Version 4
SHEET 1 880 680
WIRE 16 128 -16 128
WIRE 208 128 96 128
WIRE -176 224 -240 224
WIRE -144 224 -176 224
WIRE -32 224 -64 224
WIRE -16 224 -16 128
WIRE -16 224 -32 224
WIRE 16 224 -16 224
WIRE -240 240 -240 224
WIRE 208 240 208 128
WIRE 208 240 80 240
WIRE 16 256 -16 256
WIRE 208 256 208 240
WIRE -240 352 -240 320
WIRE -16 352 -16 256
WIRE 48 352 48 272
WIRE 208 352 208 336
FLAG -240 352 0
FLAG -16 352 0
FLAG 208 352 0
FLAG 48 352 0
FLAG -176 224 1
FLAG -32 224 2
FLAG 208 240 3
SYMBOL res -48 208 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R1
SYMATTR Value 5K
SYMBOL res 112 112 R90
WINDOW 0 44 104 VBottom 0
WINDOW 3 16 4 VTop 0
SYMATTR InstName R2
SYMATTR Value 50K
SYMBOL res 192 352 M180
WINDOW 0 36 76 Left 0
WINDOW 3 36 40 Left 0
SYMATTR InstName R3
SYMATTR Value 20K
SYMBOL voltage -240 224 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
WINDOW 0 14 15 Left 0
WINDOW 3 -25 58 Left 0
SYMATTR InstName V1
SYMATTR Value 50m
SYMBOL opamp_4pin 32 240 R0
SYMATTR InstName U1
SYMATTR Value opamp
TEXT -232 328 Left 0 ;.DC V1 -50m 50m 1
TEXT -272 40 Left 0 !* subcirciut of internal connections of opamp\n.SUBCKT Opamp p_in n_in com out\nEX int  com   p_in n_in 1e5\nRi p_in n_in  500K\nRo int  out   50.0\n.ENDS
TEXT -216 360 Left 0 !.OP