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I've been trying to simulate a simple oscillator using 2 BJT transistors in KiCad, and I'm having some trouble. I've tried it in both KiCad 5.0.2 and 8.0.7. I'm not sure what information to provide for help (netlist, schematic, something else?), so I'll start with two pictures and some NGSPICE code. Here's the one from KiCad 5.0.2:

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And here's the one from 8.0.7:

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I've gotten it to work directly in NGSPICE as shown in this plot:

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Here's the working NGSPICE code if it helps:

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* Vname PosNode NegNode ...
VCC 6 0 DC 5V

* Rname PosNode NegNode Value
RC1 6 1 1K
RC2 6 2 1K
R1 ?6 3 30K
R2 ?6 4 30K

* Cname PosNode NegNode Value
C1 ?1 4 150PF
C2 ?2 3 150PF

* Q1 and Q2 with model QM and substrate connected to ground by default
* ?C B E
Q1 1 3 0 QM
Q2 2 4 0 QM

* Model statement defining QM as an NPN transistor
.MODEL QM NPN (IS=2E-16 BF=50 BR=1 RB=5 RC=1 RE=0 TF=0.2NS TR=5NS)

.NODESET V(1)=0 V(3)=0

.TRAN 0.1US 20US
.OP

* Generate the plots (running twice for some reason)
.control
reload
run
reset
run
plot V(1) V(2) V(3) V(4)
.endc

.END

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It also works in real life on a bread board.? :)

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Any suggestions would be helpful. Thanks.

I've been trying to simulate a simple oscillator using 2 BJT transistors
in KiCad, and I'm having some trouble. I've tried it in both KiCad 5.0.2
and 8.0.7. I'm not sure what information to provide for help (netlist,
schematic, something else?), so I'll start with two pictures and some
NGSPICE code. Here's the one from KiCad 5.0.2:
And here's the one from 8.0.7:
I've gotten it to work directly in NGSPICE as shown in this plot:
Here's the working NGSPICE code if it helps:
* Vname PosNode NegNode ...
VCC 6 0 DC 5V
* Rname PosNode NegNode Value
RC1 6 1 1K
RC2 6 2 1K
R1 ?6 3 30K
R2 ?6 4 30K
* Cname PosNode NegNode Value
C1 ?1 4 150PF
C2 ?2 3 150PF
* Q1 and Q2 with model QM and substrate connected to ground by default
* ?C B E
Q1 1 3 0 QM
Q2 2 4 0 QM
* Model statement defining QM as an NPN transistor
.MODEL QM NPN (IS=2E-16 BF=50 BR=1 RB=5 RC=1 RE=0 TF=0.2NS TR=5NS)
.NODESET V(1)=0 V(3)=0
.TRAN 0.1US 20US
.OP
* Generate the plots (running twice for some reason)
.control
reload
run
reset
run
plot V(1) V(2) V(3) V(4)
.endc
.END
It also works in real life on a bread board.? :)
Any suggestions would be helpful. Thanks.

I just tried to implement the in the 5.0.2 version of KiCad:

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It gave me these errors:

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Circuit: KiCad schematic
Error on line 3 :
q2 0 net-_c1-pad2_ out 2n3904
could not find a valid modelname
Error on line 4 :
q1 0 net-_c2-pad1_ net-_c1-pad1_ 2n3904
could not find a valid modelname

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I'll look into the GND issue. Thanks for both suggestions.

The Holger version (from the Zip file) wouldn't open in 5.0.2, but it did open and run in 8.0.7 on Windows:

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That pretty much matches the pure NGSPICE simulation I'd posted earlier.

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Should the 5.0.2 version be able to run that kind of simulation (assuming that I could get entered correctly)?

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Thanks for all of the suggestions. I'll be working on them.
BTW, here's what it looks like in real life (before I thought of
modelling it in KiCad).? :)