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Re: tube library models supplied by GFR


 :
4/19/2000 9:57 PM
Carl Z
Re: tube library models supplied by GFR
I've been fiddling on and off with the simulator from MicroCap. They have what may well be the absolute best interface I've ever seen. You can figure everything out inside of 10 minutes. There are animated tutorials that will step you thru all the major features and that helps a lot too. Fourier analysis is a real pain with this version though.  
 
I'm sort of curious about the protel software myself. It's supposedly a fully functional 30 day demo. I'm wondering if you can do the ole roll the clock forward, install, then reset the clock trick.  
 
Carl Z
 
4/20/2000 11:59 AM
GFR

I love the interface of Microcap, but I have had some problems with its simulations. Specifically, when driving a device hard (I've tried tubes, JFETs and bipolars), it does not saturate but instead the plate/drain/collector goes negative... I've had the same problem with the triode model on EWB. The Orcad package works OK and so does CircuitMaker.
 
4/20/2000 6:26 PM
Carl Z

Another thing in a very long "to do" list is to play around with the macro and see what happens using that modified 3/2 power formula devised by Koren, I believe is the name. A treatment of his formula is in that article named vacuum tube parameter identification using computer methods. It seems to track the tube curves much closer.  
 
Carl Z
 
4/20/2000 7:27 PM
GFR

It's done :)  
 
On my CM libs it's the following model  
 
*Vacuum Tube Triode (Audio freq.) pkg:VT-9 [grid current + low B+] (A:1,2,3)(B:6,7,8)  
.SUBCKT X12AX7A 1 2 3  
B1 7 0 V=(V(1,3)/682*LOG(1+EXP(682*(1/107.6+V(2,3)/SQRT(8837+V(1,3)*V(1,3))))))  
RE1 7 0 1G  
B2 1 3 I= 2*URAMP(V(7)^1.03)/851  
RCP 1 3 1G ; TO AVOID FLOATING NODES IN MU-FOLLOWER  
C1 2 3 1.6P ; CATHODE GRID  
C2 2 1 1.6P ; GRID-PLATE  
C3 1 3 0.33P ; CATHODE-PLATE  
D3 5 3 DX ; FOR GRID CURRENT  
R1 2 5 2000 ; FOR GRID CURRENT  
.MODEL DX D(IS=1N RS=1 CJO=10PF TT=1N)  
.ENDS X12AX7A  
 
I optmized it with EXCEL's solve function, trying to match a curve from a Phillips manual.
 
4/20/2000 7:31 PM
GFR

Note: on JC's site (viva analog) he compares the Koren model with some other model and says it sucks. However due to spice version differences I was not able to use JC's model.
 
4/20/2000 6:09 PM
Brad Myers
Re: CircuitMaker!!!!!!
Has anyone tried McCAD? Goto www.mccad.com. The Lite version is free and the purchase version isn't all that much. You can build libraries and the Lite version is limited to 200 nodes per drawing.  
 
It's also crossplatform (IBM or MAC) and the price is right. You are limited as to what file types to export, however, that's nothing that a good printer & cheap scanner can't fix!  
 
BradM.
 

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