Version 4
SHEET 1 880 680
WIRE -112 96 -160 96
WIRE 0 96 -32 96
WIRE 32 96 0 96
WIRE 144 96 112 96
WIRE 176 96 144 96
WIRE 288 96 256 96
WIRE 320 96 288 96
WIRE 432 96 400 96
WIRE 480 96 432 96
WIRE -160 128 -160 96
WIRE 0 160 0 96
WIRE 32 160 0 160
WIRE 288 160 288 96
WIRE 320 160 288 160
WIRE 144 176 144 96
WIRE 144 176 96 176
WIRE 432 176 432 96
WIRE 432 176 384 176
WIRE 32 192 0 192
WIRE 320 192 288 192
WIRE -160 224 -160 208
WIRE 0 224 0 192
WIRE 288 224 288 192
FLAG -160 96 IN
FLAG 480 96 OUT
FLAG 288 224 0
FLAG 0 224 0
FLAG -160 224 0
SYMBOL Opamps\\opamp 64 112 R0
SYMATTR InstName U1
SYMBOL Opamps\\opamp 352 112 R0
SYMATTR InstName U2
SYMBOL res -16 80 R90
WINDOW 0 5 56 VBottom 2
WINDOW 3 27 56 VTop 2
SYMATTR InstName R1
SYMATTR Value 30k
SYMBOL res 128 80 R90
WINDOW 0 5 56 VBottom 2
WINDOW 3 27 56 VTop 2
SYMATTR InstName R2
SYMATTR Value R=R2
SYMBOL res 272 80 R90
WINDOW 0 5 56 VBottom 2
WINDOW 3 27 56 VTop 2
SYMATTR InstName R3
SYMATTR Value 6k2
SYMBOL res 416 80 R90
WINDOW 0 5 56 VBottom 2
WINDOW 3 27 56 VTop 2
SYMATTR InstName R4
SYMATTR Value R=R4
SYMBOL voltage -160 112 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value 0
TEXT 64 24 Left 2 !.step param R2 list 510, 1k6, 5k1, 16k, 51k, 160k
TEXT 64 48 Left 2 !.step param R4 list 18k, 22k, 27k, 33k, 39k, 47k
TEXT -104 48 Left 2 !.lib opamp.sub
TEXT -104 24 Left 2 !.dc dec V1 50m 50 100