jones]

On 04/04/2014 14:03, Clifford Heath wrote:

Folk,

Thanks to some good help here in the past, I have a nice clean
oscillator (for my new fox transmitters), but I'm having trouble with
the LTSpice simulation at higher frequencies. I'm assuming that the
Intersil Spice model for the CA3046 is bad, and I know JT has a better one.

Anyhow, I have two questions about the attached LTSpice schematic.

1) When I set it to 30MHz, LTSpice says the oscillator will start nicely
(even up to 150MHz in fact). Now I know that the (calculated) Colpitts
capacitance ratio is bad, as is the base capacitor, but with the
physical circuit built in a tight layout in SMD and a range of more
sensible capacitances substituted, I can't get it to oscillate above
about 12MHz. Why does it not want to run in real life, when Spice says
it should? Can someone provide me a better CA3046 model please, or say
what else might be going on?
[snip]

I would suggest estimating the length of some of the more critical
physical wires on the hardware version, and putting appropriate
parasitics back into the simulation model. Particularly in series with
the emitter of transistors, it can affect gain at RF. I would suggest
modelling the emitter pin and leadframe and the wiring as 1nH per
millimetre of length, as a first guess, plus another nanohenry for the
bondwire (unless it is already in your transistor model). Whilst this
probably isn't the cause, it might start to expain something.

Another thing that may be worth trying, though it isn't usually
necessary until you get to GHz frequencies: The capacitance across
unwanted junctions on chips (perhaps collector to substrate in your
case) can be lossy. If you model it as a pure capacitor then you can
simulate better Q or gain or noise figure than reality. Of course if you
add an infinite value resistor in series with the parasitic capacitances
then that also gives zero losses and artificially good performance.
There is some intermediate value of resistance to put in the model in
series with the parasitic capacitance, between zero and infinity Ohms,
that will result in the worst possible losses. There is some other value
of series resistance that is the best model of reality. Often the most
representative value is close to the worst case losses value, except
when you don't want things to oscillate in which case it is very different.

It is important to put some losses in the model of your inductor also,
as another poster mentioned. Beware of metal very close to the inductor.
I sometimes like to put inductors in screened cans, but all metalwork
should ideally be spaced away from the turns of the inductor by at least
the inductor diameter, to avoid causing more losses.

Hopefully you have some low-ESR decoupling (e.g. 100n chip ceramic)
capacitor(s) across your supply right near the oscillator. Otherwise the
impedance of the supply wiring might stop things from working, in a way
that would not be simulated.

I suggest you get one of those label machines, and affix a label to your
prototype that says "unconditionally stable amplifier". It will surely
oscillate then.

Are you able to verify the DC collector current and Vce of your
not-oscillating transistor? I would check that the collector current is
close to (but slightly lower than) the value that gives the peak Ft
value. (I have been warned that above the current that gives peak Ft,
models are often not very good and/or device performance is more
unpredictable, and to therefore stay somewhat below that current if good
Ft is important). Also make sure the Vce is well over a volt, and more
if the transistor has a poorly contacted collector with lots of
distributed resistance (which could cause parts of the device to
saturate before other parts, and wouldn't usually be modelled).

For oscillators, I like to pick a transistor with an Ft that is about 10
times higher than the highest desired oscillation frequency. Something
like an old BFY90, in your case, or one of the many surface mount RF
transistors that you can get these days. Actually I prefer FET LC
oscillators but none of this is really relevant to the simulation problem.

Chris

 

[o pere o]

On 04/04/2014 10:44 AM, Clifford Heath wrote:

On 04/04/14 14:33, RobertMacy wrote:
On Thu, 03 Apr 2014 20:03:58 -0700, Clifford Heath <no.spam@please.net
wrote:

1. SAME model for CA3046 is that in a package, or as a chip?

I'm using LM3046, which is the replacement for the CA3046 - all five
transistors are meant to be the same (though one - the one I use for
AGC) has its emitter joined to the substrate. I don't know how its
parameters differ, but I'm sure its Ft and gain are not worse than the
CA3046.

Note that the circuit implemented at 3.6MHz behaves almost exactly as it
simulates. It's at higher frequencies that things go awry.

2. L3 is a 'perfect' inductor??

Well, no, obviously. It's a T37-6 toroid up to 12MHz, air-core on 8mm or
6mm for my experiments at 30Mhz, 50MHz and 150MHz.

any photos? of the circuitry? Don't wish to cast aspersions, but layout
above 10 MHz starts to become important. up there a short connection is
no longer a connection,

Yes, I'm aware of that. I've routed it single-sided on a copper rear
plane, using 0805 components throughout. Within that constraint, I'll be
very surprised if you can find a way to substantially improve it... but
here are the snapshots of this part of the circuit (from Eagle):
http://cjh.polyplex.org/electronics/fox/Oscillator.brd.png
http://cjh.polyplex.org/electronics/fox/Oscillator.sch.png

A solid copper plane introduces a significant amount of capacitance from
each node to ground. You can simulate this adding parasitic capacitances
here and there. Furthermore, you have to make sure that the gnd points
on the top layer are really gnd. At higher frequencies this usefully
means a lot of vias to gnd. It could be that some node that should be
gnd has a long path to the bottom plane. I can't tell from your pictures.

Pere

<snipped rest of post>

 

[Chris Jones]

On 04/04/2014 19:44, Clifford Heath wrote:
[snip]

any photos? of the circuitry? Don't wish to cast aspersions, but layout
above 10 MHz starts to become important. up there a short connection is
no longer a connection,

Yes, I'm aware of that. I've routed it single-sided on a copper rear
plane, using 0805 components throughout. Within that constraint, I'll be
very surprised if you can find a way to substantially improve it... but
here are the snapshots of this part of the circuit (from Eagle):
http://cjh.polyplex.org/electronics/fox/Oscillator.brd.png
http://cjh.polyplex.org/electronics/fox/Oscillator.sch.png
[snip]

Thanks for posting the diagrams.

Some loss in the inductor would certainly be more realistic. I hope the
inductor is not sitting right on the PCB unless you make a big hole in
the ground plane under the inductor, at least 2x the diameter of the
inductor. Otherwise it is going to reduce the Q like a shorted turn. As
long the hole is big enough so that the ground plane is spaced far
enough from the turns, it is no longer a problem and actually helps with
shielding the inductor.

I note that you are taking the output via C9 from the top of the tank,
which is a very sensitive node. I hope it is going to something with
really low loss, or that could be a cause for reducing the Q and
tendency to oscillate. I would suggest taking the output from some
low-impedance node, such as a tap on the inductor, or the top of R6 or
something like that.

Also not related to the present problem, I think you could probably get
rid of C6 and R7 - the DC voltage on each side of C6 is the same,
assuming the varactors stay reverse biased.

Chris

 

[Tauno Voipio]

On 4.4.14 11:44, Clifford Heath wrote:

But first, I'd like a better guess (or I know, math...) at plausible
values for these parts to make it oscillate at 30MHz, before I try 50 or
150.

You are running the transistor at a very low current.
It may be limiting its capability of handling the
strays from the ground plane at higher frequencies.

Out of curiosity, I dropped the resistances by a factor
of 10, and the thing at least simulates well.

Another vote to dropping the R and C from the top
of the varactor chain. Also, another vote to taking
the output from the emitter.

--

Tauno Voipio