* circuit no. 1   

.model nbjt NPN IS=1e-16 BF=100 BR=1

r1  2  0   4
r2  3  0   9
r3  1  2   12
r4  1  3   18
r5  3  2   6
v1  1  0   12
  .nodeset v(0)=0 

.op