* SPICE netlist
R1 P6 P7 15k
R2 P7 N002 15k
R3 P8 N002 150
R4 P1 P8 1.35k
R5 P5 P1 15k
D1 N001 N003 1N4148
D2 N003 N006 1N4148
I1 P6 N001 3m
Q1 P6 N001 P5 0 2N3904
Q2 P5 N009 P4 0 2N3904
Q3 N006 N008 P4 0 2N2222
Q4 N008 N007 P4 0 2N2222
Q5 N007 N007 P4 0 2N2222
Q6 N007 N004 N002 0 2N2907
Q7 N009 N006 P5 0 2N2907
Q8 P4 P2 N004 0 2N2907
Q9 N008 N005 P1 0 2N2907
Q10 P4 P3 N005 0 2N2907
R6 P3 P4 50k
R7 P2 P4 50k
.tran 0 50m 0 startup

* LTspice schematic (.asc)
Version 4
SHEET 1 1600 976
WIRE 64 -488 -368 -488
WIRE 320 -488 64 -488
WIRE 624 -488 320 -488
WIRE 624 -440 624 -488
WIRE 320 -392 320 -408
WIRE 560 -392 320 -392
WIRE -368 -376 -368 -488
WIRE 320 -280 320 -392
WIRE -368 -216 -368 -296
WIRE -368 -216 -544 -216
WIRE -368 -104 -368 -216
WIRE 112 -24 32 -24
WIRE 624 -24 624 -344
WIRE 624 -24 192 -24
WIRE 800 -24 624 -24
WIRE -368 -8 -368 -24
WIRE -352 -8 -368 -8
WIRE -256 -8 -272 -8
WIRE -240 -8 -256 -8
WIRE -80 -8 -160 -8
WIRE -32 -8 -80 -8
WIRE 32 -8 32 -24
WIRE 32 -8 -32 -8
WIRE 320 -8 320 -216
WIRE -368 8 -368 -8
WIRE 624 8 624 -24
WIRE 624 8 480 8
WIRE -80 24 -80 -8
WIRE 480 40 480 8
WIRE -432 56 -544 56
WIRE 48 72 -16 72
WIRE 320 88 320 56
WIRE 416 88 320 88
WIRE -544 104 -544 56
WIRE 48 136 48 72
WIRE 624 136 624 8
WIRE -688 152 -800 152
WIRE -608 152 -688 152
WIRE -368 152 -368 104
WIRE -208 152 -368 152
WIRE -80 152 -80 120
WIRE -32 152 -80 152
WIRE -368 184 -368 152
WIRE -80 184 -80 152
WIRE 144 184 112 184
WIRE 192 184 144 184
WIRE 480 184 480 136
WIRE 560 184 480 184
WIRE -688 232 -688 152
WIRE -208 232 -208 152
WIRE -208 232 -304 232
WIRE -144 232 -208 232
WIRE 144 232 144 184
WIRE 320 248 320 88
WIRE 256 296 224 296
WIRE -688 424 -688 312
WIRE -544 424 -544 200
WIRE -544 424 -688 424
WIRE -368 424 -368 280
WIRE -368 424 -544 424
WIRE -80 424 -80 280
WIRE -80 424 -368 424
WIRE 48 424 48 232
WIRE 48 424 -80 424
WIRE 144 424 144 312
WIRE 144 424 48 424
WIRE 320 424 320 344
WIRE 320 424 144 424
WIRE 432 424 320 424
WIRE 624 424 624 232
WIRE 624 424 432 424
WIRE -32 488 -32 152
WIRE 224 488 224 296
WIRE 224 488 -32 488
FLAG -544 -216 P7
IOPIN -16 64 BiDir
FLAG -32 -8 P1
IOPIN 496 272 BiDir
FLAG -256 -8 P8
IOPIN 272 272 BiDir
FLAG 64 -488 P6
IOPIN 592 -208 BiDir
FLAG 800 -24 P5
IOPIN 1328 256 BiDir
FLAG 432 424 P4
IOPIN 960 704 BiDir
FLAG -800 152 P2
IOPIN -272 432 BiDir
FLAG 192 184 P3
IOPIN 720 464 BiDir
SYMBOL res -384 -392 R0
SYMATTR InstName R1
SYMATTR Value 15k
SYMBOL res -384 -120 R0
SYMATTR InstName R2
SYMATTR Value 15k
SYMBOL res -256 -24 R90
SYMATTR InstName R3
SYMATTR Value 150
SYMBOL res -144 -24 R90
SYMATTR InstName R4
SYMATTR Value 1.35k
SYMBOL res 208 -40 R90
SYMATTR InstName R5
SYMATTR Value 15k
SYMBOL diode 304 -280 R0
SYMATTR InstName D1
SYMATTR Value 1N4148
SYMBOL diode 304 -8 R0
SYMATTR InstName D2
SYMATTR Value 1N4148
SYMBOL current 320 -488 R0
SYMATTR InstName I1
SYMATTR Value 3m
SYMBOL npn 560 -440 R0
SYMATTR InstName Q1
SYMATTR Value 2N3904
SYMBOL npn 560 136 R0
SYMATTR InstName Q2
SYMATTR Value 2N3904
SYMBOL npn 256 248 R0
SYMATTR InstName Q3
SYMATTR Value 2N2222
SYMBOL npn -144 184 R0
SYMATTR InstName Q4
SYMATTR Value 2N2222
SYMBOL npn -304 184 M0
SYMATTR InstName Q5
SYMATTR Value 2N2222
SYMBOL pnp -432 104 M180
SYMATTR InstName Q6
SYMATTR Value 2N2907
SYMBOL pnp 416 136 M180
SYMATTR InstName Q7
SYMATTR Value 2N2907
SYMBOL pnp -608 200 M180
SYMATTR InstName Q8
SYMATTR Value 2N2907
SYMBOL pnp -16 120 R180
SYMATTR InstName Q9
SYMATTR Value 2N2907
SYMBOL pnp 112 232 R180
SYMATTR InstName Q10
SYMATTR Value 2N2907
SYMBOL res 128 216 R0
SYMATTR InstName R6
SYMATTR Value 50k
SYMBOL res -704 216 R0
SYMATTR InstName R7
SYMATTR Value 50k