Zener diode below-threshold reverse current

--
Y'know, John, I'm continually amazed - as time goes by - at your 
uncanny grip of the obvious.

e:

:

rote:

ote:

at silly, even by your standards.

verbial barbed wire canoe.

d-wire canoe" and since I've now found and posted your original 0.5H induct or with zero parallel capacitance and zero series resistance, I think it do es apply to your debating position.

True. But a real 0.5H inductor with a resonant frequency above 100kHz is a very rare beast indeed, as a real electronic engineer would know - I certai nly did.

Date: Sun, 28 Aug 2016 01:32:24 -0700 (PDT)

It's certainly present in the thread I'm looking at, and I've cut and paste d the relevatn links. below

.html

is your post, and

.html

is my response, listing a couple of real inductors, their self-resonant fre quencies, and how they performed in simulation.

--
Bill Sloman, Sydney

Then you'd better look more carefully.

--
Bill Sloman, Sydney

--
So you want to put yourself on a par with Shakespeare and compare your 
work with his? 

Let's hear your eloquent defense of circuit designs which equal Hamlet 
or Romeo and Juliet and I'll agree with you. 

John Fields 

>>>We just solved a problem with thrust measurement in a GTF. Things like 
>>>that are satisfying. 
>> 
>>--- 
>>Indeed. 
>> 
>>you managed to sell a painting. 
> 
>We did some Fourier analysis and told the user how to filter out test 
>stand vibration modes. The engine stand is a huge structure that sits 
>on a gigantic concrete footing. Unfortunately, it's in Florida and 
>under the footing is mush.

--
My schematic comes through and simulates OK, but LTspice flags yours 
with this error: 

https://www.dropbox.com/s/wusv3r6uycxaf8q/Osc1a.png?dl=0 

There may be something funny going on in the translation from HTML, so 
if you just post the circuit list here, in vanilla ASCII, that might 
work. 

On the other hand, if you're using models which aren't in LTspice's 
libraries, you'll need to include those files as well. 

To that end, I'll direct you to

e:

:

rote:

ote:

ewhat silly, even by your standards.

proverbial barbed wire canoe.

rbed-wire canoe" and since I've now found and posted your original 0.5H ind uctor with zero parallel capacitance and zero series resistance, I think it does apply to your debating position.

a very rare beast indeed, as a real electronic engineer would know - I cer tainly did.

sted the relevatn links. below

528.html 837.html

frequencies, and how they performed in simulation.

I already posted the version from my files earlier in this thread.

I ran it under the current version of LTSpice before I posted it.

The BFR92A model included in the LTSpice .asc file isn't in the LTSpice lib rary, which is why it's included in the text posted.

I'd gotten it from the NXP web-site, and managed to shoe-horn it into LTSpi ce as a Spice directive.

The model includes long strings of text which don't always wrap well.

You might look at the text strings before you try to run the simulation. So metimes you can edit a mangled version into a shape that works.

--
Bill Sloman, Sydney

On Wed, 31 Aug 2016 19:44:00 -0700 (PDT), snipped-for-privacy@ieee.org wrote:

