Version 4
SHEET 1 880 680
WIRE 576 16 80 16
WIRE 576 112 576 16
WIRE 576 144 576 112
WIRE 80 176 80 16
WIRE 400 192 368 192
WIRE 496 192 480 192
WIRE 512 192 496 192
WIRE 368 224 368 192
WIRE 496 240 496 192
WIRE 80 352 80 256
WIRE 368 352 368 304
WIRE 368 352 80 352
WIRE 496 352 496 320
WIRE 496 352 368 352
WIRE 576 352 576 240
WIRE 576 352 496 352
WIRE 80 400 80 352
FLAG 80 400 0
FLAG 576 112 C
FLAG 496 192 B
SYMBOL voltage 80 160 R0
WINDOW 3 -117 296 Left 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR Value PULSE(15 30 0 0 0 1 2)
SYMATTR InstName V1
SYMBOL npn 512 144 R0
SYMATTR InstName Q1
SYMATTR Value BC547C
SYMBOL voltage 368 208 R0
WINDOW 0 -49 16 Left 2
WINDOW 3 -51 97 Left 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V2
SYMATTR Value 20.5
SYMBOL Misc\\EuropeanResistor 496 176 R90
WINDOW 0 5 56 VBottom 2
WINDOW 3 27 56 VTop 2
SYMATTR InstName R1
SYMATTR Value 18K
SYMBOL Misc\\EuropeanResistor 512 336 R180
WINDOW 0 31 76 Left 2
WINDOW 3 31 40 Left 2
SYMATTR InstName R2
SYMATTR Value 560
TEXT -40 480 Left 2 !.tran 0 3 1.2