CircuitMaker Vacuum Tube model - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 5th July 2005, 10:51 AM   #1
diyAudio Member
 
Steen Bentzen's Avatar
 
Join Date: Jul 2005
Location: Hilleroed, Denmark
Question CircuitMaker Vacuum Tube model

Can anyone explain the vacuum tube model parameters in CircuitMaker 2000. Below the original 12AU7 model.

*Vacuum Tube Triode (Audio freq.) pkg:VT-9 (A:1,2,3)(B:6,7,8)
.SUBCKT X12AU7 1 3 4
B1 2 4 I=((URAMP((V(2,4)/18)+V(3,4)))^1.5)/1151
C1 3 4 1.6E-12
C2 3 1 1.5E-12
C3 1 4 0.5E-12
R1 3 5 10E+3
D1 1 2 DX
D2 4 2 DX2
D3 5 4 DX
.MODEL DX D(IS=1.0E-12 RS=1.0)
.MODEL DX2 D(IS=1.0E-9 RS=1.0)
.ENDS X12AU7

I think that I have found some of the parameters:

?=Don't know

*Vacuum Tube Triode (Audio freq.) pkg:VT-9 (A:1,2,3)(B:6,7,8)
.SUBCKT X12AU7 1 3 4
B1 2 4 I=((URAMP((V(2,4)/18=my)+V(3,4)))^1.5=?)/1151=?
C1 3 4 1.6E-12 = Grid cap.
C2 3 1 1.5E-12 = Grid-Plate cap.
C3 1 4 0.5E-12 = Plate cap.
R1 3 5 10E+3 = Ri
D1 1 2 DX = ?
D2 4 2 DX2 = ?
D3 5 4 DX = ?
.MODEL DX D(IS=1.0E-12 RS=1.0) = ?
.MODEL DX2 D(IS=1.0E-9 RS=1.0) = ?
.ENDS X12AU7
  Reply With Quote
Old 5th July 2005, 02:59 PM   #2
diyAudio Member
 
Join Date: May 2005
Location: Stittsville, Ontario, Canada
Steen
mu is approximately 18
exact values of mu, gm and rp can be calculated, but I will have to get back to you on that

1151 sets the overall emission

^1.5 is the exponent, ie sets the rate of curvature of each grid curve

R1 is not rp. R1 is there to set grid current for 1ve grid voltage, which is modeled by a resistor and diode in series.

D1 is a diode to make sure current only flows from plate to cathode.

I am not sure why D2 is used.
__________________
Robert McLean
  Reply With Quote
Old 5th July 2005, 03:16 PM   #3
diyAudio Member
 
Join Date: May 2005
Location: Stittsville, Ontario, Canada
Actually, I must correct myself. After doing the math I see that for this model mu is exactly 18 for all voltages.

gm is given by 1.5 * sqrt( Vp/18 + Vg) / 1151,
and rp is given by 1151 * 18 / ( 1.5 * sqrt( Vp / 18 + Vg ))
mu = gm * rp

The constant mu is an indication of the simplicity of the model, but it is quite useful anyway.
__________________
Robert McLean
  Reply With Quote
Old 5th July 2005, 03:37 PM   #4
diyAudio Member
 
Join Date: Nov 2003
Location: Genova, Italy
d3 with R1 (badly) models grid current

Federico
  Reply With Quote
Old 6th July 2005, 07:29 AM   #5
diyAudio Member
 
Steen Bentzen's Avatar
 
Join Date: Jul 2005
Location: Hilleroed, Denmark
Hello Robert

Thank's for your qiuck answer and explanation of the parameters of the model.
Now the values makes sense, so I can add new models.
I planning to add the 12AT7 and 6922 tube.

I know it's a simple model, but i works ok.
I have used CircuitMaker's build-in models and the simulation results are ok and within what you can exspect.

Steen
  Reply With Quote
Old 6th July 2005, 08:22 AM   #6
diyAudio Member
 
Join Date: Nov 2003
Location: Genova, Italy
Hi Steen

Quote:
I know it's a simple model, but i works ok.
However, do not use that model for distorsion prevision, analisys or optimization.

Child's law, in fact, describes in a satisfactory way the real behavior of a triode only in case of great currents values and small potential differences Vak.

the posted figure shows the behavior of a real world triode in comparison to the model of Child, the fitting has been obtained imposing minimum error in case of Vgk=0 and -2. Curves obtained with Child’s law for different values of Vgk are simply translation of the one for Vgk=0. In real curves instead, current fixed, the slope of the curves decreases as Vak increases and we see a remarkable departure of the model from the real behavior.

Use Koren model for a better fitting

bye
Federico

curves from http://www.audiomatica.com/tubes/6sn7.htm
Attached Images
File Type: gif 6sn7.gif (9.8 KB, 417 views)
  Reply With Quote
Old 6th July 2005, 08:23 AM   #7
ilimzn is offline ilimzn  Croatia
diyAudio Member
 
Join Date: Feb 2005
Location: Zagreb
They will be fine for operating point analysis, unless you are using very low currents (for a given tube), or want to analyse distortion, in which case you will get wildly optimistic results (as in 10x better than reality).
  Reply With Quote
Old 6th July 2005, 10:33 AM   #8
diyAudio Member
 
Steen Bentzen's Avatar
 
Join Date: Jul 2005
Location: Hilleroed, Denmark
Hi

Thank's again.
I won't use the CircuitMaker for any optimation and distortion analysis, only for schematic capture and some first hand operating point settings. I belive that if serious analysis is the quest, then PSpice is the answer.

P.S.: I'm new to Spice simulation.

Steen
  Reply With Quote
Old 7th July 2005, 12:25 AM   #9
wa2ise is offline wa2ise  United States
diyAudio Member
 
wa2ise's Avatar
 
Join Date: Apr 2005
Location: NJ
Look at this thread in this forum:
Vacuum tube modeling software - beta testers wanted
He wrote a program that allows you to create spice models from an image of the tube curves, for diodes and triodes. I used it, and it works well.
  Reply With Quote
Old 7th July 2005, 12:32 AM   #10
ilimzn is offline ilimzn  Croatia
diyAudio Member
 
Join Date: Feb 2005
Location: Zagreb
Quote:
Originally posted by Steen Bentzen
Hi

Thank's again.
I won't use the CircuitMaker for any optimation and distortion analysis, only for schematic capture and some first hand operating point settings. I belive that if serious analysis is the quest, then PSpice is the answer.

P.S.: I'm new to Spice simulation.

Steen
Circuitmaker IS PSpice, speciffically, a front end to a speciffic variant of spice 3F4. There are very few simulators that do not use the spice engine.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Homemade Vacuum Tube dhaen Tubes / Valves 50 13th July 2011 06:48 PM
WTB: Vacuum Tube Tester mrdon Swap Meet 0 22nd May 2009 05:01 AM
S3E Vacuum Tube angsuman Tubes / Valves 12 15th March 2008 06:12 AM
Vacuum Tube Pre O.C.L. gianmaria Tubes / Valves 13 16th February 2006 07:32 PM
DIY Vacuum tube amp turbo_h4 Tubes / Valves 2 1st July 2004 02:48 AM


New To Site? Need Help?

All times are GMT. The time now is 12:12 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2