Version 4
SHEET 1 1872 680
WIRE 544 16 384 16
WIRE 624 16 544 16
WIRE 720 16 704 16
WIRE 384 32 384 16
WIRE 544 96 544 16
WIRE -112 112 -144 112
WIRE 96 144 32 144
WIRE 176 144 96 144
WIRE 272 144 256 144
WIRE 384 144 384 112
WIRE 384 144 336 144
WIRE 480 144 384 144
WIRE -112 176 -288 176
WIRE 384 192 384 144
WIRE -288 208 -288 176
WIRE -144 208 -144 112
WIRE -112 208 -144 208
WIRE 544 208 544 192
WIRE 640 208 544 208
WIRE 704 208 640 208
WIRE 736 208 704 208
WIRE 544 224 544 208
WIRE 640 240 640 208
WIRE -288 320 -288 288
WIRE -144 320 -144 208
WIRE -144 320 -288 320
WIRE 384 320 384 272
WIRE 384 320 -144 320
WIRE 544 320 544 304
WIRE 544 320 384 320
WIRE 640 320 640 304
WIRE 640 320 544 320
WIRE 736 320 640 320
WIRE -288 336 -288 320
FLAG -288 336 0
FLAG 96 144 AM
FLAG 704 208 out1
FLAG 720 16 0
SYMBOL SpecialFunctions\\modulate -112 112 R0
WINDOW 0 5 -83 Left 2
WINDOW 3 2 -52 Left 2
SYMATTR InstName A1
SYMATTR Value space=1Meg mark=1Meg
SYMBOL voltage -288 192 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V2
SYMATTR Value SINE({ampl} {ampl*0.7} 2k)
SYMBOL res 528 208 R0
SYMATTR InstName R2
SYMATTR Value 4.7k
SYMBOL cap 624 240 R0
SYMATTR InstName C2
SYMATTR Value 22n
SYMBOL npn 480 96 R0
WINDOW 0 -34 77 Left 2
WINDOW 3 -44 111 Left 2
SYMATTR InstName Q1
SYMATTR Value BC547C
SYMBOL cap 336 128 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C3
SYMATTR Value 10µ
SYMBOL res 368 16 R0
SYMATTR InstName R3
SYMATTR Value 100k
SYMBOL res 400 176 M0
SYMATTR InstName R4
SYMATTR Value 100k
SYMBOL voltage 608 16 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 -32 56 VBottom 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V1
SYMATTR Value 6V
SYMBOL res 272 128 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R5
SYMATTR Value 1k
TEXT -344 -8 Left 2 !.tran 0 5m 0 100n
TEXT -232 344 Left 2 !.param ampl=1V