Version 4
SHEET 1 880 828
WIRE -144 80 -272 80
WIRE -64 80 -144 80
WIRE 16 80 -64 80
WIRE 48 80 16 80
WIRE 160 80 128 80
WIRE -272 112 -272 80
WIRE 16 128 16 80
WIRE 160 176 160 80
WIRE 160 176 80 176
WIRE 208 176 160 176
WIRE 304 176 288 176
WIRE 384 176 304 176
WIRE -272 224 -272 192
WIRE 384 224 384 176
WIRE -272 256 -272 224
WIRE 304 272 304 176
WIRE 320 272 304 272
WIRE -272 400 -272 336
WIRE 16 400 16 224
WIRE 16 400 -272 400
WIRE 272 400 16 400
WIRE 384 400 384 320
WIRE 384 400 272 400
WIRE 272 432 272 400
WIRE 384 512 384 400
WIRE 320 560 304 560
WIRE 16 624 16 400
WIRE 160 672 80 672
WIRE 192 672 160 672
WIRE 304 672 304 560
WIRE 304 672 272 672
WIRE 384 672 384 608
WIRE 384 672 304 672
WIRE -64 784 -64 80
WIRE 16 784 16 720
WIRE 16 784 -64 784
WIRE 32 784 16 784
WIRE 160 784 160 672
WIRE 160 784 112 784
FLAG 272 432 0
FLAG -144 80 out_zerr
FLAG -272 224 in_sin
SYMBOL npn 80 128 M0
WINDOW 3 -74 109 Left 2
SYMATTR InstName Q1
SYMATTR Value BC547C
SYMBOL npn 320 224 R0
SYMATTR InstName Q2
SYMATTR Value BC547C
SYMBOL Misc\\EuropeanResistor 304 160 R90
WINDOW 0 5 56 VBottom 2
WINDOW 3 27 56 VTop 2
SYMATTR InstName R1
SYMATTR Value 470
SYMBOL Misc\\EuropeanResistor 144 64 R90
WINDOW 0 5 56 VBottom 2
WINDOW 3 27 56 VTop 2
SYMATTR InstName R2
SYMATTR Value 33K
SYMBOL Misc\\EuropeanResistor -256 208 R180
WINDOW 0 31 76 Left 2
WINDOW 3 31 40 Left 2
SYMATTR InstName R3
SYMATTR Value 2K2
SYMBOL voltage -272 240 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
WINDOW 3 -107 187 Left 2
SYMATTR InstName V1
SYMATTR Value SINE(0 {Uin} 400)
SYMBOL pnp 80 720 R180
WINDOW 3 -64 118 Left 2
SYMATTR InstName Q3
SYMATTR Value BC557C
SYMBOL pnp 320 608 M180
SYMATTR InstName Q4
SYMATTR Value BC557C
SYMBOL Misc\\EuropeanResistor 128 768 R90
WINDOW 0 5 56 VBottom 2
WINDOW 3 27 56 VTop 2
SYMATTR InstName R4
SYMATTR Value 10K
SYMBOL Misc\\EuropeanResistor 288 656 R90
WINDOW 0 5 56 VBottom 2
WINDOW 3 27 56 VTop 2
SYMATTR InstName R5
SYMATTR Value 1K
TEXT -384 472 Left 2 !.tran 0 15ms 2m5 150µ
TEXT -384 504 Left 2 !.step dec param Uin 0.01 8
TEXT -384 536 Left 2 !.op