JFET spice model pin assignment wrong, not sure how to fix

[DaveH]

I’ve created a simple circuit with a Fairchild J112 JFET, self-biased using a resistor (R3) between the source pin and ground. Here is the schematic: JFET-ClassA.sch (3.5 KB)

When I run a simulation with a voltage sweep at the input, the voltage across R3 is essentially zero the whole time, as is current. It should definitely be non-zero as there is current running through R2 and it should be the same as the current through R3.

But, looking at the netlist, I can see why. JFET-ClassA.cir (202 Bytes)

On line 2, it’s got the pins for gate and source swapped, at least in relation to the Spice NJF reference I found here: http://bwrcs.eecs.berkeley.edu/Classes/IcBook/SPICE/UserGuide/elements_fr.html

The expectation of the NJF model is drain, gate, source. The J112 is drain, source, gate. I’ve searched the forum and the web, but I have yet to find a solution for getting the proper pin order.

Any help is appreciated.

[holger]

Please see http://ngspice.sourceforge.net/ngspice-eeschema.html#OpAmp

and/or https://docs.kicad.org/5.1/en/eeschema/eeschema.html#simulator

[DaveH]

Thank you. Alternate Node Sequence was the solution. I appreciate the help, as always.

Here’s a screenshot of the solution specific to my JFET problem in case it might be useful to anyone in the future.