I tried that some time ago but, not surprisingly, the model didn't behave quite
the same as the real thing in the lab. I concluded )to myself, only!) that chip
self-heating and thermal coupling between the two devices was the stumbling
block. Then after I sent the question to you yesterday, I did a bit of idle
googling and came across this
bbs.38hot.net/thread-105042-1-1.html
(Not sure if the url pasted correctly...here are the salient bits
"Hello fellow forum users,
I just finished with a telephone conversation with Bob Dobkin, and he was short
on time, so I was not able to get all of the answers to every question I [and
we] had, but here are the ones I was able to get:
5) They *could* make a model for LTspice, but the temperature effects are very
difficult to simulate, and the market need is not large enough to support the
development effort [my words]. He said the best way is to build the circuit
and test it out in real life.
,,,"
Anyway, good job. I don't have a 732A, but am looking to get more than I paid
for out of a 332B which happens to have had its RefAmp replaced with an LTFLU
(before I got it). I am looking at your circuit now as food for a bit of
improvement, perhaps...
Roman
-Original Message-
From: volt-nuts [mailto:volt-nuts-boun...@febo.com] On Behalf Of David C.
Partridge
Sent: Tuesday, 23 January 2018 10:03 PM
To: 'Discussion of precise voltage measurement'
Subject: Re: [volt-nuts] Redrafted schematic of Fluke 732A reference circuit
It's nothing fancy just a glom of a 2n3904 and a 6.2V Zener wrapped up in
.subckt/.ends and makes no claim to a an accurate model (I somehow doubt that
either Fluke or LT would be willing to share that).
** LTFLU **
*
* NI Multisim to SPICE Netlist Export
* Generated by: amonra
* Sat, Jan 20, 2018 15:16:41
*
.SUBCKT LTFLU C B EK A
*## Multisim Component LFLUD1 ##*
xLFLUD1 A EK BZX84B6V2LT1/ON__ZENER__1
*## Multisim Component LFLUQ1 ##*
qLFLUQ1 C B EK 2N3904__BJT_NPN__1
.SUBCKT BZX84B6V2LT1/ON__ZENER__1 2 1
**
* Model Generated by MODPEX *
*Copyright(c) Symmetry Design Systems*
* All Rights Reserved*
*UNPUBLISHED LICENSED SOFTWARE *
* Contains Proprietary Information *
* Which is The Property of *
* SYMMETRY OR ITS LICENSORS *
*Commercial Use or Resale Restricted *
* by Symmetry License Agreement*
**
* Model generated on Dec 11, 03
* MODEL FORMAT: PSpice
* anode cathode
*node: 2 1
*Forward Section
D1 2 1 MD1
.MODEL MD1 D IS=5.21532e-16 N=1 XTI=1 RS=0.5
+ CJO=9.5e-11 TT=1e-08
*Leakage Current
R 1 2 MDR 2e+07
.MODEL MDR RES TC1=0 TC2=0
*Breakdown
IZG 4 2 0.12
R4 4 2 300
D3 2 4 MD3
.MODEL MD3 D IS=2.5e-12 N=0.37046 XTI=0 EG=0.1
D2 5 4 MD2
.MODEL MD2 D IS=2.5e-12 N=1.16158 XTI=0 EG=0.1
EV1 1 5 6 0 1
IBV 0 6 0.001
RBV 6 0 MDRBV 5792.79
.MODEL MDRBV RES TC1=0.000353198
*-- PSpice DIODE MODEL DEFAULT PARAMETER
* VALUES ARE ASSUMED
*IS=1E-14 RS=0 N=1 TT=0 CJO=0
*VJ=1 M=0.5 EG=1.11 XTI=3 FC=0.5
*KF=0 AF=1 BV=inf IBV=1e-3 TNOM=27
.ENDS bzx84b6v2lt1
.MODEL 2N3904__BJT_NPN__1 NPN(Is=6.734f Xti=3 Eg=1.11 Vaf=74.03 Bf=416.4
Ne=1.259
+ Ise=6.734f Ikf=66.78m Xtb=1.5 Br=.7371 Nc=2 Isc=0 Ikr=0 Rc=1
+ Cjc=3.638p Mjc=.3085 Vjc=.75 Fc=.5 Cje=4.493p Mje=.2593 Vje=.75
+ Tr=239.5n Tf=301.2p Itf=.4 Vtf=4 Xtf=2 Rb=10)
.ENDS LTFLU
-Original Message-
From: volt-nuts [mailto:volt-nuts-boun...@febo.com] On Behalf Of romeo987
Sent: 23 January 2018 10:31
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] Redrafted schematic of Fluke 732A reference circuit
David,
Thank you for that - much easier to follow. I infer from this that you have a
Spice model for the LTFLU. Can you elaborate, please?
Roman
> On 22 Jan 2018, at 2:15 pm, David C. Partridge
> <david.partri...@perdrix.co.uk> wrote:
>
> OK folks here's another location for anyone who can't get it from eevblog.com:
>
> <http://www.perdrix.co.uk/manuals/Fluke%20732A%20Reference%20Circuit.p
> df>
>
> Dave
>
> -Original Message-
> From: volt-nuts
> [mailto:volt-nuts-bounces+david.partridge=perdrix.co...@febo.com] On
> Behalf Of m k
> Sent: 21 January 2018 22:29
> To: Bob Albert; Discussion of precise voltage measurement
> Subject: Re: [volt-nuts] Redrafted schematic of Fluke 732A reference
> circuit
>
>> you possibly need to be logged into eevblog at the same time as you follow
>> the link?
> ___
> volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to
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