Version 4
SHEET 1 1200 1172
WIRE 336 -320 336 -352
WIRE 448 -320 448 -352
WIRE 336 -208 336 -240
WIRE 448 -208 448 -240
WIRE -80 -112 -128 -112
WIRE 32 -112 0 -112
WIRE 128 -112 32 -112
WIRE 272 -112 208 -112
WIRE 160 16 160 -16
WIRE 32 32 32 -112
WIRE 128 32 32 32
WIRE 272 48 272 -112
WIRE 272 48 192 48
WIRE 336 48 272 48
WIRE -224 64 -320 64
WIRE -144 64 -160 64
WIRE -112 64 -144 64
WIRE 32 64 -48 64
WIRE 128 64 32 64
WIRE 32 80 32 64
WIRE -320 96 -320 64
WIRE 160 112 160 80
WIRE 32 176 32 160
WIRE -320 208 -320 176
WIRE -144 240 -144 64
WIRE 128 240 -144 240
WIRE 272 240 272 48
WIRE 272 240 208 240
FLAG 448 -208 0
FLAG -320 208 0
FLAG 336 48 out
IOPIN 336 48 Out
FLAG 336 -208 0
FLAG -320 64 in
FLAG 160 -16 V+
FLAG 160 112 V-
FLAG 336 -352 V-
FLAG 448 -352 V+
FLAG -128 -112 0
FLAG 32 176 0
SYMBOL voltage 448 -336 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V1
SYMATTR Value 9
SYMBOL voltage 336 -336 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V2
SYMATTR Value -9
SYMBOL voltage -320 80 R0
WINDOW 3 38 75 Left 2
WINDOW 123 34 105 Left 2
WINDOW 39 0 0 Left 2
SYMATTR Value 0
SYMATTR Value2 AC 1
SYMATTR InstName V3
SYMBOL Opamps\\opamp2 160 -16 R0
SYMATTR InstName U2
SYMATTR Value NE5532
SYMBOL cap -224 80 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName C1
SYMATTR Value 330n
SYMBOL cap -112 80 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName C2
SYMATTR Value 330n
SYMBOL Misc\\EuropeanResistor 112 -96 R270
WINDOW 0 27 56 VTop 2
WINDOW 3 5 56 VBottom 2
SYMATTR InstName R1
SYMATTR Value 3.3k
SYMBOL Misc\\EuropeanResistor 112 256 R270
WINDOW 0 27 56 VTop 2
WINDOW 3 5 56 VBottom 2
SYMATTR InstName R4
SYMATTR Value {RP}
SYMBOL Misc\\EuropeanResistor 16 -128 R90
WINDOW 0 5 56 VBottom 2
WINDOW 3 27 56 VTop 2
SYMATTR InstName R2
SYMATTR Value 4.7k
SYMBOL Misc\\EuropeanResistor 16 64 R0
SYMATTR InstName R3
SYMATTR Value {RP}
TEXT -368 -280 Left 2 ;.tran 0 50u 0 50n
TEXT -368 -392 Left 2 !.include  NE5532.LIB
TEXT -368 -520 Left 2 ;The NE5532 can be sued with he universal symbol "opamp2".
TEXT -368 -248 Left 2 ;.options plotwinsize=0
TEXT -368 -480 Left 2 ;Model of NE5532 from http://www.beis.de/Elektronik/Filter/NE553x.lb
TEXT -368 -320 Left 2 !.step param RP 3k 8k 1k
TEXT -368 -352 Left 2 !.ac dec 20 20 20k