Why doesn't my simulation work (beginner)

Schematic Simulation (Ngspice)
1

I’m trying to get to grips with the Kicad simulator. I successfully simulated a simple op-amp circuit using a TL071 symbol. I then changed this to a TL072 symbol and I can no longer get it to work - I used the alternative node sequence to change the pins but still nothing, the simulation window says -

warning, can’t find model vm
Circuit: KiCad schematic
Error on line 9 :
u2 vout net-c1-pad2 0 vm vp tl072
Unable to find definition of model vm
Error: circuit not parsed.

I’m using the same spice model as I used for the first (successful) simulation (the model for a LF356) but this seems to be telling me that it can’t find a model for the op-amp.

opamp_sim
opamp_sim1007×907 28.8 KB

hopefully someone can help!

2

the TL072 is a multiple unit symbol (one unit for each amplifier and one for the power pins), so you’ll need to do some extra work to simulate it. Basically you’ll need to make a wrapper model that connects each unit to the relevant pins in the underlying amplifier model.

I think you’re already following this tutorial, but see section 8 for an explanation: http://ngspice.sourceforge.net/ngspice-eeschema.html

1 Like
3

Maybe the thing I encountered before is the same as your problem, I found the reason.

4

thanks, the problem was I didn’t create the dual package information. sorted now