Version 4
SHEET 1 880 680
WIRE -144 -64 -176 -64
WIRE 16 -64 -80 -64
WIRE 208 -64 16 -64
WIRE 320 -64 272 -64
WIRE -176 16 -176 -64
WIRE -144 16 -176 16
WIRE 112 16 -64 16
WIRE 192 16 112 16
WIRE 320 16 320 -64
WIRE 320 16 272 16
WIRE 320 32 320 16
WIRE 16 48 16 -64
WIRE -176 64 -176 16
WIRE -176 64 -224 64
WIRE 112 64 112 16
WIRE 320 128 320 112
WIRE 16 160 16 144
WIRE 64 160 64 96
WIRE 64 160 16 160
WIRE 112 160 112 128
WIRE 112 160 64 160
WIRE 272 176 240 176
WIRE 320 256 320 224
WIRE 320 256 240 256
WIRE 16 272 16 240
WIRE 64 272 16 272
FLAG 64 272 G_nd
FLAG -224 64 oa_out
FLAG 240 256 Jnc
FLAG 240 176 non_inv_in
SYMBOL potentiometer 16 144 M0
SYMATTR InstName U1
SYMATTR SpiceLine R=5k
SYMATTR SpiceLine2 wiper={wpf}
SYMBOL cap -80 -80 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C1
SYMATTR Value 22n
SYMBOL cap 272 -80 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C2
SYMATTR Value 10n
SYMBOL res -48 0 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R1
SYMATTR Value 68k
SYMBOL res 288 0 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R2
SYMATTR Value 6k8
SYMBOL cap 96 64 R0
SYMATTR InstName C3
SYMATTR Value 12n
SYMBOL res 0 144 R0
SYMATTR InstName R3
SYMATTR Value 100R
SYMBOL potentiometer 320 224 R0
SYMATTR InstName U2
SYMATTR SpiceLine R=22k
SYMATTR SpiceLine2 wiper={wpbc}
SYMBOL res 304 16 R0
SYMATTR InstName R4
SYMATTR Value 27k
TEXT 336 -64 Left 2 !.param wpf=.5
TEXT 336 -32 Left 2 !.param wpbc=.5