Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Software Tools SPICE, PCB CAD, speaker design and measurement software, calculators

Spice simulation
Spice simulation
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 14th April 2017, 08:38 AM   #1501
de Ocampo is offline de Ocampo  Philippines
diyAudio Member
 
de Ocampo's Avatar
 
Join Date: Nov 2010
Location: Ocean front, The Pacific
Quote:
Originally Posted by keantoken View Post
8.5m sounds more realistic to be, but is small enough it might not matter. You can look at the Vbe plot and look at where Vbe becomes resistive, because the emitter resistance takes over and it becomes a straight line. You can calculate the resistance from that line. But this can be due to both Re and Rb, so more information is helpful. Rc can be adjusted when doing Vcesat curves.
Maestro keantoken,

Im working on this circuit using your spice directives, copy pasted from ampsim2.asc I think. The squarewave swings on + rail only. I wanted to see how the negative swing looks like because clipping behaviour is assymetrical. Can you please check it out if I miss something in the directives?

Thank you!

Albert
Attached Files
File Type: zip bootstrap_folded_cascode.zip (7.3 KB, 20 views)
__________________
To know that is Wisdom. To use it is the Art. - Clive Barker
  Reply With Quote
Old 14th April 2017, 04:42 PM   #1502
keantoken is offline keantoken  United States
diyAudio Member
 
keantoken's Avatar
 
Join Date: Aug 2006
Location: Texas
It looks like you deleted one of the square sources and some directives. They are not meant to be broken up and used separately, but all together in series, using directives to turn them on and off. Maybe you got an old version. This is what I'm currently using.

Also you OLG probe placement is wrong. It needs to have the output stage on one side and the load and feedback point on the other side.
Attached Files
File Type: asc ampsim8beta.asc (6.5 KB, 22 views)
__________________
The Kmultiplier rail filter! -=- The Simple Kuartlotron Superbuffer!
Need something built, repaired or modded? PM me and ask what I can do!

Last edited by keantoken; 14th April 2017 at 04:44 PM.
  Reply With Quote
Old 14th April 2017, 09:23 PM   #1503
de Ocampo is offline de Ocampo  Philippines
diyAudio Member
 
de Ocampo's Avatar
 
Join Date: Nov 2010
Location: Ocean front, The Pacific
Ok thanks I will correct the errors when the sun goes up..
__________________
To know that is Wisdom. To use it is the Art. - Clive Barker
  Reply With Quote
Old 15th April 2017, 11:36 AM   #1504
de Ocampo is offline de Ocampo  Philippines
diyAudio Member
 
de Ocampo's Avatar
 
Join Date: Nov 2010
Location: Ocean front, The Pacific
Quote:
Originally Posted by keantoken View Post
It looks like you deleted one of the square sources and some directives. They are not meant to be broken up and used separately, but all together in series, using directives to turn them on and off. Maybe you got an old version. This is what I'm currently using.

Also you OLG probe placement is wrong. It needs to have the output stage on one side and the load and feedback point on the other side.
I'm puzzled, I got triangle waves. Did I connect it alright? I had it set to output squarewave.
Attached Files
File Type: zip de_oc_amp.zip (7.9 KB, 9 views)
__________________
To know that is Wisdom. To use it is the Art. - Clive Barker
  Reply With Quote
Old 24th August 2017, 02:27 PM   #1505
Mrcloc is offline Mrcloc  South Africa
diyAudio Member
 
Join Date: May 2016
Location: Pretoria
Default Simple Bridge Rectifier LTSpice Model

Hi. I wonder if this is the right place to add this. I created a basic bridge rectifier ltspice model. I'm sick of creating the same thing every time I start a power supply circuit, or test certain things. So for anyone who wants it, put the BR.asy into your sym folder (I put my way down into sym\Misc\Custom). Put the BR.sub into sub.

You can edit the .sub to change the diode if you want. This model uses D - the generic diode.
Attached Files
File Type: zip BR.zip (640 Bytes, 9 views)
  Reply With Quote
Old 3rd September 2017, 09:51 PM   #1506
john_ellis is offline john_ellis  United Kingdom
diyAudio Member
 
Join Date: Sep 2006
SPICE model of BD139-BD140
I recently ran a simulation of a "Bailey" 30W using these as driver and pre-driver transistors. SImualtions showed worse distortion than expected. CHecked the models and found that they are still the old ones which lineup reported 10 years ago as not being suitable.
Just started making a model of the BD140. What I can say is that the particular device I measured had a forward gain of 220, reverse 12, VAF of 86, VAR 31 compared with the spice file I had which gives VAF=20, BF=335, so clearly not ideal.
Without optimising the new model (still to be completed) the distortion in the amplifiers reduced by a factor of 2, more in line with expectations.
I do not recall the origin of the model I am using but one well known company once produced models based on data sheet parameters which is pessimistic particularly for VAF as the model appears to describe the leakage current (and the SPICE model treats this linearly: in practice the leakage current is due to an increasing pre-avalanche breakdown field and rises sharply near BVceo. At lower Vce's the output current is much flatter with voltage.

Last edited by john_ellis; 3rd September 2017 at 10:18 PM. Reason: mistyped
  Reply With Quote
Old 3rd September 2017, 10:00 PM   #1507
keantoken is offline keantoken  United States
diyAudio Member
 
keantoken's Avatar
 
Join Date: Aug 2006
Location: Texas
I haven't seen pessimistic models so much as models that were just plain garbage, with parameters which made no sense and that didn't resemble the intended transistor very well.

Bob Cordell has handmade models of the BD140/139 here:

CordellAudio.com - SPICE Models
__________________
The Kmultiplier rail filter! -=- The Simple Kuartlotron Superbuffer!
Need something built, repaired or modded? PM me and ask what I can do!
  Reply With Quote
Old 3rd September 2017, 10:14 PM   #1508
john_ellis is offline john_ellis  United Kingdom
diyAudio Member
 
Join Date: Sep 2006
Thanks for the link. But there are already apparent differences. The Bob Cordell BD140 model gives a lower gain and higher VAF than I have measured!
This just shows that individual transistor parameters can vary significantly from the models. And one SPICE model will not cover the range of devices possible. However, for the particular parameters VAF and hfe the product tends to be (almost) constant. Bob's figures are 113 x 140=15820 while my measured data is 220 and 86 =18920. EIther would work better than the original model.
  Reply With Quote
Old 3rd September 2017, 10:30 PM   #1509
keantoken is offline keantoken  United States
diyAudio Member
 
keantoken's Avatar
 
Join Date: Aug 2006
Location: Texas
Yes, there is a lot of variation, especially in Vaf. It seems most common transistors these days have very low Vaf, which is a pain. Bob didn't mention which manufacturers his parts came from which is also an ambiguity when you have parts like the BD140/139 which can be totally different depending on who makes them.
__________________
The Kmultiplier rail filter! -=- The Simple Kuartlotron Superbuffer!
Need something built, repaired or modded? PM me and ask what I can do!
  Reply With Quote
Old 4th September 2017, 08:34 AM   #1510
Mrcloc is offline Mrcloc  South Africa
diyAudio Member
 
Join Date: May 2016
Location: Pretoria
I don't use BD139/140 simply because they are far too inconsistent. This short discussion should be enough for amplifier designers to abandon them altogether.
  Reply With Quote

Reply


Spice simulationHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Need help with Spice simulation overmind Everything Else 4 23rd December 2002 05:58 PM


New To Site? Need Help?

All times are GMT. The time now is 11:29 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright ©1999-2017 diyAudio
Wiki