Unwrapping the string works, and I thank you for that clue but, once run, the code produces a schematic of an RC bistable multivibrator with nary an inductor in sight, which makes your position Version 4 SHEET 1 2848 1240 WIRE -576 576 -736 576 WIRE -112 576 -576 576 WIRE -576 608 -576 576 WIRE -112 608 -112 576 WIRE -576 704 -576 688 WIRE -464 704 -576 704 WIRE -384 704 -464 704 WIRE -240 704 -320 704 WIRE -112 704 -112 688 WIRE -112 704 -240 704 WIRE -736 720 -736 576 WIRE -464 736 -464 704 WIRE -240 736 -240 704 WIRE -576 832 -576 704 WIRE -112 832 -112 704 WIRE -496 880 -512 880 WIRE -464 880 -464 816 WIRE -464 880 -496 880 WIRE -448 880 -464 880 WIRE -384 880 -320 704 WIRE -320 880 -384 704 WIRE -240 880 -240 816 WIRE -240 880 -256 880 WIRE -208 880 -240 880 WIRE -176 880 -208 880 WIRE -208 912 -208 880 WIRE -496 928 -496 880 WIRE -576 1008 -576 928 WIRE -496 1008 -496 992 WIRE -496 1008 -576 1008 WIRE -208 1008 -208 976 WIRE -112 1008 -112 928 WIRE -112 1008 -208 1008 WIRE -736 1040 -736 800 WIRE -576 1040 -576 1008 WIRE -112 1040 -112 1008 FLAG -112 1040 0 FLAG -576 1040 0 FLAG -736 1040 0 SYMBOL RES -592 592 R0 SYMATTR InstName R1 SYMATTR Value 1000K SYMBOL res -128 592 R0 SYMATTR InstName R2 SYMATTR Value 1000K SYMBOL cap -384 864 R90 WINDOW 0 0 32 VBottom 0 WINDOW 3 32 32 VTop 0 SYMATTR InstName C1 SYMATTR Value 1.5p SYMBOL cap -256 864 R90 WINDOW 0 0 32 VBottom 0 WINDOW 3 32 32 VTop 0 SYMATTR InstName C2 SYMATTR Value 1.5p SYMBOL VOLTAGE -736 704 R0 SYMATTR InstName V1 SYMATTR Value 5 SYMBOL npn -176 832 R0 SYMATTR InstName Q1 SYMATTR Value BFR92A SYMBOL npn -512 832 M0 SYMATTR InstName Q2 SYMATTR Value BFR92A SYMBOL res -256 720 R0 SYMATTR InstName R3 SYMATTR Value 4700K SYMBOL res -480 720 R0 SYMATTR InstName R4 SYMATTR Value 4700.1K SYMBOL cap -512 928 R0 SYMATTR InstName C3 SYMATTR Value 0.68p SYMBOL cap -224 912 R0 SYMATTR InstName C4 SYMATTR Value 0.68p TEXT -768 1176 Left 0 !.tran 0 150u 50u startup TEXT -776 1224 Left 0 ;This example schematic is supplied for informational/educational purposes only. TEXT -480 1176 Left 0 !.model BFR92A NPN(IS=0.1213E-15 VAF=30 BF=94.73 IKF=0.46227 XTB=0 BR=10.729 CJC=946.47E-15 CJE=10.416E-15 TR=1.2744E-9 TF=26.796E-12 ITF=0.0044601 VTF=0.32861 XTF=0.3817 RB=14.998 RC=0.13793 RE=0.29088 Vceo=15 Icrating=4m mfg=Infineon)ble.

Is that what you had in mind?

:

e:

e:

rote:

ote:

somewhat silly, even by your standards.

he proverbial barbed wire canoe.

barbed-wire canoe" and since I've now found and posted your original 0.5H inductor with zero parallel capacitance and zero series resistance, I think it does apply to your debating position.

is a very rare beast indeed, as a real electronic engineer would know - I certainly did.

pasted the relevatn links. below

g00528.html

g00837.html

nt frequencies, and how they performed in simulation.

library,

Spice as a Spice directive.

Sometimes you can edit a mangled version into a shape that works.

If you went back to the thread, you'd find that my first response to the or iginal post was that a simple 100kHz oscillator drawing 10uA wouldn't work with conventional transistors because charging and discharging the internal capacitances would chew up too much current.

It took me a while to set up an LTSpice model around the BFR92A - which doe s offer low internal capacitances - to illustrate the point.

I haven't a clue if it might have solved the OP's problem because he never came back to the thread.

Your high-Q LC oscillator is another solution, but you did cheat by using a n infinite Q inductor. As I pointed, you scheme could be made to work with off-the-shelf inductors, but a 500mH inductor with a self-resonant frequenc y above 100kHz wasn't commercially available anywhere I looked.

--
Bill Sloman, Sydney

--
I've downloaded your circuit list, parsed it so the model decription 
shows up on the schematic as a single line of text with a leading dot 
delimiter and yet, in my box, your circuit shows up as something that 
won't multivibrate.  

What do you think might be the problem? 

John Fields

did you set the start up voltage at 0? Jamie

te:

e:

ote:

rote:

rote:

is somewhat silly, even by your standards.

n the proverbial barbed wire canoe.

n a barbed-wire canoe" and since I've now found and posted your original 0.

5H inductor with zero parallel capacitance and zero series resistance, I th ink it does apply to your debating position. n

kHz is a very rare beast indeed, as a real electronic engineer would know - I certainly did.

ng,

and pasted the relevatn links. below

/msg00528.html

/msg00837.html

onant frequencies, and how they performed in simulation.

s

so

t

ce library,

LTSpice as a Spice directive.

ab

on. Sometimes you can edit a mangled version into a shape that works.

original post was that a simple 100kHz oscillator drawing 10uA wouldn't wo rk with conventional transistors because charging and discharging the inter nal capacitances would chew up too much current.

does offer low internal capacitances - to illustrate the point.

er came back to the thread.

g an infinite Q inductor. As I pointed, you scheme could be made to work wi th off-the-shelf inductors, but a 500mH inductor with a self-resonant frequ ency above 100kHz wasn't commercially available anywhere I looked.

