Version 4
SHEET 1 880 680
WIRE 528 -80 304 -80
WIRE 304 -32 304 -80
WIRE -16 64 -112 64
WIRE 192 64 64 64
WIRE 304 64 304 48
WIRE 304 64 192 64
WIRE 192 80 192 64
WIRE -112 112 -112 64
WIRE 304 112 304 64
WIRE 304 144 304 112
WIRE 528 160 528 -80
WIRE -112 192 -112 176
WIRE -48 192 -112 192
WIRE 48 192 16 192
WIRE 80 192 48 192
WIRE 192 192 192 160
WIRE 192 192 144 192
WIRE 240 192 192 192
WIRE -112 256 -112 192
WIRE 48 256 48 192
WIRE 304 288 304 240
WIRE 304 288 224 288
WIRE 528 288 528 240
WIRE 528 288 304 288
WIRE -112 368 -112 336
WIRE 48 368 48 336
WIRE 48 368 -112 368
WIRE 224 368 224 288
WIRE 224 368 48 368
WIRE 304 384 304 288
FLAG 304 384 0
FLAG 304 112 C
SYMBOL npn 240 144 R0
SYMATTR InstName Q1
SYMATTR Value BC547C
SYMBOL Misc\\EuropeanResistor 288 -48 R0
SYMATTR InstName R1
SYMATTR Value 10K
SYMBOL voltage 528 144 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V1
SYMATTR Value 5
SYMBOL Misc\\EuropeanResistor 176 64 R0
SYMATTR InstName R2
SYMATTR Value 2Meg2
SYMBOL cap 144 176 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C1
SYMATTR Value 100n
SYMBOL cap 16 176 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C2
SYMATTR Value 100n
SYMBOL cap -96 176 R180
WINDOW 0 24 56 Left 2
WINDOW 3 24 8 Left 2
SYMATTR InstName C3
SYMATTR Value 100n
SYMBOL Misc\\EuropeanResistor 32 240 R0
SYMATTR InstName R3
SYMATTR Value 22K
SYMBOL Misc\\EuropeanResistor -128 240 R0
SYMATTR InstName R4
SYMATTR Value 22K
SYMBOL voltage 80 64 R90
WINDOW 0 -32 56 VBottom 2
WINDOW 3 -89 40 VTop 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V2
SYMATTR Value PULSE(0 0.1 0 0 0 0.05 0.1 2)
TEXT -96 424 Left 2 !.tran 0 1 0.5 1m
TEXT -200 384 Left 2 ;R4=Poti 22K+10K