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AC128 PNP Germanium Transistor Spice Model (Rare!)
AC128 PNP Germanium Transistor Spice Model (Rare!)
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Old 11th February 2008, 06:42 PM   #1
pweaudiotech is offline pweaudiotech  United States
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Default AC128 PNP Germanium Transistor Spice Model

I found it!...i found it!...i have searched the internet for years looking for this..the one...the only! Ac128 pnp germanium transistor spice model!

Note: this is a typical .cir type file spice model:

*AC128 PNP Germanium Transistor Spice Model
*
.MODEL AC128_X PNP IS=1.41f ISC=0 ISE=0 IKF=80m IKR=0 ITF=0.4
+NC=2 NE=1.5 BF=70 BR=4.977 RB=10 RC=2.5 CJC=9.728p CJE=8.063p
+TR=33.42n TF=179.3p FC=0.5 EG=1.11 VJC=0.2 VJE=0.2 VTF=4
+MJC=0.5776 MJE=0.3677 XTB=1.5 XTF=6 XTI=3


Note for a "matched" npn germanium transistor spice model:

*AC127 NPN Germanium Transistor Spice Model
*
.MODEL AC127_X NPN IS=1.41f ISC=0 ISE=0 IKF=80m IKR=0 ITF=0.4
+NC=2 NE=1.5 BF=70 BR=4.977 RB=10 RC=2.5 CJC=9.728p CJE=8.063p
+TR=33.42n TF=179.3p FC=0.5 EG=1.11 VJC=0.2 VJE=0.2 VTF=4
+MJC=0.5776 MJE=0.3677 XTB=1.5 XTF=6 XTI=3

Last edited by jazbo8; 19th July 2017 at 03:33 PM. Reason: Restore to original post
 
Old 29th April 2009, 06:45 PM   #2
orbanp is offline orbanp  Canada
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These models are quite bad!
Vbe is around 0.7V, a common emitter amplifier with about 50dB gain has an upper frequency of about 7MHz! That is nothing like using those old germanium transistors with an Ft of 1.5MHz!
If you plug in 2N3906, a jelly bean type Si PNP transistor, you get similar results.
Looks like someone just renamed a simple Si transistor model!

Peter
 
Old 29th April 2009, 07:05 PM   #3
wg_ski is online now wg_ski  United States
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What is the world coming to? First, fake transistors, now fake transistor models.

Back in the Ge days, nobody had spice. So it looks like if you want to play around with that old stuff you have to do it the old fashioned way.
 
Old 29th April 2009, 07:36 PM   #4
kenpeter is offline kenpeter  United States
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Yes, I saw this same complaint in regard to a book review.
That improperly hacked silicon models were abused.

http://www.amazon.com/Digital-Guitar.../dp/3836461943

I do not yet know if its true or not. But I have a forklift of
opposing Aleph offset voltage followers to sim and build.
(Giant basakwerdized diamond buffer)... And was wanting
to use complimentary germanium VBE's for the smallest
reasonable offset tracking references.

Tighter the offset voltage gap (similar function to VAS in
my circuit), the better output damping in my application.
But I couldn't make either of these germanium emitters
simulate as expected...

My actual transistors are 2N169A, which is an NPN I think?
I have to go home and look what the PNP number was....
Suspect it was a 2N383, but thats goin by foggy memory.

I am using LTSpice IV.
 
Old 29th April 2009, 11:07 PM   #5
kenpeter is offline kenpeter  United States
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So, which spice parameter of the above is the most broken?
 
Old 30th April 2009, 02:11 PM   #6
wg_ski is online now wg_ski  United States
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Quote:
Originally posted by kenpeter
So, which spice parameter of the above is the most broken?

Probably all of them. To do it right, you'd have to generate Gummel plots and CV characteristics for those Ge devices, and hope the model has enough flexibility to fit the data. Spice models weren't designed with germanium in mind. I work mostly with microwave FET models, and models originally designed for one material and technology don't always fit well with newer devices. Sometimes you have to go in and alter the code and equations to even get close.
 
Old 30th April 2009, 02:24 PM   #7
peranders is offline peranders  Sweden
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AC128 PNP Germanium Transistor Spice Model (Rare!)
You didn't check with Netlist here? He has every SPICE model to be found
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Old 30th April 2009, 03:51 PM   #8
orbanp is offline orbanp  Canada
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I used the "bjt.xls" application <http://www.analogservices.com/excel.htm> to fit Spice data for the AC128. The data in the manual ('69 Tungsram Transistor Handbook) I have for that transistor is a bit sparse, only Cbc at a given voltage and Ft was given for dynamic values. Still, the common emitter amplifier with that model looks a lot more "credible".

Peter
 
Old 30th April 2009, 03:53 PM   #9
orbanp is offline orbanp  Canada
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I used the "bjt.xls" application <http://www.analogservices.com/excel.htm> to fit Spice data for the AC128. The data in the manual I have for that transistor ('69 Tungsram Transistor Handbook) is a bit sparse, only Cbc at a given voltage and Ft was given for dynamic values. Still, the common emitter amplifier with that model looks a lot more "credible".

Peter
 
Old 1st May 2009, 01:13 AM   #10
GK is offline GK  Australia
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Default F-ing BS microsoft

That looks like a fantastic application. I just started creating a spice model for the MJE15028.

I got to the point in the instructions - "Invoke solver".

Where the Fk is that then!

Argghh!
Attached Images
File Type: jpg solver.jpg (77.5 KB, 996 views)
 

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