Forums » General Electronics Discussion

As I previously said, nice app.

Here is some food for thought to the designers.

Not working in Sim mode obviously.

Assuming that you make some Custom Circuits, how do you define some models for them?

Say you want to include the following file:

*-----------------------------------------------------------------------

• Filename: 6bq5.inc 23/01/2004 V4

• Simulator: PSpice

• Device type: Power pentode

• Device model: 6BQ5/EL84

*

• Author: Duncan Munro

• Date: 12/5/97

• Copyright: (C)1997-2004 Duncan Amplification

*

*

• V3 [12/10/97]: Screen current limited to prevent screen current

• draw at Vs = 0.

*

• V4 [23/01/04]: LIMIT{x,y,z} statements changed to LIMIT(x,y,z)

• The following parameters are not modelled:

*

• (1) Heater

• (2) Grid current is an approximation

*

• Please note that this model is provided "as is" and

• no warranty is provided in respect of its suitability

• for any application.

*

• This model is provided for educational and non-profit use.

*

• Queries via the forum at http://www.duncanamps.com/

*

• Pins A Anode

• S Screen

• G Grid

• K Cathode

*

*-----------------------------------------------------------------------

.SUBCKT 6BQ5 A S G K

*

• Calculate contribution to cathode current

*

Eat at 0 VALUE={0.636*ATAN(V(A,K)/15)}

Egs gs 0 VALUE={LIMIT(V(S,K)/19+V(G,K)+V(A,K)/1400,0,1E6)}

Egs2 gs2 0 VALUE={PWRS(V(gs),1.5)}

Ecath cc 0 VALUE={V(gs2)*V(at)}

*

• Calculate anode current

*

Ga A K VALUE={3.2E-3*V(cc)}

*

• Calculate screen current

*

Escrn sc 0 VALUE={V(gs2)*(1.1-V(at))}

Gs S K VALUE={2.0E-3V(sc)LIMIT(V(S,K),0,10)/10}

*

• Grid current (approximation - does not model low va/vs)

*

Gg G K VALUE={PWR(LIMIT(V(G,K)+1,0,1E6),1.5)*50E-6}

*

• Capacitances

*

Cg1 G K 10.8p

Cak A K 6.5p

Cg1a G A 0.5p

.ENDS

*===============================

Any constructive idea would be welcomed!

Tubester

I've posted an example for a work-around using subcircuit-like schematics : https://www.circuitlab.com/circuit/ry7f7v/diff_pair/. But you have to then build the subcircuit on the schematic page AS A SCHEMATIC. This still won't quite work for your tube sub circuits as you need the equivalent to a SPICE "B" sources (dependent sources controlled by equations). Your code illustrates how PSPICE handles this in a unique and very non-standard way, as a special case of E, G elements, but Circuit lab just needs a similar construct and we could model arbitrary circuit elements. (PSPICE was based on ancient SPICE2 sources, and their equivolent solution was different than that chosen for SPICE3 and its descendants)

Here are the images that I previously reffered to.

Cheers,

Tubester