Beats me. E-mail me your .asc file and I'll take a look at it.

You will note that the original version worked for James Arthur back in 200

8, so there's not going to be anything wrong with the actual circuit.

--
Bill Sloman, Sydney

--
No need to. 

I've looked over the .model statement again, noticed some crowding and 
added some spaces, and the circuit now simulates OK. 

But, I don't see a square wave out with a 50% duty cycle which, I seem 
to recall, you specified as a criterion needing to be met in order to 
yield a successful solution.

We had this discussion back in 2008. You get alternating pulses with exponential rising and falling edges.

If you current budget is 10uA, a square wave is an inaccessible luxury, and even a trapezium wave demands more stray-capacitance charging current than you can afford.

My attitude from the start was that a 100kHz oscillator drawing 10uA or less was an unrealistic request, and the BFR92A-based oscillator illustrated the point.

Scarcely. Getting somebody else's .asc file to run isn't a spectacular achievement.

Fine by me.

--
Bill Sloman, Sydney

--
"nver be bother watching"? 

Even butchering the English langage, as you are wont to do, it sounds 
to me like you'd rather die than explore alternatives which might 
afford you insight from a source you hate.  
Your loss... 

>  
>> Perhaps, on that basis, you and I might also agree to bury the 
>> hatchet?  
> 
>Fine by me.

e:

: n

ot

at

onential rising and falling edges.

and even a trapezium wave demands more stray-capacitance charging current t han you can afford.

less was an unrealistic request, and the BFR92A-based oscillator illustrate d the point.

in 2008, so there's not going to be anything wrong with the actual circuit.

chievement.

You do enjoy getting excited over typos. Kind of you to include the word "l angage" in your comment, to illustrate the point that we all make typos, an d miss them.

Why bother? Every resistor has a parallel capacitance - for Philips spiral- cut through-hole metal films it was about 0.3pF, but L-trimmed surface moun t parts do better - and a capacitance to ground, which depends, to some ext ent, on the circuit board underneath it.

You haven't done anything about estimating what these might be.

The Linear Technology LTC1441 micropower capacitor is also going to have an input capacitance to ground, which doesn't show up anywhere in its datashe et.

It may be built into Linear Technology's macromodel.

You've stuck a single 1pF capacitor in the circuit diagram - which is going to be comparable with LTC1441's input capacitance - but still think that t he circuit is worth simulating.

It might be worth building - though the OP specified a 5V rail, not 2V.

You've repeated the error you made in 2008, this time with capacitance-free resistors rather than a capacitance-free inductor, once again illustrating that you don't understand what's involved in simulating a real circuit.

In most applications, 0.3pF is small enough to ignore. This doesn't happen to be one of those applications.

--
Bill Sloman, Sydney

--
Unless it makes you lose face, why not?

:

rote:

ote:

tion

g dot

that

and

eem

to

exponential rising and falling edges.

y, and even a trapezium wave demands more stray-capacitance charging curren t than you can afford.

or less was an unrealistic request, and the BFR92A-based oscillator illustr ated the point.

ck in 2008, so there's not going to be anything wrong with the actual circu it.

r achievement.

Granting that the simulation isn't all that realistic, it's a waste of effo rt.

I did note that shifting R2 from 10M to 2.2M got the mark to space ratio c loser to 50%, but trying to work out what was actually going on with a comp arator with hysterisis was more like hard work than I felt like doing at th e time - I had to head off to my IEEE committee meeting then anyway.

Turning R2 and R3 into a high resistance pot might give you a mark-to-space twiddle. Element 14 has a 10M trimmer

but I'd be happier with a Bourns 2M 25-turn 19mm part - they are much nicer parts, offering finer adjustment, and a cermet element rather than carbon film.

And you clearly don't.

It's your circuit, not mine.

Obviously. Another typo ...

Their macromodels aren't open to inspection, or they weren't the last time I tried to look under the bonnet.

There's nothing of the wild-assed guess in asserting that the device will h ave input capacitances, probably around 1pF or so, but what isn't specified has to be estimated or measured.

The wild-ass guess here is your idea that it's worth sticking together a si mulation where you leave out all the interesting stray capacitances.

--
Bill Sloman, Sydney

--
Ostrich tactics.