Version 4
SHEET 1 880 680
WIRE -608 -96 -1168 -96
WIRE -608 -64 -608 -96
WIRE -608 64 -608 16
WIRE -608 64 -768 64
WIRE -560 64 -608 64
WIRE -608 112 -608 64
WIRE -976 160 -1040 160
WIRE -848 160 -896 160
WIRE -672 160 -848 160
WIRE -1296 192 -1296 144
WIRE -1168 192 -1168 -96
WIRE -1040 192 -1040 160
WIRE -768 208 -768 64
WIRE -1296 336 -1296 272
WIRE -1168 336 -1168 272
WIRE -1168 336 -1296 336
WIRE -848 336 -848 160
WIRE -768 384 -768 288
WIRE -768 384 -784 384
WIRE -736 384 -768 384
WIRE -608 384 -608 208
WIRE -608 384 -656 384
WIRE -608 448 -608 384
WIRE -1168 544 -1168 336
WIRE -1040 544 -1040 272
WIRE -1040 544 -1168 544
WIRE -848 544 -848 432
WIRE -848 544 -1040 544
WIRE -608 544 -608 528
WIRE -608 544 -848 544
WIRE -1168 560 -1168 544
FLAG -1168 560 0
FLAG -1296 144 VR
FLAG -560 64 VC
SYMBOL npn -672 112 R0
SYMATTR InstName Q1
SYMATTR Value BC546B
SYMBOL npn -784 336 M0
SYMATTR InstName Q2
SYMATTR Value BC546B
SYMBOL voltage -1168 176 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value 24
SYMBOL res -624 432 R0
SYMATTR InstName R1
SYMATTR Value 12
SYMBOL res -624 -80 R0
SYMATTR InstName R5
SYMATTR Value r=v(vr)
SYMBOL voltage -1296 176 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
WINDOW 3 -135 187 Left 2
SYMATTR Value PULSE(1000 0 0 1 1 1)
SYMATTR InstName V2
SYMBOL res -640 368 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R2
SYMATTR Value 1k
SYMBOL res -784 192 R0
SYMATTR InstName R3
SYMATTR Value 39k
SYMBOL voltage -1040 176 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
WINDOW 3 24 95 Left 2
SYMATTR Value 3.3
SYMATTR InstName V3
SYMBOL res -880 144 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R4
SYMATTR Value 1k
TEXT -1352 504 Left 2 !.tran 0 1 0 10u